Experimental Study On Fatigue Behavior Of HRB335 Steel In Low Cycle And Medium Cycle Under Tensile And Torsional Loading

Fatigue failure or structural component life has already become the modern equipment and the major problems affecting component used.In the process of material fatigue research,people divide fatigue into low cycle fatigue and high cycle fatigue according to cycle life range,and then divide medium cycle fatigue life range in low and high cycle fatigue transition stage.For metals,low cycle fatigue is different from medium and high cycle fatigue in failure mechanism and life rule.In order to explore the low cycle fatigue life rule and the medium cycle fatigue behavior of metallic materials under tension and torsion cyclic loading,this paper conducted an experimental study on HRB335 steel samples,conducted uniaxial tensile test,pure torsion test and a series of multi-amplitude low cycle fatigue and medium cycle fatigue cycle tests,and studied the cycle characteristics and fatigue behavior of this kind of steel samples,and attempted to link low cycle fatigue with the law of medium cycle fatigue and high cycle fatigue,so as to supplement and perfect the low cycle fatigue theory.In this study,the combined hardening model of Chaboche was used to describe the cyclic hardening,softening and apparent Bauschinger effect of materials during cyclic loading.According to the characteristics of tensile and torsional deformation of hollow thin-wall cylinder,the implicit integral algorithm of Chaboche combined hardening model was used to degenerate the three-dimensional model into one-dimensional one.The program does not rely on finite element software and can be used for real-time test data processing.The rationality and validity of the program are verified by experiments.Combined with the program,the author proposes a simple and practical method to determine the parameters of Chaboche model,which can be used to calibrate the model parameters of test results.According to the fatigue test data,the existing several kinds of typical low cycle fatigue life prediction model to assess the analysis.For the tensile and torsion cycle fatigue tests,the equal effect variation and the KBM model can use low-cycle fatigue data to predict the low-medium cycle fatigue life range within the order of 105,while the Socie shear model and the stretch factor model can use the low-cycle fatigue data to predict the low-medium cycle fatigue life range within the order of 104.At the same time,preliminary explored the cumulative plastic strain fatigue life and cumulative plastic work and relationship.