A stress relaxation test has been carried out for Hastelloy C-276 at temperature of 800 ~C and initial stress level of 250 MPa. Based on the experimental stress relaxation curve, the relationship between creep strain ...A stress relaxation test has been carried out for Hastelloy C-276 at temperature of 800 ~C and initial stress level of 250 MPa. Based on the experimental stress relaxation curve, the relationship between creep strain rate and stress has been derived. Then, a set of creep constitutive equations has been built and the values of constants arising in the constitutive equations have been determined by fitting the creep strain rate-stress curve. Close agreement between computed results and experimental ones is obtained for stress relaxation data. The creep constitutive equation set has been integrated with the commercial FE （finite element） solver MSC.Marc via the user defined subroutine, CRPLAW, for the vacuum hot bulge forming process modelling of Hastelloy C-276 thin-walled cylindrical workpiece. The temperature field, the radius-direction displacement field and the stress-strain field are calculated and analyzed. Furthermore, the bulging dimension and the final internal diameter of workpiece are predicted and the test results verify the reliability of the finite element method.展开更多
Temperature is one of the key parameters for BT20 titanium alloy cylindrical workpiece manufactured by vacuum hot bulge forming. A two-dimensional nonlinear thermo-mechanical coupled FE model was established. Numerica...Temperature is one of the key parameters for BT20 titanium alloy cylindrical workpiece manufactured by vacuum hot bulge forming. A two-dimensional nonlinear thermo-mechanical coupled FE model was established. Numerical simulation of vacuum hot bulge forming process of titanium alloy cylindrical workpiece was carried out using FE analysis software MSC Marc. The effects of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece were analyzed by numerical simulation. The simulated results show that the Y-direction displacement and the equivalent plastic strain of the workpiece increase with increasing bulge temperature. The residual stress decreases with increasing bulge temperature. The optimal temperature range of BT20 titanium alloy during vacuum hot bulge forming is 750-850 ℃. The corresponding experiments were carried out. The simulated results agreed well with the experimental results.展开更多
It was investigated how react molecular clusters in water, starch, bio-matrices, polymers and in quartz on gravitation radiation from planets. Gravitation radiation (GR) was found to influence the proton jumping in hy...It was investigated how react molecular clusters in water, starch, bio-matrices, polymers and in quartz on gravitation radiation from planets. Gravitation radiation (GR) was found to influence the proton jumping in hydrogen bonds that stabilize the cluster structure. There was given a method calculating parameters of GR as well as a mechanism of its resonance interaction with weak GR from molecular matter (WGR). WGR has been defined as the result of proton dissolving in vacuum connected with its simultaneous condensation in the nearest free space. Both dissolving and condensation proceed with super light velocity. The gravitation wave length has been determined experimentally and it depends on the planet masses (between Earth and Sun λ ≥ 62 km, between Earth and Milky Way center λ ≥ 330 km). GR has been characterized with super light velocity. After analyzing the Sun influence on water two forms of protons were found: in a condensed and dissolved state. A new model for the atomic nucleus has been suggested according to which the protons in the nucleus oscillate between condensed and dissolved state, where in the case of isotopes this state is partially destroyed. The models for H2 and Be shall be given. Electron orbitals in atoms and molecules were found to be caused by a stationary front of shock waves from condensing protons.展开更多
-The contributions of vacuum fluctuations to energy density in a weak momen-tum dependence of self-energy are calculated in Walecka model.After adjusting modelparameters and introducing momentum dependent form factors...-The contributions of vacuum fluctuations to energy density in a weak momen-tum dependence of self-energy are calculated in Walecka model.After adjusting modelparameters and introducing momentum dependent form factors at meson-nucleonvertices to reproduce the empirical nuclear matter saturation properties,Hartree-Fockresults including vacuum effects at low to moderate densities are similar to those in therelativistic Hartree approximation.展开更多
基金Project(2009CB724307)supported by the Major State Basic Research Development Program(973 Program)of China
文摘A stress relaxation test has been carried out for Hastelloy C-276 at temperature of 800 ~C and initial stress level of 250 MPa. Based on the experimental stress relaxation curve, the relationship between creep strain rate and stress has been derived. Then, a set of creep constitutive equations has been built and the values of constants arising in the constitutive equations have been determined by fitting the creep strain rate-stress curve. Close agreement between computed results and experimental ones is obtained for stress relaxation data. The creep constitutive equation set has been integrated with the commercial FE （finite element） solver MSC.Marc via the user defined subroutine, CRPLAW, for the vacuum hot bulge forming process modelling of Hastelloy C-276 thin-walled cylindrical workpiece. The temperature field, the radius-direction displacement field and the stress-strain field are calculated and analyzed. Furthermore, the bulging dimension and the final internal diameter of workpiece are predicted and the test results verify the reliability of the finite element method.
文摘Temperature is one of the key parameters for BT20 titanium alloy cylindrical workpiece manufactured by vacuum hot bulge forming. A two-dimensional nonlinear thermo-mechanical coupled FE model was established. Numerical simulation of vacuum hot bulge forming process of titanium alloy cylindrical workpiece was carried out using FE analysis software MSC Marc. The effects of temperature on vacuum hot bulge forming of BT20 titanium alloy cylindrical workpiece were analyzed by numerical simulation. The simulated results show that the Y-direction displacement and the equivalent plastic strain of the workpiece increase with increasing bulge temperature. The residual stress decreases with increasing bulge temperature. The optimal temperature range of BT20 titanium alloy during vacuum hot bulge forming is 750-850 ℃. The corresponding experiments were carried out. The simulated results agreed well with the experimental results.
文摘It was investigated how react molecular clusters in water, starch, bio-matrices, polymers and in quartz on gravitation radiation from planets. Gravitation radiation (GR) was found to influence the proton jumping in hydrogen bonds that stabilize the cluster structure. There was given a method calculating parameters of GR as well as a mechanism of its resonance interaction with weak GR from molecular matter (WGR). WGR has been defined as the result of proton dissolving in vacuum connected with its simultaneous condensation in the nearest free space. Both dissolving and condensation proceed with super light velocity. The gravitation wave length has been determined experimentally and it depends on the planet masses (between Earth and Sun λ ≥ 62 km, between Earth and Milky Way center λ ≥ 330 km). GR has been characterized with super light velocity. After analyzing the Sun influence on water two forms of protons were found: in a condensed and dissolved state. A new model for the atomic nucleus has been suggested according to which the protons in the nucleus oscillate between condensed and dissolved state, where in the case of isotopes this state is partially destroyed. The models for H2 and Be shall be given. Electron orbitals in atoms and molecules were found to be caused by a stationary front of shock waves from condensing protons.
文摘-The contributions of vacuum fluctuations to energy density in a weak momen-tum dependence of self-energy are calculated in Walecka model.After adjusting modelparameters and introducing momentum dependent form factors at meson-nucleonvertices to reproduce the empirical nuclear matter saturation properties,Hartree-Fockresults including vacuum effects at low to moderate densities are similar to those in therelativistic Hartree approximation.
