| In the process of working,the three crossbeams of hydraulic press often bear alternating load instead of single load.In the process of bearing alternating load,the ratchet effect of the three crossbeams will cause the plastic deformation of some high stress areas in the structure and lead to the generation of residual stress.At present,many scholars have done a lot of research on the evolution law of residual stress,but the research on the evolution law of residual stress in structures under cyclic loading is relatively few.In general,the design and check of the three crossbeams of hydraulic press are based on the elastic mechanics,the yield of materials is used as the criterion of structural strength failure.However,in the actual production process,plastic deformation is bound to occur in part of the material under the action of cyclic load.When plastic deformation occurs,the initial equilibrium state in the hydraulic press crossbeam is destroyed,resulting in residual stress.Failure occurs if the residual stress of the material is not less than its yield strength when superimposed with the external load.Therefore,it is very important to explore the law of residual stress evolution in hydraulic press crossbeam under cyclic load,and to provide a basis for predicting the fatigue life of hydraulic press.In this paper,a 1:12 box structure crossbeam model is designed and manufactured by taking the lower crossbeam of a hydraulic press as the reference object.At room temperature,unidirectional tensile with strain rate of 0.1%/s and cyclic loading tests under srain and stress control mode were carried out on Q235 steel used in the box crossbeam model.The performance parameters of Q235 steel and the deformation characteristics of the material under different loading conditions were obtained by collating and analyzing the data obtained from the test.The 1/4 model constructed by UG was imported into ABAQUS,and the material performance parameters were obtained by using the follow-up hardening model A-F.Meanwhile,the large finite element software ABAQUS was used for the numerical simulation of the box structure crossbeam.The evolution law of residual stress in box structure crossbeam with cycle numbers,structure size,the size of load and loading history is investigated.The cyclic loading experiment system of box structure beam with Nantong 500 kN hydraulic press was set up.IMC equipment was used to collect the output force in real time.Meanwhile,the deformation behavior of box structural crossbeam was observed by digital spattering equipment method and electric measurement method.By comparing and analyzing the results of simulation and experiment,it can be seen that the simulation results of box structure crossbeam in this paper are relatively accurate. |
