Experimental Prediction of Buckling Load of Rectangular composite Plate with through-the-width Delamination using Nondestructive Vibration Correlation Technique

One of the most important analysis during designing composite structures is its stability under compressive loads or buckling behavior analysis. Vibration correlation technique is one of the most accurate method to determine buckling load of structures non-destructively. The vibration correlation technique is a non-destructive method based on a modal analysis which predicts the buckling load of the structure by means of measuring the natural frequencies under different loads. One of the most common damages occurring to composites during manufacturing or in-service is debonding between layers known as delamination. Consequently, investigation of buckling of delaminated structures is in a great importance and in this study has tried to cover this issue experimentally using non-destructive vibration correlation technique and comparing its results with common destructive buckling tests. In fact, this paper investigates applicability of applying VCT on damaged structures. In order to reach to this goal, rectangular composite plates with through-the-width delamination using VARTM process has been fabricated. The buckling load of each specimen was determined using common destructive buckling test. Consequently, In order to measure the natural frequencies at different loadings, experimental modal analysis was conducted. The results show that the vibration correlation technique has a very good accuracy in determining the buckling load of the delaminated composite plate and the difference percentage between destructive tests results and the non-destructive vibration correlation technique results which is less than 8% approves it.