SU903743A1 - Method of testing material for impact compression - Google Patents

Description

(54) METHOD FOR TESTING MATERIAL FOR IMPACT

COMPRESSION

one

The invention relates to the investigation of the strength properties of materials, in particular, to methods for testing a material for shock compression.

The known method of shock compression testing, which consists in striking the end of a cylindrical sample, records the propagation of elastic compression waves over the sample and is used to judge the stresses in the sample tl J.

The disadvantage of this method is that with such a test, only a monotonous stress state is realized.

The closest to the invention in technical terms is the method of testing a material for shock compression, which consists in applying a flat shock to a plate sample and measuring the load on the sample using a dynamometer, the magnitude of which determines the stress in the sample. In the known method, the loading is subjected to a continuous plate-like sample 1.

The disadvantage of this method is the impossibility of testing under conditions of plane strain.

The purpose of the invention is to conduct a compression test under plane strain conditions.

This goal is achieved by using a sample with evenly spaced variable through slots, the dimensions of which are chosen from

t77S —XB and S “ct / 2,

where I is the length of the slot;

S is the plate thickness;

b — width of the jumper;

c is the speed of sound in the sample material;

Claims (2)

t is the time from the start of loading to the moment of determining the voltage in the sample. 39a, the load on the sample is measured at the center of the middle web. Fig. I shows a sample for testing, and Fig. 2 shows a test circuit. The method is carried out as follows. A plate-like sample is used, for example, in the form of a circular plate with thickness S. In sample 1, parallel through slots 2 are uniformly spaced out with a step h and bridges 3 with length I and width L are formed between the slots. The sample is mounted on a dynamometer, which is an assembly of two steel plates 4, between which a sensor 5, for example, a dielectric one, is arranged. The loading of the specimen is carried out by striking a flat die 6, for example, in a pneumatic-powder installation. The narrow strip of bridges is deformed under plane deformation conditions. The width of the jumpers 3 is chosen from the condition that the force of deformation of the sample does not cause a noticeable plastic deformation at the contact surface with the striker 6 and dynamometer. Step h is selected from the condition of maintaining the gap between the bridges 3 when they are deformed (for example, at deformation 507, the width increases by 50% and, consequently, -H 7 1.5 V). The deformation of the sample is accompanied by the propagation of a wave along the striker 6 and the dynamometer. At a distance from the contact surface of the dynamometer with a sample equal to approximately one step h, the wave in the dynamometer is close to flat. The homogeneous stress-strain state in the sample is determined by the result of a repeated short run of stress waves along the height of the sample, i.e. the force of deformation of the dynamometer will correspond to the force of deformation of the sample only after repeated wave travel, hence to accurately determine the pressure at time t, with the corresponding signal acquisition time from the sensor, the condition S Ct Ct / 2 is also required. influenced by the effects of radial inertia, the width of the jumpers 3 is chosen approximately equal to its height b S. The pressure value P is measured at the center of the middle ridge 3. According to the measured pressure value P in the dynamometer at The plane wave voltage is the stress (J of the sample is determined from the ratio ph b (Y, from which G ph / b. The method of testing materials for shock compression allows high-speed tests of materials for compression under conditions of plane deformation of the sample, and the accuracy of the determination of stress Due to the reasonable choice of sample sizes. Formula of the method of testing the material for shock compression, concluded that a flat impact was applied to the plate sample and a load on the sample was measured using a dynamometer by determining the stress in the sample, which is different from the fact that, for the purpose of conducting the compression test under plane deformation conditions, the sample is used - with evenly spaced parallel through slots, the dimensions of which are chosen from the conditions E7 S ctb {i S "ct / 2, where i is the length of the slot; S is the plate thickness; B is the width of the web between the slits; c is the speed of sound in the sample material; t is the time from the beginning of loading to the moment of determining the voltage in the sample, and the load on the sample is measured at the center of the middle jumper. Sources of information taken into account in the examination. Davis P.M. Waves of stresses in solids. M., IIL, 1961, p.50. 2. Ibid, p. 20, 34-37 (prototype) Ф11Л.1 tput-z