Study on mechanical properties of carbon fiber honeycomb curved sandwich structure and its application in engine hood

Honeycomb sandwich structures possess many excellent characteristics such as light weight, high stiffness, high modulus and good vibrate isolation, which have became important structures for energy saving and emission reduction. However, most of the researches are concentrated on flat honeycomb sandwich structures and few of that considers the curved structures. In this paper, double-curved honeycomb sandwich core is investigated by mechanical analysis, and equivalent mechanical model is established. Detailed models of the honeycomb sandwich structure are established. Simultaneously, the corresponding equivalent models are built on the sandwich theory and curved sandwich theory, respectively. Afterward, a double-curved sandwich hood consisting of two carbon fiber reinforced plastic (CFRP) skin and Nomex honeycomb core was designed and optimized based on equivalent model and a traditional aluminum alloy engine hood. The whole optimization progress composed of free-size optimization, size optimization and stacking sequence optimization. The optimized structure with a weight reduction by 20.1% while maintaining the original rigidity. In addition, compared with the referenced aluminium alloy engine hood structure, the weight of the optimal structure was reduced 61.8% on the condition of better stiffness performance.