DEVELOPMENT OF A DEFLECTION CONTROLLED MULTIAXIAL FATIGUE TESTING MACHINE

Abstract

This paper discusses the development of a multiaxial fatigue testig machine. The deflection controlled eccentric disk type testing machine produces mode Ⅰ, mode Ⅱ, or combination of both, of crack surface displacements on round or flat specimens. These loadings are necessary for research on complex multiaxial stresses which are common in engineering practice, such as crankshafts. This machine achieved the objective with very simple mechanisms (vector sum of two crank throws of eccentric disks yield bending moments; vector differences, twisting moments), but with more computation in setting the desired parameters. Bending data and torsion data produced by the machine were in good agreement with the data by a conventional fatigue testing machine. Multiaxial data produced by the machine were also in good agreement with the prediction by a well proved multiaxial fatigue theory. Applications of the multiaxial fatigue testing machine are described.