GB/T 33100-2025 "Test Method for Belt Flex Fatigue of Adhesive-Dipped Cord" specifies the method for determining the fatigue resistance of skeleton materials for rubber products, such as adhesive-dipped cords, adhesive-dipped yarns, and cords. This method uses a belt flex fatigue machine to repeatedly flex vulcanized strip-shaped samples bonded with rubber, simulating the dynamic fatigue process that materials undergo in actual use. After the fatigue test, a tensile testing machine (also known as an electronic universal testing machine) is used to measure the adhesive peel force of the sample and the breaking strength of the peeled cord. Key indicators, such as the breaking strength retention rate, are calculated to comprehensively evaluate the material's fatigue resistance. This standard provides a unified testing basis for quality control and research and development of skeleton materials for rubber products, such as tires and rubber hoses.