An Experimental Study on the Buckling Behavior of Composite Stiffened Panel under the Combined Load of Compression and Shear Using the Digital Image Correlation (DIC) Technique

The composite stiffened panel is widely utilized in aerospace applications owing to its lightweight construction and superior strength. The prediction and evaluation of mechanical properties in composite structures are highly complex due to the intrinsic diversity and structural intricacies of composites, further complicated by the nature of the loads they experience. Therefore, the analysis of the buckling modes of composite stiffened panels with openings constitutes a significant challenge in engineering applications. This paper presents a study investigating the combined effects of compression and shear loading on a typical open-hole composite T-stiffened panel. The testing procedure was monitored utilizing digital image correlation (DIC) and strain gauge measurement techniques. The results indicate that stress concentration occurred at the opening in the skin, with material damage initiating in the stress concentration zone adjacent to the opening. Local buckling manifests in the skin, characterized by interval-distributed convex or concave regions. Additionally, high-fidelity numerical simulation approaches were used to further validate the accuracy of the DIC technique, and the results of both showed excellent consistency. DIC technology proves to be both effective and efficient in measuring strain fields and out-of-plane displacement fields, as well as in determining the initiation points of failure surrounding circular cutouts under combined compression and shear loading.