Warm Forming Constitutive And Failure Behavior Prediction Of 7075 Aluminum Alloy

7075 aluminum amalgam has a place to ultra-high quality aluminum combination,which has great comprehensive mechanical properties and could be a kind of lightweight and tall quality auxiliary fabric.Be that as it may,due to its restricted shaping capacity at room temperature,it is difficult to be processed into complex parts and poor surface quality,which greatly limits its wide application in automobile manufacturing industry.Therefore,warm forming is often used.Compared with hot forming,the temperature of warm forming is lower,which can effectively save energy,improve efficiency and prolong the life of die.In the warm forming process,temperature and strain rate have serious effects on the tensile properties and fracture behavior of aluminum alloy.Therefore,it is very important to accurately describe the rheological behavior of aluminum alloy at medium temperature and predict its failure behavior at warm forming.In this paper,7075 aluminum amalgam rolled sheet was taken as the inquire about protest.The ductile tests were carried out at room temperature,473K,523K,573K,623K,and diverse misshapening conditions of 0.00 1s-1,0.01s-1,0.1s-1.A few sets of stream push bends were gotten.Combined with SEM,OM and other hardware,the impacts of diverse misshapening conditions on the mechanical properties and microstructure close the break were analyzed The comes about appear that:(1)with the increment of temperature and the diminish of strain rate,due to the softening effect,the yield strength and tensile strength of aluminum alloy decrease,and the elongation at break increases.The elongation at break at 623k is nearly five times higher than that at room temperature,but the elongation at break at 523K is almost the same as that at room temperature(2)It is found that the softening mechanism of temperature on the material is mainly dynamic recovery,but with the increase of temperature and the decrease of strain rate,a small amount of recrystallization occurs near the fracture(3)The fracture morphology of the samples was observed and it was found that the normal temperature tensile fracture was quasi dissociative fracture;At medium temperature,the main fracture features of 7075 aluminum alloy are dimples and pores,showing typical ductile fracture characteristics;With the increment of temperature,the dimples ended up bigger and more profound.With the increment of strain rate,the number of dimples diminishes and the profundity gets to be shallow.Moreover,based on the stress-strain bend gotten from the try,the misiolek unified constitutive equation describing 7075 aluminum alloy under different temperature and strain rate in warm forming range is established by introducing the temperature and strain rate related variable correction model.The equation is simple in form and has high fitting accuracy.In LS-DYNA finite element simulation,Johnson cook material constitutive model matching Cockcroft Latham ductile fracture failure criterion is used to fit material constitutive parameters,and a value in the model is modified,so that J-C constitutive model can describe flow stress of aluminum alloy with higher accuracy;The critical fracture strain energy values of failure model parameters are calculated by combining test and finite element simulation,The results of numerical simulation are verified by the sample with double inducers?In this paper,the research on the constitutive model of 7075 aluminum alloy warm forming and the prediction of its medium temperature failure behavior are of certain guiding significance for guiding the warm forming process and the design of aluminum alloy thin-walled parts.