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Friction stir welding (FSW) experiments were conducted, using a work hardened aluminium alloy and a cast aluminium alloy followed by examination focusing on the upper weld zone. The examination has revealed the feature of the major forward flow due to the forward motion of the shoulder. A thin shear layer was identified between the tool shoulder and the workpiece with a distinctive shear flow direction. The thickness of the shear layer was alloy dependent. An embedded layer in the upper weld zone has also been identified. The flow phenomena leading to this will be discussed. A velocity profile in the shear layer, based on the apparent alignment of Si particles in the cast alloy after FSW, has suggested a dominant sliding contact condition.

In this paper, the orbital forming simulation of an automotive hub bearing was studied to predict forming conditions and performances using the explicit finite element method. To set up an efficient solution technique for the orbital forming, axisymmetric finite element models and 3D solid element models were numerically solved and compared to each other. The time scaling and mass scaling techniques were introduced to reduce the excessive computational time caused by small element size in case of the explicit finite element method. It was found from the numerical results on the orbital forming that the axisymmetric element models showed the similar results to the 3D solid element models in forming loads whereas the deformations at the bearing inner race were quite different. Finally the strains at the bearing inner race and the forming forces of the peen were measured by test for the same product used in the numerical analysis, and were compared with the 3D solid element results. It was shown that the test results were in good agreements with the numerical ones.

In this paper, the numerical convergence, accuracy, stability, efficiency, and reality of the SPH simulation of the impact problem are analyzed by using several different kernel functions. Three are traditional kernel functions of the quadratic function, the cubic bell function, and the quintic function. Others are their corresponding corrected zero-order consistency kernel functions with different denominators. Several unnoticed features in the formulations and the simulation results of the corrected kernel are pointed out. The availability of these kernel functions on the impact problem is discussed. To achieve reality, an unphysical adhesive phenomenon is avoided by introducing three separation conditions.

The overtopping-inundation process of a tsunami results in the collisions of drifting objects on the coast, which damage structures, thereby increasing the risk of collapse. This study conducted laboratory experiments on the collision between a drifting container caused by the overtopping-inundation process of a solitary wave and a fixed port crane’s leg. The movement trajectory and velocity of the container as well as the collision velocity by solitary wave inundation, were analyzed using motion analysis software. Overall, increasing solitary wave scale, collision velocity, and drifting object weight and decreased distance between the two objects tended to increase the collision force. However, different experiment results were also obtained due to pitching in objects that fully floated without bottom friction owing to the solitary wave bore. This resulted in line-to-surface collisions. Thus, surface-to-surface contact occurred under the incomplete floating condition owing to the difficulty because of interference with the bottom; however, the collision force decreased under complete floating conditions owing to line-to-surface contact. Therefore, the contact condition according to the floating behavior must be considered a parameter while predicting the collision forces of drifting objects. Thus, surface-to-surface contact occurred under the incomplete floating condition owing to the difficulty because of interference with the bottom; however, the collision force decreased under complete floating conditions owing to line-to-surface contact. Therefore, the contact condition according to the floating behavior must be considered a parameter while predicting the collision forces of drifting objects.

In order to reveal the influence of contact condition of spindle-holder to the dynamic characteristics of high speed spindle system, a milling spindle is taken as the research object, and the change rule of the spindle natural frequency is simulated based on the contact condition which is influenced by the drawbar force, interference and centrifugal force. The result shows that the contact clearance is decrease with the increase of drawbar force and interference, while rise with the increase of rotate speed; the natural frequency can be increased by both drawbar force and interference, however, it is decease with the increase of rotate speed.