Proposal of a simple identification method of Young’s modulus based on ball impact tests

Abstract

Young’s modulus is one of the most important mechanical properties of materials, and several methods, such as the indentation method, ultrasonic pulse method, and laser-induced surface acoustic wave method, have been developed to measure it both statistically and dynamically. However, these methods have characteristic advantages and disadvantages, including accuracy, specimen shape, environment temperature, and equipment simplicity. In this study, a simple identification method for Young’s modulus based on ball impact tests was developed. In this method, two hard balls with different Young’s moduli were impacted on a flat homogeneous isotropic target material to make their maximum contact radii equal. Young’s modulus of the target material was identified by measuring the rebound velocities and using the predetermined material properties of each ball. The fundamental equation was derived based on Hertzian contact theory. The proposed method was verified by ball impact simulations using the finite-element method and the ball impact tests. The simulations confirmed that Young’s modulus of the target identified by the proposed method agrees well with the input value, irrespective of the target material properties. In addition, the ball impact tests revealed that the proposed method exhibits the potential for identifying Young's modulus, although improvements in identification accuracy are necessary.