CN109283046B - Non-contact automatic measuring system for elastic stress and strain of material - Google Patents

Abstract

The invention relates to a non-contact material elastic stress-strain automatic measurement system, which is characterized by at least comprising: an internally modulated semiconductor laser, the internally modulated semiconductor laser is divided into a first band collimating fiber coupling output device and a second band by a beam splitter A collimating fiber coupler, the first one with a collimating fiber coupler is vertically irradiated on the sample held by the sample holder through the focusing lens group; there is a photothermal infrared radiation stress and strain measurement module on the other side of the sample, the optical The thermal infrared radiation stress-strain measurement module acquires the photothermal infrared radiation image when the sample is strained, and transmits the photothermal infrared radiation image to the computing unit. It provides a non-contact material elasticity that can measure average/local, tensile/compression, torsional stress, strain and deformation of the material, and can visualize the effective inversion and reconstruction of the stress-strain field through digital image processing Stress and strain automatic measurement system.

Description

A non-contact material elastic stress-strain automatic measurement system

technical field

The invention relates to industrial non-destructive testing and mechanical measurement evaluation of elastic materials, in particular to a non-contact material elastic stress-strain automatic measurement system.

Background technique

In the industrial production process, the mechanical strength of the material is an important detection index, and the characterization of the mechanical strength can be quantitatively described by the stress-strain characteristics. For the produced raw materials, the material is generally processed into a columnar sample and placed on a tensile testing machine to complete the tensile test. The characteristics of elasticity, plastic deformation and the mechanical strength.

The traditional tensile stress-strain measurement system has three limitations: first, the stress and strain of the material are recorded in the form of the average value of the entire sample, the distribution of stress and strain on the sample cannot be obtained, and it is more difficult to achieve imaging; second , the material needs to be processed into a cylindrical shape to ensure the accuracy of parameter measurement, which cannot be measured for material samples of other shapes; third, the measurement system generally only provides axial tensile load, and cannot perform normal stress (strain) and shear stress. (strain) comprehensive analysis.

Therefore, the improvement of the stress-strain measurement system can be carried out in two aspects: (1) Research and use the fully non-contact local stress-strain measurement technology, which can be obtained by scanning the measured sample without contacting the measured material. where the stress-strain field distribution. (2) Add bending and torsional load application modules to realize comprehensive mechanical strength test of sample materials.

For non-contact stress-strain measurement, photothermal infrared radiation imaging technology can be used for quantitative characterization. In recent years, studies at home and abroad have shown that the local stress and strain of the material will change its local thermal diffusion characteristics and form an anisotropic diffusion field. Therefore, the local stress and strain parameters can be obtained by measuring and analyzing the thermal wave field generated by the incident modulated laser. On the other hand, the deformation of the sample in a single direction under load can be achieved by a fully non-contact laser deflection measurement method. The fully non-contact measurement module can not only characterize the local stress-strain parameter distribution of the sample, but also effectively test the mechanical strength of the sample in special environments (such as high temperature, high pressure, vacuum, etc.) significant practical value.

At present, there is no relevant report on the application of the fully non-contact optical measurement system to the material tensile mechanical strength measurement system.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a non-contact method that can measure the average/local, tensile/compression, torsional stress, strain and deformation of the material, and can realize the effective inversion and reconstruction of the visualized stress-strain field through digital image processing. An automatic measurement system for elastic stress and strain of materials.

The purpose of the present invention is to achieve in this way, a non-contact material elastic stress and strain automatic measurement system, which is characterized by: at least comprising: an internally modulated semiconductor laser, the internally modulated semiconductor laser is divided into a first band by a beam splitter and coupled with a collimated optical fiber The output device and the second output device with collimating fiber coupler, the first one with collimating fiber coupler is vertically irradiated on the sample clamped by the sample holder through the focusing lens group; there is photothermal infrared radiation on the other side of the sample Stress and strain measurement module, photothermal infrared radiation The stress and strain measurement module obtains the photothermal infrared radiation image when the sample is strained, and transmits the photothermal infrared radiation image to the calculation unit; the second optical-thermal-infrared radiation image is transmitted through the collimating lens group. Then, the sample is irradiated at the same time with an incident angle of less than 90°, and there is a light deflection deformation measurement module in the direction of the exit angle symmetrical with the normal line, and the light deflection deformation measurement module outputs the light deflection information generated by the sample strain and transmits it to the calculation unit at the same time; The calculation unit performs information processing according to the light deflection information generated by the sample strain and the photothermal infrared radiation image information when the sample is strained, and obtains the deformation, stress and strain characteristic quantities of the sample measurement points.

The second collimating fiber coupler with a collimating lens passes through the collimating lens group and simultaneously illuminates the sample with an incident angle of less than 90°, which is achieved by moving the scanning unit at different measurement illumination points to obtain different measurements of the sample. Deformation, stress, and strain characteristic quantities of a point.

The first collimated fiber coupler output device obtains more than 70% of the energy of the internally modulated semiconductor laser for output; the second collimated fiber coupler output device obtains less than 30% of the energy of the internally modulated semiconductor laser for output.

The beam splitter or the optical fiber coupler, the internally modulated semiconductor laser is split into more than 70% energy output and less than 30% energy output through the optical fiber through the optical fiber beam splitter.

The internally modulated semiconductor laser is controlled by a signal generating module, which is controlled by a computing unit, and the signal generating module sends laser modulation signals to the internally modulated semiconductor laser; the computing unit sends a signal source control signal to the signal generating module.

The signal generating module simultaneously outputs two reference signals, one reference signal is connected to the optical deflection deformation measurement module, and the other reference signal is connected to the photothermal infrared radiation stress and strain measurement module.

The optical deflection deformation measurement module includes: an optical knife edge, a photodetector, a preamplifier, and a phase-locked detection module. The modulated laser is led out to a beam splitter through an optical fiber, and one channel of the energy is lower than 30% through a band collimator. The output of the optical fiber output coupler is collimated by the lens group and then irradiates the sample surface, which is used as the induction laser of the light deflection measurement system; the reflected light generated by the sample surface passes through the optical knife edge, and then a small amount of light is irradiated to the photodetector to generate an electrical signal , amplified by the preamplifier, and then detected by the phase-locked module and sent to the calculation unit; when the sample is deformed under the load, the reflected light will change accordingly, and the light energy passing through the knife edge is directly related to the deformation amount, so The output signal has the deformation information of the material sample.

The photothermal infrared radiation stress and strain measurement module includes: a mid-infrared CCD camera, germanium glass, and mid-infrared thermal radiation; more than 70% of the energy of the internally modulated semiconductor laser is focused and irradiated to the sample surface through a focusing lens, as photothermal red thermal radiation. The induced laser of the signal; the irradiated sample locally generates periodic thermal diffusion waves and diffuses to its backside. After the mid-infrared thermal radiation passes through the germanium glass, the stray part of the incident laser is effectively filtered out and detected by the mid-infrared CCD camera as The thermal radiation image is output as a radiation image signal after being phase-locked and detected by the phase-locked detection module, and transmitted to the computing unit.

The mobile scanning unit includes: a guide rail group and a motor group, the guide rail group is composed of two groups of straight guide rails and a group of rotating guide rails, the motor group is composed of two groups of linear motors, and the first has a collimating fiber coupler and a collimating lens. The group and the light deflection deformation measurement module are fixed in the guide rail seat on the guide rail group. The guide rail seat is connected with the motor group shaft. The motor group is driven by the computing unit to generate motor control signals, and different intensities, directions and types of loads are applied to the sample through the motor group. (stretching, bending, torsion); the sample holder cooperates with the guide rail group and the motor group to realize continuous stress and strain loading. The two guide rails in the guide rail group are straight guide rails, which can provide the axial tensile load of the tested sample and the vertical Axial bending moment load; the third guide rail is a rotating guide rail, which cooperates with a high-torque motor to apply a torsional load; the loads in the three directions can be applied sequentially or simultaneously, which can simulate when the material sample is subjected to various external forces deformation and internal stress-strain conditions.

The non-contact material elastic stress and strain automatic measurement system provided by the present invention only relies on a single light source, the light source is an internal modulation mode, and the laser output adopts harmonic modulation. The frequency domain optical signal is extracted for evaluation by means of phase-locked detection.

The reference signal of the phase-locking module of the non-contact material elastic stress and strain automatic measurement system proposed by the present invention is the same as the laser energy modulation signal, and is provided by the automatic control module of the computing unit. The detection signal is output to the data acquisition module of the computing unit and completed by the computing unit. Subsequent data processing and efficient feature extraction.

Description of drawings

Fig. 1 is the structure diagram of the non-contact material elastic stress and strain automatic measurement system of the present invention;

Fig. 2 is the principle schematic diagram of the non-contact material elastic stress-strain automatic measurement system of the present invention;

Fig. 3 is the principle schematic diagram of the light deflection deformation measurement module of the present invention;

FIG. 4 is a schematic diagram of the principle of the photothermal infrared radiation stress measurement module of the present invention.

Each label and its components in the figure are: 1-fixed base, 2-sample holder, 3-guide rail group (two sets of straight guide rails, one set of rotating guide rails), 4-motor group (two sets of linear motors, one set of Torque motor), 5-stress sensor unit (normal stress, shear stress sensor), 6-all-optical measurement unit, 61-internally modulated semiconductor laser, 62-signal generation module, 63-fiber, 64-beam splitter, 65A -1st with collimating fiber coupler, 65B-2nd with collimating fiber coupler, 66-focusing lens group, 67-collimating lens group, 68-light deflection deformation measurement module, 69-photothermal infrared radiation Stress-strain measurement module, 610-reference signal, 611-laser modulation signal, 681-optical knife edge, 682-photodetector, 683-preamplifier, 684-phase-lock detection module, 685-modulated laser, 691-medium Infrared CCD camera, 692-germanium glass, 693-mid-infrared thermal radiation, 7-sample, 8-computing unit, 9-optical deflection signal, 91-signal source control signal, 92-optical deflection measurement signal, 93-photothermal infrared Radiometric signal, 10- stress sensor reading, 11- motor control signal.

Detailed ways

As shown in FIG. 2, a non-contact material elastic stress and strain automatic measurement system at least includes: an internally modulated semiconductor laser 61, and the internally modulated semiconductor laser 61 is divided into a first band collimated fiber coupling output device 65A by a beam splitter 64 and the second collimating fiber coupler 65B, the first collimating fiber coupler 65A is vertically irradiated on the sample 7 held by the sample holder 2 through the focusing lens group 66; on the other side of the sample 7 There is a photothermal infrared radiation stress and strain measurement module 69, the photothermal infrared radiation stress and strain measurement module 69 obtains the photothermal infrared radiation image of the sample 7 when it is strained, and transmits the photothermal infrared radiation image to the calculation unit 8; the second belt is collimated The optical fiber coupler 65B passes through the collimating lens group 67 and irradiates the sample 7 at the same time with an incident angle of less than 90°, and there is a light deflection deformation measuring module 68 at the exit angle symmetrical with the normal line, and the light deflection deformation measuring module 68 outputs the output The light deflection information 9 generated by the strain of the sample 7 is simultaneously transmitted to the calculation unit 8; Deformation, stress and strain feature quantities 10.

The second optical fiber coupler 65B with collimation passes through the collimating lens group 67 and simultaneously irradiates the sample 7 with an incident angle of less than 90° by moving the scanning unit to irradiate the sample 7 at different measurement points, so that Obtain the deformation, stress and strain characteristic quantities of different sample 7 measurement points.

The first band collimating fiber coupler 65A obtains more than 70% of the energy of the internally modulated semiconductor laser 61 for output; the second band collimating fiber coupler 65B obtains 30% of the internally modulated semiconductor laser 61 The following energy is output.

The beam splitter 64 is also a fiber beam splitter, and the internally modulated semiconductor laser 61 is split into more than 70% energy output and less than 30% energy output through the fiber 63 through the fiber beam splitter.

The internally modulated semiconductor laser 61 is controlled by the signal generation module 62, and the signal generation module 62 is controlled by the calculation unit 8. The signal generation module 62 sends a laser modulation signal 611 to the internally modulated semiconductor laser 61; the calculation unit 8 sends the signal generation module 62 sends a signal source control signal 91 .

The signal generating module 62 simultaneously outputs two channels of information reference information 610 , one channel of reference information is electrically connected to the optical deflection deformation measurement module 68 , and the other channel of reference information is connected to the photothermal infrared radiation stress and strain measurement module 69 .

As shown in FIG. 3 , the optical deflection deformation measurement module 68 includes: an optical blade 681 , a photodetector 682 , a preamplifier 683 , and a phase-locked detection module 684 , and the modulated laser 685 is led out to the beam splitter through the optical fiber 63 64, the energy of one channel is lower than 30%, and the best output is 10% through the optical fiber output coupler with collimation. After collimated by the lens group 67, the surface of the sample 7 is irradiated and used as the induced laser of the optical deflection measurement system; The reflected light generated on the surface of the sample 7 passes through the optical knife edge 681 and a small amount of light irradiates the photodetector 682 to generate an electrical signal, which is amplified by the preamplifier 683 and detected by the phase lock module 684 and sent to the computing unit 8 . When the sample deforms under load, the reflected light will change accordingly, and the light energy passing through the knife edge is directly related to the deformation amount, so the output signal 92 has the deformation information of the material sample.

As shown in FIG. 4 , the photothermal infrared radiation stress and strain measurement module 69 includes: a mid-infrared CCD camera 691, germanium glass 692, and mid-infrared thermal radiation 693; more than 70% of the energy of the internally modulated semiconductor laser 61 (the best solution is 90 %) focused and irradiated to the surface of the sample 7 through the focusing lens 66, as the induction laser of the photothermal red thermal radiation signal; the irradiated sample 7 locally generates periodic thermal diffusion waves and diffuses to its back, and the mid-infrared thermal radiation 693 passes through the germanium After the glass 692, the stray part of the incident laser 685 is effectively filtered out and detected as a thermal radiation image by the mid-infrared CCD camera 691. After phase-locked detection by the phase-locked detection module 684, the output is a radiation image signal 93, which is transmitted to the calculation in unit 8.

As shown in Figure 1, the mobile scanning unit includes: a guide rail group 3 and a motor group 4. The guide rail group 3 consists of two sets of straight guide rails and a set of rotating guide rails, and the motor group 4 consists of two sets of linear motors. The coupling output device 65A, the collimating lens group 67, and the light deflection deformation measuring module 68 are fixed in the guide rail seat on the guide rail group 3, and the guide rail seat is connected with the motor group 4 shaft, and the motor group 4 is driven by the calculation unit 8 to generate the motor control signal 11 , and the moving scanning unit can detect different positions of the sample 7 through the 4-axis movement of the motor group.

The guide rail group 3 and the motor group 4 realize continuous strain detection at different strain points, wherein the two guide rails in the guide rail group 3 are straight guide rails, and the motor can provide the axial tensile load of the tested sample and the bending moment load perpendicular to the axial direction; The third guide rail is a rotating guide rail, which is used with a high-torque motor to apply a torsional load; the loads in the three directions can be applied sequentially or simultaneously, which can simulate the deformation and internal stress and strain of the material sample when it is subjected to various external forces. .

The working principle of the present invention is shown in FIG. 1 , the material sample 7 is fixed on the sample holder 2 to start the test. The motor control signal 11 output by the calculation unit 8 applies a certain load to the sample to be tested and keeps it stable. At this time, the actual average value of the applied load can be measured by the stress sensing unit 5 and transmitted to the calculation unit through the signal flow 10; Then the calculation unit modulates the laser output energy through the signal source control signal 91, and outputs a reference signal 610 from the signal generator; the modulated laser 685 is led out to the beam splitter 64 through the optical fiber 63, and one of the channels has a lower energy (10% ) is output through the optical fiber output coupler with collimation, and is collimated by the lens group 67 to irradiate the sample surface, which is used as the induced laser of the light deflection measurement system; the reflected light generated by the sample surface passes through the optical knife edge and a small amount of light is irradiated to the photoelectric The detector 682 is then generated as an electrical signal, which is amplified by the preamplifier 683 and then detected by the phase lock module 684 and sent to the computing unit. When the sample is deformed under load, the reflected light will change accordingly, and the light energy passing through the knife edge is directly related to the deformation amount, so the output signal 92 has the deformation information of the material sample. The other laser output with higher energy (90%) is focused and irradiated to the surface of the sample through the focusing lens 66, as the induction laser of the photothermal red heat radiation signal; the irradiated sample locally generates periodic thermal diffusion waves to the back of the sample. Diffusion, the stray part of the incident laser 685 is effectively filtered out of the infrared thermal radiation signal 693 after passing through the germanium glass, detected as a thermal radiation image by the mid-infrared CCD camera 691, and output as a radiation image signal 93 after two-dimensional phase-locked detection , transferred to the computing unit. When there is stress and strain in the material sample, its thermal diffusivity will change, so the radiation signal 93 carries the information of the local stress and strain near the laser irradiation point, and the calculation unit completes the data analysis and feature extraction to complete the test. The non-contact all-optical detection system will be placed on the guide rail 3 to realize the scanning test along the axial direction of the sample to obtain the deformation, stress and strain characteristics of different measurement points.

The motor unit 4 generates multiple stress loads under the action of the control signal 11, and the sample 7 may be deformed by elongation, necking, torsion, etc., and the local deformation of the sample is measured according to the optical deflection system provided by the present invention. The light source used in the deflection measurement is the same light source as the photothermal excitation source, and a small part of the energy derived from it is collimated/focused and then incident on the sample where the deformation needs to be measured. The light deflection signal 9 is detected.

The motor unit 4 generates multiple stress loads under the action of the control signal 11, and the corresponding stress and strain will accumulate inside the sample 7. The local stress and strain is measured according to the photothermal infrared radiation stress measurement system provided by the present invention. Most of the energy in the multi-mode high-power laser is focused on the part of the sample through the output of the coupler, and the spot size is variable. The thermal diffusion field is imaged by the mid-infrared CCD camera on the back of the sample, and the effective thermal diffusion parameters are extracted through the corresponding algorithm, and the quantitative relationship between the thermal diffusion parameters and the stress and strain is established, and finally the purpose of non-contact stress and strain measurement is achieved. .

Components and structures not described in detail in this embodiment belong to well-known components and common structures or common means in the industry, and will not be described one by one here.

Claims (6)

1. a non-contact material elastic stress-strain automatic measuring system, it is characterized in that: comprise at least: the internal modulation type semiconductor laser, the inner modulation type semiconductor laser is divided into the first band collimation fiber coupling output device and the second band collimation by the beam splitter Straight fiber coupler, the laser output from the first collimated fiber coupler is vertically irradiated on the sample held by the sample holder through the focusing lens group; there is a photothermal infrared radiation stress and strain measurement module on the other side of the sample , the photothermal infrared radiation stress-strain measurement module obtains the photothermal infrared radiation image when the sample is strained, and transmits the photothermal infrared radiation image to the calculation unit; The sample is irradiated at the same time with an incident angle less than 90° relative to the normal direction of the sample surface, and there is a light deflection deformation measurement module at the exit angle symmetrical with the normal. The light deflection deformation measurement module outputs the light deflection information generated by the sample strain at the same time. It is transmitted to the calculation unit; the calculation unit performs information processing according to the light deflection information generated by the sample strain and the photothermal infrared radiation image information when the sample is strained, and obtains the deformation, stress and strain characteristic quantities of the sample measurement point; The optical deflection deformation measurement module includes: an optical blade, a photodetector, a preamplifier, and a phase-locked detection module. The modulated laser is led out to a beam splitter through an optical fiber, and one channel of energy below 30% passes through a collimated optical fiber. The output of the output coupler is collimated by the lens group and then irradiates the sample surface, which is used as the induced laser of the light deflection measurement system; the reflected light generated by the sample surface passes through the optical knife edge and then a small amount of light is irradiated to the photodetector to generate an electrical signal. After the preamplifier is amplified, it is detected by the phase-locked module and sent to the calculation unit; when the sample is deformed under the load, the reflected light will change accordingly, and the light energy passing through the knife edge is directly related to the amount of deformation, so the output The signal has the deformation information of the material sample; The photothermal infrared radiation stress and strain measurement module includes: a mid-infrared CCD camera, germanium glass, and mid-infrared thermal radiation; more than 70% of the energy of the internally modulated semiconductor laser is focused and irradiated to the surface of the sample through a focusing lens as a photothermal infrared radiation signal. The irradiated sample locally generates periodic thermal diffusion waves and diffuses to its back. After the mid-infrared thermal radiation passes through the germanium glass, the stray part of the incident laser is filtered out, and the effective radiation is detected by the mid-infrared CCD camera as The thermal radiation image is output as a radiation image signal after phase-locked detection by the phase-locked detection module, and transmitted to the computing unit; It also includes a stress applying unit. The stress applying unit includes: a guide rail group and a motor group. The guide rail group consists of two sets of straight guide rails and a group of rotating guide rails. The motor group consists of a group of linear motors and a group of rotating motors. The guide rail is a straight guide rail, which cooperates with the motor and provides the axial tensile load of the tested sample and the bending moment load perpendicular to the axial direction under the motor control signal generated by the calculation unit; the third guide rail is a rotating guide rail, which cooperates with a high-torque motor to apply Torsional load; loads in three directions are applied sequentially or simultaneously, simulating the deformation and internal stress-strain of a material sample when subjected to various external forces. 2. A kind of non-contact material elastic stress-strain automatic measuring system according to claim 1, is characterized in that: the laser outputted by the said second band collimating fiber coupler output device passes through the collimating lens group with relative to Simultaneously irradiating the sample with an incident angle with the normal direction of the sample surface less than 90° is realized by moving the scanning unit at different measurement irradiation points, so as to obtain the deformation, stress and strain characteristic quantities of different measurement points of the sample. 3. The non-contact material elastic stress-strain automatic measuring system according to claim 1, characterized in that: the first band collimation fiber coupler obtains more than 70% of the energy of the internally modulated semiconductor laser for output. ; The second band collimation fiber coupler output device obtains 30% or less of the energy of the internally modulated semiconductor laser for output. 4. The non-contact material elastic stress-strain automatic measurement system according to claim 1, wherein the beam splitter is an optical fiber beam splitter, and the internally modulated semiconductor laser is divided into The beam is more than 70% of the energy output and less than 30% of the energy output. 5. The non-contact material elastic stress-strain automatic measurement system according to claim 1, wherein the internally modulated semiconductor laser is controlled by a signal generating module, the signal generating module is controlled by a computing unit, and the signal The generating module sends a laser modulation signal to the internally modulated semiconductor laser; the computing unit sends a signal source control signal to the signal generating module. 6. The non-contact material elastic stress-strain automatic measurement system according to claim 5, wherein the signal generation module outputs two reference signals simultaneously, and one reference signal is connected to the optical deflection deformation measurement module, The other reference signal is electrically connected with the photothermal infrared radiation stress and strain measurement module.

Images