Cheng LÜ
材料科学技术（英）
Thermal, mechanical and microstructural phenomena are involved in the process of steel quenching. Based on the coupled metallo-thermo-mechanics theory, a calculation model has been developed in this study to simulate the quenching process of a gas turbine compressor disk by finite element method. The thermal physical and mechanical properties were treated as a functions of temperature. Moreover, a series of subroutines were developed on the MARC software platform. Consequently, simulated results on temperature, internal stress and distortion during the quenching were illustrated. With the aid of the simulated results, an optimum quenching scheme was proposed. The quenching process simulated in this study appears to be a promising tool in design of heat-treatment processing parameters for gas turbine compressor disks.
关键词:
Quenching stress
,
stress
,
Distortion
,
Finite
,
eleme
Hongwu ZHANG
,
Zhao ZHANG
材料科学技术（英）
Rate-dependent constitutive model was used to simulate the friction stir welding process. The effect of the viscosity coefficient and the process parameters on the material behaviors and the stress distributions around the pin were studied. Results indicate that the stress in front of the pin is larger than that behind the pin. The difference between the radial/circumferential stress in front of the pin and that behind it becomes smaller when the material gets closer to the top surface. This difference increases with increasing the viscosity coefficient and becomes smaller when the welding speed decreases. The variation of the angular velocity does not significantly affect the difference.
关键词:
Friction stir welding
,
stir
,
welding
,
Finite
,
element
,
met
Ming CHENG
材料科学技术（英）
A finite element analysis (FEA) model has been developed to analyze microimprinting of bulk metallic glasses (BMG) near the glass transition temperature (Tg). The results reveal an approximately universal imprinting response for BMG, independent of surface feature length scale. The scale-independent nature of BMG imprinting derives from the flow characteristics of BMG in the temperature range above Tg. It also shows that the lubrication condition has a mild influence on BMG imprinting in the temperature range above Tg.
关键词:
Bulk metallic glasses
,
metallic
,
glasses
,
Finite
,
element
,
ana
A.Cherouat
,
H.Borouchaki
材料科学技术（英）
Ductile damage often occurs during metal forming processes due to the large thermo-elasto (visco) plastic flow localisation. This paper presents a numerical methodology, which aims to virtually improve any metal forming processes. The methodology is based on elastoplastic constitutive equations accounting for nonlinear mixed isotropic and kinematic hardening strongly coupled with isotropic ductile damage. An adaptive remeshing scheme based on geometrical and physical error estimates including a kill element procedure is used. Some numerical results are presented to show the capability of the model to predict the damage initiation and growth during the metal forming processes.
关键词:
Finite elastoplasticity
,
elastoplasticity
,
Ductile
,
damage
,
E
