Tire hardness modeling based on longitudinal ultrasonic velocity using the Gaussian Process Regression

Non-destructive tests have capabilities to investigate and identify the defects and properties of the test piece without changing the physical and mechanical properties of the sample. Non-destructive ultrasonic test has been used in many researches to study different material properties such as mechanical and structural properties. The ultrasonic wave propagation velocities have been widely used for metal hardness measurement. In this study, for the first time nondestructive ultrasonic testing has been employed to measure the hardness of rubber compounds using Gaussian Process Regression. Eighty seven samples with different formulations were prepared and vulcanized. After the vulcanization the compound hardness of the samples and the longitudinal ultrasonic wave velocity through them was measured. Result of Gaussian Process Regression model show that this model perform well and able to predict tire hardness. Also investigating repeatability shows that this method can be a good alternative for conventional hardness testing method in measuring hardness of rubbers. According to low time of test in this method and no need to sample preparation, the proposed method can be used in tire production lines.