The Stability And Impact Analysis Of The Light Sandwich Structures

With the development of technology, sandwich structures are abroad used to achieve light weight and sound insulation. In traffic field, honeycomb sandwich and foam sandwich are used to support the main force. Such as: The head crust of magnetically levitated train is made up of two large sandwiches with complex shape and joint, supported structures and the body crust is the same. Due to high speed(300-500km/h), the aerodynamic pressure on train is large, especially when two train encounter or go into the tunnel, the instance is worse. Then the sandwiches were in pressure field, so it's necessary to study the stability of sandwiches. At the same time, the stone strike of foam sandwich is serious. Thus, the impact of sandwiches and the stability of sandwich with damage should be studied.According to practical problem above, in this paper we study the closed-cell foam sandwich, the core of which is PMI foam; and discuss the linear, non-linear stability, the influences of the elastic modulus of core, facesheet and the thickness ratio of facesheet to core on the buckling of sandwich shell with foam core; the impact of sandwich; the stability of sandwich with damage. The exploratory works in this paper are following.i. According to strength theory and stress analysis of sandwich we use composite theory to get constitutive equation of sandwich. Then, we modify the stiffness of shell element, and we use the shell element with modified stiffness to analyze the stability of sandwich. Lastly we prove that the shell element with modified stiffness can simulate sandwich with foam core effectively.ii. We used the shell element with modified stiffness to study the non-linear stability of sandwich and discussed the influences of the elastic modulus of core, facesheet and the thickness ratio of facesheet to core on the buckling of sandwich shell with foam core. Some suggestions to enhance the stability of sandwich shell with foam core are then drawn out.iii. We studied the stone impact of sandwich with PMI core, summarized the special damages due to weak core. Developed the FE model of sandwich with damage, and carried out the non-linear stability analysis of sandwich with damages. At last, we discussed the influences of the damages on stability of sandwiches.