In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to ...In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to steel.In this paper a study on friction stir welding of aluminum alloys was presented.The present investigation deals with the effects of different friction stir welding tool geometries on mechanical strength and the microstructure properties of aluminum alloy welds.Three distinct tool geometries with different types of shoulder and tool probe profiles were used in the investigation according to the design matrix.The effects of each tool shoulder and probe geometry on the weld was evaluated.It was also observed that the friction stir weld tool geometry has a significant effect on the weldment reinforcement,microhardness,and weld strength.展开更多
In order to reveal the constant-fatigue fracture form and mechanism of the welded cross plate-hollow sphere joints(WCPHSJs)and establish its formula,the WCPHSJs were fatigue tested.A total of 19 specimens were tested ...In order to reveal the constant-fatigue fracture form and mechanism of the welded cross plate-hollow sphere joints(WCPHSJs)and establish its formula,the WCPHSJs were fatigue tested.A total of 19 specimens were tested under constant amplitude fatigue loads using a specially designed test rig.The joint was analyzed statically by t e finite element analysis(F3A),and metallographic analysis of fatigue fracture was done by the electron scanning microscope.Numerical simulation and experimental results show that the hot-spot of WCPHSJ lies at the weld toe location where severe stress is concentrated.Fatigue cracks initiate at the weld toe and then propagate circumferentially around the sphere with a diameter equivalent to the width of the cross plate up to the fatigue facture.The initial welding defects and constructional detail constitute the main factor of fatigue failure.The S-N curves for the joints were developed through a linear regession analysis of fatigue data.A formula for calculating constant amplitude fatigue,base on the concept of the hot spot stress amplitude,is proposed.展开更多
文摘In marine application,marine grade steel is generally used for haul and superstructures.However,aluminum has also become a good choice due to its lightweight qualities,while rusting of aluminum is minimal compared to steel.In this paper a study on friction stir welding of aluminum alloys was presented.The present investigation deals with the effects of different friction stir welding tool geometries on mechanical strength and the microstructure properties of aluminum alloy welds.Three distinct tool geometries with different types of shoulder and tool probe profiles were used in the investigation according to the design matrix.The effects of each tool shoulder and probe geometry on the weld was evaluated.It was also observed that the friction stir weld tool geometry has a significant effect on the weldment reinforcement,microhardness,and weld strength.
基金The National Natural Science Foundation of China(No.51578357)the Natural Science Foundation of Shanxi Province(No.2015011062)Talent Training Program in the Postgraduate Joint Training Base of Shanxi Province(No.2016JD11)
文摘In order to reveal the constant-fatigue fracture form and mechanism of the welded cross plate-hollow sphere joints(WCPHSJs)and establish its formula,the WCPHSJs were fatigue tested.A total of 19 specimens were tested under constant amplitude fatigue loads using a specially designed test rig.The joint was analyzed statically by t e finite element analysis(F3A),and metallographic analysis of fatigue fracture was done by the electron scanning microscope.Numerical simulation and experimental results show that the hot-spot of WCPHSJ lies at the weld toe location where severe stress is concentrated.Fatigue cracks initiate at the weld toe and then propagate circumferentially around the sphere with a diameter equivalent to the width of the cross plate up to the fatigue facture.The initial welding defects and constructional detail constitute the main factor of fatigue failure.The S-N curves for the joints were developed through a linear regession analysis of fatigue data.A formula for calculating constant amplitude fatigue,base on the concept of the hot spot stress amplitude,is proposed.