Design and Application of Fatigue Test Machine under Cantilever Bend Loading

The pressure vessel,bridge structure and marine engineering structure often fail during service under the bend stress,therefore,it is of significance to study the mechanical properties of the materials or components of above structures under bend stress action. By adjusting the length of force-arm of the specimen under cantilever bend loading,a stress even higher than yield strength of materials could be produced near the maximum bending moment when a small force is exerted on the loading end of the specimen which has made the fatigue test machine under this loading style very popular in the field of test. In this paper,clamps at loading end and limiting end of the specimen,adjusting device for force-arm of the specimen,actuator's capability against eccentricity of the test machine and rigidity of the test machine frame were analyzed,designed and discussed according to the features of the cantilever bend loading. Taking 10CrNiMo structural steel as a research object,some test applications by this loading method were introduced,including high and low cycle fatigue,surface crack propagation rate of low cycle fatigue,and static tension or compression tests of materials and components.