Evaluation of the mechanical properties of friction stir lap welded joints for dissimilar aluminum alloys(AA1100 To AA6061)
In this study friction stir lap welding (FSLW) joints are made for similar and dissimilar aluminum alloys (AA1100 to AA6061-T6) sheets of 3mm thickness by varying the welding parameters, such as tool rotation speeds (1000, 1250 & 1600 rpm) and welding speeds (35, 75 & 100 mm/min) and pin length of (2.8, 5.4 & 5.7mm) with using cylindrical threaded tool pin profile. Many tests and inspections were performed such as X-Ray radiographic and tensile shear test to evaluate the weld quality and joint efficiency under different welding parameters. Microhardness and microstructure observations were carried out at the best welding parameters. The maximum tensile shear force (4.93 KN) and joint efficiency (93%) were obtained when welding process was conducted by a new technique with using friction stir diffusion welding process at the welding speed of 75 mm/min, tool rotation speed of 1250 rpm and using pin length of 2.8 mm. It was found that the Vickers hardness of the similar and dissimilar joints reached to the maximum value at stir zone and drop toward the base metals.
Analysis of fatigue properties in similar friction stir welding joints of aluminum alloy ( AA5086-H32 )
Similar aluminum alloys (AA5086-H32 with AA5086-H32) were welded by friction stir welding (FSW) using three different values of linear speeds; namely 50, 75 and 90 mm/min.and different and rotating speed namely 680, 920 and 1500 rpm. Tensile test was used to determine the joint efficiency of welded samples. The microstructure, hardness, tensile tests and fatigue properties were studied for the welded sample which gave the highest tensile strength. The fatigue test was carried out at a constant stress amplitude cantilever fully reversed( R=-1) in the stir zone of weld and nearby zone or region at a distance of 5, 10 and 15 mm from the welding line. The fracture fatigue surface was analyzed using SEM. It was found that the maximum joint efficiency of 80% was obtained at rotating speed of 680 RPM and linear speed of 75 mm/min. The maximum value of hardness was at the stir zone center of the weld and started to decrease away from it. Fatigue strength of the FSW welded samples was less than the parent or base alloy.
Which Law Governs During Armed Conflict? The Relationship Between International Humanitarian Law and Human Rights Law
Although international human rights and humanitarian law share common roots in their respective efforts to protect human dignity, the two bodies of law appear to have incompatible requirements in armed conflicts. This article draws on jurisprudence, state practice, and scholarship to describe three approaches to evaluating what is lawful in armed conflicts, explores the consequences of the various applications, and recommends that the United States employ interpretive strategies to minimize discrepancies. In situations where states’ obligations remain irreconcilable, the article endorses a “specificity decision rule” to determine the applicable legal regime.