Research On Failure Mechanism Of Bursting-type Composite Canister Cover

With the rapid development of National Defense Industry, it becomes much more difficult tomeet the requirement of the quick-reaction capability of missile force, which mainly depend on thelaunching system. As the important component of launching system, canister cover is the key ofresearch. Although the research of composite canister cover grows rapidly, especially the compositefragile cover, the actual application of the structure always lags behind the developed countries.Because of this, this paper studies the failure mechanism of composite fragile cover in the case ofbreaking though to provide the reference to design the fragile cover.Firstly, the common composite fragile cover is analyzed using finite elements simulation methodto get the main load and its distribution. And the result shows that the failure and separation of thejoint in the weak area results from the circular bending moment.Secondly, joint specimens of different weak area types are molded using RTM technology toconduct the four-point bending test. The bending property of joint is studied from the test phenomenaand analysis of the test results.Thirdly, based on composite progressive damage analysis and Cohesive contact method, a newprogressive damage analysis method is proposed to simulate the proceed of bending though usingFEM. The bending mechanical property and the failure mechanism of three kinds of joints areresearched using this method. And the cohesive behavior function in the ABAQUS contact module isused to simulate the mechanical behavior of adhesive interface. The constitutive relation of compositeis programmed in the UMAT subroutine, which was used to research the failure mechanism of jointunder bending by the finite element model of joints. The failure mechanism including the damageposition, proceed, cause and failure mode and the influence of different structure and its size on thestrength and stiffness of joints are studied.Finally, a new weak area design flow applied the failure mechanism of the cover is proposed toimprove the empirical method. For the new cover, the FEM is used to analyze the distribution ofbending moment in the broadside under different loads, which used as the design boundary of theweak area. A database of bending strength of different joints is established by analyzed the new designwith different structure parameter to support of designing the weak area. According to the distributionof bending moments and the database of joint strength, an envelope line of design is fitted to make thedesign scheme of the weak area. The breaking though test and pressure bearing test are carried out toverify the FEM method and the reliability of design flow, and most importantly the practicability offailure mechanism of the cover is proved.