ELAS-PLASTIC IMPACTS BY RIGID BODY ON RECTANGLE TUBE COLUMNS CONSIDERING LOCAL BUCKLING

The rectangle tube columns are modeled by shell elements, and their behaviors under rigid body impacts are investigated. Tracing the whole impact procedure using numerical method, this paper obtains elastic and elas-plastic impact loads with variant mass ratios and impact speeds. The impact loads exerted on rectangle tubes are compared with those of the bar models. The calculation results show that for elastic rectangle tubes, the bigger the mass ratio and the higher the rigid body speed, the bigger the peak elastic impact load, the longer the contact time, and the more significant reduction of the peak impact load due to local buckling. Therefore, the peak impact load of the rectangle tube is not proportional to the rigid body speed. Due to the bidirectionality of stress wave in the tubes, the impact load curves of the tube model are not as smooth as those of the bar model which has unidirectional stress wave. Similar to elas-plastic bars, the peak impact load on elas-plastic tubes increases with the speed of rigid body because of the expanding of plasticity. But the changing of the peak impact load on elas-plastic tube is much smoother than that on elastic tube. Because of local buckling, the peak elas-plastic impact load of rectangle tubes is always smaller than that of bars. The higher the rigid body speed and the smaller the mass ratio, the bigger the peak impact load of rectangle tubes and the longer the contact time.