Torque measurements of an automotive halfshaft using micro double-ended tuning fork strain gauges

• First measurement of double-ended tuning forks (DETF) at high strains (1000 μϵ).
• Computational models accurately model strain transfer from halfshaft to DETF.
• Measured high strain sensitivity 96 ppm corresponding to 233.2 ppm/Nm.
• Metal induction bond provides superior range and sensitivity to epoxy bond.
• Epoxy bond simple to implement and provides reduced temperature sensitivity.

Double-ended tuning fork (DETF) strain gauges have potential applications in measuring a number of structural components, improving safety and reducing maintenance costs. Furthermore, their small size, high bandwidth, high shock tolerance, and extreme sensitivity make them useful for high performance applications. To demonstrate the potential of a DETF strain gauge, we bond silicon substrates with gauges to a modified automotive halfshaft, a component which is difficult to monitor due to its high stiffness and structural strength, enabling real-time monitoring of wheel conditions. Using a simple and rapid induction bonding process, we show for the first time a DETF strain gauge measuring strains of 1000 μϵ, near the design limits of the testing apparatus. We also present for the first time system level temperature dependence data for a silicon gauge induction bonded to metal. Through a combination of analytical and computational models, we are able to predict the strain transfer through the substrate to the tuning fork. By using the insights from these models combined with the experimental data presented, this work can be extended to a number of different structural components, enabling highly sensitive, ubiquitous strain sensing networks.