A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum allo...A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum alloy sheet was calculated based on the two flow stress—strain relations using Yld2000-2d yield function. By comparing the theoretical and experimental results, it is found that the calculated FLD-strain based on the modified Swift flow stress—strain relation can reasonably describe the experimental results. However, though the common Voce flow stress—strain relation can describe the deformation behavior during homogenous deformation phase accurately, the FLD-strain calculated based on it is obviously lower than the experimental result. It is concluded that the higher the hardening rate of sheet metal is, the higher the forming limit is. A method for determining the reasonable flow stress—strain relation is recommended for describing the material behavior during inhomogenous phase and the forming limit of sheet metal.展开更多
Fiber-metal laminates(FMLs)consist of three layers of aluminum alloy 2024-T3 and two layers of glass/epoxy prepreg,and it(it means FMLs)is laminated by Al alloy and fiber alternatively.Fatigue crack growth rates in no...Fiber-metal laminates(FMLs)consist of three layers of aluminum alloy 2024-T3 and two layers of glass/epoxy prepreg,and it(it means FMLs)is laminated by Al alloy and fiber alternatively.Fatigue crack growth rates in notched fiber-metal laminates under constant amplitude fatigue loading were studied experimentally and numerically and were compared with them in monolithic 2024-T3 Al alloy plates.It is shown that the fatigue life of FMLs is about 17 times longer than monolithic 2024-T3 Al alloy plate;and crack growth rates in FMLs panels remain constant mostly even when the crack is long,unlike in the monolithic 2024-T3 Al alloy plates.The formula to calculate bridge stress profiles of FMLs was derived based on the fracture theory.A program by Matlab was developed to calculate the distribution of bridge stress in FMLs,and then fatigue growth lives were obtained.Finite element models of FMLs were built and meshed finely to analyze the stress distributions.Both results were compared with the experimental results.They agree well with each other.展开更多
Recycling of aluminum alloy scrap obtained from delaminated fibre metal laminates （FMLs） was studied through high temperature refining in the presence of a salt flux. The aluminum alloy scrap contains approximately ...Recycling of aluminum alloy scrap obtained from delaminated fibre metal laminates （FMLs） was studied through high temperature refining in the presence of a salt flux. The aluminum alloy scrap contains approximately mass fraction w（Cu） = 4.4%, w（Mg） = 1.1% and w（Mn） = 0.6% （2024 aluminum alloy）. The main objective of this research is to obtain a high metal yield, while maintaining its original alloy compositions. The work focuses on the metal yield and quality of recycled A1 alloy under different refining conditions. The NaCI-KC1 salt system was selected as the major components of flux in the A1 alloy recycling. Two different flux compositions were employed at NaC1 to KC1 mass ratios of 44：56 and 70：30 respectively, based on either the euteetic composition, or the European preference. Different additives were introduced into the NaCI-KC1 system to study the effect of flux component on recycling result. Although burning and oxidation loss of the alloying elements during re-melting and refining take place as the drawbacks of conventional refining process, the problems can be solved to a large extent by using an appropriate salt flux. Experimental results indicate that Mg in the alloy gets lost when adding cryolite in the NaCI-KC1 salt system, though the metal yield can reach as high as 98%. However, by adding w（MgF2） = 5% into the NaCI-KC1 salt system （instead of using cryolite） all alloying elements were well controlled to its original composition with a metal yield of almost 98%.展开更多
基金Project(51005010)supported by the National Natural Science Foundation of China
文摘A modified Swift type flow stress—strain relation was presented in order to describe the uniaxial tension test curve reasonably. The FLD-strain （forming limit diagram made up of limit strain） of 5754O aluminum alloy sheet was calculated based on the two flow stress—strain relations using Yld2000-2d yield function. By comparing the theoretical and experimental results, it is found that the calculated FLD-strain based on the modified Swift flow stress—strain relation can reasonably describe the experimental results. However, though the common Voce flow stress—strain relation can describe the deformation behavior during homogenous deformation phase accurately, the FLD-strain calculated based on it is obviously lower than the experimental result. It is concluded that the higher the hardening rate of sheet metal is, the higher the forming limit is. A method for determining the reasonable flow stress—strain relation is recommended for describing the material behavior during inhomogenous phase and the forming limit of sheet metal.
基金supported by Chengdu Aircraft Design&Research Institutethe National Natural Science Foundation of China(Grant No.11002111)the Scholarship of Study Abroad Council
文摘Fiber-metal laminates(FMLs)consist of three layers of aluminum alloy 2024-T3 and two layers of glass/epoxy prepreg,and it(it means FMLs)is laminated by Al alloy and fiber alternatively.Fatigue crack growth rates in notched fiber-metal laminates under constant amplitude fatigue loading were studied experimentally and numerically and were compared with them in monolithic 2024-T3 Al alloy plates.It is shown that the fatigue life of FMLs is about 17 times longer than monolithic 2024-T3 Al alloy plate;and crack growth rates in FMLs panels remain constant mostly even when the crack is long,unlike in the monolithic 2024-T3 Al alloy plates.The formula to calculate bridge stress profiles of FMLs was derived based on the fracture theory.A program by Matlab was developed to calculate the distribution of bridge stress in FMLs,and then fatigue growth lives were obtained.Finite element models of FMLs were built and meshed finely to analyze the stress distributions.Both results were compared with the experimental results.They agree well with each other.
基金the Royal Netherlands Academy of Science and Arts(KNAW)(No.10CDP026)the National Outstanding Young Scientist Foundation of China (No.50825401)the National Natural Science Foundation of China(No.50821003)
文摘Recycling of aluminum alloy scrap obtained from delaminated fibre metal laminates （FMLs） was studied through high temperature refining in the presence of a salt flux. The aluminum alloy scrap contains approximately mass fraction w（Cu） = 4.4%, w（Mg） = 1.1% and w（Mn） = 0.6% （2024 aluminum alloy）. The main objective of this research is to obtain a high metal yield, while maintaining its original alloy compositions. The work focuses on the metal yield and quality of recycled A1 alloy under different refining conditions. The NaCI-KC1 salt system was selected as the major components of flux in the A1 alloy recycling. Two different flux compositions were employed at NaC1 to KC1 mass ratios of 44：56 and 70：30 respectively, based on either the euteetic composition, or the European preference. Different additives were introduced into the NaCI-KC1 system to study the effect of flux component on recycling result. Although burning and oxidation loss of the alloying elements during re-melting and refining take place as the drawbacks of conventional refining process, the problems can be solved to a large extent by using an appropriate salt flux. Experimental results indicate that Mg in the alloy gets lost when adding cryolite in the NaCI-KC1 salt system, though the metal yield can reach as high as 98%. However, by adding w（MgF2） = 5% into the NaCI-KC1 salt system （instead of using cryolite） all alloying elements were well controlled to its original composition with a metal yield of almost 98%.
