SU903745A1 - Device for testing specimens with hole - Google Patents

Description

(54) DEVICE FOR TESTING SAMPLES WITH OPENING

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The invention relates to the study of the strength properties of materials, and specifically to devices for testing samples with a hole, and can be used to grow a fatigue crack, which is opHeHTjiped in a given direction relative to the longitudinal axis of the sample.

A device for strength testing of samples is known. abutting the sample mounted on the fixed support til,

The disadvantage of the device is the impossibility of growing fatigue cracks, since the loading of the sample can be carried out only by static load.

The closest to the technical essence of the invention is a device for testing samples with a hole, containing an expanding mandrel for the sample, consisting of segment inserts, and two oppositely directed punches installed between the inserts, which

to evenly spaced around the perimeter of the hole, and the interacting surfaces of the punch and inserts are made, respectively, of spherical and conical t2l ..

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A disadvantage of the known device is that the load is applied evenly around the perimeter of the hole and the direction of development of the fatigue crack cannot be determined in advance.

Claims (2)

The purpose of the invention is to provide the possibility of growing a fatigue crack. The goal is achieved by the fact that the mandrel contains two inserts, each of which is made with a protrusion serving as a support for the sample, and the interacting surfaces of the input and the punches are made flat and between them are installed rolling bodies. Figure 1 shows a device for testing samples with a hole, a general view; Fig, 2 is a section A-A in Fig.1. The device includes an expanding mandrel consisting of two longitudinally shaped symmetric wedge segment liners 1 and 2 installed in the hole of sample 3, two oppositely directed jx wedge-shaped punches 4 and 5, installed between the liners I and 2 and fixed respectively, in fixed 6 and movable 7 grips of the testing machine. Each of the inserts 1 and 2 is made with a protrusion 8 serving as a support for sample 3. The interacting surfaces 9 and 10, respectively, of the 1,2 and punches 4.5, are made flat and between them are rolling bodies 11. The device works as follows. The punch 5, fixed in the movable gripper 7, is moved relative to the punch 4 by the action of the pooling force generated by the testing machine. Through the rolling bodies 11, the force is transferred to the inserts 1 and 2, which expand the sample 3. After the load is removed, due to the accumulated deformation energy, the inserts 1 are compressed and return the plug 5 to its original position for the next loading cycle. The force transferred to the specimen acts perpendicular to the proposed direction of crack development. By placing the liners accordingly, you can achieve the development of a fatigue crack in the desired direction. Thus, the proposed device allows to increase the accuracy of tests and reduce the number of test samples required for research. Claims An orifice testing apparatus comprising an expanding mandrel for a specimen consisting of segmental inserts and two oppositely directed punches installed between the inserts, which in order to allow the fatigue crack to grow in the specimen, the mandrel contains two inserts , each of which is made with a protrusion serving as a support for the sample, and the interacting surfaces of the liners and punches are made flat and between them are rolling bodies. Sources of information taken into account in the examination 1. US patent 3264867, cl. 73-95, 1976. 2. Authorship certificate of the USSR No. 761874, cl. G 01 N 3/08, 1978 (prototype).