Impact-acoustic evaluation method for rubber–steel composites: Part I. Relevant diagnostic concepts

Recycling and retreading is critical for reducing costs and energy consumption for the manufacture of tire casings. An effective retread requires tire casings with good structural integrity and no internal damage. This paper presents an impulse-acoustic nondestructive technique to investigate internal defects in rubber–steel composites such as truck tires. The technique employs a light impactor that taps the structure to be inspected, measuring the impact force with a load cell and analyzing the resulting sound recorded with a microphone in order to discriminate defective regions from defect free regions. Acoustic signatures of both the defective and non-defective side walls of a tire were recorded. The acoustic signatures of were analyzed and the peak amplitude and decay rates demonstrated a suitable correlation in the presence of internal delaminations. This paper seeks to presents an understanding of the fundamental principles underlying the individual measurement and analysis techniques. The results of this investigation show that the acoustic responses can be used to identify the presence of internal delaminations and also may potentially be used to determine their size and location. The effort is part of a project to develop an automated inspection system for truck tires to determine the integrity of the base structure before a retreading operation is performed.