In mechanics of materials and machine design:
Fatigue failure is the progressive, localized structural damage and eventual sudden catastrophic fracture that occurs when a material is subjected to cyclic, alternating, fluctuating, or repeated application of stresses well below its ultimate tensile strength (or even below its yield strength).
Classic examples in agricultural engineering include tractor crankshafts, PTO shafts, cultivator spring tines, and chassis beams undergoing repeated stress reversals.
सामग्री विज्ञान और मशीन डिजाइन में, थकान विफलता (Fatigue failure) तब होती है जब किसी मशीन घटक पर उसकी चरम सामर्थ्य से कम मान का चक्रीय या बार-बार दोहराया जाने वाला प्रतिबल (Repeated/fluctuating stress) लंबे समय तक लगाया जाता है।