The complex phenomena that occur during the plastic deformation process of aluminum alloys,such as strain rate hardening,dynamic recovery,recrystallization,and damage evolution,can significantly affect the properties ...The complex phenomena that occur during the plastic deformation process of aluminum alloys,such as strain rate hardening,dynamic recovery,recrystallization,and damage evolution,can significantly affect the properties of these alloys and limit their applications.Therefore,studying the high-temperature flow stress characteristics of these materials and developing accurate constitutive models has significant scientific research value.In this study,quasi-static tensile tests were conducted on 5754 aluminum alloy using an electronic testing machine combined with a hightemperature environmental chamber to explore its plastic flow behavior under main deformation parameters(such as deformation temperatures,strain rates,and strain).On the basis of true strain-stress data,a BP neural network constitutive model of the alloy was built,aiming to reveal the influence laws of main deformation parameters on flow stress.To further improve the model performance,the ant colony optimization algorithm is introduced to optimize the BP neural network constitutive model,and the relationship between the prediction stability of the model and the parameter settings is explored.Furthermore,the predictability of the two models was evaluated by the statistical indicators,including the correlation coefficient(R^(2)),RMSE,MAE,and confidence intervals.The research results indicate that the prediction accuracy,stability,and generalization ability of the optimized BP neural network constitutive model have been significantly enhanced.展开更多
In the present study,the mechanical and ballistic properties of friction stir welded(FSW)aluminum alloy(AA5754)samples were investigated,both untreated and cryogenically treated,when impacted by a 7.62 mm armour-pierc...In the present study,the mechanical and ballistic properties of friction stir welded(FSW)aluminum alloy(AA5754)samples were investigated,both untreated and cryogenically treated,when impacted by a 7.62 mm armour-piercing(AP)bullet at an impact velocity of 682±20 m/s.The FSW technique was used to prepare the welded samples for AA5754,with an axial force of 7 kN,a feed rate of 20 mm/min,and a speed of 1200 rpm.The cryogenic treatments performed after welding,including deep cryogenic treatment(DCT)at196℃ and shallow cryogenic treatment(SCT)at80℃,for 6 and 72 h,respectively.The microstructure and mechanical characteristics of cryogenically treated and untreated joints were examined.The cryogenic treatment refined the grain size(1.05 μm)and enhanced the microhardness(93 Hv).Moreover,DCT-FSW significantly improved the tensile strength(13.93%)and impact strength(8.45%)compared to untreated FSW sample.Additionally,in untreated FSW samples,the fracture behaviour varied:the impact fracture mode primarily exhibited ductile failure,while the tensile fracture exhibited a mixed fracture mode.In contrast,the tensile and impact fracture modes of the DCT-FSWwere dominated by a ductile failure mode.The DCT-FSW target demonstrated a lower depth of penetration(DOP)of 31 mm compared to the SCT-FSWand untreated FSW targets.Post-ballistic SEM analysis in the crater region of all three zones revealed the formation of frictional grooves,small cracks,and adiabatic shear bands(ASBs).展开更多
基金funded by the Talent Introduction Project of Anhui Science and Technology University(RCYJ202105)Design and Key Technology Research of Multi Parameter Intelligent Control Instrument Junction Box(tzy202218)+3 种基金Natural Science Research Project of Higher Education Institutions in Anhui Province(2024AH050296)Research and Development of Fermentation Feed Drying Automatic Line(881314)Anhui Provincial Key Laboratory of Functional Agriculture and Functional Food,Anhui Science and Technology University(iFAST-2024-6)Key Technologies and Applications of Impinging Stream Based Plant Protection Hedge Spray System(2024AH050318).
文摘The complex phenomena that occur during the plastic deformation process of aluminum alloys,such as strain rate hardening,dynamic recovery,recrystallization,and damage evolution,can significantly affect the properties of these alloys and limit their applications.Therefore,studying the high-temperature flow stress characteristics of these materials and developing accurate constitutive models has significant scientific research value.In this study,quasi-static tensile tests were conducted on 5754 aluminum alloy using an electronic testing machine combined with a hightemperature environmental chamber to explore its plastic flow behavior under main deformation parameters(such as deformation temperatures,strain rates,and strain).On the basis of true strain-stress data,a BP neural network constitutive model of the alloy was built,aiming to reveal the influence laws of main deformation parameters on flow stress.To further improve the model performance,the ant colony optimization algorithm is introduced to optimize the BP neural network constitutive model,and the relationship between the prediction stability of the model and the parameter settings is explored.Furthermore,the predictability of the two models was evaluated by the statistical indicators,including the correlation coefficient(R^(2)),RMSE,MAE,and confidence intervals.The research results indicate that the prediction accuracy,stability,and generalization ability of the optimized BP neural network constitutive model have been significantly enhanced.
文摘In the present study,the mechanical and ballistic properties of friction stir welded(FSW)aluminum alloy(AA5754)samples were investigated,both untreated and cryogenically treated,when impacted by a 7.62 mm armour-piercing(AP)bullet at an impact velocity of 682±20 m/s.The FSW technique was used to prepare the welded samples for AA5754,with an axial force of 7 kN,a feed rate of 20 mm/min,and a speed of 1200 rpm.The cryogenic treatments performed after welding,including deep cryogenic treatment(DCT)at196℃ and shallow cryogenic treatment(SCT)at80℃,for 6 and 72 h,respectively.The microstructure and mechanical characteristics of cryogenically treated and untreated joints were examined.The cryogenic treatment refined the grain size(1.05 μm)and enhanced the microhardness(93 Hv).Moreover,DCT-FSW significantly improved the tensile strength(13.93%)and impact strength(8.45%)compared to untreated FSW sample.Additionally,in untreated FSW samples,the fracture behaviour varied:the impact fracture mode primarily exhibited ductile failure,while the tensile fracture exhibited a mixed fracture mode.In contrast,the tensile and impact fracture modes of the DCT-FSWwere dominated by a ductile failure mode.The DCT-FSW target demonstrated a lower depth of penetration(DOP)of 31 mm compared to the SCT-FSWand untreated FSW targets.Post-ballistic SEM analysis in the crater region of all three zones revealed the formation of frictional grooves,small cracks,and adiabatic shear bands(ASBs).
