Dynamic response characteristics and failure mechanism of rectangular wind window under impact load

In the process of shock wave propagation of gas and coal dust explosion,there will be many oscillating wave crest at the fixed structures with significant overpressure and oscillation phenomenon,which have obvious damage effect on the ventilation facilities,but the dynamic damage process and mechanism are not clear. Based on the rectangular thin plate model,the dual equation of Hamilton system and the frequency equation of rectangular wind window (C-C-C-C) and its mode analysis function are established. According to the orthogonality of the vibration function and Duhame integral,the deflection dynamic distribution is obtained. Based on the Newton iterative method and MATLAB software,the vibration modes of rectangular wind window under impact load are mainly composed of the first,fifth and sixth order main modes,and the natural frequencies are obtained respectively. The dynamic distribution characteristics of stress,strain,bending moment,transverse shear force,maximum principal stress and principal strain are analyzed,which are mainly distributed in the middle of four sides and its vicinity,the center of rectangular wind window and the four corners of rectangular wind window. According to the third strength theory,it is concluded that under the impact load,the starting position of the damage of the four side fixed rectangular wind window is the central area of the four sides,and then the central area of the rectangular wind window; the development trend is mainly along the central area of the long axis of the rectangular wind window,and then along the central area of the short axis. The initial failure position of the rectangular wind window can be inferred from the first order main mode (main frequency),and the development direction and trend of the failure can be judged from the fifth and sixth order main modes. Based on LSDYNA software and PLASTIC_ KINEMATIC model,the dynamic failure process of rectangular wind window with four sides fixed is simulated and analyzed under impact load,the correctness of theoretical research results is verified,and the failure mechanism of rectangular wind window is preliminarily revealed under impact load.