含损伤复合材料AGS结构固有频率数值预测

Numerical Prediction of Frequency of Delaminated Advanced Grid Stiffened plate

通过共振峰法求解了蒙皮内含分层损伤复合材料格栅加筋板的固有频率.分别采用复合材料板单元梁单元模拟蒙皮和肋骨,结合Adams应变能法与Rayleigh阻尼相结合的阻尼模型,并引入Hertz型非线性接触单元模型来避免上、下子板间的嵌入现象,推导了求解含损伤复合材料格栅加筋结构动力响应的有限元列式.在上述模型和理论基础上,首先采用精细积分法求解含损伤AGS结构的动力响应,再由外载频率与板内最大动挠度曲线的峰值确定结构的各阶固有频率,从而为蒙皮含分层损伤AGS结构固有频率的数值预测提供了一个较为有效的途径.

The paper aims to investigate natural freque hump resonance method. The composite laminated plate ncy of delaminated advanced grid stiffened composite plates by element and the rib element are adapted to simulate the laminated plate and the ribs. Based on the composite laminated plate and beam element model considering first-order shear effect, a damping model on the basis of Rayleigh damping model in conjunction with Adams＇ strain energy method （MSE） and a Hertz nonlinear dynamic contact model to avoid the overlap and penetration phenomenon between the upper and lower sub-laminates at the delaminated region. A numerical analysis method of dynamic response for the delaminated composite plates is carried out by precise time-integration method, and then the natural frequencies are achieved when the dynamic deflections reach the hump peak. For the frequency-domain analysis provided in the former research papers, it is a difficult problem to avoid the embedded phenomenon in the mode shapes at the delamination zone, while in the current time-domain analysis, the embedded phenomenon can be successfully overcome by using nonlinear contact model. By vibration excitation test, the specimens were excited by different excited frequency and the amplitude frequency response characteristics obtained are used to extract the frequency. The extracted frequencies of the narrow delaminated composite plates measured, which agrees well with the predicted natural frequencies.