Application of Cumulative Fatigue Damage Theory to Farm and Construction Equipment

This paper considers the various aspects of estimating the fatigue life of the structure of construction equipment under severe service loads, assuming that representative service load measurements are available and the fatigue characteristics of the structure in the form of a constant amplitude σ-N relation are known. This method is generally applicable to metal components subjected to a spectrum of load amplitudes; however, the details differ depending upon material, the method of fabrication, the load history, the number of load sources, and the nature of the loads. The paper emphasizes large vehicles made of structural steel and fabricated by welding. A scraper frame including the gooseneck, the draft tube, and the draft arms is considered as a typical structure.

The basic approach to the problem is reviewed. A sample computation is included and the questions and uncertainties that arise in the estimation of fatigue life are discussed.