ETC Technical Design & Engineering Principles 3 — Questions and Answers
Question 1: In engineering design, what does FMEA stand for and what is its primary purpose?
- Finite Method Engineering Analysis — to calculate stress
- Failure Mode and Effects Analysis — to identify potential failures and their impacts (Correct answer)
- Functional Mechanical Engineering Audit — to review drawings
- Force and Motion Engineering Assessment — to analyze dynamics
Correct answer: Failure Mode and Effects Analysis — to identify potential failures and their impacts
FMEA (Failure Mode and Effects Analysis) is a systematic method for identifying potential failure modes, their causes, and their effects on system performance.
Question 2: Which type of fit allows two mating parts to be assembled and disassembled by hand without special tools, with a guaranteed clearance?
- Interference fit
- Transition fit
- Clearance fit (Correct answer)
- Press fit
Correct answer: Clearance fit
A clearance fit guarantees a positive space (clearance) between mating parts in all cases, allowing easy hand assembly.
Question 3: A cantilever beam with a point load at its free end experiences maximum bending moment at:
- The free end
- Midspan
- The fixed support (Correct answer)
- One-quarter span from the fixed end
Correct answer: The fixed support
For a cantilever with a point load at the free end, the bending moment is zero at the free end and increases linearly to a maximum at the fixed support.
Question 4: What is the function of a tolerance stack-up analysis in mechanical design?
- To calculate the weight distribution of an assembly
- To determine the cumulative effect of individual part tolerances on assembly dimensions (Correct answer)
- To specify the manufacturing process for each part
- To identify the best material for each component
Correct answer: To determine the cumulative effect of individual part tolerances on assembly dimensions
Tolerance stack-up analysis evaluates how individual part tolerances accumulate through an assembly to determine if functional requirements will be met.
Question 5: Which section view type is used to show the interior of a part that is not symmetrical by rotating the cutting plane?
- Full section
- Half section
- Offset section (Correct answer)
- Revolved section
Correct answer: Offset section
An offset section view uses a cutting plane that bends or offsets to pass through features not aligned along a single straight line.
Question 6: In materials science, what does the modulus of elasticity (Young's modulus) describe?
- The stress at which a material permanently deforms
- The ratio of stress to strain in the elastic region (Correct answer)
- The maximum stress a material can withstand before fracture
- The energy absorbed before fracture
Correct answer: The ratio of stress to strain in the elastic region
Young's modulus is the slope of the linear elastic portion of the stress-strain curve, representing a material's stiffness.
Question 7: When selecting a welding process for joining thin sheet metal (less than 1/8 inch), which process typically provides the best control and least distortion?
- Shielded Metal Arc Welding (SMAW)
- Gas Metal Arc Welding (GMAW/MIG)
- Gas Tungsten Arc Welding (GTAW/TIG) (Correct answer)
- Flux-Cored Arc Welding (FCAW)
Correct answer: Gas Tungsten Arc Welding (GTAW/TIG)
GTAW (TIG) provides precise heat control via a separate filler rod and non-consumable tungsten electrode, making it ideal for thin materials.
ETC Technical Design & Engineering Principles 3
In engineering design, what does FMEA stand for and what is its primary purpose?