SU1325325A1 - Appliance for cyclic plasto-elastic deformation of flat specimens - Google Patents

Abstract

The invention relates to a testing technique and is intended to study low-cycle fatigue of flat samples. The purpose of the invention is to expand the range of deformations being investigated by preventing the sample from losing stability during its elastic-plastic cyclic compression. Pairs of flat parallel plates 1 and 2 are rigidly connected by thickened ends. mi with appropriate grips. Between the two plates of each pair, one of the plates of the other pair and sample 5 is placed. Each pair is clamped with the sample with electrical clamps 4. At the free end of each patch there is a protrusion located in the U-shaped groove 6 of the corresponding patch of the other pair. Under cyclic loading, including compression of the specimen, the lining with protrusions in contact with it prevent the specimen from losing stability, allowing the range of deformations to be expanded. 3il. with S (Л С у i bg: s 7 5 / / / CO to ate 4 / igZ ®К Л гV 7

Description

The invention relates to a test technique and is intended to study the low-cycle fatigue of flat specimens.

The purpose of the invention is to expand the range of deformations under investigation by preventing the sample from losing stability during its elastic cyclic compression.

FIG. 1 shows the adaptation, the general view; in fig. 2 - the same, side view; in fig. 3 - the same, in isometry ,.

The fixture consists of a pair of lamellar overlays 1 and a similar pair of overlays 2. The lamella overlays of each pair have a thickened end, rigidly connected to the corresponding grip 3, with the overlays of each pair oriented by thickened ends in one direction, and the different pairs in opposite directions. Each pair of overlays has a set of elastic clamps 4 designed to tighten the overlays with sample 5. Between the overlays of each pair there is an overlay of another pair designed to interact with sample 5 {Each overlay has a U-groove 6 on the thickened end, and opposite - protrusion 7, located in the groove 6 of the corresponding lining of the other pair, both pairs are mounted with the possibility of axial movement relative to each other. The device works in the following way.

Clamps 4 are loosened and sample 5 is placed between the corresponding labels. To reduce the contact tangential stresses between the sample and the plates, a lubricant, such as finely divided graphite powder, is preliminarily applied to the surface of the sample. After securing sample 5 in the grippers 3, they are set to the position corresponding to the maximum deformation of the test cycle, and both pairs of plates are tightened with clamps 4, which ensures that the plates are pressed against the sample during the entire sample deformation. The selection of clamps 4 is carried out in such a way that the forces they generate are sufficient to prevent the specimen from losing stability, but remain significantly smaller than those required for constrained compression of the lamellar specimen. Such a choice is possible due to the fact that the transverse contact forces arising at the initial stage of loss of stability are always small. Since it is always possible to ensure that the rigidity of the cantilever sections of the clamps is bent — much less than the transverse rigidity of the specimen under study, the lateral deformation of the clamping force will be small. When cyclically deforming a flat sample 5, interacting with the sample} 1ac.pads prevent the specimen from losing stability along its entire length; The formation of plastic hinges in zones 8, where the lining is not partially in contact with the specimen.

Formula I.3 gain

A device for cyclic elastoplastic deformation, flat samples containing two coaxial grippers, a pair of identical flat lining and elastic clamps for tightening the lining with the sample. Characterized by the fact that, in order to expand the range of deformations, it is equipped with a second pair of similar plates installed with the possibility of axial movement relative to the first pair, and additional clamps for tightening the second pair of sample plates, one end of each plate is thickened. A U-shaped guide groove is rigidly connected with a corresponding gripper, at the opposite end of each lining, a lug on the protrusion placed in the groove of the corresponding lining of the other pair, and between the lining another pair located plate pairs intended for reacting with the sample.

(pu $ l

Editor A. Vorovich

Compiled by A. Pospelov

Tehred L. Serdyukova Proofreader E. Roshko

Order 3042/37 Circulation 776 Subscription

VNIIPI USSR State Committee

for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5

Production and printing company, Uzhgorod, Projecto st., 4

(pye2

Claims (1)

A device for cyclic elastoplastic deformation, flat specimens containing two gripping joints, a pair of identical plate overlays and elastic clamps to tighten the overlays with the specimen, characterized in that, in order to expand the deformation range, it is equipped with a second pair of similar overlays, mounted with axial movement relative to the first pair, and additional clamps for tightening the second pair of plates with the sample, one end of each plate is made thickened with P-o a sharp guide groove and is rigidly connected to the corresponding grip, a protrusion is made at the opposite end of each lining located in the groove of the corresponding lining of the other pair, ⁴ and between the overlays of each pair there is a lining of the other pair, designed to interact with the sample.