This paper focuses on the isogeometric vibration analysis of curvilinearly stiffened composite panels. The stiffness matrices and the mass matrices are derived using the first-order shear deformation theory (FSDT). The present method models the plate and the stiffener separately, which allows the stiffener element nodes to not coincide with the plate shell-element nodes. The stiffness and mass matrices of a stiffener are transformed to those of the plate through the displacement compatibility conditions at the plate/stiffener interface by interpolation using NURBS basis functions. Cutouts are modeled using a single NURBS patch generated by creating a ruled surface between two curves. The proposed formulation is first validated by comparing it with available literature. The effects of width-to-thickness ratio, fiber orientation, ply layups, shape and size of the cutouts and the boundary conditions on the response of stiffened composite plates are then analyzed and the numerical results are used to derive useful conclusions.

翻译：本文聚焦于曲线加筋复合材料板的等几何振动分析。基于一阶剪切变形理论（FSDT）推导了刚度矩阵与质量矩阵。该方法将板与加筋肋分别建模，使得加筋肋单元节点无需与板壳单元节点重合。通过NURBS基函数插值，利用板/加筋肋界面处的位移协调条件，将加筋肋的刚度矩阵与质量矩阵转换至板的对应矩阵。开孔通过在两曲线间创建直纹曲面生成单一NURBS片进行建模。首先通过与现有文献对比验证所提公式的正确性，随后分析了宽厚比、纤维取向、铺层顺序、开孔形状与尺寸以及边界条件对加筋复合材料板响应的影响，数值结果被用于推导有价值的结论。