Thin-walled composite structures operating in the post-buckling regime needs a thorough understanding of their stability behavior and failure mechanisms. For the accurate prediction of the collapse loads, one needs to account for the damage evolution precisely. In the current study, we have proposed a unified and generic numerical modeling approach that accounts for both the intra and inter-laminar damage modes in stiffened CFRP panels. A 3D finite element based progressive damage model (PDM) is proposed to simulate the collapse behavior of the single blade stiffened composite (SSC) CFRP panels with and without embedded de-bonding defects under uniaxial compression loading. A user-defined material subroutine based on 3D Hashin failure criteria is developed in Abaqus software to study the evolution of intra-laminar damages in SSC panel. Further, the skin-stiffener bonded interface, the inter-laminar interfaces in the skin, stiffener, including the noodle region, is modeled using the cohesive zone elements to simulate the de-bonding/delamination growth. The stability response and collapse load results obtained using the proposed PDM are compared with the experimental observations. Also, the damage evolution, failure mechanisms, the ultimate load, and the corresponding displacement data obtained from the developed PDM are validated with the experimental estimates. A comprehensive damage assessment involving the ultrasonic C-scans, infrared thermograms, and micrographic study is also carried out to supplement the PDM predictions. Thus, the proposed PDM is generic in terms of damage studies and can be used for investigating the collapse behavior of CFRP panels with multiple stiffeners.

在后屈曲状态下运行的薄壁复合结构需要对它们的稳定性和破坏机理有透彻的了解。为了准确预测倒塌载荷，需要精确地说明破坏的演变。在当前的研究中，我们提出了一种统一的通用数值建模方法，该方法考虑了加筋CFRP板中的层内和层间损伤模式。提出了一种基于3D有限元的渐进损伤模型（PDM），以模拟单叶片加劲复合材料（SSC）CFRP面板在单轴压缩载荷下具有和不具有嵌入的脱胶缺陷的坍塌行为。在Abaqus软件中开发了一个基于用户定义的3D Hashin破坏准则的材料子程序，以研究SSC面板中层内损伤的演变。进一步，蒙皮-加劲剂粘合界面，蒙皮中的层间界面，包括面区域在内的加劲剂，是使用内聚区元素模拟脱粘/分层增长的模型。使用建议的PDM获得的稳定性响应和崩溃荷载结果与实验观察结果进行了比较。同样，从发展的PDM获得的损伤演变，破坏机理，极限载荷和相应的位移数据也可以通过实验估算得到验证。还进行了包括超声C扫描，红外热像图和显微照相研究在内的全面损伤评估，以补充PDM预测。因此，提出的PDM在损伤研究方面是通用的，可用于研究具有多个加劲肋的CFRP面板的塌陷行为。