Studies On Dynamic Response And Heat Transfer Of Metallic Honeycomb Structures

Metallic honeycomb thermal protecting system is the key technology and development trend for reducing the cost of Reusable Launch Vehicles. A honeycomb sandwich structure, which is the first protecting layer of the MTPS, is generally consisted of honeycomb cores and facesheets covering on the top and bottom, with its abilities of loading capacity and thermal protecting. As the typical2D lattice structures, metallic honeycomb structures have many advantages such as high specific strength and specific modulus, good performances in anti-fatigue and heat stability, high efficiency in energy absorbing as well as the flexibility of optimizing design, etc. Thus, they had been widely used in aeronautics, astronautics, mobile vehicles, ships, architectures and so on.In this paper, we studied the dynamic response and heat transfer in metallic honeycomb sandwich structures. First, a modal analysis was performed and the relationships to natural vibration characteristics by size effect and material choosing were introduced. Frequencies and error estimating between different elements of equivalent laminated panels showed that the equivalent modeling was simple and reasonable. Then, analytical method was applied to solve the variance response of the structures under the exciting load of limited band-width white noise whose average value is zero. The Power Spectrum Density and variances of modal response with different parameters were gained and results showed that solutions by analytical methods and FEM were matched well. Studies on parallel computing efficiency of FEA for large scale structure’s dynamics were implemented and it showed that besides the algorithm optimizing, choosing suitable type of computers and number of CPUs were also very important for upgrading the computing efficiency. At last, to find the thermal-structural coupling effect of honeycomb sandwich structures, we solved the temperature fields and thermal stresses under high temperature and large heat flux boundary conditions respectively. Besides, thermal modal analysis under prestress was performed as well. Results showed that when the temperature level of the honeycomb cores was high enough, the heat radiation in cores could not be ignored. Temperature fields and thermal stresses could make the natural frequencies decline, they had large influences to the structure’s vibration characteristics and the thermal-structural coupling effect acted evidently.