GB/T 31057.2-2018 "Granular materials—Test method for the determination of physical properties—Part 2: Measurement of tapped density": This standard is an important component of the series on physical property testing of granular materials. It specifies the terminology, definitions, principles, measurement apparatus, and operational procedures for tapped density testing. It is applicable to powder materials with an average particle size ranging from 5 μm to 5 mm. The test can be conducted using either the fixed mass method or the fixed volume method. By measuring the mass and volume of the powder after vibration under specified conditions, the tapped density is calculated. This provides a standardized basis for evaluating the related properties of granular materials.