Objective  In order to improve the explosion and impact resistance of the protective structures of unmanned underwater vehicles (UUVs), autonomous underwater vehicles (AUVs), air bottles, etc., the structural response and failure modes of carbon fiber reinforced plastic (CFRP) cylindrical shells under underwater explosion and high hydrostatic pressure are investigated.

  Method  A computational model of CFRP cylindrical shell implosion under the combined action of hydrostatic pressure and impact load is established using ABAQUS software and the coupled Euler-Lagrange (CEL) method. The effectiveness of the numerical simulation method is then verified by comparison with the experimental results. On this basis, the failure modes and parametric effects of CFRP cylindrical shell implosion are obtained.

  Results  The underwater implosion of composite cylindrical shells can be divided into three stages: buckling, wall contact and failure propagation. Reducing the length-to-diameter ratio of the CFRP cylindrical shell can improve the impact resistance ability and affect the failure mode of the structure. With the increase in the number of fiber layers, the static water bearing capacity and impact resistance ability of the shell structure increase. With the increase in the impact block velocity, the wall boundary contact and failure propagation of the cylindrical shell become more obvious, matrix fractures occur more frequently and the cracks show an obviously increasing trend in the lengthwise direction of the cylindrical shell.

  Conclusion  The results of this study can provide data guidance for the structural design of underwater vehicles and promote the application of composite materials in the field.