摘要：3D elastic-plastic FE model for simulating the force controlled stretch-bending process of double-cavity aluminum profile was established using hybrid explicit−implicit solvent *** the computational accuracy and efficiency,the optimal choices of numerical parameters and algorithms in FE modelling were *** formation mechanisms of cross-section distortion and springback were *** effects of pre-stretching,post-stretching,friction,and the addition of internal fillers on forming quality were *** results show that the stress state of profile in stretch-bending is uniaxial with only a circumferential *** stress distribution along the length direction of profile is non-uniform and the maximum tensile stress is located at a certain distance away from the center of *** aluminum profile is gradually attached to bending die,the distribution characteristic of cross-section distortion along the length direction of profile changes from V-shape to *** unloading the forming tools,cross-section distortion decreases obviously due to the stress relaxation,with a maximum distortion difference of 13%before and after *** pre-stretching and post-stretching forces increase,cross-section distortion increases gradually,while springback first decreases and then remains *** increasing friction between bending die and profile,cross-section distortion slightly decreases,while springback ***-section distortion decreases by 83%with adding PVC fillers into the cavities of profile,while springback increases by 192.2%.

摘要：To solve the defects of bottom concave appearing in the extrusion experiments of complex hollow aluminium profiles,a 3D finite element model for simulating steady-state porthole die extrusion process was established based on HyperXtrude software using Arbitrary Lagrangian–Eulerian(ALE)*** velocity distribution on the cross-section of the extrudate at the die exit and pressure distribution at different heights in the welding chamber were quantitatively *** obtain an uniformity of metal flow velocity at the die exit,the porthole die structure was optimized by adding baffle *** optimization,maximum displacement in the Y direction at the bottom of profile decreases from 1.1 to 0.15 mm,and the concave defects are remarkably *** research method provides an effective guidance for improving extrusion defects and optimizing the metal flow of complex hollow aluminium profiles during porthole die extrusion.

摘要：Four different welding sequences of double-pulse MIG welding were conducted for 6061-T6 aluminum alloy automobile bumpers by using nonlinear elastoplasticity finite element method based on ABAQUS *** post-welding residual stress and deformation were definitely different among the four welding *** results showed that the highest temperature in Solution A was approximately 200℃higher than the melting point of base *** residual stress was resulted from this large temperature gradient and mainly concentrated on the welding vicinity between beam and crash *** welding deformation primarily occurred in both of the contraction of two-ends of the beam and the self-contraction of crash *** with other welding sequences,the residual stress in Solution A was the smallest,whereas the welding deformation was the ***,the optimal sequence was Solution B because of the effective reduction of residual stress and good assembly requirements.

摘要：Bending deformation behaviors of solution treated(ST),natural aged(NA)and T6tempered6063aluminum alloy sheetswere studied by three-point bending *** changes of bending force,interior angle,bending radius and sheet thickness in thefillet region were analyzed by experimental measurements and numerical *** results showed that the bendingcharacteristics were strongly dependent on the heat treatment *** T6alloy sheets were bent more sharply and localplastic deformation occurred severely in the fillet ***,the ST and NA alloy sheets exhibited relatively uniform bendingdeformation and large bending *** bending force of T6alloy was the highest,followed by the NA alloy and that of the STalloy was *** unloading,as compared with the ST and NA alloys,the springback of T6alloys was markedly *** time showed a positive sensitivity on the springback and non-uniform bending *** bending characteristics areattributed to the combined effects of yield strength,yield ratio and coefficient of neutral layer.

摘要：6061 aluminum alloy T-joints were welded by double-pulsed MIG welding process. Then, the post-weld heat treatment was performed on the welded T-joints. The weld microstructure under different aging temperature and time was investigated by transmission electron microscopy and scanning electron microscopy. The mechanical properties were examined by hardness test and tensile test. The results showed that the micro-hardness was sensitive to heat treatment temperature and time. Increasing temperature was beneficial to the shortening of peak aging time. There were a large number of dislocations and few precipitates in the welded joints. With the increase of post-weld heat treatment temperature and time, the density of dislocation decreased. Meanwhile, the strengthening phase precipitated and grew up gradually. When the post-weld heat treatment temperature increased up to 200℃, large Q' phases were observed. And they were responsible for the peak value of the micro-hardness in the welded joints.