SU1552088A1 - Apparatus for investigating mechanical characteristics of materials - Google Patents

Abstract

The invention relates to the testing of the mechanical properties of materials and can be used to determine their mechanical characteristics. The purpose of the invention is to make it possible to determine third order elastic moduli. The device measures the velocity of the longitudinal acoustic waves and the deformations of the sample of the material under investigation at various loads, from which the modules of the third order of material are calculated. 1 il.

Description

The invention relates to the testing of the mechanical properties of materials and can be used to determine their mechanical characteristics.

The purpose of the invention is to make it possible to determine third order elastic moduli.

The drawing shows a block diagram of a device for studying the mechanical characteristics of materials.

The device contains ngecc (not shown) with fixed 1 and movable 2 punches designed to compress the samples under study, emitting 3 and receiving 4 transducers of longitudinal oscillations mounted respectively in fixed 1 and movable 2 punches, sequentially connected synchronizer 5 and generator 6 pulses, the output of which is connected to the radiating transducer 3 longitudinal vibrations connected to the output of the receiving transducer 4 longitudinal vibrations serially connected amplifier 7,

detector 8, comparator 9 and meter, 10 time intervals, element OR 1 1, strain gauge 12 and the first 13 and second 14 strain gauges-j connected to its outputs, designed to measure, respectively, the longitudinal and transverse deformations of the surface of the sample under study connected to the second pulse generator 15 and a shear oscillation transducer 16, a third pulse generator 17 and a second shear oscillating transducer 18, the first 19 and the second 20 receiving transducers in series shear-wave oscillators whose outputs are connected to the input of amplifier 7. The first output of synchronizer 5 is connected to the first input of the element OR 11, the second output of synchronizer 5 is connected to the inputs of the second generator 15 of pulses and to the second input of the element OR 11, the third output of synchronizer 5 is connected to the input the third generator 17 and the third input element

oh

(L

OR 1 I, the output of which is connected to the trigger input of the meter 0 time intervals, and the fourth output of the synchronizer 5 is connected to the trigger input g of the strain gauge 12. The first radiating 3 and receiving 19 transducers of shear oscillations and repeat the radiating 18 and receiving 19 transducers of shear oscillations form two pairs transducers of recipients with mutually orthogonal polarization, directed respectively parallel and perpendicular to the direction of compression of the sample under study 21 .15

The device works as follows.

Synchronizer 5 alternately generates sync pulses for starting generators 6, 15 and 17 and strain gauge 12. Simultaneously with starting generators 6, 15 and 17, an OR pulse is fed through the OR element to the trigger input of the meter 10. The generators 6, 15 and 17 alternately excite the transducer 3 of the longitudinal oscillations and the transducers 16 and 18 of the shear vibrations with mutually orthogonal polarization. Sample 21 is alternately probed by a longitudinal acoustic wave and shear waves with a polarization parallel and perpendicular to the direction of compression of the sample under investigation, carried out by a press. The acoustic waves passing through the sample 21 are received by the receiving converters 4, 19 and 20. The signals from their outputs are amplified by the amplifier 7, detected by the detector 8 and fed to the input of the comparator 9. The signal from the output of the latter stops the meter in 10 time intervals. In the JBKHM manner, at the output of the latter, information is received in succession on the propagation time in the sample of a longitudinal acoustic wave and two shear waves with a polarization parallel to and perpendicular to the direction of compression of the sample. Then, using the fourth synchronizer pulse of the synchronizer 5, a strain gauge is triggered, measured using strain gauges 13 and 14, the longitudinal and transverse relative deformations of the sample 21 "These measurements are carried out for a number of loads specified by the press.

0

five

g 5

0

35

40

45

50

55

R

Third order elastic moduli

 GpMepDeL with taking into account the measured values from the ratios

1 PVij + Cijk6mm Ј, „,,

where C ;: second-order elastic moduli of the unloaded material, (i is the direction of propagation of the elastic wave; j is the direction of oscillation of the particles in the wave; i, j, m is 1.2, 3);

density of the studied material; V: | - speed ultrasound

waves; relative deformations.

Claims (1)

Invention Formula A device for studying the mechanical characteristics of materials, comprising a press with fixed and movable punches designed to compress the specimens examined, radiating and receiving longitudinal oscillation transducers mounted coaxially in fixed and movable punches, respectively, connected in synchronizer and pulse generator, the output of which is connected to the radiating transducer longitudinal oscillations connected to the output of the receiving transducer longitudinal oscillations An amplifier, a detector, a comparator and a time interval meter, an OR element, a strain gauge and first and second strain gauges connected to its outputs, designed to measure, respectively, the longitudinal and transverse deformations of the surface of the sample under study, in order to make it possible to determine the elastic moduli the third order, it is equipped with series-connected second pulse generator and a shear-wave emitting transducer; data of the third pulse generator and the second emitting transducer of shear oscillations, the first and second receiving transducers of shear oscillations whose outputs are connected to the amplifier input, the first synchronizer output5 pa is connected to the first input of the OR element, the second output of the synchronizer is connected to the inputs of the second pulse generator and to the second input of the OR element, the third output of the synchronizer is connected to the input of the third generator and to the third input of the element OR whose output is connected to the trigger input of the time interval meter, the fourth output synchronizer 520886 connected to the trigger input of the strain gauge, and the first emitting and receiving transducers of shear vibrations and the second emitting and receiving transducers of shear vibrations form two pairs of transducers with mutually orthogonal polarization, directed respectively parallel and perpendicular to the direction of compression of the sample.