Mechanical Evaluation
Dynamic fatigue testing evaluates the ability of a textile to endure repeated elongation and subsequent recovery without permanent structural deformation. Under cyclic tensile loading, a fabric strip is mounted in a universal testing machine and pulled to a specific load or length for a designated number of rounds. Results indicate the mechanical endurance of garments like activewear that face continuous movement.
Analysis Parameter
Engineers look for changes in the slope of the stress-strain curve as the number of repetitions increases. During cyclic tensile loading, the fabric often exhibits a phenomenon called stress relaxation where the force required to reach a certain extension decreases. This shifting profile suggests how the material will behave after months of daily use in the field.
Lab Procedure
Standard methods require environmental control of temperature and humidity to avoid skewing the results of the elastomer tests. After several hundred applications of cyclic tensile loading, the specimen is removed to measure any unrecovered extension, known as set. Maintaining a consistent rate of extension ensures that heat generation inside the fibre does not influence the breakdown.
Functional Boundary
Performance limits are reached when the fabric no longer returns to within a specific percentage of its original rest state. While cyclic tensile loading identifies potential failure points, it does not account for the additional impact of UV exposure or perspiration.
