Studied by 10 people
What is a Component
Object that makes up an assembly
What is an Abutment
identical objects brought into an assemblies just oriented differently
What are Instances
Copies of a component within an assembly
What is a Subassembly
a grouping of components that serve a single purpose
Why are subassemblies useful
linking them in a subassembly allows for later modification, if needed, rather than making it a whole part.
What is Associativity
If you change the geometry of a part the components and all instances will change by the same amount
What’s a good example of Associativity
If a company wants to modify a part of a foot bridge, they use across a rec center, then associativity will change the rest of the bridges
What is assembly hierarchy
Is subassembly to subassembly to subassembly until the subassembly is fully defined.
What us a Parent-Child relationship
association b/w components and subassemblies
Example of a Parent-Child relationship
Parent: Handrail is the parent
Child: The horizontal, vertical components, and the angled assembly are children.
What is a Base instance
is a component that remains stationary while other instances are being placed
Why are assembly constraints useful
So instances can maintain dimensional or geometric relationship with respect to each other within an assembly
Once you bring a instance into an assembly what is one thing to note?
The instance will have 6 Degrees of freedom (DOF)
Concentric constraints
Useful when dealing with cylindrical shafts within a cylindrical hole
what is Mating surfaces
Used to defined two surfaces
Mating surfaces coincides with each other, in other words line up[ on top of each other.
you are forcing the normal of two objects to be parallel
What is an Offset
The surfaces normal are still parallel, but the surfaces are now not on top of each other
Coincident constraints
Two entities that take up one space
Typically you select the corner or edge of two object to coincide with one another
Distance Constraints
Define a distance relationship b/w two instances
what are some inertial properties
Radii-of-gyration
moments-of-inertia
principle-axes of rotation
Products of inertia
Measure analysis
can determine dimensions and other geometric parameter of the CAD
What are some Measure analysis?
Measure point- Used to find coordinates of a point
Measure line length - Used to measure the length of a line
Measure line distance- Measure the shortest distance of a line to another identified entity
Measure circle- Measure diameter
Measure arc
Measure surface - Measure area and perimeter of the surface
Mass properties
Static Properties of a solid body
Depends on two things: Geometry and its density
Mass properties are related to one another through various formulas
Offers fast insight into the appearances of a design concept
Examples of Mass properties
Density- Mass/volume
Radius of gyration- object inertia about that same axes
moments-of-inertia - The weight of the mass multiplied by a distance the mass is away from the rotational axis
Interference
the amount that two instances overlap
Clearences
the distances b/w parts
Common places to check for instances and clearance
shafts and circular holes
Finite Element Analysis (FEA)
advance design technique obtained by 3-D CAD tools
Is in the category of engineers analysis tools that apply computational approximation to classic field problems
Example of FEA: stress
can be calculated by the pulling force divided by the cross-sectional area of the rod
What happens if stress is to large
can result into permanent changes in the object
What a way to reduce stress
increase the cross-sectional area
FEA’s method
Dividing the part into individual pieces called a mesh
What is a single part of a mesh
They are called elements
Types of FEA methods
Mechanical stress and displacement fields - object that experience loads
Shear stress - tries to slides molecules apart in motion and possibly shear them/disoriented
FEA methods : Fluid flow and pressure fields
Allows engineers to compute the airflow around airplane wings
FEA methods: Thermal flows and temperature fields
Computation of thermal flow and temp.
FEA methods: Electromagnetic fields
When electricity flows through a wire a electromagnetic field is created
How are the finite elements connect
The finite elements are connect through their edges and nodal points that specify the boundary conditions
FEA Process
Create the model geometry
apply constraints (FEA requires a fully defined constraint)
applying loads
Meshing.
For stress analysis What are the two interest quantities
Stresses and displacement
What is Von Mises
used to predict yielding of materials under complex loading
Red contours: signify high stress
Blue contours: signify low stress
Note 
Flashcard (31)