Digantara Structural Engineer Interview: Rounds, Questions and Preparation

What the job involves

Structural engineers in space and defence tech design and analyse lightweight, high-strength structures for satellites, launch vehicles, and ground support equipment. At a fast-growing company like Digantara, you would work on spacecraft buses, payload mounts, and deployable mechanisms, ensuring they survive launch loads and the harsh space environment. Day to day involves CAD modelling, finite element analysis (FEA), material selection, and testing support.

Role and Technical Knowledge

1. 1

   What are the typical load cases a satellite structure must withstand during launch?

   Cover quasi-static loads, sinusoidal vibration, random vibration, acoustic, and shock. Mention factors of safety and how they drive design.

2. 2

   Explain the difference between static and dynamic analysis in the context of spacecraft structures.

   Static analysis assumes loads are constant; dynamic includes time-varying loads and inertia effects. Discuss when each is used and why modal analysis is critical.

3. 3

   How do you select materials for a satellite primary structure?

   Consider specific strength, stiffness, thermal expansion, outgassing, and cost. Mention common choices like aluminium alloys, titanium, and carbon fibre composites.

4. 4

   What is the significance of a factor of safety in space structures, and how is it determined?

   Explain that factors of safety account for uncertainties in loads, material properties, and analysis. Reference standards like NASA-STD-5001 or ECSS.

Practical Scenarios

1. 5

   You are designing a mounting bracket for a payload on a small satellite. Walk me through your design process.

   Start with requirements, loads, and interfaces. Then concept design, material selection, FEA, optimisation, and verification. Mention iteration and testing.

2. 6

   During a vibration test, your structure shows high amplification at a certain frequency. How would you address it?

   Identify if it is a resonance. Suggest stiffening, adding damping, or changing mass distribution. Discuss notching or redesign to shift natural frequency.

3. 7

   How would you validate a finite element model of a satellite panel?

   Compare with hand calculations, perform mesh convergence, and validate against test data from a modal survey. Mention boundary conditions and material properties.

4. 8

   You need to reduce the mass of an existing structure by 20 percent without compromising strength. What approaches would you take?

   Consider topology optimisation, composite materials, honeycomb panels, and redesign of joints. Discuss trade-offs with cost, manufacturability, and schedule.

Behavioural and HR

1. 9

   Why do you want to work in the space and defence sector, and specifically at a fast-growing company?

   Show passion for space technology and awareness of the company's work. Highlight desire to work in a dynamic environment with broad responsibilities.

2. 10

   Describe a time you worked in a team to solve a complex engineering problem.

   Use STAR method. Focus on your role, the technical challenge, and how you collaborated. Emphasise communication and iteration.

3. 11

   How do you handle tight deadlines when analysis results are not ready?

   Discuss prioritisation, communicating risks, and using preliminary calculations. Show adaptability and focus on critical path.

4. 12

   Where do you see yourself in five years in this role?

   Align with company growth. Mention deepening technical expertise, taking ownership of structural subsystems, and contributing to innovative space missions.

Advanced Concepts and Sector Awareness

1. 13

   What are the challenges of structural design for a debris monitoring satellite like those in low Earth orbit?

   Consider thermal cycling, atomic oxygen, radiation, and micrometeoroid impacts. Discuss how these affect material choice and design margins.

2. 14

   Explain how you would perform a random vibration analysis and what outputs you would look for.

   Mention power spectral density input, modal analysis, and response in terms of grms and 3-sigma displacements. Discuss Miles' equation for quick estimates.

3. 15

   What is the role of structural adhesives and fasteners in spacecraft assembly?

   Compare bonded vs bolted joints. Discuss advantages like weight saving, stress distribution, and challenges like outgassing and thermal expansion mismatch.

4. 16

   How do you ensure that a deployable solar panel structure will lock reliably in space?

   Discuss mechanism design, tolerances, thermal effects, and testing. Mention redundancy, lubrication, and verification through deployment tests.