RU2327135C1 - Method of material damping properties investigation - Google Patents

Abstract

FIELD: technological processes; measurement.

SUBSTANCE: invention is related to the equipment for testing of materials and structures, in particular, to methods of structural materials damping properties investigation. The sample is made in the form of thin wall cylinder, and mass of inertial weights is symmetrically distributed in relation to sample axis. In the plane that passes through the sample axis, pairs of equal forces of opposite directions are applied to inertial weights, and they are evenly rotated until stabilised movement is obtained, after that the values of applied forces and weights displacement are measured, and they are used to determine the value of material damping property.

EFFECT: increase of material damping properties investigation accuracy.

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Description

The invention relates to techniques for testing materials and structures, and in particular to methods for studying the damping properties of structural materials.

A known method for studying the damping properties of materials is that a sample in the form of a prismatic rod is cantilevered in a massive plate suspended on thin strings, an inertial load is attached to the free end of the sample, transverse resonance vibrations are excited in the sample, and parameters of these vibrations are recorded and, according to these parameters, judge the damping properties of the sample material [1].

The disadvantage of this method is the low accuracy due to an inhomogeneous stress state along the length and thickness of the sample, as a result of which the indicators characterizing the energy dissipation during oscillations represent the integral characteristic of the sample.

The closest technical solution is a method for studying the damping properties of materials, which consists in the fact that inertial weights are attached to the ends of the sample made in the form of a prismatic beam and suspended on thin strings, applying forces in the form of periodically changing bending moments, and excite periodic movements of goods , register the forces and movements of goods, which judge the damping properties of the material of the sample [2].

The disadvantage of this method is the low accuracy due to an inhomogeneous stress state over the thickness of the sample, as a result of which uneven amounts of energy are dissipated at different points in the thickness of the sample over the oscillation period and the test results represent the integral characteristic of the sample.

The purpose of the invention is to increase accuracy by ensuring the same amplitude values of deformation in the volume of the sample.

This goal is achieved by the fact that, in contrast to the known method of studying the damping properties of materials, which consists in the fact that inertial weights are attached to the ends of the sample, hanging them on thin strings, they apply forces to them and inform the loads of the movement, after which the forces and movements of the loads are recorded , in the claimed method, the sample is made in the form of a thin-walled cylinder, and the mass of inertial loads is symmetrically distributed relative to the axis of the sample by the mass. In a plane passing through the axis of the sample, pairs of equal forces of the opposite direction are applied to inertial loads and rotate them uniformly until a steady motion is obtained, after which the magnitude of the applied forces and the movement of the loads are measured and the value of the damping ability of the material is judged from them.

In the prototype, analogues, as well as in other well-known solutions to the problem (see the reviews given in the books of G.S. Pisarenko, A.P. Yakovlev, V.V. Matveev. Vibration-absorbing properties of structural materials. - Kiev: Science. Dumka 1971. - 376 pp. And VV Matveev, Damping oscillations of the damped bodies, Kiev: Science Dumka. 1985. - 264 p.) These signs were not found, this suggests that the solution has novelty and significant differences.

The method is as follows.

Inertial loads with mass symmetrically distributed about the axis of the sample are attached to the ends of a sample made in the form of a thin-walled cylinder by hanging them on thin strings. A pair of equal forces of the opposite direction is applied to inertial loads and the loads are evenly rotated around the axis of the sample in one direction until steady motion is obtained. Then, the magnitude of the applied forces and the movement of goods are measured and the value of the damping ability of the material is judged by them.

An example implementation of the method:

Inertial weights 2 are attached to the ends of sample 1 (Fig. 1) in the form of a thin-walled cylinder and suspended on thin strings 3. A pair of equal forces are applied to inertial weights, forming bending moments in the opposite direction, for example, using the following system of magnets 4 mounted on brackets 5 rotating on cylindrical hinges 6 (figure 2). The applied pairs of forces uniformly rotate around the axis of the sample in one direction until a steady motion of inertial loads is obtained. The decrement of vibrations is determined by the known dependencies as the ratio of the energy dissipated during the period of inertial load movement to the potential strain energy of the sample (see, for example, Pisarenko G.S., Yakovlev A.P., Matveev V.V. Vibration absorbing properties of structural materials .-- Kiev: Science.Dumka. 1971.p.12). In this case, the scattered energy is defined as the work of bending moments on the angular displacements of inertial loads, and the potential energy of deformation of the sample is determined by the known dependence (see, for example, G. Pisarenko and others. Resistance of materials. - Kiev: Vishcha school, 1986. - p. .676) using the amount of deformation of the sample.

During the movement of inertial loads, the material at all points of the sample successively experiences cyclic tensile and compression strains with the same strain amplitude, which ensures the same energy dissipation at all points in the sample material during the period of movement of inertial loads.

The application of the proposed method will improve the accuracy of the test results of materials in the study of their damping properties.

The proposed method can be implemented in any laboratory involved in the study of the mechanical properties of materials.

Information sources

1. Pisarenko G.S., Yakovlev A.P., Matveev V.V. Vibration-absorbing properties of structural materials. - Kiev: Naukova Dumka, 1971, p.104-105.

2. Yakovlev A.P., Matveev V.V. To the technique of experimental study of the damping properties of materials under bending vibrations. Energy dissipation during vibrations of mechanical systems. - Kiev: Naukova Dumka, 1974. p.135-139 (prototype).

Claims (1)

A method for studying the damping properties of a material, namely, that inertial weights are attached to the ends of the sample, suspended on thin strings, apply forces to them and give the loads movement, after which the forces and movements of the loads are recorded, and the damping properties of the material are judged from them the fact that the sample, to the ends of which inertial loads are attached, is made in the form of a thin-walled cylinder, the mass of inertial loads is symmetrically distributed relative to the axis of the sample, and the forces applied to the inertial loads dissolved in a plane passing through the axis of the sample, and to loads applied equal forces in opposite directions and rotate them uniformly until a steady motion, after which the measured magnitude of the applied forces and the movement of goods, and it is judged by the magnitude dempfiruschey ability of the material.

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