The energy conversion during ultrasonic plastic welding is analyzed on the basis of the theory of vis- coelastic mechanics,.The temperature field and the temperature change of the ABS specimen with ener- gy direc...The energy conversion during ultrasonic plastic welding is analyzed on the basis of the theory of vis- coelastic mechanics,.The temperature field and the temperature change of the ABS specimen with ener- gy director during ultrasonic welding is simulated with finite element method(FEM). In the simu- lation process,the melting of the energy energy is also considered. The calculation results are in good agreement with the temperature measurement results, which proves that the simulation results are reli- able.展开更多
The effect of strain hardening and strain softening behavior of flow stress changing with temperature on welding residual stress, plastic strain and welding distortion of ATN0 1-T4 aluminum alloy was studied by finite...The effect of strain hardening and strain softening behavior of flow stress changing with temperature on welding residual stress, plastic strain and welding distortion of ATN0 1-T4 aluminum alloy was studied by finite simulation method. The simulation results show that the weld seam undergoes strain hardening in the temperature range of 180-250 ℃, however, it exhibits strain softening at temperature above 250 ℃ during welding heating and cooling process. As a result, the strain hardening and strain softening effects counteract each other, introducing slightly influence on the welding residual stress, residual plastic strain and distortion. The welding longitudinal residual stress was determined by ultrasonic stress measurement method for the flat plates of A7N01-T4 aluminum alloy. The simulation results are well accordant with test ones.展开更多
In our previous study, metals have been used as absorbers in the clear plastic laser transmission welding. The effects of metal thermal conductivity on the welding quality are investigated in the present work. Four me...In our previous study, metals have been used as absorbers in the clear plastic laser transmission welding. The effects of metal thermal conductivity on the welding quality are investigated in the present work. Four metals with distinctly different thermal conductivities, i.e., titanium, nickel, molybdenum, and copper, are selected as light absorbers. The lap welding is conducted with an 808 nm diode laser and simulation experiments are also conducted. Nickel electroplating test is carried out to minimize the side-effects from different light absorptivities of different metals. The results show that the welding with an absorber of higher thermal conductivity can accommodate higher laser input power before smoking, which produces a wider and stronger welding seam.The positive role of the higher thermal conductivity can be attributed to the fact that a desirable thermal field distribution for the molecular diffusion and entanglement is produced from the case with a high thermal conductivity.展开更多
Effects of molten state of ultrasonic welded joints of plastics on their strength were investigated. Physical parameters such as temperature, viscosity and thickness of melting layers of plastic material joints were m...Effects of molten state of ultrasonic welded joints of plastics on their strength were investigated. Physical parameters such as temperature, viscosity and thickness of melting layers of plastic material joints were measured and analyzed. Results show that when the welding vibration amplitude and pressure increase, the temperature increases, the viscosity decreases, and the thickness of molten layer decreases. The microstructure of weld fusion zone was observed by using an optical microscope. It was found that there is strong orientation along transverse direction in the microstructure of fusion zone. Testing results show that the mechanics performance of welded joints are obviously anisotropic, and strongly affected by the thickness of molten layer and the extent of orientation.展开更多
文摘The energy conversion during ultrasonic plastic welding is analyzed on the basis of the theory of vis- coelastic mechanics,.The temperature field and the temperature change of the ABS specimen with ener- gy director during ultrasonic welding is simulated with finite element method(FEM). In the simu- lation process,the melting of the energy energy is also considered. The calculation results are in good agreement with the temperature measurement results, which proves that the simulation results are reli- able.
基金Project(2007DFR70070) supported by China-Russia Government-to-Government Scientific and Technical Cooperation Foundation
文摘The effect of strain hardening and strain softening behavior of flow stress changing with temperature on welding residual stress, plastic strain and welding distortion of ATN0 1-T4 aluminum alloy was studied by finite simulation method. The simulation results show that the weld seam undergoes strain hardening in the temperature range of 180-250 ℃, however, it exhibits strain softening at temperature above 250 ℃ during welding heating and cooling process. As a result, the strain hardening and strain softening effects counteract each other, introducing slightly influence on the welding residual stress, residual plastic strain and distortion. The welding longitudinal residual stress was determined by ultrasonic stress measurement method for the flat plates of A7N01-T4 aluminum alloy. The simulation results are well accordant with test ones.
基金Supported by the National Key R&D Program of China under Grant No 2016YFA0401100the National Natural Science Foundation of China under Grant No 61575129the National High-Technology Research and Development Program of China under Grant No 2015AA021102
文摘In our previous study, metals have been used as absorbers in the clear plastic laser transmission welding. The effects of metal thermal conductivity on the welding quality are investigated in the present work. Four metals with distinctly different thermal conductivities, i.e., titanium, nickel, molybdenum, and copper, are selected as light absorbers. The lap welding is conducted with an 808 nm diode laser and simulation experiments are also conducted. Nickel electroplating test is carried out to minimize the side-effects from different light absorptivities of different metals. The results show that the welding with an absorber of higher thermal conductivity can accommodate higher laser input power before smoking, which produces a wider and stronger welding seam.The positive role of the higher thermal conductivity can be attributed to the fact that a desirable thermal field distribution for the molecular diffusion and entanglement is produced from the case with a high thermal conductivity.
基金the National Natural Science Foundation of China (No.59675054) andNational Key Laboratory of Advanced Welding Production Techn
文摘Effects of molten state of ultrasonic welded joints of plastics on their strength were investigated. Physical parameters such as temperature, viscosity and thickness of melting layers of plastic material joints were measured and analyzed. Results show that when the welding vibration amplitude and pressure increase, the temperature increases, the viscosity decreases, and the thickness of molten layer decreases. The microstructure of weld fusion zone was observed by using an optical microscope. It was found that there is strong orientation along transverse direction in the microstructure of fusion zone. Testing results show that the mechanics performance of welded joints are obviously anisotropic, and strongly affected by the thickness of molten layer and the extent of orientation.
