Node-separation FEM simulation of typical spacecraft protective structure

A node-separation finite element method (FEM) for spacecraft protective structure hypervelocity impact simulation is developed in this paper. By the conversion of the mesh into coincident node mesh and adding set constraints, a node-separation FEM model is built. In the explicit integration iteration, the node sets which meet the fracture criteria are released, and then the crack is generated. By the analysis of the mesh distortion, a geometric identification approach is built. The distorted elements are deleted from the model and the stability of the method is improved. Node-separation FEM is applied to simulate the single plate hypervelocity impact problem and to analyze the influence of the impact velocity on the deformation of the impactor residual and the debris cloud shape. The node-separation FEM is also applied to simulate Whipple shield, Stuffed shield and Multilayer mesh shield. The simulated result shows good agreement with the experimental test. Various simulation examples indicate that the node-separation FEM improves the mesh distortion treatment, debris cloud simulation and secondary debris contact compared with the traditional fracture erosion FEM. The node-separation FEM is well adapted to typical spacecraft protective structure, it can be an available supplement and surrogate of Smoothed Particle Hydrodynamics (SPH) method.