Equipment for space exploration is almost impossible to test on Earth. Testing is expensive and cannot replicate the conditions of launch, cruise, landing, and travel across a planetary surface. As space exploration shifts to the private sector, Astrobotic Technology, Inc. is taking the lead in delivering affordable robotic technology. The company uses ANSYS technology to stay competitive, virtually testing its lunar robots on time and under budget.
Astrobotic’s rover uses an all-composite structure — a groundbreaking innovation that combines high strength and stiffness with superior heat dissipation. Engineers analyzed the structure by virtually subjecting it to both static loads and the dynamic impact loads that may be encountered during driving on the surface of the Moon. In simulation, engineers used ANSYS contact elements to automatically transfer mechanical force loads across joints between mating parts, instead of performing this task manually.
Engineers also studied the payload adapter’s ability to withstand extreme loads and to exhibit the structural flexibility necessary to damp the transfer of damaging vibrations from the launch vehicle to the lander. Numerous simulations evaluated different adapter geometries and materials, including titanium, aluminum, and various combinations of solid, sandwiched, and honeycombed carbon-fiber composite materials. For these simulations, engineers conducted parametric design optimization studies using ANSYS® DesignXplorer™ software and the scripting capabilities of ANSYS Parametric Design Language (APDL). Through hundreds of iterations performed automatically in just a few hours, engineers were able to find the lowest-cost, lightest-weight designs for the land er and the deep-space transfer stages that will deliver it to the Moon.
Astrobotic used ANSYS Mechanical software to determine stress distributions of major components and assemblies to enable the Griffin lander to withstand 13 Gs of acceleration and the vibration loads encountered during launch and landing. Static acceleration, frequency sweep, random vibration, shock, and transient loads were applied to the models to understand the behavior of each design. Dynamic vibration testing validated and calibrated the simulations. Simulation technology enabled the research team to examine alternative structures and materials to find the most effective combination in the early concept stages of development, before physical prototypes were built. Thermal analysis performed with ANSYS Mechanical™ software helped engineers determine an optimal design to survive the large temperature variations and heat dissipation challenges of the lunar environment. Understanding thermal cycling was vital because differences in thermal expansions of various components cause conventional fasteners, solder joints, snap fits, and other parts to pop, fracture, and otherwise degrade.
Engineering simulation delivers the capabilities Astrobotic requires to cost-effectively compete in the space race.
This article was written by Aaron Acton, Software Engineer, at Astrobotic Technology, Inc. For more information see ansys.com/astrobotic .