Fundamental investigation of sewn seam topography: impact on coupled mechanical and thermal properties in multilayer textile structures

Purpose The primary purpose of this research is to conduct a fundamental investigation into how sewing parameters influence sewn seam topography (pucker) and, consequently, the coupled mechanical and local thermal properties in multilayer textile structures. While seam pucker is a known issue in the clothing industry, its functional impact, particularly on thermal transport, is poorly quantified. This study aims to bridge this gap by quantitatively linking measurable pucker geometry to functional performance. The findings provide critical insights for optimizing seam design in high-performance sewn textile products, including functional apparel where both mechanical integrity and thermal management are essential. Design/methodology/approach A full factorial experimental design was employed, varying key sewing parameters (thread tension, stitch density, foot pressure) across multilayer textile structures (2–24 layers). Seam topography (pucker geometry) was quantitatively characterized using profilometry and image analysis (Mountainsmap, ImageJ, Fractalyse). Mechanical performance was evaluated via standard tensile testing (ASTM D1683). Local thermal transport properties across the seam zone were measured using a custom-built vacuum chamber under controlled hot/cold conditions. Statistical analyses, including Analysis of Variance, Taguchi method and multiple linear regression, were used to model the relationships between sewing inputs, seam geometry and functional outputs (mechanical/thermal). Findings Sewing parameters significantly impacted both seam topography (pucker) and functional performance. While lower stitch density reduced tensile strength (up to 22.4%), thread tension and foot pressure showed limited mechanical influence in highly layered structures due to complex puckering effects. Crucially, pucker geometry parameters (height, area, length ratio) emerged as dominant predictors of local thermal performance, demonstrating a stronger correlation than the input sewing parameters themselves. Linear regression confirmed that the seam's 3D topography creates thermal bridges, quantitatively linking a common sewing feature (pucker) to functional heat transfer properties in multilayer textile structures. Originality/value While seam pucker is a known aesthetic issue in clothing, its quantitative impact on functional properties, particularly local thermal transport, is largely unexplored. This study provides the first quantitative link between measurable pucker geometry (topography) and the coupled mechanical and thermal performance of sewn seams in multilayer structures. By demonstrating through regression analysis that seam topography acts as a dominant factor creating thermal bridges, this work fundamentally shifts the understanding of pucker from merely cosmetic to a critical functional parameter. The findings offer significant value for designing high-performance textiles and functional apparel where seam integrity and thermal management are crucial.