A Review of the Recent Research on the Experimental Tests of Functionally Graded Sandwich Panels

Sandwich structures usually consist of high-strength thin skins bonded to a significantly thicker, less dense, and weaker core material. Sandwich structures are most useful in engineering applications because of their ability to provide stiffness to weight ratios, such as in many aerospace and marine applications and wherever flexural rigidity is essential and drives performance parameters. This study aimed to address these issues by investigating the existing literature on mechanical experiments and sandwich panels’ recent tests. First, the survey of experimental testing of composite sandwich panels was analyzed. Second, a comprehensive study on structures made of functionally graded materials, which are the most attractive because of their lightweight and excellent energy absorption properties, was mentioned. Moreover, this article also reviews the development and application of FGM sandwich structures and different instruments and materials to demonstrate the procedures, arrangement techniques, and FGM sandwich panels’ responses. Each test can be performed on a short and an extended sample or a sample loaded in two ways, and the bending stiffness and shear mode can be determined by solving the complete deflection equations for each span or each load simultaneously. It is expected that the study will provide some necessary data and design parameters related to impact, shear, and failure mechanisms, such as core height, materials, power-law index, and skin thickness. However, the experimental work on these technologies’ practical application is still minimal, representing the main challenge and broad field of new research.