Study On Simulation Of Hot Stamping For 6016 Aluminum Alloy Using Damage Constitutive Model

The rapid development of the automotive industry has improved people’s living standards,changed people’s travel habits,and aggravated the consumption of petroleum energy and global warming issues.Lightweight vehicles can effectively reduce weight,thereby reducing fuel consumption and improving energy efficiency.6016 aluminum alloy has good fracture toughness,corrosion resistance,fatigue resistance and other characteristics,and higher specific strength,can meet the body parts performance while achieving lightweight.Due to the poor ductility of aluminum alloys,cold stamping is susceptible to problems such as cracking and springback,and it is difficult to form parts with complex structures.Although thermoforming can effectively improve the plasticity of the material,it will reduce the strength of the molded part,and subsequent aging strengthening.This will cause a decrease in forming accuracy.Therefore,based on the thermal forming technology,a hot stamping forming technology was developed that simultaneously performs the retained pressure quenching during forming,which not only improves the plasticity of the blank during the forming process,but also satisfies the properties of the structural member such as strength and hardness.Requirements,and a good solution to the rebound problem.In this paper,the mechanical behavior of 6016 aluminum alloy in the hot stamping process was investigated by the Gleeble 1500 thermal simulation tester.The deformation temperatures were obtained at 450°C,480°C and 500°C,and the strain rates were 0.1s^-1,1s^-1 and 10s^-1 The uniaxial tensile stress-strain curves under the condition of 1 were analyzed to analyze the evolution of damage.Based on continuum damage mechanics and unified viscoplastic constitutive theory,coupled with microscopic variables such as dislocations and damages,a damage constitutive model was constructed.The model can effectively perform uniform plastic deformation and damage destruction in the high temperature forming process of 6016 aluminum alloy.Describe it.For each of the three objective functions,the multi-objective genetic optimization of the material constants in the model was calculated,and the predictability of the determined material constants was compared to determine the optimal solution for the 18 material constants in the material model.A semi-implicit solution method was used to write a subroutine of the unified viscoplastic damage constitutive model.The finite element simulation of high temperature uniaxial tensile test was performed to verify the validity of the model.The experimental equipment of U-piece for hot stamping was developed for forming experiments.The finite element numerical simulations were performed on the hot stamping of U-pieces by the developed material model.The temperature field,strain field,stress field and damage evolution of the sheet during the forming process were analyzed.The analysis results of the strain field show that the large deformation is mainly distributed in the rounded corners of the U-shaped pieces,and the distribution of the damage also shows the same rule,and the amount of damage at the rounded corners is the largest.The comparison of the thickness distribution simulation results and the experimental results shows that the thinning rate at the base fillet is the largest.The developed material model can effectively predict the thermal deformation behavior of 6016 aluminum alloy during the hot stamping process.The model plays an active role in the hot stamping process design of actual parts and can be applied in actual production design.