SU949487A1

SU949487A1 - Method of determination of material stressed state

Info

Publication number: SU949487A1
Application number: SU792755298A
Authority: SU
Inventors: Виталий Николаевич Максимов
Original assignee: Таганрогский радиотехнический институт им.В.Д.Калмыкова
Priority date: 1979-04-15
Filing date: 1979-04-15
Publication date: 1982-08-07

Description

Изобретение относитс к неразрушающему контролю и может быть использовано дл определени остаточных и рабочих механических напр жений в поверхностных сло х твердых тел с помощью упругих волн.The invention relates to non-destructive testing and can be used to determine residual and working mechanical stresses in the surface layers of solids by means of elastic waves.

Известен способ измерени напр жений в твердых телах, заключающийс в том, что измер ют скоро.сть распространени ультразвуковых продольных и различно пол ризованных сдвиговых волн в исследуемом материале и по изменению этой скорости суд т о напр жении в твердом теле 1.The known method of measuring stresses in solids is that they measure soon the propagation of ultrasonic longitudinal and variously polarized shear waves in the material under study and judging by the change of this velocity, the stress in the solid 1.

Однако способ имеет низкую точность измерени , св занную с тем, что изменение скорости распространени упругих волн, вызванное напр жением , соизмеримо с изменени ми, вызванными неравномерностью структуры материала.However, the method has a low measurement accuracy, due to the fact that the change in the velocity of propagation of elastic waves caused by stress is commensurate with the changes caused by the unevenness of the structure of the material.

Наиболее близким к изобретению по технической сущности и достигаемому результату вл етс способ определени напр женного состо ни материала , заключающийс в том, что в контролируемом изделии возбуждают упругую поверхностную волну, принимают ее в различных направлени х от точки возбуждени , фиксируютThe closest to the invention to the technical essence and the achieved result is the method of determining the stress state of the material, which consists in the fact that the controlled product excites an elastic surface wave, takes it in different directions from the point of excitation, fixes it

параметры этой волны и по ним суд т о направлении в контролируемом изделии ЕЗ.the parameters of this wave and from them judge the direction in the controlled product E3.

Недостатком способа вл етс низка точность измерени из-за вли ни на скорость распределени поверхностной упругой волны режимов механотермической обработки издели .The disadvantage of this method is low measurement accuracy due to the effect on the speed of distribution of the surface elastic wave of the modes of mechano-thermal treatment of the product.

Цель изобретени - повышение точ10 ности измерени .The purpose of the invention is to improve the measurement accuracy.

Поставленна цель достигаетс тем, что согласно способу определени напр женного состо ни материа-. ла, заключающемус в том, что в .конт15 ролируемом изделии возбуждают упругую поверхностную волну, принимают ее в различных направлени х от точки возбуждени , фиксируют параметры этой волны и по ним суд т о напр 20 жении в контролируемом изделии, возбуждают упругопластичную волну, при которой в контролируемом изделии по вл ютс необратимые пластические деформации, измер ют ампли25 туду этой волны и по разнице между пределом текучести исследуемого материала и амплитудой волны определ ют напр жение в твердом теле.This goal is achieved by the fact that, according to the method of determining the stress state of a material, is. This means that, in the contour of the product being rolled, an elastic surface wave is excited, taken in different directions from the point of excitation, the parameters of this wave are recorded and the stress on the controlled product is determined in them, the elastic wave is excited at which irreversible plastic deformations appear in the controlled product, the amplitude of this wave is measured, and the stress in the solid is determined from the difference between the yield strength of the material under study and the amplitude of the wave.

Сущность предлагаемого способа The essence of the proposed method

Claims

30 is as follows. In a small area of the product being controlled, a powerful elastic-plastic surface wave of finite amplitude is excited, for example, with an inert mass, which is accelerated to a certain speed and then hit by the indenter on the surface of the product being tested. Then, in different directions from the point of excitation, this wave is taken and its amplitude is measured. The maximum amplitude of an elastoplastic wave is determined by the yield strength of the material G-, as well as by the magnitude and sign of the mechanical internal stresses (TO g acting in a given direction of wave propagation. So, for example, if the material is compressed to 0, - 2x, the maximum amplitude R of the wave, propagating in this direction will be equal to R - GY - (Go-O, 55, and for the discharge wave - 1.5 (JT-, If the excitation pulse has a large value, plastic deformation of the material prt stresses will first occur equal R, and then the propagation of an elastic wave of the same amplitude. By measuring the amplitude of the waves propagating from the excitation region in different directions, it is possible to determine the magnitude of the stresses present in the material. The yield strength, the magnitude of which is necessary to know, can be easily determined by one of the existing The register of an elastoplastic wave can be carried out by receivers of different structures: piezoelectric tensometric, capacitor, etc. The signal from the receivers arrives at the parameter registration unit of the received elastoplastic wave, where its shape, amplitude, and other parameters are recorded. The method of measuring stresses in solids makes it possible to determine the true values of stresses with a high degree of accuracy. This completely eliminates errors caused by unevenness and anisotropy of the structure, differences in the modes of mechano-thermal processing of products. In addition, since the relative changes in the registered parameter are much larger, equipment of a lower accuracy class can be used. Claim Method The method for determining the stress state of a material is that a controlled surface product is excited by an elastic surface wave, taken in different directions from the point of excitation, the parameters of this wave are recorded and the voltage in the controlled product different from In order to increase the measurement accuracy, excite an elastoplastic wave, | In which irreversible plastic deformations appear in a controlled product, the amplitude of this wave is measured and the difference between yield strength of the material and the amplitude of the wave is determined by the voltage in the solid. Sources of information taken into account in the examination 1, USSR Copyright Certificate No. 466443, class G 01 N 29/04, 1972. 2, US Patent No. 3812709, class 73-67.5, -1974 (prototype).