DMD Computer-Aided Design (CAD) & Simulation 1 — Questions and Answers
Question 1: Which neutral file format is most widely used for exchanging 3D CAD geometry between different software platforms?
- DWG
- STL
- STEP (Correct answer)
Correct answer: STEP
STEP (Standard for the Exchange of Product model data) is an ISO standard neutral format specifically designed for 3D CAD data exchange across different systems.
Question 2: In parametric CAD modeling, what happens when a base dimension is changed?
- The entire model must be rebuilt from scratch
- Only the changed feature updates while others remain fixed
- All dependent features automatically update to reflect the change (Correct answer)
- The model is converted to a static mesh
Correct answer: All dependent features automatically update to reflect the change
Parametric modeling stores relationships between features, so changing a dimension propagates updates throughout all dependent geometry automatically.
Question 3: What is the primary purpose of Finite Element Analysis (FEA) in product development?
- Generating tool paths for CNC machining
- Predicting structural behavior under applied loads and conditions (Correct answer)
- Creating photorealistic product renderings
- Automating the drafting of engineering drawings
Correct answer: Predicting structural behavior under applied loads and conditions
FEA divides a model into small elements to compute how it responds to forces, heat, or other physical loads before a physical prototype is built.
Question 4: Which modeling technique is most suitable for creating complex, aerodynamic surfaces in automotive or aerospace design?
- Boolean solid modeling
- NURBS surface modeling (Correct answer)
- Constructive Solid Geometry (CSG)
- Polygon mesh modeling
Correct answer: NURBS surface modeling
NURBS (Non-Uniform Rational B-Splines) provides the mathematical precision needed for smooth, class-A automotive and aerospace surface design.
Question 5: In assembly modeling, what is a 'mate' or 'assembly constraint' used for?
- Setting the material properties of components
- Defining dimensional tolerances on a part
- Establishing geometric relationships that control component position (Correct answer)
- Assigning colors and appearances to parts
Correct answer: Establishing geometric relationships that control component position
Mates/constraints define how parts relate spatially (e.g., coincident, parallel, concentric), controlling degrees of freedom in an assembly.
Question 6: What does Computational Fluid Dynamics (CFD) simulation primarily analyze?
- The electrical properties of circuit boards
- The flow behavior of liquids and gases around or through objects (Correct answer)
- The kinematic motion of mechanical linkages
- The thermal expansion of solid materials
Correct answer: The flow behavior of liquids and gases around or through objects
CFD solves fluid flow equations numerically to predict pressure, velocity, and temperature distributions in and around fluid systems.
Question 7: In the context of CAD modeling, what is 'design intent'?
- The manufacturing cost target for a product
- The underlying logic, relationships, and reasoning embedded in how a model is constructed (Correct answer)
- The final approval signature on engineering drawings
- The copyright notice attached to a CAD file
Correct answer: The underlying logic, relationships, and reasoning embedded in how a model is constructed
Design intent captures the engineer's logic through parameters, constraints, and feature order so the model behaves predictably when modifications are made.
DMD Computer-Aided Design (CAD) & Simulation 1
Which neutral file format is most widely used for exchanging 3D CAD geometry between different software platforms?