Wu Dafang

Low-velocity Impact Damage Analysis of Composite Laminates Using Self-adapting Delamination Element Method

Abstract On the basis of a 2D 4-node Mindlin shell element method, a novel self-adapting delamination finite element method is presented, which is developed to model the delamination damage of composite laminates. In the method, the sublaminate elements are generated automatically when the delamination damage occurs or extends. Thus, the complex process and state of delamination damage can be simulated practically with high efficiency for both analysis and modeling. Based on the self-adapting delamination method, linear dy-namic finite element damage analysis is performed to simulate the low-velocity impact damage process of three types of mixed woven composite laminates. Taking the frictional force among sublaminations during delaminating and the transverse normal stress into account, the analytical results are consistent with those of the experimental data.

Thermal Protection Performance of Metallic Honeycomb Core Panel Structures in Non-Steady Thermal Environments

The thermal protection characteristics of metallic honeycomb core panel structures in high-temperature environments are important parameters for the structure design of thermal protection for high-speed aircraft. A self-developed transient aerodynamic thermal simulation system for high-speed aircraft is used to test the thermal protection performance of metallic honeycomb core panels in a dynamic high-temperature environment at temperatures up to 950°C. The heat transfer characteristics of metallic honeycomb core panels in transient and steady states and the heat shield effects at various temperatures are determined. By considering the internal radiation of honeycomb core panels as well as the heat transfer between a metal structure and air within a honeycomb core cavity, three-dimensional finite element models are established for numerical simulations and computations of the thermal protection properties of metallic honeycomb core panels. The experimental results agree well with the numerical simulations. The credibility and effectiveness of the numerical simulation are verified. These results provide a solid foundation for replacement of expensive thermal simulations with numerical simulations to a certain extent. Several issues are discussed, such as the changes in the heat shield efficiency of the metallic honeycomb core panel in a complex dynamic high-temperature environment, the relevance of thermal protection efficiency, the rate of heating surface temperature change, and the selection of the metal surface emissivity. These findings offer important reference values for research in metal honeycomb thermal protection structures of high-speed aircraft.