基于孪晶强化Johnson-Cook本构(J-C本构)构建有限元(Finite element method,FEM)耦合黏塑性自洽模型(Visco-plastic self-consistent model,VPSC)宏细观仿真模型,研究预孪晶AZ31镁合金高速冲击过程的力学响应、变形机制和织构演变。结...基于孪晶强化Johnson-Cook本构(J-C本构)构建有限元(Finite element method,FEM)耦合黏塑性自洽模型(Visco-plastic self-consistent model,VPSC)宏细观仿真模型,研究预孪晶AZ31镁合金高速冲击过程的力学响应、变形机制和织构演变。结果表明:基于孪晶强化的J-C本构构建的宏细观仿真模型更能准确地预测高速冲击过程中次要变形机制及织构组分;引入孪晶强化的J-C本构不会对主要变形机制产生影响,主要影响次要变形机制;在次要变形机制中,棱柱面滑移活性的变化影响基面滑移的汇聚效应与锥面〈c+a〉滑移的分离效应之间的竞争关系,导致织构的组分和极密度发生变化。该宏细观仿真模型的构建,为研究高速冲击过程中潜在的变形机理提供了参考。展开更多
Numerical control（NC） warm bending is a proven strategy to form the large diameter thin-walled（LDTW） Ti-6 Al-4 V tubes, which are typical light-weight and high-performance structural components urgently required i...Numerical control（NC） warm bending is a proven strategy to form the large diameter thin-walled（LDTW） Ti-6 Al-4 V tubes, which are typical light-weight and high-performance structural components urgently required in many industries. In virtue of unveiling the thermo-mechanical coupled deformation behaviors, uniaxial tensile tests were conducted on Ti-6 Al-4 V tube within wide ranges of temperatures（25-600 ℃） and strain rates（0.00067-0.1 s～（-1））. Moreover, a modified Johnson-Cook（JC） model is proposed with a consideration of nonlinear strain rate hardening and the interaction between strain hardening and thermal softening. Resultantly, the present model gives more accurate predictions for flow stress over the entire deformation ranges and the maximum error decreases by about 90%. By employing proposed model to NC warm bending, preferable precision is obtained in predicting forming defects including fracture, wrinkling and over thinning. The present work lays foundation for the forming limit prediction and process optimization in NC warm bending of LDTW Ti-6 Al-4 V tubes.展开更多
文摘基于孪晶强化Johnson-Cook本构(J-C本构)构建有限元(Finite element method,FEM)耦合黏塑性自洽模型(Visco-plastic self-consistent model,VPSC)宏细观仿真模型,研究预孪晶AZ31镁合金高速冲击过程的力学响应、变形机制和织构演变。结果表明:基于孪晶强化的J-C本构构建的宏细观仿真模型更能准确地预测高速冲击过程中次要变形机制及织构组分;引入孪晶强化的J-C本构不会对主要变形机制产生影响,主要影响次要变形机制;在次要变形机制中,棱柱面滑移活性的变化影响基面滑移的汇聚效应与锥面〈c+a〉滑移的分离效应之间的竞争关系,导致织构的组分和极密度发生变化。该宏细观仿真模型的构建,为研究高速冲击过程中潜在的变形机理提供了参考。
基金Projects(50905144,51275415)supported by the National Natural Science Foundation of ChinaProject supported by the Program for New Century Excellent Talents in University,China+1 种基金Project(3102014KYJD001)supported by Fundamental Research Funds for the Central Universities,ChinaProject(B08040)supported by Program of Introducing Talents of Discipline to Universities("111"Project),China
文摘Numerical control（NC） warm bending is a proven strategy to form the large diameter thin-walled（LDTW） Ti-6 Al-4 V tubes, which are typical light-weight and high-performance structural components urgently required in many industries. In virtue of unveiling the thermo-mechanical coupled deformation behaviors, uniaxial tensile tests were conducted on Ti-6 Al-4 V tube within wide ranges of temperatures（25-600 ℃） and strain rates（0.00067-0.1 s～（-1））. Moreover, a modified Johnson-Cook（JC） model is proposed with a consideration of nonlinear strain rate hardening and the interaction between strain hardening and thermal softening. Resultantly, the present model gives more accurate predictions for flow stress over the entire deformation ranges and the maximum error decreases by about 90%. By employing proposed model to NC warm bending, preferable precision is obtained in predicting forming defects including fracture, wrinkling and over thinning. The present work lays foundation for the forming limit prediction and process optimization in NC warm bending of LDTW Ti-6 Al-4 V tubes.
