A numerical material model for composite laminate, was developed and integrated into the nonlinear dynamic explicit finite element programs as a material user subroutine. This model coupling nonlinear state of equation (EOS), was a macro-mechanics model, which was used to simulate the major mechanical behaviors of composite laminate under high-velocity impact conditions. The basic theoretical framework of the developed material model was introduced. An inverse flyer plate simulation was conducted, which demonstrated the advantage of the developed model in characterizing the nonlinear shock response. The developed model and its implementation were validated through a classic ballistic impact issue, i.e. projectile impacting on Kevlar29/Phenolic laminate. The failure modes and ballistic limit velocity were analyzed, and a good agreement was achieved when comparing with the analytical and experimental results. The computational capacity of this model, for Kevlar/Epoxy laminates with different architectures, i.e. plain-woven and cross-plied laminates, was further evaluated and the residual velocity curves and damage cone were accurately predicted.

We evaluated two numerical modelling methods based on different modelling scales in simulating the ballistic performance of composite laminates. An orthogonal continuous material model was developed and used to establish an equivalent macro-scale impact model of a projectile/composite target (uniform model). Combining the Chang–Chang failure model and tiebreak contact algorithm, the corresponding computational model for the cross-plied microstructure of composite laminates was constructed layer by layer (layered model). Using the two modelling methods mentioned earlier, a series of ballistic impact simulations were carried out for Kevlar/epoxy composite laminates, and the simulation results were compared with the corresponding experimental results. The computational capacities of the two methods were compared in terms of damage pattern, ballistic limit, residual velocity and computational efficiency. The results indicate that the uniform model can simulate the main ballistic impact behaviour of composite materials, whereas the layered model can simulate more detailed features of composite damage. Moreover, the predictive capability of the uniform model for ballistic limit and residual velocity is equivalent to that of the layered model, and the uniform model exhibits a higher computational efficiency than the layered model.

This paper proposed a multi-objective, multi-disciplinary design optimization and multi-attribute evaluation method for the manned lunar lander descent stage. A system design model is established considering multiple disciplines such as propulsion, structure, trajectory and cost. With the goal of minimizing mass, minimizing cost and maximizing velocity increment, the overall scheme for hybrid rocket motors was optimized by altering various grain shapes and feed systems, acting as an alternative propulsion scheme for the manned lunar lander. Under the same design conditions, the optimal scheme of hybrid rocket motors considering continuous and discrete attributes was studied and compared with that of liquid rocket engines to elucidate the characteristics of the hybrid rocket motors for deep space exploration. The results showed that the evaluation results obtained by considering only continuous attributes were different from those by considering both continuous and discrete attributes. The liquid propulsion scheme with liquid oxygen/kerosene is superior to the hybrid propulsion schemes due to its excellent cost and specific impulse performance when only continuous attributes are considered. However, hybrid rocket motors have shown good performance in terms of operability, manufacturability, safety and environmental protection. So, after introducing discrete attributes, the hybrid propulsion schemes show greater potential. In brief, based on the multi-attribute evaluation method considering comprehensive attributes, the hybrid rocket motor provided with tube grain and gas pressure feed system was considered as the optimal propulsion system for the lunar lander. Furthermore, the parametric analysis showed that the fuel grain outside diameter, the initial design thrust and the initial oxygen-to-fuel ratio had a significant influence on the performance of the hybrid rocket motor for the lunar lander, and in particular, the effect of the fuel grain outside diameter was more than 50%.