| High strength steel were widely used in practical engineering because of its good mechanical properties.In order to cope with the development of China's railway industry and promote the application of high strength steel bars in Railway Engineering,China Railway Corporation carried out a research project on the “application of high strength steel bars in Railway Engineering” in March 2014.This research was carried out under the support of this project and the fatigue properties of HRB(F)500 Grade Reinforced base material were mainly studied.In order to study the fatigue properties of HRB(F)500 grade steel base material,this paper has done the following work from the following four aspects: test,data fitting,finite element simulation and analysis of the influence factors of fatigue performance:1.The fatigue performance of HRB(F)500 grade steel base material was tested by universal material testing machine.2.By comparing the S-N curve model,the S-N curve model suitable for this study was determined and the algorithm was determined,the S-N curves of various steel bars were obtained.Based on the obtained S-N curve equation,the fatigue stress amplitude of each steel bar while 2 million,5 million and 10 million times was obtained.3.ANSYS finite element software was used to simulate the fatigue process of 16mmHRB500 steel bars under different stress ratios.4.The influence of various factors on the fatigue performance of steel bar was analyzed.The following conclusions were obtained through the above work: the “double logarithmic-double dogleg” model can well fit the fatigue test results and get the S-N curve;the S-N curves of various steel bars and the fatigue strength under different fatigue life were obtained;the results of finite element calculation fitted well with the experimental results;the S-N curve obtained by up and down method were more gentle than Haibach method,the fatigue stress amplitude corresponding to the 10 million time was larger than that of Haibach method,however,the results obtained by this method were closer to reality;the fatigue stress amplitude decreases with the increase of steel bar diameter,decreases with the increase of stress ratio,and with the increase of the stress ratio,the decrease of the fatigue stress amplitude increases gradually;the fatigue performance of HRBF500 grade steel bar is slightly better than that of grade HRB500 steel bar,and with the increase of the fatigue life,the difference of the fatigue stress amplitude between the HRBF500 grade steel bar and the HRB500 grade steel bar increases gradually.Finally,based on the statistical analysis of the data,through the analysis of the fatigue performance of steel bar,a general formula for calculating the fatigue stress amplitude of HRB(F)500 grade high strength steel bars was proposed in this paper,and the calculated results were compared with the experimental results,and the results show that the calculation method was feasible. |
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