Small strain testing system for measurement of elasticity modulus in different civil engineering materials by various vibration elements

Abstract

The small strain testing system is for measuring the velocities of pressure and shear waves in different ground materials, especially soil, and for measurement of the modulus of elasticity in various civil engineering materials by various vibrating elements. It performs non-destructive tests on a wide range of laboratory samples of ground materials. The components are the transmitter actuator, receiver sensor, function generator, oscillator, amplifier, and reducer. The types of transmitter operators and receiver sensors of this device include unidirectional bending, bidirectional bending, pressure, or combination. The electrical wave is converted into a mechanical wave by the transmitter operator, then into a stress wave in the tested materials. The wave passing through the material is received by the receiver sensor, the time difference between the transmitted, and received wave, and the distance between the operator and the sensor can obtain the moduli of elasticity of the tested ground material.

Description

Small Strain Testing System for Measurement of Elasticity Modulus in Different Civil Engineering Materials by Various Vibration Elements

[0001] This invention is classified in the field of civil engineering in the branches of geotechnics, road construction, pavement, structure, earthquake, and railway, and the field of mining engineering in the branch of rock mechanics. The use of measuring the speed of waves in the quality control process of various materials, especially steel and concrete, has a history of seven decades. Also, the measurement of shear and pressure waves in ground materials (soil and rock types) has a history of forty years. But until now, there has not been a single comprehensive device for measuring the speed of waves in a wide range of construction materials.

[0002] E04H 7 / 00

[0003] CN108225951A

[0004] A non-destructive test method for the durability of fiber-reinforced composite materials

[0005] The present invention provides a non-destructive test method for the durability of fiber-reinforced composite materials, comprising: allocating multiple fiber-reinforced composite material specimens of the same batch to a reserved specimen group and N standard specimen groups; performing a destructive strength tensile test on each reserved specimen to determine the magnitude of the tensile force of the non-destructive tensile test on the standard specimen; performing M non-destructive tensile tests on each standard specimen to obtain the average elastic modulus of the standard specimen at the initial moment; placing the standard specimen in a test environment for aging; at each aging time point, taking out each standard specimen, performing M non-destructive tensile tests, and obtaining the average elastic modulus of each standard specimen at the current aging time point. The application of the present invention can avoid the influence of different initial mechanical properties of the test samples on the durability test results of the composite material, reduce the discreteness of the test results, and improve the test accuracy and the stability and reliability of the test results.

[0006] The mentioned invention is for composite materials and has the nature of a non-destructive tensile test but is not related to the propagation of waves and is inherently not comparable.

[0007] US4567774A

[0008] Determining mechanical behavior of solid materials using miniature specimens

[0009] A Miniaturized Bend Test (MBT) capable of extracting and determining mechanical behavior information from specimens only so large as to have at least a volume or smallest dimension sufficient to satisfy continuum behavior in all directions. The mechanical behavior of the material is determined from the measurements taken during the bending of the specimen and is processed according to the principles of linear or nonlinear material mechanics or both. In a preferred embodiment the determination is carried out by a code which is constructed according to the finite element method, and the specimen used for the determinations is a miniature disk simply supported for central loading at the axis on the center of the disk.

[0010] The mentioned invention is based on the change in the materials volume and on numerical simulation. Its different nature from the present invention violates the possibility of comparison.

[0011] GB2426821

[0012] Shear wave velocity determination using evanescent shear wave arrivals

[0013] A method for determining formation shear wave velocity or slowness comprises deploying a down hole tool in borehole, generating an acoustic wave using a transmitter on the tool, receiving an acoustic waveform at a receiver on the tool and measuring the tool standoff distance. The tool standoff measurement is used to indicate the absence or presence of leaky shear wave arrivals (evanescent shear wave arrivals) in the received waveform. If leaky shear wave arrivals are present they are processed to determine the shear wave velocity, possibly using a semblance algorithm or phase velocity algorithm. If leaky shear wave arrivals are absent the shear wave velocity is estimated from a borehole guided wave velocity instead. The method may provide direct determination of shear wave formation velocity in acoustically slow formations.

[0014] This mentioned invention is about measuring the shear wave and pressure way which is similar to ours, but it operates an acoustic transmitter and receiver which we do not have.

[0015] US20210077072

[0016] Shear wave elasticity measurement method and shear wave elasticity imaging system

[0017] A shear wave elasticity measurement method and a shear wave elasticity imaging system are disclosed. For each pair of corresponding shear waves, an echo signal within a continuous period of time can be obtained only at a third position, so that an elasticity parameter corresponding to the target area can be obtained according to the echo signal within the continuous period of time. Not only the position required for obtaining an echo signal is few, but also the total data volume required for obtaining the echo signal is few. The calculation method is also easy, which significantly reduces the system performance requirement.

[0018] This patent is for determining the shear wave elasticity while our claimed patent is for measuring both shear wave and pressure wave.

[0019] WO2005098731

[0020] SYSTEMS AND METHODS TO DETERMINE ELASTIC PROPERTIES OF MATERIALS

[0021] The present invention provides systems and methods to use a measured driving point response of a nonlinear material to determine one or more elastic properties of the material. The present takes advantage of the full information represented by the transient component, the steady-state component, the anharmonic components, and the nonlinear response components of a measured driving-point response of a real nonlinear material, without limitation in the use of large-amplitude forces. The elastic properties are determined by forming and solving a time-domain system of linear equations representing a differential equitation model of the driving-point motion of the material. Based on a single, short duration, large-amplitude driving point measurement, both linear and nonlinear properties can be determined; and elastic-wave speed and elastic moduli and their variation with depth can be determined. The present invention also provides a system and a method to filter an input signal to either attenuate or preserve each of one or more selected harmonic components that are harmonics of a phase reference signal.

[0022] The mentioned patent uses similar components as ours, but it does not aim for waves and vibration and it has proposed methods, not a device.

[0023] A small strain testing system is designed to measure the modulus of elasticity in civil engineering materials. It includes piezoelectric actuators, sensors, wave generators, oscillators, amplifiers, and a chamber for the components. The device covers a wide range of ground materials and can determine the velocities of internal waves in these materials. The piezoelectric actuator creates mechanical vibration by applying electrical voltage fluctuation. The sensor cap can be made of any material and is designed based on the tested material. The speed of the waves in the material is determined by the time difference between the waves sent and received from the material. The wave generator sends a specific shape, frequency, and amplitude of electric waves, which are amplified by the amplitude amplifier. The electric wave passes through the material and reaches the sensor, and the time difference between the waves gives the speed of the shear and pressure waves.

[0024] Civil engineering and construction technology involve various materials from the beginning of a project to the operation stage. Some of these materials, such as soil and stone, exist in the place and operations are carried out on them or around them. Some of these materials are made on-site, such as foundation and structural concrete, wall cement block, and road asphalt. Some of these materials, such as wall bricks, clay blocks, and steel, are prefabricated and installed on-site. Quality control of materials is usually done by taking samples and referring them to the laboratory. In a time-consuming process, several tests on the materials are performed in the laboratory. One way to speed up the quality control process of materials is to perform small non-destructive strain tests. Currently, there are devices for independently performing non-destructive testing on soil, concrete or steel. In these devices, shear waves (for soil and stone) or pressure waves (for steel and concrete) are sent and received. The wave speed (time of wave movement divided by the distance passedcve by the wave) in the material gives very valuable information about the quality and resistance of the material. However, until now there has not been a single device that can cover a wide range of construction materials. The reason for that is the significant difference in amplitude, frequency, and time intervals of sending and receiving waves. Also, in different materials, different waves are considered. In soil and stone materials, shear wave speed is more important, and in concrete and steel materials, pressure wave speed is more important. The main purpose of the invention of this comprehensive system is to reduce the costs of research and industrial laboratory experiments, including the shear wave and pressure wave measurement system in a wide range of different construction materials by the method of passing waves (wave transmission). Therefore, the limitation of non-destructive testing devices to a certain type of material has been resolved in this device. Therefore, this device provides the capability of non-destructive tests in a wide way and for all kinds of laboratory samples of ground materials, including concrete, asphalt, soil, and stone in different dimensions.Solution of Problem

[0025] In a laboratory sample, whether for research experiments or to determine the strength of a sample of existing materials, it is necessary to make or obtain samples as many as possible or under defined conditions. In this way, the cost of tests is equal to the cost of each test in the number of variable conditions such as all-round stresses, degrees of saturation, relative density, additive percentage, etc., which are defined for the intended study or may be pre-defined for the conditions of the civil structure. In contrast to large or destructive strain tests, there are small or non-destructive strain tests. The importance of non-destructive tests of soil materials in laboratory research becomes clear when it is difficult to create the conditions for the sample of the tested material or it is not easy to prepare the sample. With the help of the small strain testing system of ground materials, it is possible to measure resistance properties such as shear modulus, confinement modulus, Young's modulus, and Poisson's ratio in small strains.

[0026] It is possible to use an integrated and comprehensive system to determine the elastic moduli of various construction materials through the measurement of wave velocities in small strainsin the multi-purpose system for testing small strains in civil engineering materials. In this system, one-way shear wave speed, two-way shear wave speed, or pressure wave speed can be measured in materials, and as a result, Young's modulus, shear modulus, confinement modulus, bulk modulus, or coefficient He got the second lama in construction materials. Previously, non-destructive testing devices in construction materials were aimed at a specific range of materials, which in this invention was made possible with the help of two stages of improving the scope of application in non-destructive testing. The first step is to create a variety of actuators and sensors, to provide a selection depending on the type of material and the type of elasticity modulus.

[0027] For example, the wave discussed in concrete materials is often the pressure wave, from which Young's modulus is extracted and used in designs, while in earthen materials, shear wave and shear modulus are discussed. In some materials, both are discussed. The second step is that the function of the wave generator and wave oscillator was expanded with the help of choosing their type as well as the amplifier and reducer of the waves. For example, the frequency range of waves in materials such as concrete or steel is more than 100 kHz, and in materials such as soil and stone is less than 20 kHz. Also, depending on the height of the sample and the type of material, the voltage applied to the wave actuators can vary from 20 volts to 200 volts. Each of the cases that have led to the improvement of the non-destructive testing system in this device is presented in the form of different sections. This invention includes the following main parts:

[0028] 1. Shear wave operators

[0029] 2. Shear wave sensors

[0030] 3. Pressure wave operators

[0031] 4. Pressure wave sensors

[0032] 5. Detachable sheath carrying actuators or sensors

[0033] 6. Caps carrying pods

[0034] 7. Wave function generator

[0035] 8. Wave amplifier

[0036] 9. Oscillation of the waves

[0037] 10. Wave reducer

[0038] Shear wave actuators and sensors work with vibration like a cantilever beam in creating and identifying shear waves. In the actuator mode, the electrical vibration is converted into mechanical vibration, and in the sensor mode, the mechanical vibration is converted into electrical vibration. These actuators and sensors are made by gluing two piezoelectrics together. When the voltage is applied to the plates of these two piezoelectrics, one expands and the other contracts, and the whole system is bent and plays the role of a wave transmitter. Similarly, a small movement of the member caused by the impact of the wave causes the generation of voltage and in this case, they act as a wave receiver. In other words, a piezoelectric element is an element that produces a stress wave as a result of electrical stimulation, and as a result of the stress wave reaching it, an electrical stimulation is also created. Therefore, the bending element can be used both as a transmitter and as a receiver. An electric pulse is applied to the transmitter member and causes a shear wave in it. When this wave reaches the other end of the sample, the deformation of the receiving member produces another electric pulse. The time difference between two electric pulses is measured with an oscilloscope and is divided by the distance between the ends of the bending element which gives the speed of the shear wave.

[0039] Actuators and sensors of pressure waves with vibration act like a beating heart in creating and identifying pressure waves. These actuators and sensors can be ultrasonic which is based on the magnetic field and piezoelectric which is based on piezo properties. In the actuator mode, the electrical vibration is converted into mechanical vibration, and in the sensor mode, the mechanical vibration is converted into electrical vibration.

[0040] Detachable sheath-carrying actuators and sensors are the holders of actuators and sensors. They are placed inside the cap and pedestal of the system by means of O-rings. These sheaths play an essential role in the working scope of the present invention because the flexibility of their design and variety allows a wide range of materials to be covered for testing. Numbers 11 to 14 inshow three different modes. High flexibility in choosing the type of operator or sensor from the following depending on the type of material and type of data is required:

[0041] 1. Actuator and pressure wave sensor (to determine the speed of the longitudinal wave)

[0042] 2. Buried one-way shear wave actuator and sensor (to determine the one-way shear wave speed in hard materials)

[0043] 3. Two-way buried shear wave actuator and sensor (to determine the speed of two-way shear waves in hard materials)

[0044] 4. One-way free shear wave operator and sensor (to determine the one-way shear wave speed in soft materials)

[0045] 5. Two-way free shear wave operator and sensor (to determine the speed of two-way shear waves in soft materials)

[0046] The caps carrying the pods are designed depending on the type of material or the type of device used.

[0047] Based on the usage, the wave function generator can form and send the transmitter wave to the operators. The adjustable parameters are waveform (sine, rectangular, triangular, noise, and arbitrary), amplitude (from 4 mV to 20 V peak to peak), frequency (from 20 μHz to 20 MHz), time intervals of sending the wave, Wave type (continuous or single pulse). The characteristics of the wave function generator are 2 outputs, 125 million samples per second, frequency accuracy of 1 microhertz, and amplitude accuracy of 14 bits.

[0048] The wave amplifier can magnify the output range of the wave function generator up to 20 times with negligible delay. The amount of magnification varies based on the capacitance of the sensor and the transmission frequency.

[0049] The generator output wave reducer can reduce the output amplitude of the wave function generator up to 10 times with a negligible delay.

[0050] The oscillation of the wave view can display and record the wave received by the sensor with a maximum frequency of 100 MHz. The characteristics of the wavefront oscillation are 2 inputs, 500 million samples per second, filtering capability in the 20 MHz band, and 8-bit amplitude accuracy.Advantage Effects of the Invention

[0051] • Comprehensiveness for conducting tests to measure the speed of waves in various construction materials such as concrete, soil, stone, asphalt, brick, and block.

[0052] • The flexibility of the multipurpose system for small strain testing in civil engineering materials from different aspects such as the range of the transmitted wave (from 4 millivolts to 400 volts peak to peak), the frequency of the transmitted wave (from 100 Hz to 20 MHz), the type of transmitted waveform (sinusoidal, rectangular, triangular, pulse and noise), and the type of transmitted wave (shear or pressure).

[0053] • Can be operated in quality control or measurement of resistance parameters of various materials.

[0054] • The advantage of compatibility of this system with various construction materials laboratory devices such as geotechnical testing devices.

[0055] Shows a front view of the system.

[0056] Shows a side cut of the figure one.

[0057] is a view from above.

[0058] shows the upper key panel.

[0059] presents the lower key panel.

[0060] is a flowchart that shows the steps of the testing process.

[0061] Shows a frontal view of the system and the parts placed in which are:

[0062] 1- The system compartment includes the main parts of the device

[0063] 2- Wave generator

[0064] 3- Waveform oscillation

[0065] 4- Operator of waves inside the sheath

[0066] 5- Wave sensor inside the sheath

[0067] 6- Wave operator cap

[0068] 7- Wace Sensor cap

[0069] 8- Wave generator output

[0070] 9- Input of the first wave ( wave generator wave-reference wave)

[0071] 10- The entrance of the second wave (Wave passing through materials)

[0072] 11- On / Off switch of the wave amplifier

[0073] 12- On / Off switch of wave view oscillation

[0074] 13- On / Off switch of the wave generator

[0075] 14- Bending actuator / sensor

[0076] shows a side cut of the figure one and a closer view of the parts:

[0077] 7- Sample of tested materials

[0078] 8- Wave generator output

[0079] is a view from above the system in which other parts are visible:

[0080] 15- Actuator / pressure sensor

[0081] 16- Sheath carrying one-way bending actuators and sensors

[0082] 17- Sheath carrying actuators and pressure sensors

[0083] 18- Sheath carrying two-way bending actuators and sensors

[0084] 19- Sheath carrying actuators and one-way pressure and bending sensors

[0085] shows the upper control panel and its buttons:

[0086] 20- Wave generator USB port

[0087] 21. Back to the previous wave generator

[0088] 22. Number keys next to the waveform keys of the wave generator

[0089] 23. Low / high wave generator

[0090] 24. Wave generator LCD screen

[0091] 25. List of wave-generating operations

[0092] 26. Wave generator function keys

[0093] 27. Wave generator direction keys

[0094] shows the other control panel and its buttons:

[0095] 28- Keys to select the wave display

[0096] 29- On / off key of the list of oscillations

[0097] 30- The general wave oscillating wheel

[0098] 31- The usual function keys of the wave display

[0099] 32- Horizontal control wheels (time)

[0100] 33- Automatic wave display button

[0101] 34- Oscillating trigger control of waves

[0102] 35- Oscillator USB port

[0103] 36- Print key

[0104] 37- Vertical control keys and knobs (voltage)

[0105] 38- Prob component

[0106] is a flowchart of the testing process that shows the starting point from the generation of waves and the steps that the waves pass through.Examples

[0107] In the following, the executive steps for using the multi-purpose system of small strain testing in civil engineering materials are explained:

[0108] 1. Depending on the type of material and the type of desired data, the desired operator and sensor are selected (pressure wave, one-way shear wave, two-way shear wave).

[0109] 2. The operator and sensor are placed in special caps (if the test must be performed in a special laboratory device, the operator and sensor are placed in pre-made and designed caps).

[0110] 3. The material sample is placed between the actuator cap and the sensor cap.

[0111] 4. The test conditions are applied to the material sample (for example, comprehensive stress or initial stress or...).

[0112] 5. The control and data collection system is turned on.

[0113] 6. The wave function generator, wave amplifier, and oscilloscope will be turned on.

[0114] 7. The frequency, amplitude, and waveform of the transmitter are determined selected, adjusted, and sent by the wave function generator.

[0115] 8. Based on the transmitter wave, the range of vision, the range, and the frequency of the received wave are set.

[0116] 9. The time interval between the peak of the transmitter and the peak of the receiver obtains the wave speed based on relations.

[0117] 10. The resistance parameters of the materials can be calculated based on the relationships in the references.

[0118] [Table. 1] shows the speed of waves in different materials:

[0119] [Pic. 1] shows the actuators and sensors of shear waves:

[0120]

[0121] [Pic. 2] displays the actuators and sensors of pressure waves:

[0122]

[0123] [Pic. 3] shows the ultrasonic kind of actuators and sensors of the pressure waves:

[0124]

[0125] [Pic. 5] presents detachable sheath plan carrying actuators and single unidirectional bending sensors:

[0126]

[0127] [Pic. 6] shows a map of the detachable sheath carrying actuators and pressure sensors:

[0128]

[0129] [Chart. 1] presents the working range of the wave amplifier:

[0130]

[0131] [Diagram. 1] shows the diagram of the wave amplifier;

[0132]

[0133] [Chart. 2] Shows an example of the result of a pressure wave speed test on a dry clay soil:

[0134]

[0135] [Chart. 3] presents a sample result of a shear wave speed test on humidity sandy soil:

[0136]

[0137] This system can be used as a non-destructive test to measure shear or pressure wave speed in various construction materials. In more detail, it can be stated that this system can be used before using the materials as design or quality control data and after the construction of the materials as execution control, quality, and improvement. The application of this system in construction materials can be as follows:

[0138] 1. Soil: the foundation under any building foundation, or the materials around road and subway tunnels

[0139] 2. Stone: the foundation under any building foundation, or the materials around road and subway tunnels

[0140] 3. Asphalt: road construction materials on roads and airports

[0141] 4. Concrete: construction materials in buildings, dams, and bridges, and road construction materials in roads and airports

[0142] 5. Bricks: construction materials in buildings, dams, bridges, etc.

Claims

A Small strain testing system for measuring the modulus of elasticity in various civil engineering materials by different vibrating elements, determining the velocities of internal waves (shear and pressure waves) in ground materials and also determining Their modulus of elasticity (equation with resistance) is in small strains comprising:1- types of piezoelectric actuators2- actuator caps3- types of piezoelectric sensors4- sensor caps5- wave generators6- oscillators7- amplitude amplifiers8- amplitude reducers9- Chamber of the system and related connections.According to claim 1, This device covers a wide range of ground materials such as soil, stone, concrete, asphalt, and other materials derived from it in addition to all types of internal waves based on the laws of physics of the propagation of waves inside the body of materials.According to claim 1, the piezoelectric actuator placed inside the actuator cap creates mechanical vibration by applying electrical vibration (voltage fluctuation).According to claim 3, the piezoelectric actuator can create two types of shear or pressure vibration or a combination of them as needed.According to claim 3, the operator cap can be made of any type of material and is designed based on the type and dimensions of the tested material.According to claim 1, the piezoelectric sensor that is placed inside the sensor cap creates electrical vibration by applying mechanical vibration.According to claim 6, the piezoelectric sensor compatible with the actuator can be sensitive to two types of shear or pressure vibration or a combination of them.According to claim 6, the sensor cap can be made of any type of material and is designed based on the type and dimensions of the tested material.According to claim 8, the time difference between the two waves sent and received from the material gives the speed of the wave in the material.According to claim 9, the wave generator is set to send a specific shape, frequency, amplitude, and sequence of electric waves depending on the type of material, the electric wave is amplified by the amplitude amplifier.According to claim 9, the electric wave output from the amplitude amplifier goes to the operator from one side and on the other hand, after passing through the amplitude reducer, it reaches the oscilloscope (first wave).According to claim 9, the operator vibrates and the electric wave is converted into a stress wave and passes through the tested material and reaches the sensor, and the stress wave is converted into an electric wave and reaches the oscillator (second wave).According to claim 9, the time difference between the first wave and the second wave, and the length of the wave in the material, gives the speed of the shear and pressure waves.

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