Abstract

The Fast Fourier Transform (FFT) has been used increasingly in such tire tests as uniformity, ride vibration analysis, acoustic intensity measurement, and modal analysis of tire and vehicle structures. A new application for the FFT is in monitoring tire endurance and high speed tests to identify significant changes in tire structural integrity and to provide advanced warning of impending tire failure so that the test may be terminated prior to ultimate failure of the tire. Greater information concerning the initiation of failure can then be obtained than is possible by trying to reconstruct the remains of a failed tire. Continuous display of FFT analysis of tire carriage vibrations reveals one to fifteen harmonics of tire rotation frequency on a new tire, with higher harmonics growing with test time. Just prior to failure, these higher harmonics grow in unison to very high levels with a “white‐harmonic” spectrum appearing. Since the tire would then fail within 5 to 20 seconds, the test should be terminated. This paper details the techniques applied and the results obtained to date in creating a test monitoring program that will notify the test operator of significant test developments, and in automatic shutdown of tires nearing failure.