PET foam core sheet is a lightweight structural core material made from polyethylene terephthalate (PET) through a physical or chemical foaming process. Used as the "middle layer" in structural sandwich composites, it combines advantages such as lightweight, high strength, heat resistance, environmental friendliness, and ease of processing. It is currently a new structural core material widely used in wind power, marine, rail transit, prefabricated building walls, and carbon fiber sandwich components.