Precision Materials Tester Using a Pendulum and a Digitizer

A practical and low-cost method of accurately measuring an impact force is proposed. In this method, a mass, which is suspended using a newly developed pendulum mechanism with negligible friction and a stable restoring force, is made to collide with the object under test. The Doppler frequency shift of a laser beam reflected by the mass is calculated from the output signal of an optical interferometer whose waveform is recorded using a digitizer. The velocity, position, acceleration and inertial force of the mass are calculated from the frequency. The performance of the proposed method is demonstrated by evaluating the viscoelasticity of a small gel block under an impact load