Strain distribution governed by evolving bending–axial compression coupling in spacer monofilaments of spacer fabrics: Implications for compression resilience improvement

Spacer fabrics are widely used in personal protection, automotive interiors, and medical support owing to their lightweight, breathable, and cushioning properties. However, their application in durability-critical scenarios is limited by insufficient resilience, associated with plastic deformation accumulation during compression. This is governed by the deformation of load-bearing spacer monofilaments. Owing to initial curvature and torsion, they experience combined bending and axial compression, leading to longitudinal strain concentration and asymmetric cross-sectional tensile–compressive strain distribution. In this paper, the role of initial configuration governing the evolution of bending–axial compression coupling and the resulting strain distribution is investigated to identify strategies for resilience improvement. Based on a validated finite-element model, the evolution of bending–axial compression coupling is examined, and strain responses along both longitudinal and cross-sectional directions are quantified in terms of maximum strain, compressed area ratio, and neutral axis offset. Results show that, in the linear elasticity stage, coupling is weak, exhibiting uniform longitudinal strain but compression-dominated cross-sectional distribution. In the subsequent deformation stages, bending becomes dominant, inducing strain concentration and shifting the neutral axis toward the centroid. Longitudinal strain localization is configuration-dependent: curvature determines strain concentration, while torsion modulates deformation distribution. Moderate curvature and torsion balance load-bearing capacity and resilience. Radial strain distribution shows that damage is dominated by the coexistence of high strain and a 50% compressed area, regardless of configuration. The near 1:1 tensile–compressed area ratio suggests that bicomponent monofilaments, combining tension- and compression-resistant materials, offer a promising strategy for enhanced durability and compression resilience.