DEVTOME.COM HOSTING COSTS HAVE BEGUN TO EXCEED 115$ MONTHLY. THE ADMINISTRATION IS NO LONGER ABLE TO HANDLE THE COST WITHOUT ASSISTANCE DUE TO THE RISING COST. THIS HAS BEEN OCCURRING FOR ALMOST A YEAR, BUT WE HAVE BEEN HANDLING IT FROM OUR OWN POCKETS. HOWEVER, WITH LITERALLY NO DONATIONS FOR THE PAST 2+ YEARS IT HAS DEPLETED THE BUDGET IN SHORT ORDER WITH THE INCREASE IN ACTIVITY ON THE SITE IN THE PAST 6 MONTHS. OUR CPU USAGE HAS BECOME TOO HIGH TO REMAIN ON A REASONABLE COSTING PLAN THAT WE COULD MAINTAIN. IF YOU WOULD LIKE TO SUPPORT THE DEVTOME PROJECT AND KEEP THE SITE UP/ALIVE PLEASE DONATE (EVEN IF ITS A SATOSHI) TO OUR DEVCOIN 1M4PCuMXvpWX6LHPkBEf3LJ2z1boZv4EQa OR OUR BTC WALLET 16eqEcqfw4zHUh2znvMcmRzGVwCn7CJLxR TO ALLOW US TO AFFORD THE HOSTING.

THE DEVCOIN AND DEVTOME PROJECTS ARE BOTH VERY IMPORTANT TO THE COMMUNITY. PLEASE CONTRIBUTE TO ITS FURTHER SUCCESS FOR ANOTHER 5 OR MORE YEARS!

Intro to Engineering Final Review

IED Summaries

Unit 1 – Design Process

  • The word design is often used as a generic term that refers to anything that was made by a conscious human effort. It is also a process that is used to systematically solve problems.
  • A design process is a systematic (step-by-step) problem-solving strategy, with criteria (guidelines to follow and rules that have to be obeyed) and constraints (something that hold you back (limitation)), used to develop many possible solutions to solve or satisfy human needs or wants and to narrow down the possible solutions to one final choice.
  • An important acronym to know is ITEA and it stands for Standards for Technological Literacy
  • There are an infinite number of possible design processes. Several of them used across different technical fields are:
  • Identify problems and opportunities and opportunities, Frame a design brief, Investigate and research, Generate alternative solutions, Choose a solution, *Developmental work, Model and prototype, Test and evaluate, and then Redesign and improve
  • Identify the need, Define the criteria, Explore and research and investigate, Generate alternate solutions, Choose a solution, Develop the solution, and then Model and prototype
  • Define the problem, Brainstorm, Research and generate ideas, Identify criteria and specify constraints, Explore possibilities, Select and approach, Develop a design process, and then Publish and present
  • However, for the purposes of IED, the design process is as follows:
  • Identify a problem, generate a concept, develop a solution, construct and test and prototype, evaluate the solution, and then present the solution
  • Design process used in IED is an example of just one design process out of an infinite number of combinations and permutations, therefore many design processes exist and are effective
  • Consistently applying a single clearly defined design process provides a basis for understanding
  • Upon further inspection of each step of the IED design process:
  • Define the problem means to identify the problem, validate the problem, determine who says it is a problem, determine needs and wants, see if there are/were any prior solutions, justify the problem, decide is the problem worth solving, create design requirements (specifications), come up with criteria and constraints, and make a project proposal
  • Generate concepts means to brainstorm possible solutions, do research, apply STEM principles, select an approach, form a decision matrix, access technology needs, and then make a design proposal
  • Develop a solution means to consider design validity, determine function, aesthetics, ergonomics, safety, cost, environmental effects, durability, and ease of maintenance, create detailed design solution, make a technical drawing, and lastly if as solution is found to be invalid, the design must return to a previous step in the design process
  • Construct and test a prototype means to construct a testable prototype, plan prototype testing, rate and determine performance, usability, durability, test the prototype and collect data, analyze test data, make a test report, and lastly if a testable prototype cannot be built or test analysis indicates a flawed design, the designer must return to a previous step of the design process.
  • Evaluate the solution means to evaluate solution for effectiveness, reflect on the design, recommend improvements, optimize/redesign solution the solution, return to prior design process steps, if necessary, revise design documents, project recommendations, and based on the evaluation of the design, product improvement or redesign may require the designer to repeat previous steps of the design process.
  • The most important step is evaluation
  • Present the solution means to document the project and make/present the project portfolio
  • It is important to note that the design process is non linear

Unit 2 – Technical Sketching and Drawing

  • A pictorial drawing is a 2D illustration of a 3D object and it shows three faces of an object in one view
  • There are three types
    1. Isometric
    2. Oblique
    3. Perspective
  • An Oblique pictorial starts with a straight-on view of one of the object’s faces, which is often the front face.
  • Angled, parallel lines are drawn to one side to represent the object’s depth. Common oblique angles are 30, 45, and 60 degrees
  • There are two types of oblique pictorials: Cavalier and Cabinet
  • The difference between the two is how the depth of the object is represented.
    1. Cavalier is deeper (cabinet is half)
    2. Oblique does not have distorted depth
  • Oblique Pictorials
  • Sketch a rectangle to represent the overall height and width of the box such that the height lines are vertical and widths lines are horizontal. Envision it in a glass box.
  • The front view is the one that has the most amount of information
  • The iso view is the projection of the side (left)
  • Isometric Pictorial
  • Isometric means equal measure
  • Three adjacent faces on a cube will share a single point
  • Edges converge at one point will appear as 120 degree angles or 30 degrees from the horizon line
  • Options for view labels are:
    • Top, front, right side view orientation
    • Top, left side, front view orientation
  • It is important to note that good sketching requires a sense of proportion, and the ability to estimate size, distance, angles, and other spatial relationships.
  • Lines of varying style and thickness are used in specific ways to develop and communicate graphic messages about an object’s geometry. The next few slides show some basic line conventions and their use.
  • Construction lines are very lightly drawn lines to guide drawing other lines and shapes
  • Object lines are thick and dark and they define the object
  • Hidden lines show interior detail not visible from the outside of the part
  • Center lines define the center of arcs, circles, or symmetrical parts and are half as thick as an object line
  • Section lines define where material is cut away
  • Short-break lines are freehand drawn lines and they show where a part is broken to reveal detail to begin the part of to shorten a long continuum part
  • Dimension lines show distance and arrows drawn on a ends to show where dimension line starts and ends. Also, actual distance is typically located in middle of this line to display distance
  • Extension lines show where a dimension starts and stops and are used in conjunction with dimension lines. Also, the line is 1/16 away from part to avoid confusion with object line
  • Long-break lines shorten very long objects with uniform detail and are typically represented as a jagged cut or break
  • Leader Line show dimensions of arcs and circles in detail
  • Line conventions are standards relate to technical drawing (more precise than freehand sketching) and these standards should be used as a guide when sketching
  • Complex objects sketches may require different line types to overlap
  • Line precedence must be used
  • Rules that govern line precedence in sketches and technical drawings
  • Object lines take precedence over hidden and center lines
  • Hidden lines take precedence over center lines
  • Cutting plane lines take precedence over all others
  • Multi-View Drawing shows two or more three-dimensional views of a three-dimensional object and it provides the shape description of an object
  • When combined with dimensions, it serves as the main form of communication between designers and manufacturers.
  • In multi-view drawing:
    • All three-dimensional objects have width, height, and depth
    • Width is associated with an object’s side to side
    • Height is top to bottom
    • Depth is front to back
  • Orthographic projection is a technique used to create multi view drawings

any projection of the features of an object onto an imaginary plane of projection

  • The projection of the features of the object is made by lines of slight that are perpendicular with respect to the plane of the feature.
  • Each wall of a glass box (6 sides) represents a projection plane onto which a two-dimensional object view will be created.
  • Projection plane is also referred to as a plane of projection or picture plane, is an imaginary surface that exists between the viewer and the object.
  • The surface onto which a two-dimensional view of a three-dimensional object is projected and created.
  • Orthographic projections start by focusing only on the front projection plane.
  • A person standing in front of the objet would only see the five corners identified in black.
  • Line of sight is a 90 degree angle to a projection plane.
  • Projection lines are used to project each corner until they reach the projection plane.
  • The visible edges of the object are then identified on the projection plane by connecting the projected corners with object lines.
  • Recommendations for how to select the front view are:
    • Most natural position or use
    • Shows best shape and characteristic contours
    • Longest dimensions
    • Fewest hidden lines
    • Most stable and natural position
    • Number of Orthographic Projections
  • One view
    • Uniform thickness or shape
    • Views would be identical
  • Two views
    • Symmetrical part
    • A third view would be identical to an existing one
  • A perspective drawing offers the most realistic three-dimensional view of all the pictorial methods, because it portrays the object in a manner that is most similar to how the human eye perceives the visual world.
  • Changing the point of view will change the horizon (and therefore perspective)
  • The one point perspective is relatively simple to make, but it somewhat awkward in appearance when compared to other types of pictorials
  • A horizontal line represents the horizon with regard to perspective views
  • Auxiliary views are orthographic projections of an angled surface and they appear foreshortened in a typical multi-view drawing. Auxiliary views are used to show true size and shape of angled surface features
  • Three types of ordinary auxiliary views
  • Depth auxiliary view derived from front or back view to show true depth
  • Width auxiliary view derived form side view to show true width
  • Height auxiliary view derived from top or bottom view to show true height

Unit 3 – Measurement and Statistics

  • Dial calipers are arguably the most common and versatile of all the precision measuring tools used by engineers and manufactures.
  • Dial calipers can take four measurements:
    • outside diameter or object thickness
    • inside diameter or space width
    • step distance
    • hole depth
  • Standard dial caliper will measure slightly more than 6 inches
  • Blade is the immovable portion of the dial caliper
  • Slider moves along blade to adjust the distance between the measuring surfaces
  • Blade scale divides each inch 10 increments
  • Each increment equals one hundred thousandths of an inch (0.100 in.)
  • Pointer rotates within the dial as the slider moves back-and-forth along the blade
  • Reference edge keeps track of larger increments (i.e., 0.100 in.) as the slider moves along the rack
  • Rear-toothed rack is used to change linear motion (slider) to rotary motion (pointer)
  • Each time the pointer completes one rotation within the dial, the reference edge on the slider moves the distance of one blade scale increment (0.100 in)
  • One revolution of the pointer within the dial represents one tenth of an inch (0.100 in.)
  • Dial is divided 100 times; therefore, each graduation equals one thousandth of an inch (0.001 in.)
  • The International System of Units is a system of units of measurements consisting of seven base units.
  • Most widely used system of measurement
  • United States is the only industrialized nation that has not adopted the SI system
  • The International System of Units
  • Often referred to as the metric scale
  • Prefixes indicate an integral power of 10
  • Measurements must always include units
  • Always errors in measurements
  • Measurements are the best “estimate” of a quantity
  • A measurement is only good if you know that it is reasonably close to the actual quantity
  • It is important to indicate the accuracy and precision of your measurements
  • Scientists and engineers use significant digits to make the accuracy and precision of measurements clear
  • Precision (repeatability) = the degree to which repeated measurements show the same result
  • Accuracy = the degree of closeness of measurements of a quantity to the actual (or accepted) value
  • A typical metric scale often includes a 30+ centimeter graduated scale
  • Each centimeter is graduated into 10 millimeters
  • The millimeter is the smallest increment found on a typical SI scale
  • The next larger marking on a SI scale shows 5 millimeters
  • The largest markings on a SI scale represents centimeters (cm)
  • For decimal scaled instruments – record all digits that you can certainly determine from the scale markings and estimate one more digit.
  • The US Customary System is the system of measurement used in the United States and it is similar to the British Imperial System of measurement, but not identical
  • Units for this system of measurement are as follows:
    • Length in inches (in), foot (ft), and mile (mi)
    • Mass in slug (slug)
    • force pounds (lb)
    • time second (s)
    • thermodynamic temperature Fahrenheit degree (F)
    • For recording measurements, it is best to use Fractionally Scaled Instruments
  • A typical ruler provides a 12 inch graduated scale in US customary units with each inch is graduated into smaller divisions, typically 1/16” units
  • Unit conversions are necessary in science and engineering to work across different systems of measurement to express quantities in different units within a single system.
  • A conversion factor is multiplied by a quantity to convert the quantity to alternate units and is a ratio (fraction) in which the quantity in the numerator is equivalent to the quantity in the denominator
  • Contains desired units in the numerator and the given units in the denominator

It is important to note that using a conversion factor to cancel unwanted units is similar to multiplying fractions

  • Technically, the number of significant digits should remain the same after conversation (when using exact conversion factors)
  • Measurements are often recorded to incorrect precision.
  • Alternately, converted measurements are often rounded to a given number of decimal places in lieu of considering significant digits.
  • Examples: nearest tenth of a meter of eighth of an inch
  • If the precision of a measurement is critical, CHECK.
  • A process known as dimensional analysis is used to convert between units

Unit 4 – Modeling Skills

  • Solid modeling is a type of 3D CAD process that represents the volume of an object, not just its lines and surfaces.
  • Solid CAD models are the result of both additive and subtractive processes.
  • All CAD solid modeling programs utilize additive and subtractive modeling methods to create vertical 3D objects.
  • A wireframe model does not give the viewer an idea of surface appearance. It is not a solid model. However, a solid model will show how an object’s surfaces will appear, and provides information on surface area, volume, and weight.
  • Properties of a solid are mass, weight, surface area, density, surface appearance, etc.
  • All CAD solid modeling programs utilize additive and subtractive modeling methods to create virtual 3D objects
  • They are also referred to as Boolean Operations, named after the 18th century English mathematician Charles Boole.
  • Basic shapes are circles, triangles, and squares
  • With regard to additive methods, a three dimensional object can be viewed as the combination of two or more simple forms
  • In the creation of real world objects, this could be welding, gluing, etc.
  • With regard to subtractive methods, an object can be viewed as the remained of a solid block that has had the geometry of one or more forms sequentially removed.
  • Real world would be milling, drilling, turning, and grinding, etc.
  • Most objects can be modeled efficiently though the combination of both additive and subtractive methods.
  • There is no right or wrong way to generate a solid model. However the processes that uses the least number of steps in the shortest amount of time is the most efficient way.
  • Assembly constraints are parameters that define geometric relationships between components in a CAD assembly. Main ones are:
    • Mate/Flush
    • Angle
    • Tangent
    • Insert
  • A component floating in space has six degrees of freedom:
    • 3 rotations around the X, Y, and Z axis
    • 3 translations along those axes as well
  • The mate constraint constraints two faces, edges, points, or axis together
  • The angle constraint constrains two faces or edges at an angle to one another
  • The insert constraint constrains a cylinder flush into a hole
  • A work point is an independent entity whose location is defined in space. Work points may be placed or projected onto part faces, linear edges, or onto an arc.
  • A work axis is a line that extends forever in two directions. Work axes are useful for locating the center of a hole or cylinder and are involved in the creation of revolved solids.
  • Work planes are continuous two dimensional planes that n be used to establish sketch planes. Assembly constraints can be applied.
  • Once a work plane is established, a sketch plane must be created on it in order to sketch geometry.
  • Mass density is a measure of mass per volume:
    • M = VDm
    • W = mg
    • W = VDw
    • V = volume
    • Dm = mass density
    • m = mass
    • Dw = weight density
    • g = acceleration due to gravity

Unit 5 - Geometry and Design

  • Area is the extent or measurement of a surface. All shapes represent enclosed two dimensional spaces and thus have area.
  • A circle is the simplest and strongest of all the shapes. Circles are found within the geometry of countless engineered products.
  • In order to calculate the area of a circle, the concept of pi must be understood. It is a constant ratio between the circumference and radius of a circle.
  • To calculate the area of a circle, the radius must be known.
    • A=pi*r^2
  • An ellipse is generated by a point moving in a plane so that the sum of its distances from the two other points (the foci) is constant is equal to the major axis.
    • A=pi*a*b
  • A polygon is any plane figure bounded by straight lines. Examples include the triangle, rhombus, and trapezoid.
  • An angle is the figure formed by the intersection of two rays. Angles are differentiated by their measure.
  • A straight angle is 180 degrees
  • A triangle has 180 degrees
  • Right triangle has one interior right angle
  • Acute triangle has only acute angles
  • Obtuse triangle has one interior obtuse angle
  • A triangle is the most structurally stable of all the polygons.
  • Examples of triangles are trusses, etc.
  • The terms inscribed and circumscribed are associated with triangles typically.
  • Inscribed is inside the circle
  • Circumscribed is circle inside of triangle
    • A=1/2*b*h
  • Examples of quadrilaterals are the square, rhombus, trapezoid, trapezium
  • All quadrilaterals have four sides and are polygons
  • A parallelogram is a four sided polygon with both pairs of sides being parallel
    • A=b*h
    • Square, rhombus, rectangle, and rhomboid
  • Regular multisided polygons include pentagons, hexagons, and octagons
  • They have equal sides and angles
  • Can be inscribed or circumscribed
    • A=n*s(0.5*f)/2
      • A is area
      • s is side length
      • f is the diameter of inscribed circle or distance between flats
      • n is the number of sides
  • Solids are 3D objects
  • In sketching, two dimensional shapes are used to create the illusion of 3d solids
  • Volume, mass, weight, density, and surface area are properties that all solids possess. These properties are used by engineers and manufactures to determine material type, cost, and other factors associated with the design of objects.
  • Volume refers to the amount of 3d space occupied by an object
  • A cube has sides of equal length
  • V = s3
  • For rectangles, V=wdh
  • For cylinders, V=πr^2 h
  • Mass refers to the quantity of matter in an object
  • SI unit is gram
  • English unit is slug
  • Weight is the force of gravity acting on an object
  • SI unit is newtons
  • English unit is lb
  • Mass and weight are not interchangeable and do not represent the same concept
  • W=mg (g is the acceleration of gravity)
    • g=32.16 ft/sec2
  • An object, whether of the surface of earth, in orbit, or on the surface of the moon, still has the same mass.
  • However, the weight of the same object will be different in all three instances because the magnitude of gravity is different.
  • Each measurement system has fallen prey to erroneous cultural practices.
  • In the SI system, a person’s weight is typically recorded in kilograms when it should be recorded in Newtons.
  • In the US Customary System, an object's mass is typically recorded in points when it should be recorded in slugs.
  • Weight density is an object’s weight per unit volume
  • To calculate the weight (W) of any solid, its volume (V) and weight density (Dw) must be known.
    • W=VDw
  • There is a distinction between area and surface area
  • Area describes the measure of the two dimensional space enclosed by a shape.
  • Surface area is the sum of all the areas of the faces of three dimensional solid.
  • In order to calculate the surface area of a cube the area of any one of its faces must be known
    • SA=6A
  • In order to calculate the surface area of a rectangular prism the area of the three different faces must be known
  • In order to calculate the surface area of a cylinder, the area of the curved face and the combined area of the circular faces must be known.

Unit 6

  • Visual design elements are:
    • line
    • Vertical- Represents dignity, formality, stability and strength.
    • Horizontal- Represents calm, peace and relaxation.
    • Diagonal- Represents action, activity, excitement and movement.
    • Curved- Represents freedom, the natural, having the appearance of softness and creates a soothing feeling or mood
  • color
    • Color has an immediate
    • and profound effect on a design.
    • Warm Colors
    • Reds, oranges, yellows
    • Cool Colors
    • Blues, purples, greens
    • Colors can affect how humans feel and act.
  • form/shape
    • The shape, outline, or configuration of anything
    • Examples
      • Squares
      • Circles
      • Ellipses
      • Ovals
      • Rectangles
      • Triangles
      • space
  • By incorporating the use of space in your design, you can enlarge or reduce the visual space.
  • Types
    • Open, uncluttered spaces
    • Cramped, busy
    • Unused vs. good use of space
  • texture
    • The surface look or feel of something
    • Types
      • Smooth surface
      • Reflects more light and, therefore, is a more intense color.
    • Rough surface
      • Absorbs more light and, therefore, appears darker.
  • value
    • The relative lightness or darkness of a color
    • Methods
    • Shade
      • Degree of darkness of a color
    • Tint
      • A pale or faint variation of a color

Visual Design Principles

  • There are five principles that encompass an interesting design
  1. Balance
  • Parts of the design are equally distributed to create a sense of stability.
  • There can be physical as well as visual balance.
  • Types
    • Symmetrical or Formal Balance
    • Asymmetrical or Informal Balance
    • Radial Balance
    • Vertical Balance
    • Horizontal Balance
  1. Rhythm
  • Repeated use of line, shape, color, texture or pattern.
  • Types
    • Regular rhythm
    • Graduated rhythm
    • Random rhythm
    • Gradated rhythm
  1. Emphasis
  • Points of attention in a design.
  • The feature in a design that attracts one’s eye.
  • The focal point.
  • Emphasis can be achieved through size, placement, color and use of lines.
  • The most personal aspect of a design.
  1. Proportion and scale
  • Comparative relationships between elements in a design with respect to size.
  • 3:5 ratio is known as the Golden Mean.
  • Scale is the proportion or size of one part of the image in relationship to the other.
  1. Unity
  • Unity is applying consistent use of lines, color, and texture within a design.
  • Goal is to be harmonious.
  • Some good things to consider when doing product disassembly are: how do the parts interact?, what are the good and bad features of the product?, form, function, what has caused the product to succeed or fail?, are the materials appropriate?, what manufacturing process was used?, and what is the estimated cost of the product?
  • The procedure is as follows:
  1. Disassemble the product
  2. Create pictorial sketches to describe the operation
  3. Carefully observe and measure each part
  4. Record your finding on the Product Disassembly Chart
  • Reverse engineering (RE) is the process of taking something apart and analyzing its workings in detail, usually with the intention of understanding its structure, function, and operation.
  • Reverse engineering is used for a variety of reasons including:
    • Documentation
    • Interoperability
    • Maintenance
    • Discovery
    • Academic/research/learning
    • Curiosity
    • Military or commercial intelligence
    • Investigation
    • Analysis and testing
    • Document patent infringement
    • Forensics: Design failure
    • Product Improvement
    • Improve or redesign a product
    • Increase efficiency
    • Improve reliability
    • Improve manufacturing techniques
    • Eliminate failure mode
    • Reduce cost
    • Increase ease of use
    • Reduce negative environmental impacts
    • Recycle parts
  • The stages of reverse engineering are:
    • Visual analysis
    • Functional analysis
    • After a product has been selected, a non-destructive functional analysis is performed
    • First, the product's purpose is identified
    • Next, observations are made to determine how the product functions. These observations are recorded in detail.
    • Lastly, the system’s inputs and outputs are listed.
    • In terms of purpose, the purpose of a toothbrush is to clean teeth and gum to prevent tooth and gum decay. Water and a cleansing paste are used in conjunction with the brush.
    • For function, an annotated sketch, with all visible components labeled, is created. A hypothesis is devised to describe (in detail) the sequential operation or function of the device using the sketches as a reference.
    • A black box systems model is used to identify what goes into and out of the product in order to make it work as system.
    • Example for a toothbrush:
      • Hand motion, toothpaste, water, and energy yields sound, heat, waste, clean teeth and gums

Unit 7

  • For alternate views, in some cases, orthogonal projections and pictorials are not sufficient to specify all the details of a part
  • Section views:
  • Cutting plane line
    • Indicates the location of the cut
    • Thick and broken line
    • Arrows indicate direction of view
    • Labeled with a letter for identification
  • Full
  • Half
  • Used on symmetrical parts
  • Quarter of the part is cut away
  • Offset
  • Interior features not in line with each other can be shown in an offset view
  • Auxiliary
  • Detailed
  • Not the same thing as a detail drawing which is any drawing that contains all the information needed to manufacture the part
  • An enlargement of a portion of a smaller or more intricate part
  • The decision matrix is used to compare design solutions against one another using specific criteria that are often based on project requirements.
  • Criteria are usually:
    • Criteria, cost, reusable, uniform geometry, self-adhering, clean-up needing, model resilience, testability with other parts, normally used, function, product life span, development time, size, material costs, development costs, safety, manufacturing capabilities, company standards, manufacturing costs
  • In order for the drawings to be dimensioned so that all people can understand them, we need to follow standards that every company in the world must follow. *It is important to note that standards are created by these organizations:
    • ANSI – American National Standards Institute. This institute creates the engineering standards for North America.
    • ISO – International organization for standardization. This is a worldwide organization that creates engineering standards with approximately 100 participating countries.
    • DOD – department of defense (US – military – weapons)
    • MIL – Military Standard (US – military, chemical, warfare)
    • DIN – Deutsches Instit fur Normung. The Germans standards institute created many standards used worldwide, including the standards for camera film
    • JIS – Japanese industrial standard. Created after WWII for Japanese standards
    • CEN – European standards Organization
    • Dimension for Text Guidelines are that if the dimension will not fit between the extension lines, it may be placed outside them and that dimension text is placed in the middle of the line horizontally and vertically
  • Dimensioning Methods are represented on a drawing using one of the two systems, unidirectional or aligned.
  • The unidirectional method means all dimensions are read in the same direction.
  • The aligned method means the dimensions are read in alignment with the dimension lines or side of the part, some read horizontally and others read vertically.
  • Unidirectional is commonly used in mechanical drafting.
  • Aligned is commonly used for architectural and structural drafting.
  • There are different classifications of dimensions
    • Size dimensions are used to identify the specific size of a feature on an object
    • Location dimensions are used to identify the physical proximity of a feature to another feature within an object.
    • Examples of linear dimensioning are Chain dimensioning, Dimensioning from feature to feature, and it is important to note that it is a common dimensioning technique
  • Chain Dimensioning Examples are twofold:
    • Method 1:
      • Dimensioning from feature to feature across entire part
      • Manufacturing inaccuracies can accumulate
    • Method 2:
      • Dimensioning from feature to feature except omit one partial dimension in the chain.
      • Dimension overall length/width height to limit manufacturing inaccuracies
      • Preferable chain dimensioning method.
  • Datum Dimensioning is dimensioning from a single point of origin called a DATUM and it reduces dimensional deviations in manufactured parts, normally how a computer generated dimensions.
  • Dimensioning Angles arise because angled surface may be dimensioned using coordinate method to specify the two location distances of the angel and angled surfaces may also be dimensioned using the angular method by specifying one location for distance and the angle.
  • Dimensioning Chamfers consist of angle of chamfer and then length and the length of both is permissible as well
  • Good dimension rules include:
  • Dimensions should reflect the actual size of the object, not the scaled size.
  • The dimension measured on the drawing is ¾ of an inch, but the actual dimension of the part is 2 in. Therefore, show 2.00 on the drawing.
  • Include overall dimension in three principle directions – length, width, and height.
  • Overall dimensions should be placed the greatest distance away from the object so that intermediate dimensions can nest closer to the object.
  • Include all dimensions necessary to produce or inspect the part.
  • Dimensions should be placed so it is not necessary to calculate or scale a dimension
  • Do not dimension hidden lines
  • Fillets are an inside radii between two intersecting planes
  • Rounds are outside radii applied to corners
  • For documentation, once a design has been approved, working drawings are used
  • A complete set of drawings that contains enough information to make the design
  • Part drawings contain information to make the part
  • Title blocks are necessary to give information on the part
  • Assembly drawings have the following primary functions:
  • Show how parts of a multi component design fit together
  • Information
    • One or more views
    • Enlarged views of small details
  • BOM
    • Types
      • Design
      • General
      • Detail
      • Erection
      • Subassembly
      • Pictorial
  • Examples of technical writing include
    • examples
    • proposals
    • regulations
    • manuals
    • procedure
    • requests
    • technical reports
    • progress reports
    • emails
    • memos
  • Type of expository writing that is used to convey information to a particular audience for a particular technical or business purposes
  • Not used to:
    • Entertain
    • Create suspense
    • Invite differing interpretations
    • Layout and Format:
      • Analog
      • Layout and format of a newspaper
  • vvStock market information is found in a specific location in a newspaper (layout) and is presented in a table (format)
  • Front Matter:
    • A label is placed on the cover to identify the report title and subtitle
    • Author’s name
    • Date
  • Variation is unavoidable
  • No two manufactured parts are identical – some degree of variation will exist
  • Tolerances are used in production drawings to control the manufacturing process and control the variation between copies of the same part
  • Tolerances are applied for mating parts and assembling them
  • ANSI/ASME Standard Y14.5
  • Each dimension shall have a tolerance, except those dimensions specifically identified as reference, maximum, minimum or stock. The tolerance may be applied *directly the dimension or indicated by a general note located in the title block of the drawing.
  • A tolerance is an acceptable amount of dimensional variation that will still allow an object to function correctly.
  • Three basic tolerances that occur most often on working drawings are:
    • limit dimensions
    • bilateral dimension (plus/minus)
    • unilateral
  • Limit Dimensions provide an upper and lower limit for the dimension and any size between or equal to the upper limit and/or lower limit is allowed
  • Bilateral tolerance provides an equal allowable variation, larger or smaller and uses a plus/minus symbol to specify the allowable variation
  • Unilateral tolerance provides an allowable variation in only one direction (either larger or smaller)
  • Uses separate plus and minus signs
  • Specify dimension is the target dimension from which the limits are calculated
  • Limits are the maximum and minimum sizes shown by the tolerated dimension
  • Upper limit is maximum
  • Lower limit is minimum
  • Tolerance is the total variance in a dimension and is equal to the difference between the upper and lower limits
  • Maximum material condition (MMC) is the condition of a part when it contains the largest amount of material
  • The MMC of an external feature, e.g., the length of a plate, is the upper limit of the dimension
  • The MMC of an internal feature, e.g., the diameter of a hole, is the lower limit of the dimension.
  • Least material condition (LMC) is the condition of a part when it contains the smallest amount of material
  • The LMC of an external feature, e.g., the length of a plate is the lower limit of the dimension
  • The LMC of an internal feature, e.g., the diameter of a hole, is the upper limit of the dimension
  • Allowance is the minimum clearance of maximum interference between parts
  • For a clearance fit, the allowance is the tightest possible fit between mating parts
  • Allowance = MMC internal feature – MMC external feature
  • General tolerances are tolerances that are assumed if no specific tolerance is given for a dimension
  • Typically tolerances are specified based on the number digits to the right of the decimal point in a dimension
  • Shown on drawing
  • Clearance Fit limits the size of mating parts so that a clearance always results when mating parts are assembled
  • Clearance fit – always a clearance between the axle and the opening
  • Interference Fit limits the size of mating parts so that an interference always results when mating parts are assembled
  • Transition fit occurs when two mating parts can sometimes have a clearance fit and sometimes have an interference fit
  • In general, the more specified the dimension, the tighter the tolerance
  • Overly previse dimensions and overly tight tolerances increase manufacturing costs
  • Specify dimensions only to the precision and tolerance necessary for the part to function properly

Unit 8

  • The exploded assembly presentation can be animated to show how the components and the subassemblies fit together.
  • Components move following tweaks
  • Result is an AVI file
  • To animate the presentation, select the animate tool from the panel bar. The animation dialog box will appear
  • Tips and hints:
    • The size of the screen will be the native size of the avi file
    • You may want to change the background of the avi movie to match or compliment the background in a PowerPoint presentation
    • An auxiliary view is an orthographic projection of an angled surface
    • Appears foreshortened in a typical multi-view drawing
    • Auxiliary views are used to show true size and shape of angled surface features
    • Foreshortened surfaces on multi-view drawings are unclear and inaccurate representation of size or shape
    • View should not be dimensioned
  • Three types of ordinary auxiliary views
    • Depth auxiliary view derived from front or back view to show true depth
    • Width auxiliary view derived form side view to show true width
    • Height auxiliary view derived from top or bottom view to show true height
  • In order to create an auxiliary view:
  • Create multiviews drawing originally
  • Determine true dimension to show on auxiliary view
  • Identify reference edges on existing view
  • Draw construction liens outward from each corner of view
  • Auxiliary view will be a 90 degree rotation
  • Foreshortened object faces can be difficult to draw because of complex shapes or curves
  • Short break lines and partial views simplify difficult curves on foreshortened faces while maintaining complete shape description.
  • Exploded CAD Assembly Models are also named
  • Pictorial assembly
  • Exploded view
  • Exploded assembly
  • Exploded pictorial
  • Exploded assembly presentation
  • Uses include:
    • Repair manuals
    • Owner’s manuals
    • Solid modeling is a type of 3D CAD process that represents the volume of an object, not just its lines and surfaces.
    • Solid CAD models are the result of both additive and subtractive processes.
    • All CAD solid modeling programs utilize additive and subtractive modeling methods to create vertical 3D objects.

Unit 9

  • Gantt Chart
  • Developed by Henry Laurence Gantt (1861 – 1919)
  • Mechanical engineer, management consultant, industry advisor
  • Visual tool to show scheduled and actual progress of projects
  • Accepted as a commonplace project management tool today, it was an innovation of world-wide importance in the 1920s’s
  • Used on large construction projects
  • Hoover Dam started in 1931
  • Interstate Highway system started in 1956
  • Purpose of Gantt Charts
  • A graphical representation of the duration of tasks against the progression of time
  • A useful planning tool for planning and scheduling projects
  • Helpful when monitoring a project’s progress
  • Allows you to assess how long a project should take
  • Allows you to see immediately what should have been achieved at a point in time
  • Tools to Create Gantt Charts
  • Any project management software packages can be used to create Gantt charts. Some are as follows:
  • Milestone Software
  • Gantt Project
  • Excel – Gantt Chart worksheet
  • Should have no more than 15 tasks per spreadsheet
  • Microsoft Project
  • Symbols
  • Use indicator symbols to show which project items need attention
  • Tips on using indicator symbols
  • Use distinct shapes and colors to clearly separate one indicator from another
  • Rely on the indicator’s shape, not color, when printing to black and white
  • Clearly define the indicators in a legend
  • Use logical symbols such as check marks for completed activities
  • Display “pie-fills” to show percent complete
  • Use Consistent Symbology
  • “What symbol do I use for a critical milestone?”
  • Use simple intuitive symbol choices
  • Be consistent in applying the Symbology
  • Clearly define the meaning of each symbol in a legend
  • Examples of Symbology
  • Green for starting activities
  • Red for finishing activities
  • Yellow for on hold
  • Check mark for completed items
  • Up arrow to start
  • Down arrow for completion
  • Slash mark for changed date
  • Sequential or Parallel Tasks
  • Project planning organizes tasks
  • Task types
  • Sequential or linear
  • Task dependent on completion of another task
  • Nondependent or parallel
  • Task not dependent on completion of another task
  • Tasks may be done at any time before or after a particular stage is reached
  • Throughout time, humanity has used natural resources, animals, plants, and inanimate materials for its survival, consumption, and enjoyment
  • It is often taken for granted that current resources will always be available
  • Many times short term monetary gain is considered a priority
  • Global population is growing at an exponential rate
  • Shows a continual change in human needs and wants
  • Energy: Non-renewable resources are becoming more and more scarce
  • Ethics
  • A set of moral principles or values; a theory or system of moral values
  • The discipline dealing with what is good and bad and with moral duty and obligation
  • Ethical Design Dilemmas
  • Situations in which decisions you make are in conflict with what may or may not be morally correct
  • Sometimes this is obvious right away, and other time it is not
  • Solutions to open-ended design problems provide dilemmas that designers face when creating the product
  • Let’s look at some pictures of products and discuss the ethics involved
  • Steps in resolving:
  • Moral Clarity – Identify the relevant moral values
  • Conceptual Clarity – Clarify key concepts
  • Just the facts – obtain all relevant information
  • Informed about options – consider all genuine options and alternative solutions
  • Well-reasoned – make a reasonable decision
  • Design Analogy
  • Engineering design as a metaphor or model for thinking about moral decision making in general, not just within engineering
  • Like design, moral choice often involves alternative permissible solutions to dilemmas
  • Product Lifecycle
  • Definition
  • Five steps
  • Raise and extract
  • Can go directly to consumer products
  • Process
  • Manufacture
  • Consumer products
  • Use
  • Can go to repair/consumer products again
  • Dispose
  • Can go to process via recycling
  • Raise and Extract
  • All consumer products begin their lifecycle with a dependence on the natural environment
  • Some form of energy is always required to extract the natural resources from the earth or its atmosphere
  • Process
  • Raw materials are processed and refined
  • Energy is required for the processing and refining
  • Manufacture
  • Additional energy is required as the processed or refined materials move through the manufacturing process
  • Use
  • Consumer products are transported to stores (consuming additional energy) and are ready for purchase
  • Products remain at this stage as long as they are useable or repairable
  • Dispose
  • When the product is no longer of use to us, we “get rid” of it
  • EPA Guidelines
  • EPA stands for the Environmental Protection Agency. The mission is to protect human health and the environment
  • The EPA works to develop and enforce regulations that are developed and enforced by congress
  • The EPA is responsible for researching and setting national standards for a variety of programs
  • The ETPA delegates to states and tries the responsibility for issuing permits and monitoring and enforcing compliance
  • OSHA Guidelines
  • Occupational Safety and Health Administration
  • The mission is to assure the safety and health of US workers by setting and enforcing standards, providing training outreach, and education; establishing *partnerships and encouraging continual improvement in workplace safety and health
  • To establish and maintain safe workplace environments, OSHA enforces standard sand reaches out to employers and employees through technical assistance and *consultation programs
  • Why Recycle
  • We recycle to attempt to reverse the damage that was previously done to the environment and to attempt to restore resources which have already been depleted *(and make use of old resources as well)
  • The Process (of Recycling)
  • Products to be recycled
  • Consumer’s role
  • Collector’s role
  • Remanufacturing process
  • Finished products
  • The Key to Recycling is the Consumer!
  • The consumer needs to be educated enough to realize that he/she can recycle products and differentiate between them and trash
  • Non-Recyclable Items
  • What can we do?
  • Tires are some of the hardest things to recycle because they contain rubber and metal among other parts/substances
  • How can we dispose of them properly?
  • A team is a group of people, each with his or her own expertise, brought together to benefit a common goal
  • Teams are often comprised of people who do not know each other and how must work hard to develop productive working relationships despite personal *differences and cultural practices
  • Benefits of a Team
  • Shared workloads and responsibility
  • Broader diversity in knowledge and skill
  • More productive brainstorming
  • Chances for leadership and personal satisfaction
  • Sense of belonging to a successful process
  • Ability to accomplish more than if work is done independently
  • Developing a Team
  • Step #1: Team members identify the team’s mission
  • What does the team have to do?
  • How will the team accomplish the task?
  • What information is needed?
  • What resources are available?
  • A design brief is required and a process must be followed
  • Step #2: Team members establish group norms
  • Develop guidelines, protocols, or rules
  • Establish norms as a team through consensus
  • Regulate proper and acceptable behavior be and between team members
  • Commit to follow the rules
  • Establishing Group Norms
  • Create list of norms by brainstorming with teammates
  • Analyze each norm and discuss its impact on the team and the overall goal
  • Identify key norms that everyone can come to consensus on
  • Establish consequences if norms are broken
  • Typical Group Norms
  • Input from all team members
  • Team meeting schedule and project timeline
  • Communication protocols
  • Conflict resolution protocols
  • Note: A copy of the established norms must be provided to each team member
  • Developing a Team
  • Steam #3: Identify team member's strengths and weaknesses
  • Team members list individual talents skills, and limitations
  • Team members identify individual responsibilities
  • Each team members strengths are the support mechanism of the other team member's weaknesses

Autodesk Inventor Summaries

Chapter 1

  • Rapid changes in the field of CAE have brought about exciting changes in the field of engineering
  • More specifically, they have brought concurrent engineering closer to a reality
  • CAE has a variety of intentions, including:
    • reducing design time
    • making prototypes faster
    • achieving higher product quality
  • Autodesk Inventor is an integrated package of mechanical computer aided engineering software tools developed by Autodesk inc.
  • It facilitates a concurrent engineering approach to the design and stress analysis of mechanical engineering products
  • Computer models can be used in a variety of locations, such as:
    • machining centers
    • lathes
    • mills
    • rapid prototyping machines
  • For now, we will only deal with solid modeling modules used for part design and part drawings
  • Computer geometric modeling is a relatively new technology
  • It has advanced along with the advances made in the field of computer hardware
  • First generation CAD programs were mostly non interactive and were developed mostly in academic research facilities
  • Originally, MIT, CMU, and CU were the developers of CAD software
  • Then, after their uses grew, the amount of companies affiliated with them grew as well:
    • General Motors
    • Lockheed
    • McDonnell
    • IBM
    • Ford Motor Co.
  • CAD systems were mostly used for automotive industry, aerospace, and government agencies that developed their own programs for specific needs
  • The 1960s also marked the beginning of the development of finite element analysis methods for computer stress analysis and computer aided manufacturing for generating machine tool paths
  • CAE consists of CAD and CAM
  • CAD and CAM consist of computer geometric modeling and finite element analysis and computer aided drafting
  • CAE stands for computer aided engineering
  • CAD stands for computer aided design
  • CAM stands for computer aided manufacturing

Chapter 2

  • Feature based parametric modeling enables the designer to incorporate the original design intent into the construction of the model
  • Parametric means the geometric definitions of the design such as dimensions can be varied at any time in the design process
  • This is accomplished by identifying and creating the key features of the design with the aid of computer software.
  • The design variables are described in the sketches and described as parametric relations
  • They can also be used to modify/update the design
  • The parametric modeling process involves the following steps:
  • Create a rough two dimensional sketch of the basic shape of the base feature of the design
  • Apply/modify constraints and dimensions to the 2D sketch
  • Extrude, revolve, or sweep the parametric 2D sketch to create the base solid feature of the design
  • Add additional parametric features by identifying feature relations and complete the design
  • Perform analyses on the computer model and refine the design as needed
  • Create the desired drawing views to document the design
  • Creating 2D and 3D sketches of 3D features is an effective way to construct solid models
  • Many designs are the same shape in one direction
  • Computer input and output devices we use today are mostly 2D which makes this especially practical
  • This method also conforms with the capability to capture design intent
  • Many engineers and designers can relate to the experience of making rough sketches to convey conceptual design ideas
  • Inventor provides many powerful modeling and design tools and there are many different approaches to accomplishing these tasks
  • The main idea behind feature based modeling is to build models by adding simple features one by one
  • The general parametric part modeling procedure is important
  • Inventor also has many viewing functions and basic 2D sketching tools for the user to use in order to improve the design

Chapter 3

  • In the 1980s, something called Constructive Solid Modeling (CSG) was developed and this was one of the main advancements in solid modeling at that time
  • CSG is built upon the principle of combining primitive solids (basic three dimensional shapes)
  • Basic primitive shapes include:
    • rectangular prism (block)
    • cylinder
    • cone
    • sphere
    • torus (tube)
  • Two solid objects can be combined into one using Boolean operations, and examples of such operations are:
    • join (union)
      • combines the two volumes included in he different solids into a single solid
    • cut (difference)
      • subtracts the volume of one solid from the other one
    • intersect
      • keeps only volume in common between both solids
  • The CSG method is also known as the Machinist’s approach
  • This method is very similar to machine shop procedures
  • CSG is also known as the method used to store a solid model in a database
  • A resulting solid can be represented with a binary tree
  • Ending branches (leaves) are the primitives while the root is the final solid object that was constructed
  • This enables the user to keep track of the history of the resulting solid
  • The solid model can be re built by going back through the binary tree
  • This makes it much easier to modify a model
  • Parts of the binary tree can be modified and then relink the tree in order to modify the part without having to create a second one
  • CSG can be used to determine how many features will be necessary to make the model that is intended
  • Inventor can use any solid as a primitive solid
  • Parametric modeling lets us have full control of the design variables that are used to make the design
  • When making a solid model, it is usually wise to sketch it out yourself first

Chapter 4

  • Design intents are embedded into features in the history tree
  • The history tree resembles that of a CSG binary tree
  • A CSG binary tree contains only Boolean operations
  • The Inventor history tree contains all features inclusive of Boolean relations
  • A history tree is a record of the features used in making any given part
  • The history tree contains the constructions steps and the rules used in defining the design intent of each operation
  • When a new modeling event is created, features that were already defined can be used to define size location, orientation, etc.
  • Because of this, you should think about your modeling strategy before actually creating anything
  • You should be sure to plan ahead for any and all changes that might occur although this might be difficult
  • This is what mainly distinguishes Inventor from previous CAD systems
  • Feature based parametric modeling is a cumulative process
  • When a new feature is added, the result is created and the feature is also added into the history tree
  • The database keeps track of the parameters of features that were used in defining any given one
  • This steps occur automatically as a feature is manipulated and/or created
  • All information is retained throughout the process and modifications are done based on the same information as input
  • In Inventor, the history tree gives information about modeling order and other assorted information about the feature
  • Part modifications can be done by accessing the features in the history tree
  • Because of this, it is very important to utilize the history tree in order to modify designs in Inventor
  • Inventor stores the history of a part which includes all the rules that were used to create it and this means that changes can be made to any action that *was performed to create the part
  • In Inventor, a feature can be modified by selecting it in the browse window

Chapter 5

  • Parametric modeling is different from previous modeling because it captures design intent
  • Shape before size is very important when using Inventor and in the profile and dimension commands especially
  • When making geometric constructions, dimensional values are necessary to describe the size and location of constructed geometric features.
  • In addition to dimensions, rules can be used to control certain geometric entities
  • Inventor can record design intent using:
    • geometric constraints
    • dimensional constraints
    • parametric relations
  • There are two main types of constraints:
    • geometric
    • dimensional
  • In Inventor, constraints are applied to 2D sketches
  • Geometric constraints are geometric restrictions that can be applied to various geometric shapes, for example:
    • horizontal
    • parallel
    • perpendicular
    • tangent
    • (are examples of geometric constraints)
  • Dimensional constraints describe the size and location of geometric entities
  • Usually, there are multiple combinations of constraints that yield the same result
  • Parametric relations are user defined mathematical equations composed of dimensional variables (or design variables)
  • Features are made of geometric shapes coupled with relations and constraints to describe design intent
  • Geometric properties such as:
    • horizontal
    • parallel
    • perpendicular
    • tangent
    • can be applied either manually or automatically
  • With the proper utilization of geometric constraints, very adjustable models can be synthesized

Chapter 6

  • Solid modeling has a couple distinguishing characteristics:
    • accuracy
    • completeness (of the geometric database of 3D objects)
  • The fact that space is three dimensional while most input devices are 2D can pose a problem
  • Inventor provides many two dimensional construction tools to overcome this problem and to make it easier and more efficient
  • Inventor has two types of wireframe geometry
    • curves
    • profiles
  • Curves are basic geometric shapes such as:
    • lines
    • arcs
  • Profiles are a collection of curves which define a boundary
  • A profile is a closed region which can contain other closed regions
  • Profiles are usually used to create:
    • extruded
    • revolved features
  • A profile is invalid if it has self-intersecting curves or open regions
  • Geometric tools such as trim and extend can assist in creating profiles
  • Profile sketch in Inventor can also help to create profiles
  • Parametric modeling relies heavily on geometric construction tools with the application of constraints and parametric relations

Chapter 7

  • The parent/child relationship is a central notion in parametric modeling
  • In Inventor, every time a new modeling event is created, features that have already been defined can be used to define:
    • size
    • location
    • orientation
    • The features that were references are parent features
  • The new features are called child features
  • This parent/child relationship controls how a model reactions when other features in it change – this captures design intent
  • It is very important to keep track of parent/child relationships
  • When modifying a parent feature, one or more of its child features may change
  • Parent/child relationships can be created one of two ways:
    • implicitly
      • implied by feature creation method
    • explicitly
      • entered manually by the user
  • Usually, the user selects a sketching plane before creating a 2D profile
  • The selected surface is thought to be the parent of the new feature
  • If the sketching plane is relocated, the child feature must move with it
  • Since this relationships can become extremely complex, it is very important to consider the notion of modeling strategy before creation
  • The goal of this is to plan ahead for possible design modifications that might occur which would be affected by the existing parent/child relationships
  • Inventor lets the user adjust feature properties so that any conflicts which arise from features can be resolved easily
  • The base feature is the first solid feature of the model
  • This feature is considered the center of all features
  • It is also considered the key feature of the design
  • Every feature constructed after the first one is built by referencing the base feature that was created
  • As such, the selection of the base features is quite important
  • The Base Orphan Reference Node (BORN) technique uses a Cartesian Coordinate System as the first feature before creating anything else

Chapter 8

  • Since there have been many recent improvements in both solid modeling and computer hardware, the significance of 2D drawings is decreasing rapidly
  • Drafting is currently believed to be one of the main applications of using solid models
  • Currently, solid models are used to create tool paths for CNC (computer numerical control) machines
  • They are also used in rapid prototyping machines which make 3D models out of plastic, resin, metal (powdered), etc.
  • Ideally, the solid model database should be used when creating the final product
  • However, most applications in many production facilities still require the use of two dimensional drawings
  • Using solid models, tools can crate all the necessary two dimensional view that are necessary to produce a part
  • Used in this context, solid modeling tools are making the process of creating 2D drawings both more efficient and effective
  • Inventor provides associate functionality in different modes
  • This allows us to change the design at any level and it is reflected throughout the system automatically
  • An example of this is how a part can be modified in part modeling mode and it will be updated in drawing mode automatically
  • The above example also works vice-verse: that is, a part can be modified in drawing mode and it will be automatically updated in all other modes

Chapter 9

  • Feature based parametric modeling is an example of a cumulative process
  • Relationships that the user defines between features determine how a feature reacts when other features in the model are altered
  • Due to this interaction, certain features must be held in a higher regard than others
  • A new feature can therefore use previously defined features to set information such as:
    • size
    • shape
    • location
    • orientation
  • Inventor provides several tools to automate this process
  • Work features can be conceptualized as user-defined datum which can be updated with the part geometry
  • Users can create work planes, axes, or points that do not already exist
  • Work features can additionally be used to align features or orient parts in an assembly
  • The offset and angled option can create new work planes (surfaces which do not currently exist)
  • Parametric work features create established feature interactions in the CAD database which also guarantee the capture of design intent
  • Default work features can be used to assist the construction of the increasingly complex geometric entities
  • Multiview drawings must contain sufficient drawings to accurately describe the design and enable it to be manufactured
  • Most of the time, this necessitates two to three regular views
  • However, some of the time, this requires auxiliary views which are required when the model has features or inclined surfaces which are not parallel to the regular places of projection
  • An auxiliary view has a line of sight that is perpendicular to the inclined surface in question
  • It is supplementary view that can be synthesized from any of the regular views
  • Using the solid model as a starting point, auxiliary views can easily be created in 2D drawings

Chapter 10

  • With regards to parametric modeling, determining the features that exist in the design is crucial
  • Feature based parametric modeling allows us to create extremely complex designs by creating smaller and simpler units
  • This works to simplify the modeling process and enables us to concentrate on the characteristics of the design
  • Symmetry is very important and it is often seen in designs
  • Symmetrical features can be accomplished by the wide range of tools that can be found in Inventor
  • A very efficient method of creating solid models is extruding 2D shapes along a straight line
  • However, for designs that necessitate cylindrical shapes (ones that are symmetrical about an axis), the simplest way to create them is by revolving two *dimensional sketches about an axis
  • Features that are created via this method are called revolved features
  • There are many tools besides the revolve command that can create revolved features which can handle symmetrical features. Examples of such features include:
  • the feature pattern command
  • creates multiple carbon copies of symmetrical features
  • the mirror feature command
  • creates mirror images of models
  • Construction geometry can assist in the creation of more complex features

Chapter 13

  • The principle task in the creation of an assembly is establishing the assembly relationships between the parts
  • Conversely, in order to assembly parts into an assembly, the assembly relationships between the parts must be considered
  • It is good practice to assemble parts in the same order they would be assembled in the manufacturing process
  • It may also be prudent to break the assembly into several smaller subassemblies to facilitate easier assembly
  • In Inventor, a subassembly is treated exactly the same way as an individual part in assembly mode
  • There are many other such parallels between assembly modeling and part modeling in Inventor
  • Inventor provides full associate functionality in all design modules, inclusive of assemblies
  • Bi-directional full associate functionality is the central feature of parametric solid modeling software that enables the user to heighten productivity by *reducing design cycle time
  • Another key feature of Inventor is that it makes use of an assembly-centric paradigm
  • This enables users to concentrate on the design without depending on any parameters or constraints
  • Users can determine how parts fit and Inventor’s assembly based fit function will determine the size and position of the parts
  • This is known as the direct adaptive assembly approach which defines part relationships with no regard to order dependency
  • The most important of adaptive design is to under constrain the part/feature
  • Assembly constraints control the sizes, shapes, and positions of under constrained sketches, parts, and features
  • In Inventor, features can be made adaptive at any time during the creation or assembly of the feature/part
  • Alternatively, the features of a part can be defined as adaptive when they are originally created in the part file
  • When a part such like this is placed into an assembly, the features will resize and change shape based on the applied assembly constraints
  • The adaptive design approach is unique to Inventor and the goal of it is to improve the design process and allows the designer to design the way you think*

Bibliography

  1. Karsnitz, John, Hutchinson, John, et al. Engineering Design: An Introduction. Singapore: Cengage Learning, 2008. Hardcover Textbook.
  2. Shih, Randy. Parametric Modeling with Autodesk Inventor 2013. Mission: SDC Publications, 2009. Softcover Manual.

QR Code
QR Code intro_to_engineering_final_review (generated for current page)
 

Advertise with Anonymous Ads