Load spectrum testing is an advance toward the ultimate purpose of fatigue testing, that is, prediction of life in advance of service. The relative merits of the three basic approaches to load spectrum testing, the Programmed Fatigue Test, the Service Duplication Test, and the Random Load Spectrum Test, are discussed and compared to the conventional Constant Amplitude Test technique.
Practical examples from car and truck engineering are given for each of the three test techniques, and a general introduction to the new test concept of random load spectrum testing is included.
Advantages cited are: good correlation to service life, low scatter of results, and reduction of overall test time. Detailed knowledge of service load histories is required, as is test machinery with suitable frequency response.