The Design And Manufacture For Composite Frangible Cover

The cover of missile launcher is a key factor in increasing the missile combating reaction capacity, so the proper cover design is very important. It could be quickly opened while the missile is launching, so it needs with high quality of tightness, bearing pressure , easy installation , self-extinguishing, erosion resistance, resistancetoageing and etc. In order to fulfill the above requirements, the cover of missile launcher usually adopt the mechanical seal, explosive bolt etc in the past, but there are shortcomings with these covers, for instance, the mechanical seal should open with hydraulic pressure system, complex mechanism not only increase the weight of launcher but also waste time. explosive bolt is faster than mechanic seal, but the reload and maintenance are more complicated, further more it has to be transported by pyrotechnics, causing difficulty in storage and transportation.Using frangible cover can light the missile carrier. Generally the structure composite material should satisfy the criteria of strength and stiffness under loading. In the defense industries, there is a kind of structure which should has a certain strength and stiffness to meet the need of working condition; in another situation, it must be ruptured under a certain impact. So there are contradictions in designing frangible cover. On one hand, the cover must withstand certain pressure, namely needs to have the enough intensity; on the other hand, it could be broken down under slight force. The propose of this article is to seek an optimum solution to these two aspects to ensure the cover to meet the requests of forming rules of the fracture and withstand the pressure.6 types of cover with different structure designs were studied in this paper which were manufactured by composites. Directional fracture is carried out under the stress concentration through regular cracks which are created by manual work molding. Then numerical simulation of the covers were carried out under the working pressure by finite element analysis , the performance of the cover was illustrated by the max displacement, stress, strain in the central point of cover under the pressure. Dynamic simulations were carried out to show the process and the max displacement, stress, strain, curve of reaction force with time using LS-DYNA in order to verify the covers whether it conforms the design requirement or not. Finally experimental results were compared with numerical simulations by LS-DYNA.The results indicated that it is possible to meet the design requirements with composite materials. Under the specific impact, the bursts of the fragile cover alongthe weak area avulsion has the rule of four parts and flew away in a short time and theforce of percussion was smaller than safety standards, so it could meet the needs ofsafety and reliability during impact, the design of the cover could achieve desiredexpectations.