Download or read book Analytical Simulations of Energy-Absorbing Impact Spheres for a Mars Sample Return Earth Entry Vehicle written by National Aeronautics and Space Administration (NASA) and published by Createspace Independent Publishing Platform. This book was released on 2018-05-29 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt: Nonlinear dynamic finite element simulations were performed to aid in the design of an energy-absorbing impact sphere for a passive Earth Entry Vehicle (EEV) that is a possible architecture for the Mars Sample Return (MSR) mission. The MSR EEV concept uses an entry capsule and energy-absorbing impact sphere designed to contain and limit the acceleration of collected samples during Earth impact without a parachute. The spherical shaped impact sphere is composed of solid hexagonal and pentagonal foam-filled cells with hybrid composite, graphite-epoxy/Kevlar cell walls. Collected Martian samples will fit inside a smaller spherical sample container at the center of the EEV's cellular structure. Comparisons were made of analytical results obtained using MSC.Dytran with test results obtained from impact tests performed at NASA Langley Research Center for impact velocities from 30 to 40 m/s. Acceleration, velocity, and deformation results compared well with the test results. The correlated finite element model was then used for simulations of various off-nominal impact scenarios. Off-nominal simulations at an impact velocity of 40 m/s included a rotated cellular structure impact onto a flat surface, a cellular structure impact onto an angled surface, and a cellular structure impact onto the corner of a step.Billings, Marcus Dwight and Fasanella, Edwin L. (Technical Monitor)Langley Research CenterMARS SAMPLE RETURN MISSIONS; REENTRY VEHICLES; DEFORMATION; FINITE ELEMENT METHOD; COMPOSITE STRUCTURES; IMPACT TESTS; SPHERES; SIMULATION; PARTITIONS (STRUCTURES); NONLINEARITY; ATMOSPHERIC ENTRY; FLAT SURFACES; HYBRID COMPOSITES; IMPACT VELOCITY