SU1645880A1 - Method of testing tubular specimens - Google Patents

Abstract

The invention relates to a test apparatus and can be used to test tubular specimens. The purpose of the invention is the expansion of information content. The tubular specimen is filled with polyurethane, an compressive force is applied to the medium in the axial direction and, at the same time, a uniformly distributed radial compressive force equal to the axial compressive force is applied to the lateral outer surface of the specimen. After that, a twisting force is applied to the sample, and the axial and radial compressive forces are maintained during the test. By varying the magnitude of the radial and compressive and torsional forces, it is possible to create various schemes of the stress-strain state, which expands the information content of the method. 2 Il.

Description

This invention relates to a testing technique.

The purpose of the invention is to expand the information content by allowing the creation of various schemes of stress-strain state.

FIG. 1 shows a scheme for implementing the method; in fig. 2 - changing the sample geometry during the test.

The method is carried out as follows.

The tubular sample 1 is filled with medium 2, for example polyurethane. After this, the medium 2 is compressed in the axial direction and simultaneously applied to the outer side surface of the sample 1 a uniformly distributed radial compressive force equal in magnitude to the axial compressive force, and the sample 1 is loaded with a twisting force. At the same time, axial and radial compressive forces are maintained at a given level during the testing process.

Example 1 A test tube was tested with an average diameter of a 54 mm, thickness h 1 mm, length 34.2 mm from AMgZM alloy. The mechanical properties of the AMgZM alloy: the ultimate strength of the stv 19 kg / mm, the modulus of elasticity E 2700 kg / mm. The sample was filled with polyurethane with a Shore hardness of 87. SKU-7L grades, to which a compressive pressure of 7.39 kg / mm2 was applied, a uniformly distributed compressive force g of 7.39 kg / mm was applied to the lateral outer surface of the tubular specimen, after which the specimen was twisted until the appearance of the first crack, not removing both efforts, while the torque was M 39.5 kg

With such a test pattern, a tensile usi acts on the tubular specimen (L

with

(

4 SP 00 00

about

line ot, in the elastic region, which is determined from the ratio

.(one)

where E is the tensile strain, determined from the geometric relationships i

-I

 0.632, (2)

 coFff Ј C,

where I is the length of the deformation zone;

/ is the angle of inclination of the risks after the test;

/ 8,1 - determined by sample after testing (see Fig. 2).

I 14.421 mm, / 66 ° 41, measurements were performed on a UIM-21 instrument microscope with an accuracy of 1 min.

If the deformation of the stretch leaves the elastic region, then az - аъ (1 + g) 19 (1+ + 0.632) 31.14 kg / mm2 (3). In addition to the tensile force Oz, tangential stresses act on the sample

2M 2.39 7ra2h 3.14

52 10J QCO. 2 8.63 kg / mm

54 1

Average pressure

(4) hydrostatic

a - | z- | o, 38 kg / mm2.

and the intensity of the tangential stresses

, 142 + 8,632

 10.50 kg / mm2 (6)

Stress indicator

a -JM8 -p

 - -tgEgg - 0.987,

R-a-r-t.

3 10-50

which can be taken as an indicator of the stress state when the sample is stretched.

Example 2. Carried out as in Example 1, but with a compressive pressure of 22.18 kg / mm2, a uniformly distributed compressive force g 22.T8 kg / mm2, the torque was M 32 kg. After measurements, the angle P 28 ° 41, the length of the zone. Deformation I 0.67 mm.

Sprain deformation 0.67 n R7

Ј - 34, 2

 0,00268.

It is located within the elastic region, therefore, OG E E 0.00268-2700 - 7.242 kg / mm. Tangential stress

t

2M

a2 h

2.32 10J cnn / 2 6.99 kg / mm.

3.14 542 1 The value of the average hydrostatic pressure is 2.414 kg / mm2.

10 T -L-V20 + t2 4 X12 7 2422 + 6,992- V6V6

 8.145 kg / mm2, R Ј - | 4y-0-296, i.e. I o, 145

1G is close to pure shear.

Example 3. Conducted as in Example 1, but the compressive pressure p 4 kg / mm was less than the uniformly distributed compressive force g

OQ 7.39 kg / mm2, as a result, the walls of the pipe were softened.

Example 4. Conducted as in Example 1, but the compressive pressure p of 7.39 kg / mm was more uniform

With a distributed compressive force of 4 kg / mm, a pipe was bulging under the action of internal pressure.

Thus, changing the value

Q compressive and torsional forces create various schemes of stress-strain state, which provides an extension of the information content of the method.

35

Claims (1)

Invention Formula The method of testing tubular samples, in which the sample is filled with a medium before testing and loaded with a twisting force, characterized in that polyurethane is used as a medium to expand the informativity by allowing the creation of various stress-strain regimes a compressive load is applied to the polyurethane in the direction of the sample axis and a uniformly distributed radial compressive is applied to the outer side surface of the sample a force equal to the force applied to the polyurethane, which itOft- is kept in the test process.  Mf 1 -sch & Before deformation After de- Formations