What mechanical property is critical for long-term TENG performance under cyclic stress?

The critical mechanical property for long-term TENG performance under cyclic stress is fatigue resistance. Fatigue resistance refers to a material's ability to withstand repeated cycles of stress or strain without failure. TENGs often operate under continuous mechanical deformation, such as bending, stretching, or compression, which induces cyclic stress in the materials. If the materials have low fatigue resistance, they are prone to crack initiation and propagation, leading to mechanical failure and degradation of the TENG's performance over time. High fatigue resistance ensures that the TENG can maintain its structural integrity and functional performance even after millions or billions of cycles of operation. Factors that influence fatigue resistance include the material's yield strength, tensile strength, ductility, and the presence of defects or stress concentrators. For example, using flexible polymers with high tensile strength and good elasticity, such as PDMS or TPU (thermoplastic polyurethane), can improve the fatigue resistance of TENGs compared to using brittle materials.