How to Answer: You're asked to take the design for a load-bearing steel plate and create an aluminum design that can withstand the same load. What design considerations would you keep in mind?
Advice and answer examples written specifically for a Mechanical Engineer job interview.
1. You're asked to take the design for a load-bearing steel plate and create an aluminum design that can withstand the same load. What design considerations would you keep in mind?
How to Answer
This question is being asked to gauge knowledge in material selection as it pertains to machine design. In material science, strength refers to the resistance to deformation when a load is applied. Steels are generally stronger than aluminum alloys, so one important change is that an aluminum plate would need to be thicker in order to handle the same load. This is a fairly open-ended question, so you can be creative in your response and draw upon many different material properties. These may include machinability, hardness, corrosion resistance, weldability, density, cost, or malleability.
Written by Jason Toby on October 12th, 2020
Answer Example
"I know that aluminum has a Young's Modulus that is roughly one third that of steel, and is also roughly three times less dense. Due to the difference in strength between the two materials, the aluminum plate would need to be thicker in order to bear the same load. This may result in a more expensive part, especially to optimize thickness with higher strength alloys that are more energy-intensive to produce. I also know that aluminum is difficult to weld when compared to steel, so I would use fasteners or rivets in the design unless welding was absolutely necessary."
Written by Jason Toby on October 12th, 2020