Abstract
Measurement of strain of tires in-service is effective to improve reliability of tires and ABS system. Since conventional strain gages have high stiffness and require lead wires, the conventional strain gages are cumbersome for the strain measurement of the tires. Sensors of Micro-electro-mechanical systems are also usually high stiffness themselves, and those are not applied to tires. These backgrounds require a new low cost wireless sensor for tires. In the present study, a new strain measurement system utilize electric capacitance change of steel wire reinforced tires is proposed and experimentally investigated. A small oscillating circuit is embedded in the tire; deformation of the tire brings capacitance change of the tire comprises steel wire and rubber; the change of the capacitance makes the change of oscillating frequency of the oscillating circuit. Measurement of the frequency of the oscillating circuit enables us to measure the strain of the tire wirelessly. A rectangular specimen cut from a commercially available tire is adopted as a specimen. Tension test is performed and the frequency of the oscillating circuit is measured during the test. As a result, the method is experimentally proved to be effective for the wireless strain monitoring of tires.
