CAD CAD Simulation and Analysis 2 — Questions and Answers
Question 1: What is the safety factor in FEA results, and how is it calculated?
- Ratio of applied load to model weight
- Ratio of material yield strength to calculated stress (Correct answer)
- Ratio of mesh size to part thickness
- Ratio of displacement to original length
Correct answer: Ratio of material yield strength to calculated stress
Safety factor equals the material's yield strength divided by the peak calculated stress, indicating how much additional load the part can safely handle.
Question 2: In thermal simulation, what property describes a material's ability to conduct heat?
- Specific heat capacity
- Thermal conductivity (Correct answer)
- Emissivity
- Thermal expansion coefficient
Correct answer: Thermal conductivity
Thermal conductivity (k) quantifies how readily a material transfers heat through conduction, measured in W/(m·K).
Question 3: What does mesh convergence testing verify in FEA?
- That material properties are correct
- That results stabilize as element size decreases (Correct answer)
- That boundary conditions are applied symmetrically
- That the model file size is minimized
Correct answer: That results stabilize as element size decreases
Mesh convergence testing confirms that refining the mesh no longer significantly changes the results, ensuring numerical accuracy.
Question 4: Which FEA element type is most commonly used for thin-walled sheet metal parts?
- Tetrahedral solid elements
- Hexahedral brick elements
- Shell elements (Correct answer)
- Beam elements
Correct answer: Shell elements
Shell elements efficiently model thin structures by representing thickness as a parameter rather than meshing through the wall, saving computation time.
Question 5: In motion simulation, what term describes the joint that allows rotation about one axis only, like a door hinge?
- Slider joint
- Revolute joint (Correct answer)
- Ball joint
- Planar joint
Correct answer: Revolute joint
A revolute (or hinge) joint constrains all translations and two rotational degrees of freedom, permitting only single-axis rotation.
Question 6: What is the purpose of applying symmetry boundary conditions in FEA?
- To add extra load paths
- To reduce model size by analyzing only a representative portion (Correct answer)
- To increase mesh density automatically
- To assign material properties faster
Correct answer: To reduce model size by analyzing only a representative portion
Symmetry boundary conditions allow engineers to model only half or quarter of a symmetric part, cutting solve time without losing accuracy.
CAD CAD Simulation and Analysis 2
What is the safety factor in FEA results, and how is it calculated?