In this article, a multi-crack detection method, which is based on natural frequency changes and the concept of modal strain energy, is for the first time developed for the general cross-section swept tapered wings under coupled bending-torsional vibration and applied to the solid and thin-walled airfoil cross-section wings. The presented method is able to handle the problems with an unknown number of cracks and predicts the number of existent cracks, their locations and depths by optimization of an appropriate objective function. The stress intensity factors of airfoil-shaped crack surfaces are obtained using an approximation method. Inputs of the detection method are natural frequencies of uncracked and cracked wings which are calculated by using a mathematical model and finite element method software ANSYS, respectively, and validated by comparison with former research studies. In the mathematical model, the Rayleigh–Ritz method is used to calculate the coupled bending-torsional mode shapes of the uncracked wing and their corresponding natural frequencies. Results demonstrate that the proposed method has precisely predicted the number, locations and depths of cracks in all case studies.

在本文中，首次开发了一种基于自然频率变化和模态应变能概念的多裂纹检测方法，该方法针对耦合扭转-扭转振动下的普通横截面后掠锥形机翼进行了研究。实心薄壁机翼横截面机翼。所提出的方法能够处理裂纹数量未知的问题，并通过优化适当的目标函数来预测存在的裂纹数量，裂纹的位置和深度。使用近似方法获得翼型裂纹表面的应力强度因子。检测方法的输入是未破裂和破裂的机翼的固有频率，分别通过数学模型和有限元方法软件ANSYS计算得出。并通过与以前的研究比较进行验证。在数学模型中，使用Rayleigh-Ritz方法计算未破裂机翼的弯曲扭转模态耦合形状及其相应的固有频率。结果表明，在所有案例研究中，该方法都能准确预测裂纹的数量，位置和深度。