A lunar mission requires a stiff and strong structure to support the spacecraft during launch. Stiffness is essential to preclude coupling with the launch vehicle, which could impact launch performance. Strength is essential to survive shaking and acceleration at launch, which produce a g-force of 6.
The total spacecraft mass is 2,500kg (5,500lbs) at launch, with the majority, 1,700kg (3,750lbs), being the fuel contained in four spherical tanks. The structures team generated several lander structure concepts to provide load paths from these tanks to the round launch vehicle adapter at the base of each design.
Structural analysis was performed in ANSYS on each configuration to determine stiffness through natural frequency analysis and strength through random vibration analysis. Results were plotted in a weighted matrix along with rankings for mass, manufacturability, and volume available for payload. Each feature was ranked 1-5, with 5 being the highest score. The analysis concluded that the two-segment radial bulkhead was the best design.
