A coupled contact-mechanics computational model for studying deformable human-artifact contact

Abstract

Gas-pressurized spacesuits are necessary for human spaceflight, most notably for extravehicular activity (EVA). Legacy EVA suits have been primarily rigid, and operation in such suits can result in significant metabolic expense, or even injury, for the wearer. To reduce these effects, modern spacesuits are more flexible, through the incorporation of more softgood materials and specially designed joint interfaces such as hip bearings. However, modeling the effects of human-suit interaction for these softgood materials is challenging due to the highly deformable nature of the suit coupled with the deformable nature of the human. To enable improved analysis and design of modern spacesuits, a computational model that can resolve the structural deformations of the suit and human resulting from contact interactions is developed. This thesis details the development and validation of a coupled contact-mechanics solver architecture for use in studying the effects of human-artifact interaction, particularly with respect to pressurized softgood exosuit design. To resolve contact and structural mechanics interactions for a deformable human and artifact, a finite element model is developed. First, the SUMMIT computational framework is employed for resolving the structural deformations of the system, and is coupled to an explicit contact mechanics scheme. The explicit contact scheme is implemented so as to resolve both external- and self-contact problems. Next, the model architecture is integrated to enable parallelization of both the structural deformation and contact systems, and computational scaling investigated. A computational trade study is performed to benchmark the coupled contact-mechanics method against a simpler rigid body model employing a penalty method. Following this, the model is validated against experimental data for various artifact contact problems. The explicit coupled contact-mechanics model is found to effectively capture contact interactions of the experimental data, with improved fidelity for deformable contact interactions. With careful tuning of the system properties, the coupled contact-mechanics model enables an architecture for an integrated human-suit analysis and design model.