The clinch–adhesive process,which combines mechanical clinching and adhesive bonding,is one of the most applied pro-cesses for joining aluminum alloy and steel in the manufacturing of vehicle bodies.In this hybrid pr...The clinch–adhesive process,which combines mechanical clinching and adhesive bonding,is one of the most applied pro-cesses for joining aluminum alloy and steel in the manufacturing of vehicle bodies.In this hybrid process,the clinching joints and adhesive bonds are coupled and influenced by each other,posing challenges to the process design and joining strength evaluation.To understand the influence of the clinching process on the performance of the adhesive layer,this study analyzes the mechanical behavior of clinch–adhesive joints between high-strength steel JSC780 and aluminum alloy A5052-H34 with different stack-up orientations and varying numbers of clinching points.The results reveal that,under the steel-on-top condition,the clinching process causes a discontinuous distribution of the adhesive layer,which significantly decreased the bonding strength.In contrast,under the aluminum-on-top condition,the clinching process has a lesser impact on the distribution of the adhesive layer,resulting in much higher strength than the steel-on-top condition.Simulation mod-els are constructed to quantify the effect of clinching points on the performance of the adhesive layer.The results highlight the need to consider diverse cohesive zone model parameters for the different stack orientations and clinching points in the design of clinch–adhesive aluminum alloy/steel structures.展开更多
A recently developed friction self-piercing riveting(F-SPR)technique based on the combination of fric-tion stir processing and riveting has been reported to possess both solid-state bonding and mechanical fastening ch...A recently developed friction self-piercing riveting(F-SPR)technique based on the combination of fric-tion stir processing and riveting has been reported to possess both solid-state bonding and mechanical fastening characteristics.However,there is still a lack of quantitative understanding of the hybrid en-hancement mechanism,hindering its engineering application.To fill in this gap,the current research investigated the microstructure evolution,microhardness distribution,and miniature-tensile performance of the aluminum alloy AA7075-T6 F-SPR joints by experiments.An accurate numerical simulation model was established to quantitatively evaluate the individual contributions of microstructure,local bonding strength,and macro interlocking to the performance of the joint,which could well explain the experi-mental results.It was found that due to the friction stirring of the rivet,solid-state bonding driven by dynamic recrystallization is realized between the trapped aluminum in the rivet cavity and the bottom aluminum sheet.The solid-state bonding zone has 75%yield strength,81%ultimate tensile strength,and 106%elongation compared to the base material.This solid-state bonding enables the internal interlock-ing between the trapped aluminum and the rivet to withstand the additional load,which forms a novel dual-interlock fastening mechanism and increases the peak cross-tension force by 14.3%compared to the single-interlock joint.展开更多
The Al alloy and carbon fiber reinforced polymer(CFRP)hybrid structures,incorporating the performance advantages of the two materials,have been attracting more attention in high-end manufacturing fields.In the current...The Al alloy and carbon fiber reinforced polymer(CFRP)hybrid structures,incorporating the performance advantages of the two materials,have been attracting more attention in high-end manufacturing fields.In the current investigation,the flat friction spot joining(FSJ)was employed in joining the AA6061-T6 alloy and CFRP sheets.The significance of temperature distribution in influencing joint quality was highlighted through analyzing interface microstructural features,weld defect formation as well as fractography.To understand the role of thermal energy generation and conduction in the process comprehensively,a 3D thermal-mechanical coupling finite element model was established.The interfacial temperature was characterized by an uneven distribution behavior due to the inhomogeneous heat distribution.The peak temperatures on the top surface and Al alloy to CFRP interface at 1500 rpm rotational speed with 0.1 mm/s plunging speed were 498℃and 489°C,respectively.The peak interface temperature was reduced to286℃at 250 rpm,which produced an extremely small melted area.Compared with the plunging speed,rotational speed was found to be the predominant parameter for determining the joint property,which could be optimized to simultaneously realize the avoidance of thermal decomposition of CFRP,the sufficient melting duration time,and the wide enough melted area.Simulated thermal histories and melted area profiles were in agreement with experimental ones.The findings could be utilized to provide some feasible guidance for process optimization of dissimilar FSJ of metals and composites.展开更多
基金supports of the National Key Research and Development Program of China(2022YFB3402200)Young Elite Scientists Sponsorship Program by CAST(2022-2024QNRC001)Shanghai Pujiang Program(22PJ1407200)。
文摘The clinch–adhesive process,which combines mechanical clinching and adhesive bonding,is one of the most applied pro-cesses for joining aluminum alloy and steel in the manufacturing of vehicle bodies.In this hybrid process,the clinching joints and adhesive bonds are coupled and influenced by each other,posing challenges to the process design and joining strength evaluation.To understand the influence of the clinching process on the performance of the adhesive layer,this study analyzes the mechanical behavior of clinch–adhesive joints between high-strength steel JSC780 and aluminum alloy A5052-H34 with different stack-up orientations and varying numbers of clinching points.The results reveal that,under the steel-on-top condition,the clinching process causes a discontinuous distribution of the adhesive layer,which significantly decreased the bonding strength.In contrast,under the aluminum-on-top condition,the clinching process has a lesser impact on the distribution of the adhesive layer,resulting in much higher strength than the steel-on-top condition.Simulation mod-els are constructed to quantify the effect of clinching points on the performance of the adhesive layer.The results highlight the need to consider diverse cohesive zone model parameters for the different stack orientations and clinching points in the design of clinch–adhesive aluminum alloy/steel structures.
基金support of the National Natural Science Foundation of China(Grant Nos.52025058 and U1764251)the State Key Laboratory of Mechan-ical System and Vibration(Grant No.MSVZD202111)+1 种基金the Japan Society for the Promotion of Science(JSPS)KAKENHI(Grant No.21K14439)Shanghai Jiao Tong University.
文摘A recently developed friction self-piercing riveting(F-SPR)technique based on the combination of fric-tion stir processing and riveting has been reported to possess both solid-state bonding and mechanical fastening characteristics.However,there is still a lack of quantitative understanding of the hybrid en-hancement mechanism,hindering its engineering application.To fill in this gap,the current research investigated the microstructure evolution,microhardness distribution,and miniature-tensile performance of the aluminum alloy AA7075-T6 F-SPR joints by experiments.An accurate numerical simulation model was established to quantitatively evaluate the individual contributions of microstructure,local bonding strength,and macro interlocking to the performance of the joint,which could well explain the experi-mental results.It was found that due to the friction stirring of the rivet,solid-state bonding driven by dynamic recrystallization is realized between the trapped aluminum in the rivet cavity and the bottom aluminum sheet.The solid-state bonding zone has 75%yield strength,81%ultimate tensile strength,and 106%elongation compared to the base material.This solid-state bonding enables the internal interlock-ing between the trapped aluminum and the rivet to withstand the additional load,which forms a novel dual-interlock fastening mechanism and increases the peak cross-tension force by 14.3%compared to the single-interlock joint.
基金financially supported by the New Energy and Industrial Technology Development Organization(NEDO)under the"Innovation Structural Materials Project(Future Pioneering Projects)"。
文摘The Al alloy and carbon fiber reinforced polymer(CFRP)hybrid structures,incorporating the performance advantages of the two materials,have been attracting more attention in high-end manufacturing fields.In the current investigation,the flat friction spot joining(FSJ)was employed in joining the AA6061-T6 alloy and CFRP sheets.The significance of temperature distribution in influencing joint quality was highlighted through analyzing interface microstructural features,weld defect formation as well as fractography.To understand the role of thermal energy generation and conduction in the process comprehensively,a 3D thermal-mechanical coupling finite element model was established.The interfacial temperature was characterized by an uneven distribution behavior due to the inhomogeneous heat distribution.The peak temperatures on the top surface and Al alloy to CFRP interface at 1500 rpm rotational speed with 0.1 mm/s plunging speed were 498℃and 489°C,respectively.The peak interface temperature was reduced to286℃at 250 rpm,which produced an extremely small melted area.Compared with the plunging speed,rotational speed was found to be the predominant parameter for determining the joint property,which could be optimized to simultaneously realize the avoidance of thermal decomposition of CFRP,the sufficient melting duration time,and the wide enough melted area.Simulated thermal histories and melted area profiles were in agreement with experimental ones.The findings could be utilized to provide some feasible guidance for process optimization of dissimilar FSJ of metals and composites.
