SU377682A1 - METHOD FOR DETERMINING INDEPENDENT COMPONENTS OF MATRIX OF RIGIDITY ORTHOTROPIC MATERIAL - Google Patents

Description

one

This invention relates to the field of determining the elastic constants of orthotropic materials.

Methods are known for determining the independent components of stiffness matrices for orthotropic materials using ultrasonic pulsed longitudinal and shear vibrations. In this case, three prismatic or three cylindrical mutually perpendicular oriented samples are used, in which the main axes coincide with the main directions of the orthotropy, respectively, and provide a measurement of six independent constituent stiffness matrices.

Since the test material "has a certain structural anisotropy, then, in turn, the test system consisting of three samples gives a variation of the results of the same acoustic measurements for this material.

The aim of the invention is to determine all nine and one independent components of the stiffness matrix of an orthotropic material and to increase the measurement accuracy.

This is achieved by using one sample of an orthotropic material of spherical shape and its diameter is chosen depending on the speed of propagation of ultrasonic vibrations in the orthotropic material, the required accuracy of its measurement and instrumental error of measurement of the propagation time of ultrasonic vibrations.

The method is as follows.

A spherical specimen is placed between the sensors of the ultrasonic measuring line to determine all the independent components of the stiffness matrix.

From an orthotropic material, for example, from plasticized birch wood, they grind a shash, the diameter of which is determined depending on the speed of propagation of ultrasonic vibrations, the instrumental error of measuring the propagation time of ultrasonic vibrations and the required accuracy of measuring the velocity according to the formula:

,

Bc

where d is the diameter of the specular sample, mm. At is the instrumental error of measurement of the propagation time of ultrasonic oscillations, sec, s is the velocity of propagation of ultrasonic oscillations, mm / sec.

8c is the required accuracy of the velocity measurement,%.

For plasticized birch wood with a density of kg / m, the diameter of the ball is 25 mm.

The ball has three main axes of symmetry, Xy xi and Xs, which coincide with the radial, tangential and axial axes of plasticized birch wood, respectively.

To determine the independent components of the CuCzzCss stiffness matrix, it is necessary to measure the propagation velocity of longitudinal pulsed ultrasonic oscillations in the direction of the main axes of symmetry XiXz, xc. To determine the independent components of the stiffness matrix C44C55Ci, it is necessary to measure the propagation velocities of shear pulsed ultrasonic vibrations in which the propagation direction and polarization direction form planes of symmetry XiXz,, XiXs.

To determine the independent components of the Ciz, Cis, Cz3 stiffness matrix, it is necessary to measure the propagation velocities of quasi-shear pulsed ultrasonic vibrations, in which the directions of propagation of vibrations are at an angle of 45 ° to the two main axes of symmetry with polarization in the direction of the third.

All these measurements are possible with a certain orientation of the spherical sample between the ultrasonic sensors of longitudinal and shear vibrations, which are connected to a pulsed ultrasonic flaw detector.

Subject invention

The method of determining the independent components of the stiffness matrix of an orthotropic material by exposing the material to ultrasonic pulsed oscillations, characterized in that, in order to determine all nine independent components of the stiffness matrix of the orthotropic material and to improve the accuracy of measurement, one sample of an orthotropic material spherical

The shape and its diameter are chosen depending on the speed of propagation of ultrasonic vibrations in an orthotropic material, the required accuracy of its measurement and the instrumental error of measuring the time of propagation of ultrasonic vibrations.