A constitutive law is offered for an AZ31B-H24 Mg alloy within a strain rate range of 10-5-10-2 s-1 at a temperature of 400 ℃ The constitutive law, which is developed by curve fitting the tensile tests data, is expre...A constitutive law is offered for an AZ31B-H24 Mg alloy within a strain rate range of 10-5-10-2 s-1 at a temperature of 400 ℃ The constitutive law, which is developed by curve fitting the tensile tests data, is expressed as a flow stress function of strain and strain rate. Furthermore, the constitutive law is embedded into a proper FE model to simulate the tensile experiments for the purpose of verifying reliability, where the incremental stress-strain relationships are calculated by an elastic-plastic theory in the finite element analysis （FEA）. The results show that the stress-strain characteristics and the final deformed shapes in the FEA agree well with the experiments. In addition, the predicting analysis of constant-velocity stretch conditions and the verification of a free bulge forming experiment show that the proposed FE model is practicable for mechanical analysis on superplastic forming problems. A selective numerical method is offered for advanced superplastic analysis on AZ31 Mg alloys.展开更多
Flexible roll forming is a promising manufacturing method for the production of variable cross section products. Considering the large plastic strain in this forming process which is much larger than that of uniform d...Flexible roll forming is a promising manufacturing method for the production of variable cross section products. Considering the large plastic strain in this forming process which is much larger than that of uniform deformation phase of uniaxial tensile test, the widely adopted method of simulating the forming processes with non-supplemented material data from uniaxial tensile test will certainly lead to large error. To reduce this error, the material data is supplemented based on three constitutive models. Then a finite element model of a six passes flexible roll forming process is established based on the supplemented material data and the original material data from the uniaxial tensile test. The flexible roll forming experiment of a B pillar reinforcing plate is carried out to verify the proposed method. Final cross section shapes of the experimental and the simulated results are compared. It is shown that the simulation calculated with supplemented material data based on Swift model agrees well with the experimental results, while the simulation based on original material data could not predict the actual deformation accurately. The results indicate that this material supplement method is reliable and indispensible, and the simulation model can well reflect the real metal forming process. Detailed analysis of the distribution and history of plastic strain at different positions are performed. A new material data supplement method is proposed to tackle the problem which is ignored in other roll forming simulations, and thus the forming process simulation accuracy can be greatly improved.展开更多
文摘A constitutive law is offered for an AZ31B-H24 Mg alloy within a strain rate range of 10-5-10-2 s-1 at a temperature of 400 ℃ The constitutive law, which is developed by curve fitting the tensile tests data, is expressed as a flow stress function of strain and strain rate. Furthermore, the constitutive law is embedded into a proper FE model to simulate the tensile experiments for the purpose of verifying reliability, where the incremental stress-strain relationships are calculated by an elastic-plastic theory in the finite element analysis （FEA）. The results show that the stress-strain characteristics and the final deformed shapes in the FEA agree well with the experiments. In addition, the predicting analysis of constant-velocity stretch conditions and the verification of a free bulge forming experiment show that the proposed FE model is practicable for mechanical analysis on superplastic forming problems. A selective numerical method is offered for advanced superplastic analysis on AZ31 Mg alloys.
基金Supported by National Natural Science Foundation of China(Grant Nos.51205004,51475003)Beijing Municipal Natural Science Foundation of China(Grant No.3152010)Beijing Municipal Education Committee Science and Technology Program,China(Grant No.KM201510009004)
文摘Flexible roll forming is a promising manufacturing method for the production of variable cross section products. Considering the large plastic strain in this forming process which is much larger than that of uniform deformation phase of uniaxial tensile test, the widely adopted method of simulating the forming processes with non-supplemented material data from uniaxial tensile test will certainly lead to large error. To reduce this error, the material data is supplemented based on three constitutive models. Then a finite element model of a six passes flexible roll forming process is established based on the supplemented material data and the original material data from the uniaxial tensile test. The flexible roll forming experiment of a B pillar reinforcing plate is carried out to verify the proposed method. Final cross section shapes of the experimental and the simulated results are compared. It is shown that the simulation calculated with supplemented material data based on Swift model agrees well with the experimental results, while the simulation based on original material data could not predict the actual deformation accurately. The results indicate that this material supplement method is reliable and indispensible, and the simulation model can well reflect the real metal forming process. Detailed analysis of the distribution and history of plastic strain at different positions are performed. A new material data supplement method is proposed to tackle the problem which is ignored in other roll forming simulations, and thus the forming process simulation accuracy can be greatly improved.
