Dynamic response of chain mail fabrics with variable stiffness

Abstract

Variable stiffness fabrics have gained considerable attention due to their advantages in repeatability, deformability, and controllability of stiffness. However, existing variable stiffness fabrics are limited in fitting complex geometrical surfaces and understanding their dynamic mechanical response. This study aims to address these gaps through experimental testing and numerical simulations. Three fabric samples with different single-cell particles were fabricated to investigate the low-velocity impact response of variable stiffness chain mail fabrics. Impact tests were conducted on the fabrics using small balls at three velocities (2.5 m/s, 3.8 m/s, and 4.8 m/s) to analyze the influence of confining pressure variation on the mechanical properties. The results demonstrate that the impact resistance of chain mail fabric significantly improves as the confining pressure increases from 0 kPa to 60 kPa. That fabric consisting of traditional rings velocity decay value increased from 19.3% to 50.2 % at an impact velocity of approximately 4.8 m/s. Notably, the fabric composed of octahedral particles exhibited limited resistance to ball impact without applying confining pressure. However, when a pressure of 60 kPa was applied, the fabric effectively resisted ball impact and caused upward ball velocity. Multiple impact tests on single-layer fabrics and single impact tests on double-layer fabrics confirmed that fabrics consisting of square ring particles demonstrated better resistance to multiple impacts. The degree of interlocking within the topological interlocking structure, influenced by confining pressure, emerged as a crucial factor contributing to enhanced impact resistance. Numerical simulations revealed that the application of confining pressure promoted the formation of new contacts between interlocking particles. The number and quality of these contacts directly affected the overall mechanical properties, resulting in a solid-like structure. This research provides novel insights for developing structural fabrics with fast, reversible, and controllable stiffness adjustment characteristics.