Unavoidably,Fe impurities are mixed into Al alloys during recycling of aluminum automotive parts.High Fe content recyclefriendly aluminum alloy sheets(RASs)are discussed in terms of their applications to car body par...Unavoidably,Fe impurities are mixed into Al alloys during recycling of aluminum automotive parts.High Fe content recyclefriendly aluminum alloy sheets(RASs)are discussed in terms of their applications to car body parts and closures.RASs have advantages,such as they are low cost and light weight,they require less energy to process,and they reduce emissions when used in vehicles.The hemming ability of RASs was investigated through various quenching rates and hot-rolling reduction rates.The hemming factor(HF)values of low Fe content samples(0.1 and 0.3 wt%Fe content)were 2 and 3.The hemming ability of samples with an Fe content of 0.5 wt%was unacceptable for applications to automotive outer closures(i.e.,HF values of 4 and 5).The HF values changed from 3 to 5 for even higher Fe content samples(0.8 wt%Fe),depending on the quenching and hot-rolling reduction rates.Lower quenching(air quenching)and lower hot-rolling reduction rates(6-pass hot rolling)both improved the hemming ability of the high Fe content samples.A low-cost and recycle-friendly aluminum alloy automotive sheet from end-of-life vehicles is presented,and its hemming properties are characterized.展开更多
An analytical model for straight hemming was developed based on minimum energy method to study the effect of flanging die corner radius on hemming qualities.In order to calculate plastic strain and strain energy more ...An analytical model for straight hemming was developed based on minimum energy method to study the effect of flanging die corner radius on hemming qualities.In order to calculate plastic strain and strain energy more exactly,the neutral layer of specimen corner after hemming is assumed to be a half ellipse with its major semi-axis unknown.Isotropic hardening rule is adopted to describe bending and reverse bending processes neglecting Bauschinger effect.The model takes into account the material property parameters in order to satisfy a wide application range of different materials.Specimen profile,creepage/growing(roll-in/roll-out) and maximum equivalent strain are predicted,which are greatly influenced by the flanging die corner radius.Experimental facilities were designed and hemming experiments were undertaken.The predicted results of the present analytical model were compared to experimental data as well as finite element(FE) simulation results.It was confirmed that they are in good agreement,and the model can be used to evaluate whether the material used as an outer panel for hemming is appropriate and to optimize process parameters when the material used for hemming is changed.展开更多
The purpose of this research is to explore the feasibility of roller hemming of AZ31 B magnesium alloy sheet. During the test, a special experimental setup considering the current flow and insulation was designed and ...The purpose of this research is to explore the feasibility of roller hemming of AZ31 B magnesium alloy sheet. During the test, a special experimental setup considering the current flow and insulation was designed and employed. For the sake of simplicity, the flat surface-straight edge hemming style was selected. Electrical pulses were introduced in the pre-hemming and final hemming processes. The results show that when hemming at 448 K with hemming speed of 30 mm/min, AZ31 B magnesium alloy sheet was successfully hemmed with excellent perceived quality. No recoil/warp defect, cracking or springback was observed. Electrical pulses induced dynamic recrystallized grains were observed along the grain boundaries in the severely deformed area, which is of great importance to the improvement of the ductility of the material. The hardness was slightly increased after hemming with electrical pulses, and this fact could improve the friction resistance performance of the hemmed part.展开更多
居民负荷由于用电时间集中,已成为电力峰荷的主要组成部分,同时随着智能电网技术的发展,需求侧响应作为缓解电力供需矛盾的有效途径备受关注。以智能社区为背景,结合冷热电联供(Combined Cooling Heating and Power,CCHP)系统能效高、...居民负荷由于用电时间集中,已成为电力峰荷的主要组成部分,同时随着智能电网技术的发展,需求侧响应作为缓解电力供需矛盾的有效途径备受关注。以智能社区为背景,结合冷热电联供(Combined Cooling Heating and Power,CCHP)系统能效高、经济效益好等优势,与居民需求侧响应的潜力,提出两阶段优化模式。第一阶段,社区物业根据负荷预测及光伏出力预测,优化CCHP系统各部分出力,最大化物业净收益。第二阶段,家庭能量管理系统(Home Energy Management System,HEMS)根据CCHP系统启停及出力情况与分时电价,优化家庭负荷工作时间,最小化用户费用。最后通过对比不同案例仿真结果,证明了该两阶段优化模式能够实现供能侧与用能侧的双赢。展开更多
基金The authors would like to acknowledge the financial contribution from the National Science and Technology Pillar Program during the 12th Five-year Plan Period(Grant No.2011BAG03B00).
文摘Unavoidably,Fe impurities are mixed into Al alloys during recycling of aluminum automotive parts.High Fe content recyclefriendly aluminum alloy sheets(RASs)are discussed in terms of their applications to car body parts and closures.RASs have advantages,such as they are low cost and light weight,they require less energy to process,and they reduce emissions when used in vehicles.The hemming ability of RASs was investigated through various quenching rates and hot-rolling reduction rates.The hemming factor(HF)values of low Fe content samples(0.1 and 0.3 wt%Fe content)were 2 and 3.The hemming ability of samples with an Fe content of 0.5 wt%was unacceptable for applications to automotive outer closures(i.e.,HF values of 4 and 5).The HF values changed from 3 to 5 for even higher Fe content samples(0.8 wt%Fe),depending on the quenching and hot-rolling reduction rates.Lower quenching(air quenching)and lower hot-rolling reduction rates(6-pass hot rolling)both improved the hemming ability of the high Fe content samples.A low-cost and recycle-friendly aluminum alloy automotive sheet from end-of-life vehicles is presented,and its hemming properties are characterized.
基金Project supported by the National Natural Science Foundation for Key Program of China (No. 50835002),the National Natural Science Foundation of China (No. 50975174),the National Natural Science Foundation for Innovative Research Group of China (No. 50821003)
文摘An analytical model for straight hemming was developed based on minimum energy method to study the effect of flanging die corner radius on hemming qualities.In order to calculate plastic strain and strain energy more exactly,the neutral layer of specimen corner after hemming is assumed to be a half ellipse with its major semi-axis unknown.Isotropic hardening rule is adopted to describe bending and reverse bending processes neglecting Bauschinger effect.The model takes into account the material property parameters in order to satisfy a wide application range of different materials.Specimen profile,creepage/growing(roll-in/roll-out) and maximum equivalent strain are predicted,which are greatly influenced by the flanging die corner radius.Experimental facilities were designed and hemming experiments were undertaken.The predicted results of the present analytical model were compared to experimental data as well as finite element(FE) simulation results.It was confirmed that they are in good agreement,and the model can be used to evaluate whether the material used as an outer panel for hemming is appropriate and to optimize process parameters when the material used for hemming is changed.
基金the National Natural Science Foundation of China(Nos.50975174 and 51275297)
文摘The purpose of this research is to explore the feasibility of roller hemming of AZ31 B magnesium alloy sheet. During the test, a special experimental setup considering the current flow and insulation was designed and employed. For the sake of simplicity, the flat surface-straight edge hemming style was selected. Electrical pulses were introduced in the pre-hemming and final hemming processes. The results show that when hemming at 448 K with hemming speed of 30 mm/min, AZ31 B magnesium alloy sheet was successfully hemmed with excellent perceived quality. No recoil/warp defect, cracking or springback was observed. Electrical pulses induced dynamic recrystallized grains were observed along the grain boundaries in the severely deformed area, which is of great importance to the improvement of the ductility of the material. The hardness was slightly increased after hemming with electrical pulses, and this fact could improve the friction resistance performance of the hemmed part.
文摘居民负荷由于用电时间集中,已成为电力峰荷的主要组成部分,同时随着智能电网技术的发展,需求侧响应作为缓解电力供需矛盾的有效途径备受关注。以智能社区为背景,结合冷热电联供(Combined Cooling Heating and Power,CCHP)系统能效高、经济效益好等优势,与居民需求侧响应的潜力,提出两阶段优化模式。第一阶段,社区物业根据负荷预测及光伏出力预测,优化CCHP系统各部分出力,最大化物业净收益。第二阶段,家庭能量管理系统(Home Energy Management System,HEMS)根据CCHP系统启停及出力情况与分时电价,优化家庭负荷工作时间,最小化用户费用。最后通过对比不同案例仿真结果,证明了该两阶段优化模式能够实现供能侧与用能侧的双赢。
