A three-dimensional finite-element model (FEM) used for calculating electron beam (EB) welding temperature and stresses fields of thin plates of BT20 titanium has been developed in which the nonlinear thermophysical a...A three-dimensional finite-element model (FEM) used for calculating electron beam (EB) welding temperature and stresses fields of thin plates of BT20 titanium has been developed in which the nonlinear thermophysical and thermo-mechanical properties of the material has been considered. The welding temperature field, the distributions of residual stresses in as-welded (AW) and electron beam local post-weld heat treatment (EBLPWHT) conditions have been successfully simulated. The results show that: (1) In the weld center, the maximum magnitude of residual tensile stresses of BT20 thin plates of Ti alloy is equal to 60%- 70% of its yield strength σs. (2) The residual tensile stresses in weld center can be even decreased after EBLPWHT and the longitudinal tensile stresses are decreased about 50% compared to joints in AW conditions. (3) The numerical calculating results of residual stresses by using FEM are basically in agreement with the experimental results. Combined with numerical calculating results, the effects of electron beam welding and EBLPWHT on the distribution of welding residual stresses in thin plates of BT20 have been analyzed in detail.展开更多
This paper dealt with the influence of residual stress on the dimensional instability of 7075 aluminum cone-shaped shells. Finite element method was introduced to calculate residual stress distributions in 7075 alumin...This paper dealt with the influence of residual stress on the dimensional instability of 7075 aluminum cone-shaped shells. Finite element method was introduced to calculate residual stress distributions in 7075 aluminum cone-shaped shells during conventional heat treatment (CHT) and deep cryogenic treatment (DCT). An example was given to demonstrate effects of deep cryogenic treatment (DCT) and conventional heat treatment (CHT) on dimensional instability. It is concluded that initial residual stresses have detrimental influence on the dimensional instability of 7075 aluminum cone-shaped shells.展开更多
文摘A three-dimensional finite-element model (FEM) used for calculating electron beam (EB) welding temperature and stresses fields of thin plates of BT20 titanium has been developed in which the nonlinear thermophysical and thermo-mechanical properties of the material has been considered. The welding temperature field, the distributions of residual stresses in as-welded (AW) and electron beam local post-weld heat treatment (EBLPWHT) conditions have been successfully simulated. The results show that: (1) In the weld center, the maximum magnitude of residual tensile stresses of BT20 thin plates of Ti alloy is equal to 60%- 70% of its yield strength σs. (2) The residual tensile stresses in weld center can be even decreased after EBLPWHT and the longitudinal tensile stresses are decreased about 50% compared to joints in AW conditions. (3) The numerical calculating results of residual stresses by using FEM are basically in agreement with the experimental results. Combined with numerical calculating results, the effects of electron beam welding and EBLPWHT on the distribution of welding residual stresses in thin plates of BT20 have been analyzed in detail.
文摘This paper dealt with the influence of residual stress on the dimensional instability of 7075 aluminum cone-shaped shells. Finite element method was introduced to calculate residual stress distributions in 7075 aluminum cone-shaped shells during conventional heat treatment (CHT) and deep cryogenic treatment (DCT). An example was given to demonstrate effects of deep cryogenic treatment (DCT) and conventional heat treatment (CHT) on dimensional instability. It is concluded that initial residual stresses have detrimental influence on the dimensional instability of 7075 aluminum cone-shaped shells.
