SU1208491A1 - Arrangement for determining fatique durability of structure material - Google Patents

Abstract

The invention makes it possible to increase the reliability of the determination of the fatigue life of structural materials by more fully taking into account the effect of loading cycle parameters on durability. The device contains a strain gauge transducer, three measuring channels connected in parallel to it. and a unit for storing and converting measured deformation parameters. In the first canape, the amplitude of the variable strain component is measured. The second channel serves to generate signals corresponding to the frequency of loading. In the third channel, the average strain cycle value is measured. The second channel contains maximum and minimum detectors connected in parallel to the output of the strain gauge transducer and a time interval meter. The output of the time interval meter and the outputs of the first and third channels are connected to the information inputs of the memory and conversion unit. The output of the maximum detector is connected through the first pulse shaper to the sampling-enabled input of the memory and conversion unit, to the first input of the time interval meter and the reset key 4 of the minimum detector, and the output of the minimum detector to the second input of the time interval meter and reset key of the detector maximum, 1 Il. § “L with to oo {with

Description

one

The invention relates to a study of the strength of materials, namely, devices for determining the fatigue life of structural materials.

The purpose of the invention is to improve the reliability of the determination of fatigue life by more fully taking into account the effect of load cycle parameters on durability.

The drawing shows a diagram of the proposed device.

A device for determining the fatigue life of a construction material contains a strain gauge converter 1, a parallel channel connected thereto to the first channel 2 measuring the amplitude of the variable component of deformation, second channel 3 for producing signals; corresponding to the frequency of loading. and a unit 5 for memorizing and transforming the measured deformation parameters; connected to the outputs of channels 2, 3 and 4

The first channel 2 comprises a series-connected amplitude measurement unit 6 of the variable component of deformation and a first analog-to-digital converter (ADC) 7, the output of which is connected to the information inputs of the memory and conversion unit 5. The second channel 3 contains in parallel to the output of the measuring transducer 1 the deformation detector 8 minimum and the detector 9 maximum; the output of the latter through the first phase of the spin puller 10 pulses is connected to the first input of the meter 11 time intervals, with a reset key detecting aa 8 minimum and allowing sample. the input of the memory unit 5 and the conversion of the minimum detector output 8 through the second pulse shaper 12 are connected to the reset key of the maxigum detector 9 and at the second, second input of the meter 11 time intervals whose output " 1 is connected to the information inputs of the memory and conversion unit 5. The third channel 4 contains a series-connected unit 13 for measuring the average value of the deflucade cycle and the second analog-to-digital converter (LCP) 14, the output of which is connected to the information inputs of the storage and conversion unit 5.

2084912

B. Pok 5, memory and transfer, contains consistently connected permanent memory (ROM) 15, adder 16 and

ir-dikator

the address inputs of the ROM 15 are the information inputs of the storage and conversion unit 5 and connected to the outputs of the meter 11 time intervals J of the first 7 and second A1 (P 14,

and input 5, which allows memory sampling, - with the output of the first frm1 1 pulse generator 10.

The device works as follows.

in a way.

The deformation arising under the influence of a mechanical load in the material of the structure, converted by the measuring transducer 1, the deformation of the electric signal, enters the first 2, second 3 and third 4 channels: the measurement is altered in the first channel 2 . a deformation component, the values of which convert the OTs in the first ADP 7 into a parallel binary code and are fed to a part of the address inputs of the ROM 15. In the third channel 4 s

by means of block 13, the average strain distortion per cycle of load change5 is extracted, which is converted in the second ADC 14 into a parallel binary code and fed to another part

address inputs ROM 15. At the time

the time when the cycle deformation reaches the minimum value, the detector 8 of the minimum of the fop fflpryt at the output of the second driver 12 a voltage pulse applied to

reset key of the detector 9 maximum and the second input of the meter 11 time intervals. In doing so, the maximum detector 9 is prepared for operation,

and the time interval meter 11 starts counting the half-cycle deformation time. At the time of the subsequent deformation cycle maximum, the signal of the maxi detector 9: - gum forms 10 pulse pulses at the output of the first generator of 10 pulses applied to the minimum detector key 8, the first meter of the interval 11 time and

This allows the detector 8 of the minimum to prepare: to determine the strain minimum in the next cycle, the time interval meter 11 stops counting and fixes the duration of the time interval between the minimum and the strain cycle maximum that follows.

Stored in the memory cells ROM 1 is information about the level d of the resource consumption of fatigue life of the material of the construction during one deformation cycle, corresponding to the binary values of the deformation cycle parameters converted to channels 2-4 and fed to the address inputs of the ROM 15 (amplitude of variables the deformation component, the average value of the cycle and the duration of the half-cycle deformation), at the time of applying the voltage pulse from the output of the first shaper 10 to the memory permitting the memory input, the ROM 15 is output to the input of the adder 16, de summed with the previously obtained la. Thus, a well-known linear summation algorithm is implemented.

AND;.

at T o

(“P, ea

,

t N I - IR,

de t | 0 .. is the recorded amplitude level of the variable component of the deformation;

, ... VTi is the recorded level of the average value of cyclic de. formations;

 ... P, is the recorded level of the half-cycle strain duration;

t is the operation time of the device Tprelel; the time limit for the operation of the structure;

Lx is the number of deformation cycles with the values of i, d, and K cycle parameters that occurred during the operation of the device;

bfiJK - the number of cycles with

i, j,; deformation parameters to failure of the structure (determined experimentally when the material of the structure is tested for fatigue life);

c - spent

fatigue life of the structure,

The value of the spent fatigue life of the material of construction cv from the output of the adder 16 is fed to the input of the indicator 17 and displayed on a light board. The device schematizes a random non-stationary process according to a set of parameters, the effect of fatigue life: according to the amplitude of the variable component deformation, average value and frequency. Accounting for these parameters allows to increase the reliability of the determination of the fatigue life of the material of construction.

Claims (1)

Invention Formula A device for determining the fatigue life of a construction material, comprising measuring a strain transducer, a first channel connected in parallel with it, including a unit for measuring the amplitude of the variable component of deformation, and a second channel for generating signals corresponding to the loading frequency, a unit for memorizing and transforming the measured deformation parameters, characterized in that reliability due to a more complete account of the effect of loading cycle parameters on durability, it is equipped with a third channel that is connected to the strain gauge in parallel the first and second channels and includes a unit for measuring the average value of the strain cycle, and the second channel contains maximum and minimum detectors connected in parallel to the output of the strain gauge and a time interval meter, the output of which and the output of the first and third channels connected to the information inputs of the memory and transformation unit, the output of the maximum detector through the first pulse shaper 5 .1208491b It is connected to the minimum input through the second generator of the memory and conversion unit, the pulse is connected to the second input to the first input of the meter ib1) the measuring device of time intervals and the key to reset the minimum maximum detector, and the output of the detector 5 mum.