SU991248A1 - Method of determination of artical durability in cyclic compression - Google Patents

Description

The invention relates to the study of the strength properties of a material. and products, and in particular to methods for determining the durability of the product under cyclic compression.

A known method for determining the compressive strength of a material is that the specimen is loaded with compression prior to fracture, the fracture force and the cross-sectional area of the specimen are recorded and the strength of the Cl material is judged by it.

The disadvantage of this method is the lack of information about the behavior of the material under cyclic loading of the sample.

The closest to the invention to the technical essence and the achieved result is a method for determining the durability of a product under cyclic compression, which means that before the destruction of samples of a material material, cyclical alternating bending with a constant amplitude of stresses is destroyed, the stresses and the number of cycles before destruction are recorded samples and judged on the durability of the product. In the known method, the sample material under bending undergoes stretching, compression and durability under cyclic compression, and is determined by durability under cyclic stretching 2.

The disadvantage of the known method is the low accuracy of determining the durability of the material and product. During cyclic compression.

The purpose of the invention is to improve the accuracy of determining the durability of the product under cyclic compression.

This goal is achieved by the fact that in the method of determining the durability of lzdeli under cyclic compression, which consists in loading the samples from the material of the product to destruction by cyclic alternating bending at a constant amplitude of stresses, the stresses and the number of cycles are recorded until the samples are destroyed and He is judged on the durability of the product, determines the ultimate strength of the product in compression, tests an additional group of samples when loaded with a bend at a constant load. to destroy, establish dependencies of distributions of the probability of destruction for example

Claims (2)

30 bends with a constant loading rate and the probability of specimen longevity with symmetrical loading cycles, and the product durability under cyclic compression is judged by the indicated distributions m and the ultimate strength of the product. The method is carried out as follows. The non-destructive method, for example, on the basis of measuring the parameters of acoustic emission, determines the ultimate compressive strength. In this case, the value of 6 takes into account the scale factor affecting the strength of the product. In addition, samples for cyclic bending tests are made from the same material as the product material. One group of samples is loaded to destruction by cyclic alternating bending with a symmetric cycle and a constant amplitude (in tension. At the same time, the number of N cycles before the destruction of samples is recorded and, depending on the test result, the probability distribution 52 is determined, the durability at a certain (s). Additional a group of samples is tested under bending by a constant loading rate before destruction and the dependence of the probability distribution of destructive stresses jp is established. Dependencies and 57p calculations give dependencies, 3b "capacity, time-relative reduction of the strength of the bvrz cycle on the loading parameter e1 / (BO- In the operational parameters of the compression load-loading cycle, dN / d (jBp integrate, use that at the time of destruction the ratio, md4 / ci p is equal to one, and determine the durability of the product under cyclic compression. Using the invention improves the accuracy of determining durability under compression by conducting additional tests at a constant speed. loading and taking into account the relationship between the change in strength under cyclic loading, the durability of the material and the ultimate compressive strength of the product. Claims The method of determining the durability of a product under cyclic compression, is that the samples from the material of the product are loaded to destruction by cyclic alternating bending at a constant amplitude of stresses, the stresses and the number of cycles are recorded to the destruction of the samples, and the life of the product is measured characterized in that, in order to increase the determination accuracy, the ultimate compressive strength of the product is determined by a non-destructive metol, an additional group of specimens is tested during loading and bend with a constant loading rate to failure, determine the dependencies of the distributions of the probability of destructive stresses under bending with a constant loading rate and the probability of durability of the Samples with symmetrical loading cycles, and the durability of the product under cyclic compression is judged by the specified distributions AND strength products. Sources of information taken into account in the examination 1. Semushkin b.G. Mechanical testing of metals, M., Higher School, 1972, p. 114. 2.Ponomarev S.D. and others. Strength calculations in mechanical engineering. M., Mashgiz, 1959, p. 589-591 (prototype).