MODELING THE VISCOELASTIC BEHAVIOR OF SEWN MULTI-LAYER INSULATION FABRICS: A NON-LINEAR RESPONSE AND OPTIMAL NUMBER OF LAYERS

Abstract

Investigating the time-dependent mechanical behavior of hybrid multi-layer textile structures, designed for high-performance technical applications, is critical for ensuring their dimensional stability. This study comprehensively investigates the influence of the number of layers (2, 6, 12, and 24) on the viscoelastic creep mechanism within the seam zone of these structures. To this end, a dual-analysis methodology was employed, incorporating mathematical modeling using the four-parameter Burgers model and a complementary phenomenological analysis based on creep rate, applied to both seamed and seamless specimens. The results revealed a non-linear relationship between the number of layers and the viscoelastic properties. Mechanical performance peaked in the 12-layers structure, where the instantaneous elastic modulus (E_M) reached a maximum of 460.83 MPa, and the dynamic retardation time (τ) achieved a minimum of 2.29 min. Comparative analysis demonstrated that the seam plays a dual role: acting as a stiffness-weakening factor in thin structures (2 layers), while functioning as a mechanism that significantly retards system dynamics in thick structures (24 layers). The most significant finding was the critical role of the seam in the 12-layers structure; here, the stitched seam transformed an inherently unstable structure into an optimal structure with superior structural cohesion, acting as a stabilizing and reinforcing agent. These findings highlight the necessity of understanding the complex interaction between the seam and the multi-layer assembly for the optimal design of structures requiring high dimensional stability.