Shipborne Safety Assessment Of Solid Rocket Motor Composite Shell

The development of naval military forces has prompted shipboard equipment to move from offshore to the open sea,facing a more severe and complex marine environment.As the main bearing structure of most missiles,the solid rocket motor shell also needs to be improved.Carbon fibre composite material has the characteristics of strong weather resistance,light weight and high strength.As a solid rocket motor shell,it can effectively improve the manoeuvrability,environmental adaptability and low vulnerability of the missile.However,for missiles with small diameters and large aspect ratios,due to the compact structure,the connection between composite materials and metal parts will face the problem of large volume or insufficient strength if the traditional connection method is adopted.Meanwhile,to prevent the chain reaction of the shipboard ammunition depot under accidental stimulation,the composite shell also needs to have vulnerability performance under high internal pressure.Therefore,it is necessary to carry out shipborne design and safety evaluations of the composite shell of solid rocket motors,which lays a foundation for the development of shipborne missile weapon equipment.Based on this,this paper mainly carried out the following work:(1)The overall stiffness and strength model of the composite shell is established,and the damage of the composite material is judged by using the USDFLD subroutine and the maximum stress criterion.The analysis results show that the overall strength of the composite cylinder can be effectively carried under the severe service load,and there is only slight debonding and delamination damage in the external load part and the initial part of the composite shell and the two ends of the ring.The stiffness and strength test results of the composite shell test piece are in good agreement with the simulation results.(2)According to the characteristics of the compact structure of the missile,a nailed end ring structure is designed.Through integrated winding forming with the composite cylinder,an effective connection between the large opening end ring and the composite cylinder is realized.The connection strength model of the composite shell with both ends of the ring,hanging and wing metal parts is established.The safety under their respective design loads is analysed,and the weak points are designed and reinforced.The USDFLD subroutine and Hashin criterion are used to analyse the progressive damage of the connecting structure at both ends of the composite shell.The results show that the ultimate strength of the composite shell under axial tensile load is 997 MPa,the failure mode is axial fibre fracture,and the composite shell is separated from the rings at both ends.(3)The ship-borne storage vulnerability assessment of the composite shell was carried out,and a high-speed impact model of the composite shell with ammunition and thermal insulation lining was established.By writing the VUMAT subroutine and using the Hashin criterion to determine the damage of the composite shell,the mechanical response,damage mechanism and energy loss of the composite shell under the impact of fragments at one speed and two angles were analysed.The results show that the composite shell can release the internal pressure in time under the high-speed impact of the fragment.The main damage mechanism of the composite shell is fibre compression damage and tensile and compressive damage of the matrix.The material loss of the composite shell is larger when the fragment is impacted by the attitude angle,and the internal pressure and delamination damage of the composite shell are larger when the vertical impact.