Measurement of tiny moment of inertia based on flexure hinge for automobile collision testing

Abstract The moment of inertia is a critical parameter for determining the motion state of an object and achieving precise control. At present, measurement techniques for the moment of inertia of large and heavy objects (greater than 0.5 kgm 2 ) are very mature. However, it is still a challenge to achieve high precision for smaller objects (less than 0.5 kgm 2 ). In this paper, a measuring device based on flexure hinges is proposed to achieve high-accuracy measurement of tiny moments of inertia, without additional friction. A theoretical model of measurement is developed and optimised to obtain the rotational inertia by measuring swing periods. The experimental results show that the maximum load of the device is 20 kg, and the resolution reaches 4 × 10 −5 kgm 2 . For a 5 kg head model, the moment of inertia was measured to be 0.011 58 kgm 2 , with a combined standard uncertainty of 0.000 29 kgm 2 .