SU1366910A1 - Method of testing for relaxation of stresses - Google Patents

Abstract

This invention relates to a testing technique. The purpose of the invention is to improve accuracy by providing conditions of pure relaxation. Consistently with the sample in the grips of the test device, an elastic link is installed, the sample is loaded to a predetermined deformation, kept constant by changing the longitudinal length of the elastic link, and the load is measured by the magnitude of which the current stress is measured. The change in the longitudinal length of the elastic link is made by moving one gripper relative to another. In this case, the rate of change of voltage in the sample is measured, and the change in the distance of one gripper relative to another is regulated by the law V (z / K) S, where Z is the initial length of the elastic link; K - coefficient of elasticity of the elastic link; S is the rate of change of voltage. Moving one gripper relative to the other compensates for the variable in magnitude of the deformation of the elastic link for any value of the current stresses in the sample, and the deformation of the elastic link does not affect the relaxation process, since the amount of deformation of the sample remains constant. 1 il. i WITH

Description

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The invention relates to a test technique, and specifically to stress relaxation test methods.

The purpose of the invention is to increase accuracy by providing pure relaxation conditions.

The drawing shows a diagram of the device for the implementation of the proposed method.

The device for stress relaxation testing according to the inventive method comprises a fixed yoke 1 connected by means of columns 2 with a movable yoke 3. On the columns 2, nuts 4 are installed for fixing the yoke 3, and adjusters 5 for the length of columns 2, made for example , in the form of spirals, each of which covers the corresponding column 2, or in the form of hydraulic cylinders placed on the respective columns 2. On the cross-arms 1 and 3, passive 6, respectively, are fastened and 7 grips are active. In the active gripper 7, an elastic link is fixed, made in the form of a dynamometer 8. Between the cross-arms 1 and 3, a gauge 9 is placed between the grips 6 and 7, which is connected to the latter.

The method is carried out as follows.

Consistently with a dynamometer 8, a sample 10 is installed, one end of which is connected to a dinanometer 8, and the other is fixed in a passive gripper 6. Before the test, the initial distance between grips 6 and 7 is determined using gauge 9 and initial length Z of the dinanometer 8 in the unloaded condition using a meter 9. In this case, the dinanometer 8 is installed in grips 6 and 7 without applying a loading force to it, and the gauge 9 determines the distance between the grips 6 and 7. In addition, the coefficient of elasticity of the dynamometer is determined 8 r by counting, that is, as the reciprocal of the elastic modulus of the elastic link, or experimentally. For this, a series of loadings of the dynamometer 8 is carried out, followed by the construction of calibration charts. After that, through the cross bar 3, the sample 10 is loaded to a predetermined deformation, the value of which is fixed by nuts 4. In this case, initial stress arises in sample 10, the magnitude of which is recorded at

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the strengths of the dynamometer 8. In the process of relaxation of stresses, the distance between the grippers 6 and 7 is constantly measured with a meter 9, the specimen 10 is kept under load, the magnitude of the current stresses is measured with a dynamometer 8 and the rate S of voltage changes in the specimen is determined 10. The deformation of the latter is kept constant, for which the longitudinal length of the dianometer 8 is changed by moving the gripper 7 relative to the gripping 6, which is carried out using the adjusters 5 of the column length 2. At the same time, the speed V changes the distance and between the grippers 6 and 7 during the trial, they change according to the

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Moving capture 7 relative to capture 6 compensates for the variable

The magnitude of the deformation of the dynamometer 8, therefore, the elongation of the sample 10 at any oment of time corresponds to its elongation under conditions of pure stress relaxation, and the deformation of the dynamometer 8 does not affect the magnitude of the deformation of the sample 10, which remains constant.

Example. The stress relaxation tests were performed on an UR-10 machine. Samples of D16T aluminum alloy and VTZ-1 titanium alloy with a working section length of 60 mm and a dynamometer length of 7 mm were used.

The magnitude of the static load was set at 60-80 proportional limit. When changing the distance between the grippers with a speed according to the indicated dependence, the accuracy of maintaining the specified elongation of the samples was increased in proportion to the stiffness of the samples by 10-20%.

Claims (1)

Invention Formula The stress relaxation test method, in which an elastic link is placed in series with the sample in the grips of the test device, loads the sample to a predetermined deformation, is kept constant by changing the length of the elastic link, which is carried out by changing the distance between the grips, and is measured the load on which the court r 31366910 on the magnitude of the current voltage, characterized in that, in order to improve accuracy by providing conditions of pure relaxation, the rate of voltage variation in the sample is measured, and the velocity v of the distance between the grips is regulated by law v-f.S. the initial length of the elastic link; coefficient of elasticity of the elastic link; rate of change of voltage in the sample. 7z // / y // /// y // // z yy ///////////////////////