| Budget Amount *help |
¥3,930,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥330,000)
Fiscal Year 2007: ¥1,430,000 (Direct Cost: ¥1,100,000、Indirect Cost: ¥330,000)
Fiscal Year 2006: ¥2,500,000 (Direct Cost: ¥2,500,000)
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| Research Abstract |
The purpose of this research is to reveal the joining mechanism of friction spot joining process in the dissimilar lap joint between magnesium alloy and zinc coated steel, to investigate relation between the process parameters of friction spot joining and mechanical properties of dissimilar lap joint, moreover, to establish the optimization method of dissimilar friction spot joining process aided by plastic flow FE analysis of this joining process.
First of all, we investigated the weldability of friction spot joint of 2 mm thick AZ31B, AM60, and noncombustible AMC602 magnesium alloys sheets. Maximum tensile shear strength of lap joint was 4.2kN for AZ31B alloy and 3.3 kN for AM60 alloy in the same joining conditions of tool projection (probe) height 2.4 mm, tool rotational speed 1750 min^<-1>, and tool plunge downforce 9.8 kN. Then, the effect of tool rotational speed on the tensile shear strength of AM60 was surveyed. Maximum tensile shear strength was 4.3 kN for the tool rotational s
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peed 3000 min^<-1> and 2.0 kN for the tool rotational speed 5000 min^<-1>. As the AMC602 alloy has higher plastic deformability than AM60, the maximum tensile shear strength was the same as that of AZ31B for the same FSJ condition. Next, we performed the friction spot joining of 2 mm thick AZ31B and 0.8 mm thick cold rolled steel sheet (SPCC) or 0.8 mm thick zinc alloy coated steel sheet (GA). We obtained the lap joint of AZ31B-SPCC for the probe height 1.9 mm, tool rotational speed 1500 min^-1, and tool plunge downforce 9.8 kN. However, we have not obtained the lap joint of AZ31B-GA for the same joining condition.
At the same time,we analyzed the behavior of plastic deformation for the lap joint by using tool, which has three kind of probe length; 1.9 mm, 2.4 mm, and 2.9 mm. This analysis used the 2-dimensional axi-symmetric model. Computational speed and accuracy decreased according to the increasing of probe length. Moreover, frequent re-creation in FE mesh must be need for convergent result and axi-symmetric model was not treat strain in circumferential direction. Therefore, we realized that this approach was inadequate for optimization method of friction spot joining process. In order to achieve the higher tensile shear strength of dissimilar lap joint, we will need the optimized tool shape and joining parameters in the days ahead. Moreover, we will need the 3-dimensional model to optimize friction spot joining process. Less
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