Experimental Study On Multiaxial Fatigue Performance Based On WJ-7 Spring Bar Fastener Material(60Si2MnA Steel)

As an important component of the railway track,the fastener spring bar effectively connects the rail and the structure under the rail into a whole for a long time.The energy stored during elastic deformation plays a role in easing mechanical vibration and impact,preventing longitudinal and lateral displacement of the rail.Due to the complex and variable loads of the track system during train operation,the fastener system is subjected to long-term,periodic bending and torsional alternating stresses under these dynamic loads,thus triggering a series of fastener springs Fatigue problems.First of all,in order to study the stress change law of the dangerous points at different life cycle intervals of the spring bar during the fatigue test,the content of the spring bar fatigue test method accumulated by predecessors and the actual situation of this article are used to conduct content research,and a new design is suitable for general The test fixture and resistance strain test method of the axial loading fatigue testing machine analyzed the fatigue life of the spring bar under three load amplitudes(± 7.5kN,± 10 kN,± 12.5kN),based on the measured fatigue average Life,analyze the stress-life relationship,and predict life.The results show that:(1)With the increase of fatigue cycle life,the stress value at the corresponding dangerous point also increases,and when it reaches a certain stress value,the stress change value slows down with the increase of life;(2)The stress and life change are relatively Good linear relationship;Secondly,a simplified WJ-7 fastener system model was established,and the stress distribution and fatigue life distribution of the spring bar under normal operation were analyzed by numerical simulation calculations.The research shows that the stress distribution of the spring bar under different loads is consistent,And determine and optimize the location of the dangerous point of the elastic bar breakage as the heel end of the elastic bar and the bending place on both sides of the heel end.Fatigue simulation was carried out by finite element software,and the life results of finite element numerical simulation were compared with the actual test results.Provided support for the test results.Then based on the orthogonal test design scheme,the WJ-7 fastener W1 spring bar material 60Si2MnA steel was subjected to multi-axis fatigue test under different stress(tensile stress,shear stress)amplitude,and analyzed under different load conditions Under the condition of stress life relationship(ie curve),research shows that the material life is more sensitive to the change of torsion angle(shear stress).Furthermore,a reliability study was conducted on the statistical distribution of S-N data.The research shows that under the same reliability,the lower the stress amplitude,the greater the fatigue life,and the change in the smaller stress amplitude of the spring bar will cause a large change in its fatigue life.By analyzing the curve law of material torque and fatigue cycle times,according to the theory of cumulative fatigue damage,a linear cumulative damage model is used to predict the life of the spring bar.The results show that the predicted life is generally similar to the measured life.Finally,through a macro analysis of the fracture,it shows that it is a bending and torsion composite fatigue fracture;and the use of scanning electron microscopy(SEM)to analyze the fatigue fracture and discuss its failure mechanism.