复合材料薄壁结构被广泛地应用于先进的航空航天器上, 薄壁结构在工作时会承受复杂的机械力载荷、气动载荷、热载荷和声载荷, 这些载荷会导致结构以非线性方式响应。其中, 薄壁结构在热载荷和声载荷同时作用下易发生跳变响应。本文通过使用有限元法来研究复合材料薄壁结构在热声载荷下的响应计算与特征分析。首先建立热声载荷作用下复合材料薄板振动的非线性大挠度方程, 讨论非线性恢复力项对结构自由振动的影响。其次分析了热及噪声载荷造成的结构几何非线性对板动态响应的影响, 结果表明温度会改变薄板的位移及应力响应, 改变薄板基频并使功率谱密度(PSD)谱线变宽。在强噪声环境下, 板的位移响应会产生相应变化, 但由于此时声载荷完全超过了热力项从而制约了形状恢复应力, 所以薄板的应力响应不会产生变化。
Thin-walled structures of composite material have been widely applied to advanced flight vehicles in recent years. These structures will suffer severe complex loading conditions, a combination of mechanical, aerodynamic, thermal and acoustic loads, which may lead to nonlinear response of the structures. Thin-walled structures subjected to simultaneous effects of thermal and acoustic loads tend to exhibit snap-through response. This paper presents a nonlinear finite element model to study response calculation and characteristic analysis of thin-walled structures under the combined effects of thermal and acoustic loads. The nonlinear large deflection equations of composite panel under thermal acoustic loadings are established and the influence of nonlinear recovery-stress to structure vibration is discussed. Then the effect of geometry nonlinearity caused by thermal and acoustics loadings on dynamic response of panels is analyzed. The results show that temperature will change the deflection and stress response of the panel and cause frequency shifting and broaden the PSD plot. At high noise pressure levels, deflection of the panel will change accordingly, but stress response won’t change because the acoustic pressure completely exceeds the thermal items and constrains the shape-recovery stresses.
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