Identification of Damage Size Effect of Natural Frequency on Sandwich Material using Free Vibration Analysis

One of the most innovative developments in the field of advanced materials is sandwich materials. Sandwich material applications need standard requirements to be applied to marine structures, especially on ship construction. Sandwich material research is conducted on a laboratory scale to obtain the appropriate material composition in its development. In the process of developing this material, the material can be damaged. Most damage occurs in the core material, which results in difficulties in the identification process. This study compares damage identification methods based on free vibration analysis on the side sandwich plate of the ship’s hull. Damage-based identification is carried out to determine the response of vibration to the damage that occurs. Moreover, the method in this research uses a numerical approach and experimental vibration measurement. Numerical modelling is used to determine the appropriate boundary conditions and is shifted in experimental measurement. Damage modelling assumes that the material experiences core failure with a numerous variation model. Quantification of damage on the core correlates with natural frequency reduction due to a decrease in the stiffness of the sandwich material. Hence, the difference in the deviation value is used to determine the accuracy of damage identification.