Analysis of fatigue life of the steel cord used in tires in unidirectional and bidirectional bending

The results of fatigue life tests of steel cord used in construction machinery tires are presented in this paper. Steel wire used in tires, called the steel cord, is largely responsible for transferring large loads, but unfortunately it quickly undergoes fatigue. The fatigue life of this steel cord is influenced by many factors related to its construction, workmanship quality, as well as the method of bending during each working cycle. In laboratory tests, the fatigue life of steel cords was compared in the conditions of unidirectional and bidirectional bending, on a specially built, innovative fatigue testing machine for steel cords. In fatigue life tests, a fundamental difference is visible in the number of cycles leading to breaking. For one-way bending process, the number of cycles is significantly greater than for the bidirectional bending. Instead of the wire fracture process, a steel cord elongation process takes place that increases the number of fatigue cycles, which is reflected directly in the number of failures in the tires of construction machines