Deformation Behavior
Mechanical hysteresis determines the unrecovered deformation remaining in a textile material after removal of an applied tensile load. In material testing, residual strain quantifies the permanent elongation expressed as a percentage of original length following a specific extension and relaxation cycle. Physical testing measures this parameter to evaluate elastic recovery in stretch fabrics and elastomeric yarns.
Tensile Cycle
Laboratory testing exposes specimen strips to cyclic loading on a tensile testing machine at controlled extension rates. Measuring residual strain requires stretching the specimen to a designated elongation percentage, holding the strain for a specified dwell time, and recording the unrecovered length after load release.
Structural Performance
Polymer chain slipping and internal fiber realignment prevent complete elastic recovery after repeated mechanical stress. When a stretch woven fabric containing elastane undergoes twenty percent extension for thirty minutes, unrecovered yarn displacement leaves the fabric permanently stretched. High values indicate poor elastic shape retention, causing garment bagging at knees or elbows in activewear.
Tensile testing protocols report this value to confirm that stretch performance meets garment endurance standards across repeated wear cycles.
Quality Threshold
Low permanent deformation ensures dimensional stability in form-fitting apparel. Excessive residual strain triggers batch rejection during quality audit inspections.
