SU1471111A1 - Device for determining strength of materials - Google Patents

Abstract

The invention relates to a technique for testing materials by non-destructive methods and can be used to determine the strength of concrete, brick in products and structures. The purpose of the invention is to simplify the design and increase reliability by using an electromagnetic sensor that is not associated with the striker. The device includes a housing, a head, a percussion mechanism, a displacement sensor, and an electronic circuit. Upon impact, the sensor produces pulses, the phases of which are associated with the process of penetration and rebound of the striker, and the duration is due to the parameters of the collision process, which characterize the strength of materials. The pulse duration is recorded by a simple digital circuit. Strength is determined from the ratio * 98c = CT ₁ / T ₂ , where * 98c is the parameter of the calibration dependence

T ₁ -the duration of the signal occurring after impact

T ₂ -the duration of the signal as a result of the restoration of elastic deformation

C is a constant coefficient. 3 il.

Description

The invention relates to a technique for testing materials by non-destructive methods and can be used to determine the strength of concrete mortar, bricks in products and structures.

The aim of the invention is to simplify the design and increase reliability.

FIG. 1 shows a diagram of the electromechanical part of the device; in fig. 2 is a graph of the emf on an inductance coil; . in fig. 3 is a block diagram of the electronic part of the device.

A device for determining the strength of materials comprises a housing 1, a die 2,

the reciprocating movement of which is provided by a percussion mechanism, implemented in the form of a rod 3, a drummer 4, two latches 5, a cup 6 for removing the latches, a support ring 7 with stops 8 fixed to the rods 9, a working spring — 10 1, a return spring II and impactor springs 12, CioiiKa displacement sensor, made in B1 of a permanent magnet. 13, fixed on the striker 2, two coils 14 of the inductance with ferritong fixed on the case; and cores 15, polarization n using magnetic magnetization b, and the electronic circuit. n form

four

314

a signal splitter 17, the input of which is connected to inductance coils 14, two pulse generators 1 and 19, the control inputs of which are connected to the outputs of a signal splitter and two counters 20 and 21 with indication connected to high voltage pulse generators 18. and 19.

The device works as follows

After turning on the power and resetting the counters 20 and 21, the device is mounted by the stops 8 on the surface of the product and pressed against it. In the limiting position of stretching the working spring 10, the latch 5 enters the cup 6, whereby the striker 2 is released and under the action of the working spring 10 strikes the striker 4. Under the action of this blow, the striker inserts into the material under test for a certain amount, and then rebound due to the elasticity of the material.

The interaction of the impactor with the test material determines the movement of the striker 2, which is detected by the displacement transducer.

With a sharp slowdown of the striker in the process of a collision and its subsequent rebound, a self-induced emf and then an induced emf arise in the coil. On the electromotive force of the EMF, shown in figure 2, marked areas: 1-2 - EMF induction before the blow; 2-3 - phase of impact; 3-4 - self-induction EMF after impact;, 4-5 - induction EMF when restoring elastic deformation. The amplitude and, therefore, the duration of the pulses a-b and c-xi depend on the elastic and strength characteristics of the material. Experiment has shown that there is a correlation link between

0

with

by the nature of the material and the parameter / 3 s,,. where t, is the duration of the signal arising after the impact; t is the duration of the signal due to the recovery of elastic deformation; c is a constant coefficient. Pulse separation occurs in the separator 17. Each of the pulses triggers its own generator, the operation time of which is determined by the duration of the pulses and is recorded by counters. By varying the frequency of the generators, the device is easily otterized and, by the strength of known samples, construct an appropriate calibration curve, which can be used to determine the strength by the measured parameter D.

"with

Claims (1)

20 formula invented A device for determining the strength of materials, comprising a body, a firing pin installed in it with the possibility of reciprocating movement, a shock spring interacting with the body and the body, a movement sensor, and an electronic circuit that is characterized in order to simplify the construction and - no reliability, the sensor is made in the form of a permanent magnet mounted on the striker and two inductors. With polarized cores mounted on the body, and the electronic circuit is made in the form of a signal separator, the stroke of which is connected to the inductors, two pulse generators, the control inputs of which are connected to the outputs of the signal splitter, and two meters with an indication connected to the outputs of the pulse generators. 1 I FIG. g ftsg.Z Compiled by A.Paniklenko Editor sL1ekar Tehred M.Hodanich Corrector O. Kravtsova Order 1602/46 Circulation 788 VNIIPI State Committee for Inventions and Discoveries at the State Committee on Science and Technology of the USSR 113035, Moscow, Zh-35, Raushsk nab. 4/5 Production and Publishing Combine Patent, Uzhgorod, ul. Gagarin, 101 t Subscription