RU13702U1 - DEVICE FOR MEASURING STRENGTH OF BUILDING MATERIALS - Google Patents

Abstract

A device for measuring the strength of building materials, comprising a useful signal sensor in series, a matching amplifier, a low-pass filter, a first differentiator, a second differentiator and a comparator, as well as a peak detector with an analog-to-digital converter (ADC) and a decoder with an indicator connected in series, moreover the useful signal sensor is assembled in a separate housing and consists of a shock spring, a trigger, a striker with a striker and a piezoelectric element mounted on the striker, about characterized in that a key, a trigger latch and an analog key are connected in series, as well as a data processing unit consisting of a series-connected keyboard, control and synchronization device, read-only memory (ROM), arithmetic logic device (ALU) and operational a storage device (RAM), the key being installed in the sensor housing and connected with a shock spring made in the form of an elastic plate, one end of which is rigidly attached to the wall of the housing, and the other end the firing pin with a piezoelectric element and a drummer, which has the possibility of friction-free movement at the tip of the housing, is rigidly fixed, the key output is connected simultaneously with the second input of the control and synchronization device, the first input of the peak detector and the first input of the trigger latch, the second input of which is connected to the output of the comparator, analog the key is connected by the second input to the output of the second differentiator, and by the output to the second input of the peak detector, the output of which is connected to the ADC input, the output connected to the second input O

Description

DEVICE FOR MEASURING STRENGTH OF BUILDING MATERIALS

The utility model relates to the technique of non-destructive testing, namely, to means for studying the strength properties of solid materials by applying mechanical forces to them, in particular, by pressing tips under shock load into the test material, and can be used to assess the strength of concrete, reinforced concrete products, building ceramics, etc. both in the production of building materials, and at the stage of their operation in buildings and structures.

Non-resolving means for determining strength are known, that is, the properties of building materials in certain conditions and limits, without collapsing, to perceive certain influences that use the close connection of some other, more easily determined characteristics with the strength of concrete. Such a characteristic is, in particular, hardness - the resistance of the material to local elastic and plastic deformation that occurs when a harder body - a tip (indenter) is introduced into it. Applying impacts on the load to the surface of the controlled material and converting the mechanical energy of the interaction of the material and the tip into an electrical signal, the amplitude and duration of which correspond to the elastic and plastic deformations of the material, we obtain the strength characteristic of the latter. Therefore, devices for measuring hardness are also considered as analogues.

A device for measuring the strength of building materials, described in and.with. USSR J 1778675 A device for determining the strength of concrete according to class. G01N 29/04, z. 01.16.90, op. 11/30/92.

MKI-6: GO IN 3 / 00.3 / 48

a key, an analog-to-digital converter and indicator, as well as a shaper of the time interval, the input of which is connected to the output of the envelope signal shaper, and the output to the second key input; wherein the useful signal sensor comprises a coaxially mounted striker and an indenter made detachable from two parts, between which an electro-acoustic transducer is coaxially mounted, and a percussion mechanism.

The known device allows you to make single measurements of strength, however, since concrete is a heterogeneous material, according to GOST 22690 (Section 4.4), it is required to perform at least 10 measurements on one section of the product with subsequent mathematical processing of the measurement results. The device does not provide the ability to memorize individual measurement results and their mathematical processing, in connection with which, during the measurement process, it is necessary to record and calculate manually.

In addition, there are no elements in the device that prevent false alarms due to rattling of the spring of the flaw mechanism and repeated collisions of the striker after the rebound.

At the same time, this device does not provide a constructive possibility of adjusting the measurement results depending on the location of the impact mechanism (up, down, horizontally), which leads to an error of up to i 0% due to a change in the impact energy.

Thus, the disadvantages of the known device are low accuracy and control performance.

A device for measuring the strength of building materials, described in and.with. USSR No. 1221544 A device for determining the dynamic hardness of materials according to class. G01N 3/48, c. 05/31/84, SP. 03/30/86.

a static node and a digital indicator, as well as a peak detector connected by an input to the low-pass filter output, and by an output connected to the first input of an analog-to-digital converter (ADC), the output of which is connected to the second input of the arithmetic node, the second and third inputs of which are connected respectively to the output of the comparator and the first output of the clock generator, the other two outputs of which are connected respectively to the second input of the time-code converter and the third input of the arithmetic unit, the fourth input constant to the output of the setter; in this case, the clock generator plays the role of a synchronizing device, and the useful signal sensor contains a tip, a guide tube, which is placed with the possibility of reciprocating movement of the strikers, a piezo-accelerometer mounted on it and a striker in the form of a hard alloy ball interacting with the striker associated with trigger mechanism.

In the known device, using the arithmetic unit, the dynamic strength value is calculated as the ratio of the maximum amplitude of the pulse voltage proportional to the maximum amplitude of shock acceleration from the peak detector converted to binary ADC by the signal from the output of the comparator and the time of elasto-static deformation from the output of the comparator converted to code using a time-to-code converter, moreover, the conversion of both signals and the calculation of their ratio taking into account the parameters of the vessel yayuschihsya bodies synchronized by said clock pulse generator.

The disadvantages of the known devices are low accuracy and control performance due to the following.

The device allows for single strength measurements, however, due to the fact that building materials, including concrete, are heterogeneous, according to GOST 22690, clause 4.4, at least 10 measurements and their subsequent mathematical processing are required.

The device does not provide the ability to memorize the results of measurements and their subsequent mathematical processing, therefore, in the process of measurements, recordings and calculations must be done manually.

In addition, in the known device, false alarms are possible due to spring bounce and repeated impact of the striker after the rebound, since there are no elements in it that make it possible to exclude their influence on the measurement accuracy.

In this case, a significant decrease in accuracy is also associated with a change in the impact energy over time due to a change in the friction coefficient between the guide and the hammer due to wear of the sliding bearing, as well as plastic deformations of the twisted shock spring and its bounce during impact interaction of the hammer with the controlled material. Moreover, the known device does not provide a constructive possibility of adjusting the measurement results depending on the location of the impact mechanism (up, down, horizontally) during the measurement, which leads to an error of up to 10% due to a change in the impact energy.

The closest according to the measurement principle and the technical nature of the claimed device is a device for measuring the strength of building materials, described in ASSSSR No. 1483328 A device for determining the hardness of materials according to class. GO IN 3/48, c. 10.30.87, on. 05/30/89 and selected as a prototype.

The known device contains a serially connected sensor of the useful signal, a matching amplifier, a low-pass filter, a first differentiator, a second differentiator, a comparator, an analog-to-digital converter (ADC), a decoder and an indicator, as well as a peak detector, the input of which is connected to the second input of the ADC, This useful signal sensor comprises a guide tube in which a striker with a striker is placed, a piezo-accelerometer mounted on the striker, an elastic element in the form of a twisted spring and a trigger mechanism.

The signal characterizing the force interaction of the striker with the material and proportional to the second derivative of the shock acceleration is obtained by the second differentiator; its extreme value, related to the material hardness by a linear dependence, is extracted by a peak detector and converted into a digital code by an analog-digital converter according to the signal from the comparator at the moment when the signal voltage of the second derivative exceeds the set threshold. Next, the code is decrypted in the decoder and displayed on the digital indicator in units of hardness.

The known device allows you to perform single measurements of strength, but since building materials such as ceramics, concrete are heterogeneous, according to paragraph 4.4 of GOST 22690, it is necessary to perform at least 10 measurements on one site, the results of which must then be subjected to mathematical processing. The device does not provide the ability to memorize individual measurement results and their mathematical processing, therefore, during the measurement process, recording the measurement results and calculations must be done manually.

Due to the bounce of the coil spring of the percussion mechanism, repeated strikes of the striker after the rebound can occur and false triggering of the device is possible, which reduces the measurement accuracy, because there are no elements in the circuit to eliminate the influence of these factors.

In addition, a significant decrease in measurement accuracy is associated with a change in the impact energy over time due to a change in the coefficient of friction between the guide and the striker due to wear of the sliding bearing in the guide, as well as plastic deformations of the twisted shock spring, reinforcing the aforementioned bounce.

periodically), which leads to an error of up to 10% due to a change in the energy of the impact.

Thus, the known device has low accuracy and low measurement performance.

The purpose of the claimed utility model is to increase the accuracy and performance of measurements.

This goal is achieved in that in a device for measuring the strength of building materials, containing a useful signal sensor connected in series, a matching amplifier, a low-pass filter, a first differentiator, a second differentiator and a comparator, as well as a peak detector with an analog-to-digital converter (ADC) connected in series ) and a decoder with an indicator, and the useful signal sensor is assembled in a separate housing and consists of a shock spring, a trigger, a striker with a hammer a piezoelectric element mounted on the striker, ACCORDING TO THE USEFUL MODEL, a key, a trigger latch and an analog key are connected in series, as well as a data processing unit consisting of a keyboard, a device for synchronization and synchronization, a read-only memory (ROM), an arithmetic logic device ( ALU) and random access memory (RAM), moreover, the key is installed in the sensor housing and is connected with a shock spring made in the form of an elastic plate, one end of which is rigidly secured flax to the wall of the housing, and on the other end the firing pin with a piezoelectric element and a striker is rigidly fixed, having the possibility of friction-free movement at the tip of the housing, the key output is connected simultaneously with the second input of the control and synchronization device, the first input of the peak detector and the first input of the trigger latch, the second input of which is connected to the output of the comparator, the analog switch is connected by the second input to the output of the second differentiator, and the output to the second input of the peak detector, the output of which

connected to the input of the ADC, the output connected to the second input of RAM, the third and fourth inputs of which are connected respectively to the second output of the keyboard and the second output of the control and synchronization device, the third output of which is connected to the second input of the AL, connected by the third input to the RAM output, and the output also to the input of the decoder.

The execution of the shock spring of the sensor in the form of an elastic plate eliminates its bounce during the shock interaction of the sensor with the controlled material and the weakening of the elastic properties of the spring over time, thereby increasing the accuracy of measurements; it also makes it possible to rigidly fasten the striker with the striker and piezoelectric element directly on the spring, which eliminates the need for guides, exceptionally friction in them when the striker moves and changes in impact force due to wear of the sliding bearings of the guides and thereby eliminating interference in the useful signal, which also increases accuracy of measurements.

The mechanical connection of the spring with the key ensures that the latter clearly fixes its position during the shock interaction of the sensor with the material, and the electrical connection of the key with the electronic components of the circuit makes it possible to eliminate false operation on random signals, which also increases the accuracy of measurements.

The introduction to the device of the data processing unit in the above composition makes it possible to use the keyboard to enter a coefficient that takes into account the position of the sensor during measurements, to memorize the measured unit strength values in the RAM, and by setting the processing mode using the keyboard in the program recorded in the ROM using an arithmetic logic device upon command from the control and synchronization device, multiply the unit values by the coefficient of the position of the sensor, reject the extreme (minimum and maximum) values Niya, calculate the average value

strength and, comparing single values with the average, reject abnormal values, obtain a reliable and accurate value of the strength of the controlled material, store them in RAM memory, and if necessary, use the keyboard to extract the measured strength value from RAM. Since the processing of measurement results using the named block is automatic, within 1-2 seconds, this ensures high control performance.

Compared with the prototype, the inventive device for measuring the strength of building materials has a novelty, differing from it in the design of the useful signal sensor due to the implementation of the shock spring in the form of an elastic plate with a rigid fastener on it and a piezoelectric element to eliminate friction, the presence of nodes in it that provide for exclusion false operation, a clear fixation of the position of the spring, such as a key, a trigger latch and an analog key, by introducing into the device a data processing unit consisting of after They are connected to a keyboard, control and synchronization device, read-only memory, arithmetic logic device and random access memory with additional connections between these nodes, which allows you to adjust the measured values depending on the position of the sensor when measuring, memorize the measurement results, perform operational processing of measurements and obtain accurate and a reliable value of strength, which together provide a given result.

The inventive device for measuring the strength of building materials can be widely used in the construction industry to ensure accurate and productive control, therefore, it meets the criterion of industrial applicability.

-fig.2 - diagrams explaining the principle of operation of the device;

-Fig.Z - the algorithm of the device.

A device for measuring the strength of building materials contains a useful signal sensor 1, a matching amplifier 2, a low-pass filter 3, a first differentiator 4, a second differentiator 5, a comparator 6, a trigger latch 7, an analog switch 8, a peak detector 9, an analog-to-digital converter ( ADC) 10, the data processing unit 11, the decoder 12 and the indicator 13. In this case, the data processing unit 11 consists of a keyboard 14, a direction and synchronization device 15, a read-only memory 16, an arithmetic logic device 17 and an opera ivnogo storage device 18. The sensor 1 comprises a useful signal switch 19, housing 20, impact spring 21, the striker 22, piezoelectric element 23, the striker 24, the tip 25 and the trigger 26.

The nodes and elements of the device are interconnected as follows.

The output of the key 19 is connected simultaneously with the first inputs of the trigger latch 7 and the peak detector 9. The nodes 1-13 are connected together in series, the output of the comparator 6 being connected to the second input of the trigger latch 7, the output of the second differentiator 5 is also connected to the second input of the analog a key 8 connected by the output to the second input of the peak detector 9. In the data processing unit 11, the nodes 14-18 are connected in series. The ADC output 10 is connected to the second input of the RAM 18, the third input of which is connected to the second the output of the keyboard 14, and the fourth input to the second output of the control and synchronization device 15, connected to the second output with the second input of the ALU 17, the output of which is also connected to the input of the decoder 12. The output of the RAM 18 is connected to the third input of the ALU 17. The second input of the control device 15 and synchronization is connected to the output of the key 19 installed in the housing 20 of the sensor 1 and also connected to the first

the input of the peak detector 9 and with the R-input (first input) of the trigger switch 7, the second (installation) C-input of which is connected to the output of the comparator 6 (see above). The key 19 is also mechanically connected with the shock spring 21 of the sensor 1, which is rigidly attached at one end to the housing 20, and on the other end of which the hammer 22 with the piezoelectric element 23 and the hammer 24, with the possibility of friction-free movement in the tip 25, are rigidly fixed. The spring 21 is also connected with the trigger 26.

The purpose and implementation of the nodes and elements included in the device for measuring the strength of building materials is as follows (the traditional implementation of nodes and elements is not specifically specified)

The sensor 1 is a useful signal for receiving a shock acceleration signal. The implementation of the sensor is described above. It should only be noted that the striker 22 with the striker 24 is placed in the housing 20 of the sensor 1 so that the striker 24 has the possibility of friction-free movement in the tip 25 of the housing 20, made, in particular, in the form of a funnel facing the bell to the controlled material 27.

The piezoelectric element 23 of the sensor 1 is designed to convert the force of the mechanical interaction of the striker 24 with the material 27 into an electrical signal.

The trigger mechanism 26 mechanically fixes the cocked position of the shock spring 21, and the key 19 (it can be a reed switch) serves to transmit a signal of its position to the trigger latch 7, peak detector 9 and the control and synchronization device 15.

Matching amplifier 2 is designed to match the piezoelectric element 23 with the filter 3 low frequencies and signal amplification.

The low-pass filter 3 serves to filter out the high-frequency components of the signal that occur during the control of materials and cause false positives of the circuit.

The differentiators 4 and 5 are designed to obtain, respectively, the first and second derivatives of the useful signal and are, in particular, differentiating chains.

The comparator 6 gives a pulse when the voltage of the signal exceeds the second derivative of the set threshold value, which eliminates the operation of the trigger latch 7 from interference.

The trigger latch 7 is used to control the status of the analog key 8 and is, for example, an RC trigger.

The analog switch 8 passes to the peak detector 9 the signal of the second derivative only after the trigger 26.

Peak detector 9 is designed to embed the extreme value of the signal proportional to the second derivative and fed to the analog-to-digital converter 10.

An analog-to-digital converter (ADC) 10 converts an analog signal into a digital code.

The data processing unit 11 serves to process the measurement results, namely, taking into account the position of the sensor 1 during measurement, storing the measured unit strength values, averaging the measurement results, rejecting extreme and abnormal measurement values, obtaining the average accurate and reliable strength value and reproducing, if necessary, stored in measured values.

Block 11 includes a keyboard 14, control and synchronization device 15, read-only memory 16, arithmetic logic devices 17 and random access memory 18. The communications between the halls of block 11 are described above.

The keyboard 14 is used to select the measurement mode - set the correction factor taking into account the position of the sensor 1 when measuring, processing the measurement results or retrieve the measurement results from the memory. It represents, in particular, buttons located on the front panel of the housing 20 of the device 4 (not shown in the drawing

The control and synchronization device 15 is intended for issuing commands -.- coordinating the work-SHU Г77ВЗУ {Т-ЯАУУ 17-с) depending on the position of the shock spring 21 and the measurement mode selected using the keyboard 14.

ROM 16 SL5OKIT for storing the program for processing the values of the measurement results. This program includes the stages of multiplying each of the measurement values by a correction factor, rejecting the extreme (minimum and maximum) values, obtaining the average value from the series measurements, comparing all values with the crawling average, rejecting 5% of abnormal values, and re-determining the average value from remaining measurement values.

Arithmetic logic device 17 is designed to perform the above operations.

RAM 18 is used to store all values of the measurement results, the number of each measurement, the number of series of measurements, storage of the average density value.

The nodes 15-18 of the processing unit 11 Morjrr to be performed, for example, on domestic single-crystal microcomputers of the KR 1830 or KR 1835 series, as well as Intel microcontrollers.

The decoder 12 is designed to convert the binary code from the output of the ALU 17 into a seven-segment code necessary for displaying on the indicator 13.

The indicator 13 serves to indicate the results of measurements and is made, in particular, on liquid crystals.

Structurally, the device for measuring the strength of building materials is made in the form of two nodes assembled in separate buildings - a useful signal sensor and an electronic unit with a power supply (not shown in the drawing), which is used to convert, process and display measurement results connected by a flexible cable ( not indicated in the drawing).

A device for measuring the strength of building materials works as follows (see Fig. 1-3).

By pressing a button (not shown in the drawing) or by turning on the power supply voltage to the electronic components of the device. The tip 25 of the sensor 1 is pressed against the surface of the controlled product 27.

By moving the striker 22 until it engages with the trigger 26, the shock spring 21 is cocked. In this case, the key 19 is closed and the signal from its output sets the control and synchronization device 15, the peak detector 9 and the trigger latch 7 at the input R (Fig. 2a) . The trigger latch 7 while holding the analog key 8 in the closed state.

When you press the trigger (not shown in the drawing), the trigger 26 under the action of the shock spring 21 of the strikers 22 starts to accelerate and the key 19 opens. Thus from the input R of the trigger latch 7 is removed a signal prohibiting its operation. Prior to this, the possibility of the passage of any signals from the piezoelectric element 23 of the sensor 1 (from accidental blows when cocking the shock spring 21, installing the sensor 1 on the controlled product 27, as well as when the trigger 26 and at the initial moment of acceleration of the striker 22) is excluded (fig.2b - I).

After the firing pin 22 has accelerated and the key 19 has opened, the peak detector 9, the trigger latch 7, and the control and synchronization device 15 are set to working condition. When the impactor 24 collides with the surface of the controlled product in the piezoelectric element 23, the mechanical interaction signal is converted into an electrical signal proportional to the shock acceleration. This signal from the piezoelectric element 23 is fed to the input of a matching amplifier 2 and then to the input of a low-pass filter 3, which filters out interference in the form of high-frequency components. In the collision process, when the impactor 24 is introduced into the material of the controlled product 27, the material first experiences

elastic, and then plastic deformations. Changes in the stress-strain state of the material in the contact zone cause changes in the nature of the force interaction of the impactor 24 with the material of the product 26, which lead to changes in the shape of the fronts of the shock acceleration pulse (Fig.2 b - P.). A change in the nature of the force interaction is most clearly manifested on a signal proportional to the second derivative of shock acceleration, the amplitude of which A is directly proportional to the strength Ra of the material of the controlled product:

RST A, where K is the coefficient of proportionality.

To implement this estimation algorithm, the signal from the output of filter 3 is passed sequentially through two differentiators - 4 and 5. The first differentiator 4 generates a signal proportional to the first derivative of the sharpness of movement of the hammer 22 during impact (Fig. 2c), the second differentiator 5 gives a signal proportional to the second derivative of shock acceleration (Fig. 2d). The extreme value of this signal is linearly related to the strength of the material (see above). After the impact of the striker 22 with the controlled product 27, an impulse appears at the output of the differentiator 5, the amplitude of which is directly proportional to the strength of the material of the controlled product 27. To measure this amplitude, the impulse from the output of the differentiator 5 is fed simultaneously to an analog switch 8 and a comparator 6, which generates a positive rectangular pulse when exceeding the signal at its input threshold and this pulse is fed to input C of the trigger-latch 7 (Fig. 2e). The trigger latch 7 generates a positive pulse at the output, which opens the key only by the first positive pulse at its input C and corresponding to the moment when the second derivative of shock acceleration reaches an extremum proportional to the strength of the material and

Further, the trigger latch 7 does not respond to impulses at the input (see FIG. 2e).

The analog switch 8, upon receipt of an enabling positive impulse from the trigger 7, opens and passes at this moment a signal proportional to the second derivative from the output of the differentiator 5 to the input of the peak detector 9 (Fig. 2g), which captures and remembers the extreme value of this signal and feeds it further to analog-to-digital Converter 10 (Fig.2z). The ADC 10 converts the voltage into a digital code, which is supplied to the data processing unit 11 on the RAM 18.

From the keyboard 14, correction coefficients K are also entered here, taking into account the impact energy depending on the position of the sensor 1 when measuring (K 1 when the sensor is horizontal, K is less than 1 when sensor 1 is lowered down, and K is greater than 1 when sensor 1 is pointing up) measured value. The adjusted value of the measurement result is stored in RAM 18,

Using sensor 1, n measurements are taken, the results of which are received and stored in RAM 18. Then, by pressing the button on the keyboard 14, the processing starts the control and synchronization device 15, from the outputs I, 2, 3 of which commands are simultaneously issued to ROM 16 about entering ALU 17 programs for processing the results of single measurements, on RAM 18 - about freezing on ALU 17 results of single measurements and a coefficient that takes into account the position of the sensor 1, on ALU 17 - on the processing of measurement results. Moreover, the ALU 17 in accordance with the algorithm of the device (Fig.Z) compares the unit values of the measurements and rejects the minimum and maximum values. The remaining n-2 values are averaged and each of them is compared with the average R, and abnormal results are rejected that have significant deviations from the average R value. Then ALU 17 re-averages the remaining unit values.

From ALU 17, the calculated final strength value is sent simultaneously to the decoder 12 and to the RAM 18, where it is stored until the key is removed, if necessary, by pressing the button, the keyboard memory 14. On the decoder 12, the information is converted into a seven-segment code and displayed on the indicator 13 as a reliable value of the strength on controlled area of the product 27.

Preparation of the device for the next measurement is made by cocking the shock spring 21 of the sensor 1, as a result of which the key 19 is activated and the circuit is set to its original state.

In comparison with the prototype of the claimed device allows for higher accuracy to measure strength, to determine reliably its average value for the controlled area of the product and is more productive in the implementation of control.

A BTOpbi:; 3 / i - ry yHOB B.V.

Gotovilov A.v., Gershkovich G.B. Gulunov A.V.

Claims (1)

A device for measuring the strength of building materials, comprising a useful signal sensor connected in series, a matching amplifier, a low-pass filter, a first differentiator, a second differentiator and a comparator, as well as a peak detector with an analog-to-digital converter (ADC) and a decoder with an indicator connected in series, moreover the useful signal sensor is assembled in a separate housing and consists of a shock spring, a trigger, a striker with a striker and a piezoelectric element mounted on the striker, about characterized in that a key, a trigger latch and an analog key are connected in series, as well as a data processing unit consisting of a series-connected keyboard, control and synchronization device, read-only memory (ROM), an arithmetic logic device (ALU) and operational a storage device (RAM), the key being installed in the sensor housing and connected with a shock spring made in the form of an elastic plate, one end of which is rigidly attached to the wall of the housing, and the other end the firing pin with a piezoelectric element and a drummer, which has the possibility of friction-free movement at the tip of the housing, is rigidly fixed, the key output is connected simultaneously with the second input of the control and synchronization device, the first input of the peak detector and the first input of the trigger latch, the second input of which is connected to the output of the comparator, analog the key is connected by the second input to the output of the second differentiator, and by the output to the second input of the peak detector, the output of which is connected to the ADC input, the output connected to the second input O A memory device, the third and fourth inputs of which are connected respectively to the second output of the keyboard and the second output of the control and synchronization device, the third output of which is connected to the second input of the ALU connected by the third input to the RAM output, and the output also to the decoder input.