Simulation of a textile sleeve on a manikin arm undergoing elbow flexion: effect of arm-sleeve friction

Abstract

The effect of friction on the interaction between a protective fabric sleeve and a manikin arm undergoing elbow flexion has been investigated both numerically and experimentally. The experimental studies used a cylindrical Kevlar sleeve on the right arm of a Hybrid III crash-test dummy. A load frame was used to produce elbow flexion and to measure the force required to produce that motion. Friction was varied by performing the elbow flexion task with and without a tight-fitting white knit polyester undergarment, and friction coefficients were determined experimentally. Corresponding numerical simulations using LS-DYNA were also performed, with the textile sleeve represented by orthotropic shell elements with geometric non-linearity based on experimental literature data. The results show that the presence of the Kevlar sleeve significantly increases the force required to execute elbow flexion, but that the addition of the friction-reducing undergarment reduces the flexion force generated by the Kevlar sleeve. Furthermore, this behavior can be effectively captured by the numerical simulation. These results demonstrate the possibility of direct simulation of the mechanical burden generated by protective clothing, which could lead to computational design of protective garments with improved comfort, and reduced reliance on human subject testing.

Keywords:

• protective garment design
• textile modeling
• friction effects
• Kevlar

Acknowledgments

Acknowledgment is given to Larry Long, Army Research Lab (ARL), Aberdeen Proving Grounds (APG), for sewing the sleeves and for all the experimental testing. Initial simulation work was also supported in part by a grant of computer time from the DoD High Performance Computing Modernization Program at the ARL DoD Supercomputing Resource Center (DSRC). We also wish to acknowledge the computation support provided through the Center for Composite Materials at the University of Delaware.