SU1583732A1 - Method of determining strength characteristics of different modulus material - Google Patents

Abstract

The invention relates to a measurement technique, in particular, to methods for determining the strength characteristics of solids with varying resistance to tensile and compression. The purpose of the invention is to improve accuracy by taking into account the actual radius of curvature and the position of the neutral line of the sample being bent. This is achieved by simultaneously determining the deflection and the angle of rotation of the flat cross sections using a pair of equilibrium displacement measurements that are established symmetrically and parallel to each other on opposite surfaces of the bend sample with an equal cross section along the length.

Description

Yo

The invention relates to a measurement technique, in particular, to methods for determining the strength characteristics of solids with varying resistance to tensile and compression.

The purpose of the invention is to improve accuracy by taking into account the actual radius of curvature and the position of the neutral line of the sample being bent.

The method is carried out as follows.

A sample of the material is made with an equal section along the length and its height h is measured. In the middle of the sample, on opposite surfaces, it is installed symmetrically and parallel to each other a pair of displacement meters with an equal base Ј and load the specimen with a gradually increasing bending moment M in the plane of displacement meters. At each load level, readings of displacement meters are recorded.

and measure the deflection f in the middle of the stretched or compressed surface of the sample. Based on one-time readings of displacement meters, taking into account the known base t, a pair of distances {pi and ki between the supports of the meters on the stretched and compressed surfaces of the sample is determined for each fixed value of the moment MI and deflection fi measured, for example, on the compressed surface of the sample. Then the angle in the rotation of the flat sections of the sample at each time instant is determined from the geometrical dependence, and the ra2 p is the radius of the curvature of the neutral line from

R

dependencies p 7rz- Using a ratio of 2tr

Fire p-hc r + f, calculate the height he

8t

the compressed layer, and then the height hp of the stretched layer of the sample from the ratio hp - h - he. The data obtained is sufficient to determine

00

with

41 00 45

laziness of deformations; stretches of compressed specimen surfaces:

 J

hc

SS7G

Maximum stresses 7ri (7c tensile and compressive in the sample is determined from the ratios

- hc

cf m /, fc

(1 + F

 ip

&)

/ 1 + k $: (1 + fe)

where Sp jJP y d F and Sc jj ° y d F are the static moments of inertia of the stretched and compressed sections of the sample relative to the neutral line;

1p Jjjp for 2 dF and, with y2dp momen.

you inertia of the same sections;

F is the cross-sectional area;

y is the ordinate of a section.

Thus, sequential loading of the sample up to its destruction allows to obtain simultaneously on the same sample diagrams (e) of material deformation under tension and compression, elastic moduli under tension and compression, determined by Hooke's law by the relations

F ° with tp - p and bs - -,

with RB p

and the tensile strength of a and the material in bending.

Claims (1)

Invention Formula The method of determining the strength characteristics of a multimodular material, which consists in producing a sample of material of equal section along the length, measuring its height, installing a pair of mechanical value gauges on opposite surfaces of the sample, loading the sample with a bending moment in the plane of the gauge base, measuring the measurements for each a fixed level of loading and a set of measurements determine the deformations, stresses and elastic moduli of the material under tension and zhatii and its flexural strength, characterized in that, in order to increase accuracy by taking into account the actual radius of curvature and the position of the neutral line of the sample to be bent, equilibrium displacement meters are selected as mechanical value meters and set in the middle of the sample symmetrically and parallel to each other, at each loading level additionally measure the deflection in the middle of the stretched or compressed surface of the specimen and determine the actual radius of curvature and the position of the neutral line of the specimen, with which the strength characteristics of the material are determined.