Method of measuring dynamic characteristics of materials and device for effecting same

A device for measuring dynamic characteristics of materials, comprising a thermocryostatic chamber with a program temperature controller connected thereto, a specimen of a material and two holders for adjusting said specimen inside said thermocryostatic chamber;

• a rod;
• a normal stress compensator attached by said rod to said holder of the specimen, for relieving normal stresses in said specimen;
• a second rod coupled to the second holder of the specimen to transmit a mechanical moment to said specimen;
• an actuating coil comprised of wire in the form of a loop placed in a uniform field of a permanent magnet to obtain a moment by means of the interaction of the current flowing through said coil and said uniform field of the permanent magnet;
• a mirror fixed to said actuating coil to follow the rotation of said actuating coil, said actuating coil being rigidly connected to said second rod to transmit a mechanical moment to said rod;
• an infralow frequency oscillator having an output with a stabilized zero-phase voltage thereacross;
• a precision attenuator;
• a galvanometer with a mirror placed in the uniform field of the permanent magnet together with the actuating coil and connected via said precision attenuator to the output of said infralow frequency oscillator with a stabilized zero-phase voltage thereacross to obtain oscillations of said galvanometer at a preset amplitude and frequency;
• an analyzer connected to said infralow frequency oscillator, a laser;
• an optical modulator;
• said mirror of the actuating coil optically associated via said optical modulator with said laser to obtain a collimated beam modulated by a higher frequency, said mirror also being optically associated with the mirror of said galvanometer;
• a prism and two differentially connected photocells with a common load, optically associated via said prism and said mirror of the actuating coil with said mirror of the galvanometer to obtain a voltage proportional to the difference between the oscillations of said galvanometer and those of said actuating coil;
• an a.c. voltage amplifier connected to said common load of the two differentially connected photocells to amplify said voltage proportional to the difference between the angles of rotation of said galvanometer and said actuating coil;
• a demodulator connected to said a.c. voltage amplifier to obtain a voltage of a preset frequency;
• a d.c. voltage amplifier with circuits for amplitude and phase correction of the voltage proportional to the control current, connected to the demodulator and the analyzer;
• a buffer amplifier with its input and output electric circuits connected to said d.c. voltage amplifier for matching said input and output electric circuits;
• a summing amplifier connected to said buffer amplifier to receive said control current;
• said summing amplifier being connected to said actuating coil to transmit said control current through the actuating coil;
• said galvanometer with the mirror, laser, optical modulator, mirror of the actuating coil , prism, two differentially connected photocells with the common load and the series-connected a.c. voltage amplifier, demodulator, d.c. voltage amplifier, buffer amplifier, summing amplifier and actuating coil comprising a closed followup circuit, said infralow frequency oscillator having an output with a stabilized zero-phase voltage thereacross and the precision attenuator comprising means for setting the ampltude and frequency of oscillations of said specimen.