Date of Award

Summer 8-2021

Document Type

Thesis - Open Access

Degree Name

Master of Science in Aerospace Engineering

Committee Chair

Dr. Mandar Kulkarni

First Committee Member

Dr. Ali Tamijani

Second Committee Member

Dr. Alberto Mello

Abstract

The structural design of spacesuits is essential in an advancing future of both Lunar and Martian space exploration. A typical spacesuit is made of sandwich composite material and designed to withstand various pressure and loading conditions while also considering the safety and comfort of the astronauts. One of the critical load cases in spacesuit design is a low-velocity impact (LVI) which may occur due to tool drop and other similar scenarios. The objectives of this work were (a) to create a finite element (FE) model of a component of a spacesuit, (b) validation of the FE model through experiments, (c) creating an optimization framework to design the spacesuit component, and (d) investigate the effect of finite difference step size on the final optimized design.

A FE model of a plate was created to represent a part of the spacesuit's hard upper torso (HUT), which is made of a sandwich structure with S2 glass fiber composite (outer layers) and carbon fiber composite (core) materials. The FE model was used to simulate the nonlinear LVI response of the plate using MSC Nastran and ANSYS software. LVI experiments were performed in the materials lab using the Instron Impact Test instrument. The FE models were validated against the displacement and contact force history obtained for two impact velocities. Further, the sandwich plate was optimized for an impact load case with sizing variables (thickness and ply orientation) and shape variables (linear, quadratic, sinusoidal and Hicks-Henne bump shape function). The objective was to minimize weight while being subject to displacement or stress constraints. During the optimization process, it was found that the change in fiber orientation and the thickness of plies, reduced the deformation by 37.63% and increased the strength-to-weight ratio of the coupon sample, while indirectly decreasing the maximum stress. The effect of the finite difference step size variation on the shape optimization of the plate was studied. It was found that choosing an appropriate step size is not intuitive. After varying the step size over four orders of magnitude, the best step size led to a design with a deformation reduction of 30% and a total weight reduction of 34% compared to the initial design.

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