NL2026678B1 - Cruciform tensile characterization heating test platform and method - Google Patents

Cruciform tensile characterization heating test platform and method Download PDF

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Publication number
NL2026678B1
NL2026678B1 NL2026678A NL2026678A NL2026678B1 NL 2026678 B1 NL2026678 B1 NL 2026678B1 NL 2026678 A NL2026678 A NL 2026678A NL 2026678 A NL2026678 A NL 2026678A NL 2026678 B1 NL2026678 B1 NL 2026678B1
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cross
induction coil
heating
tensile test
cruciform
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NL2026678A
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Dutch (nl)
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NL2026678A (en
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Chu Xingrong
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Univ Shandong
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/18—Performing tests at high or low temperatures
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02—Details
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08—Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014—Type of force applied
    • G01N2203/0016—Tensile or compressive
    • G01N2203/0017—Tensile
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058—Kind of property studied
    • G01N2203/0069—Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0075—Strain-stress relations or elastic constants
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/022—Environment of the test
    • G01N2203/0222—Temperature
    • G01N2203/0226—High temperature; Heating means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/026—Specifications of the specimen
    • G01N2203/0262—Shape of the specimen
    • G01N2203/0272—Cruciform specimens
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0605—Mechanical indicating, recording or sensing means
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0641—Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/0641—Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
    • G01N2203/0647—Image analysis
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0676—Force, weight, load, energy, speed or acceleration
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0682—Spatial dimension, e.g. length, area, angle
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02—Details not specific for a particular testing method
    • G01N2203/06—Indicating or recording means; Sensing means
    • G01N2203/067—Parameter measured for estimating the property
    • G01N2203/0694—Temperature

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  • Physics & Mathematics (AREA)
  • Health & Medical Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • General Physics & Mathematics (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Investigating Strength Of Materials By Application Of Mechanical Stress (AREA)

Abstract

The invention provides a cruciform tensile characterization heating test platform and method. The test platform comprises an induction heating temperature control system, a stretching control system 5 and a strain measuring system; the induction heating temperature control system comprises a metal plate, an induction coil, a temperature sensor and an induction heating power supply, the adjustable induction heating power supply is connected to the induction coil, the induction coil is arranged in parallel on one side of the metal plate, the metal plate is heated by the induction coil to provide a heat environment, the metal plate is arranged in parallel on the upper side of the two-way cross stretching 10 device, the temperature reaches a set value by adjusting the current value in the induction coil. The invention accurately tests the mechanical properties and forming properties of the plate at high temperatures under equal dual tension and different loading ratios.

Description

i
CRUCIFORM TENSILE CHARACTERIZATION HEATING TEST PLATFORM AND
METHOD Field of the Invention The present invention belongs to the field of characterization and test of mechanical properties and forming properties of metal plates, and specifically relates to a cruciform tensile characterization heating test platform and method. Background of the Invention The statement of this section merely provides background art information related to the present invention, and does not necessarily constitute the prior art. Cruciform tension can obtain the mechanical properties, yield criteria and forming limits of a plate under equal dual tension and different strain paths, while the mechanical properties, yield criteria and forming limits of the plate under equal dual tension and different strain paths at different temperatures are particularly important for guiding the forming process of the plate. As the inventors know, the existing platforms that can test the two-way cruciform tensile properties of metals at different temperatures are generally composed of a hydraulic or mechanical two-way stretching device and a heating furnace. When tensile tests of different temperatures, especially high-temperature tests, are performed in the heating furnace, the non-contact strain measurement technology cannot be applied well due to the refraction of light by high-temperature air and glass in the closed furnace, which affects the test precision and cannot obtain accurate mechanical properties and forming properties of the plate. Summary of the Invention In order to solve the above problems, the present invention proposes a cruciform tensile characterization heating test platform and method, which can accurately test the mechanical properties, yield criteria and forming properties of a plate at different temperatures under equal dual tension and different loading ratios. According to some embodiments, the present invention adopts the following technical solutions:
A cruciform tensile characterization heating test platform includes an electric heating temperature control system, a stretching control system and a strain measuring system, wherein: the stretching control system includes a tester, a two-way cross stretching device, a scale grating and a force sensor; the tester is connected to the two-way cross stretching device to apply pressure thereto, the two-way cross stretching device is used to clamp and stretch a test piece, and the scale grating and the force sensor are used to read the stretched length and force value of the test piece; the electric heating temperature control system includes a metal plate, an induction coil, a temperature sensor and an induction heating power supply; the induction heating power supply 1s connected to the induction coil, the induction coil is arranged on one side of the metal plate, the metal plate is heated by the induction coil to provide a heat environment, the metal plate is arranged in parallel on the upper side of the two-way cross stretching device, and the temperature reaches a set value by adjusting the current value in the induction coil; the strain measuring system includes a measuring head and a processor connected to each other, the measuring head includes a camera for capturing an image of a stretching process, and the processor obtains a strain value of the test piece during the tensile test at a set temperature according to the image.
Through the above solution, the metal plate is heated by the induction coil to generate a heat environment, and strain measurement results are automatically obtained by using the measuring head and the processor, which can overcome the shortcoming that the existing heat environment cross tensile test platform cannot accurately obtain the strain field of the test piece, and can accurately test the mechanical properties, yield criteria and forming properties of the plate at high temperatures under equal dual tension and different loading ratios.
As an alternative embodiment, the metal plate is fixedly arranged on a support frame, so that one side of the metal plate is parallel to the test piece, and the other side is parallel to the induction coil.
As an alternative embodiment, the induction heating power supply is connected to a PLC control system for controlling the output power of the induction heating power supply to automatically adjust and control the temperature of the tensile test piece.
As an alternative embodiment, the support frame is further provided with an induction coil mounting piece, the induction coil mounting piece includes a mounting plate, and both ends of the mounting plate are fixedly mounted on the support frame through fixing members, respectively.
As an alternative embodiment, two outgoing lines of the induction coil pass through the mounting plate and are connected to the induction heating power supply.
As an alternative embodiment, a thermocouple wire is arranged in the heated area of the tensile test piece.
As an alternative embodiment, the two-way cross stretching device includes a cross base, trapezoidal block bases, trapezoidal blocks, a cross pressing assembly, clamping components, tension sensors, a spring, scale gratings and grating reading heads; the cross base is provided with a cross groove, and the trapezoidal block bases are respectively arranged in four sub grooves of the cross groove and slide along the sub grooves of the cross groove; a baffle is vertically arranged on the trapezoidal block base, the trapezoidal block is movably arranged on an inner side of the baffle, the clamping component is fixedly arranged at the end of the trapezoidal block base facing a center point of the cross base, and the tension sensor is arranged between the trapezoidal block base and the clamping component; the cross pressing assembly includes a cross pressing arm and a pressing head, the pressing head is arranged in the center of the cross pressing arm, a bottom surface of the trapezoidal block leans against the baffle, and an inclined surface of the trapezoidal block abuts against a top roller of the Cross pressing arm; an inner wall of the cross base is provided with a groove in parallel, the scale grating is arranged in the groove, and the grating reading head corresponding to the scale grating is arranged on the trapezoidal base; the angles between the bottom edges and oblique edges of the trapezoidal blocks are set to be different angles.
As a further limitation, a movable cross-beam of the tester drives the pressing head and the pressing plate of the two-way cross stretching device to press downward; four corners of the pressing plate abut against the oblique edges of the four trapezoidal blocks through rolling bearings, so that the vertical movement of the pressing plate is converted into the horizontal movement of the four trapezoidal blocks; the trapezoidal block is connected to a bottom plate through a guide rail; the clamping component is arranged at one end of each of the four trapezoidal block bases close to the center of the bottom plate, and the force sensor is arranged between the clamping component and the trapezoidal block.
As an alternative embodiment, the strain measuring system is composed of a DIC three-dimensional digital speckle strain gauge, including an adjustable measuring head and a processor; the adjustable measuring head includes a camera, a light source and a bracket; the camera and the light source are arranged on the bracket, and the distance between the bracket and the clamping component is adjustable.
A working method based on the test platform includes: constructing a heat environment of a set temperature by using the electric heating temperature control system for the tensile test of the test piece, applying pressure to the two-way cross stretching device by the tester in this heat environment, stretching the test piece by the two-way cross stretching device, capturing an image of the entire stretching process, reading the stretched length and force value of the test piece, and then calculating a strain field of the hot tensile test piece.
As an alternative embodiment, before measurement, random speckles are sprayed to the surface of the test piece with a high-temperature and oxidation resistant spray paint, the measurement distance between the measuring head and the test piece is adjusted according to the breadth parameters of the camera, and the cross central line of the camera is corrected to ensure the alignment of the measurement image.
Compared with the prior art, the beneficial effects of the present invention are: The metal plate is heated by the induction coil, the test piece is clamped in parallel below the metal plate at a certain distance, and the metal plate transfers heat to the test piece to increase its temperature to realize a heating function; the temperature of the test piece can be obtained in real time by using the thermocouple module, and the control on the temperature helps the characterization of mechanical properties of the plate at different temperatures and the test of forming properties; and the heating equipment of the platform is not restricted by device structures, which provides convenience for the test operation.
The present invention can accurately test the mechanical properties and forming properties of the plate in different temperature environments under dual tension or single tension and different loading ratios, so the test content is more comprehensive, and the test environment is more diverse, flexible and controllable.
Brief Description of the Drawings The accompanying drawings constituting a part of the present invention are used for providing a 5 further understanding of the present invention, and the schematic embodiments of the present invention and the descriptions thereof are used for interpreting the present invention, rather than constituting improper limitations to the present invention.
FIG. 1 is a schematic structural diagram of a test platform according to the present invention; FIG. 2 1s a schematic diagram of a two-way cross stretching device according to the present invention; FIG. 3 is a schematic structural diagram of a strain measuring system according to the present invention; FIG. 4 and FIG. 5 are schematic diagrams of temperature stability results according to some embodiments; FIG. 6 and FIG. 7 are schematic diagrams of uniformity experiments according to some embodiments; FIG. 8 is a schematic side view according to some embodiments; In which, l-cross base, 2-trapezoidal block base, 3-trapezoidal block, 4-cross pressing assembly, 41-cross pressing arm, 42-pressing head, 5-clamping component, 6-positioning pin, 7-baffle, 8-tension sensor, 9-spring, 10-scale grating, ll-grating reading head, 12-rolling cylinder, 13-laser heater, 14-three-dimensional digital speckle strain gauge, 15-reflector, 16 -triangular ribbed plate, 17-slide baffle, 18, support frame; a. induction coil, b. metal plate, c. sample.
Detailed Description of the Embodiments The present invention will be further illustrated below in conjunction with the accompanying drawings and embodiments.
It should be noted that the following detailed descriptions are exemplary and are intended to provide further descriptions of the present invention.
All technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical filed to which the present application belongs, unless otherwise indicated.
It should be noted that the terms used here are merely used for describing specific embodiments, but are not intended to limit the exemplary embodiments of the present invention. As used herein, the singular form is also intended to comprise the plural form unless otherwise indicated in the context. In addition, it should be understood that when the terms “contain” and/or “comprise” are used in the description, they are intended to indicate the presence of features, steps, operations, devices, components and/or combinations thereof.
In the present invention, the terms such as “upper”, “lower”, “left”, “right”, “front”, “rear”, “vertical”, “horizontal”, “side”, and “bottom” indicate the orientation or positional relationships based on the orientation or positional relationships shown in the drawings, are only relationship terms determined for the convenience of describing the structural relationships of various components or elements of the present invention, but do not specify any component or element in the present invention, and cannot be understood as limitations to the present invention.
In the present invention, the terms such as “fixed” and “connected” should be generally understood, they may be fixedly connected, detachably connected, integrally connected, directly connected, or indirectly connected by a medium. For a related scientific research or technical person in this art, the specific meanings of the above terms in the present invention may be determined according to specific circumstances, and cannot be understood as limitations to the present invention.
As shown in FIG. 1, a test platform is provided, including an induction heating temperature control system, a stretching control system, and a strain measuring system; the stretching control system includes a tester, a two-way cross stretching device, a scale grating and a force sensor; the tester is connected to the two-way cross stretching device to apply pressure thereto, the two-way cross stretching device is used to clamp and stretch a test piece, and the scale grating and the force sensor are used to read the stretched length and force value of the test piece; The induction heating temperature control system includes a metal plate, an induction coil, a temperature sensor and an induction heating power supply; the induction heating power supply is connected to the induction coil, the induction coil is arranged on one side of the metal plate, the metal plate is heated by the induction coil to provide a heat environment, and the metal plate is arranged on the upper side of the two-way cross stretching device; as shown in FIG. 8, the induction coil, the metal plate and the two-way cross stretching device (the figure is only for illustration, not all features are shown) are parallel to each other; by adjusting the current value in the induction coil, the temperature reaches a set value; The strain measuring system includes a measuring head and a processor connected to each other, the measuring head includes a camera for capturing an image of a stretching process, and the processor obtains a strain value of the test piece during the tensile test at a set temperature according to the image.
Specifically, in some embodiments, the electric heating temperature control system includes an iron plate, an induction coil, a temperature sensor and an induction heating power supply, the power supply is connected to the induction coil, the induction coil is arranged on one side of the iron plate, and the iron plate is heated by the induction coil to provide a heat environment.
The iron plate (optionally circular) is arranged around the two-way cross stretching device through a support frame.
The induction coil is located directly above and parallel to the circular iron plate, and the circular iron plate is heated by the induction coil.
The test piece is clamped in parallel below the circular iron plate with a certain distance (for example, 0.5 mm), and the circular iron plate transfers heat to the test piece to increase its temperature to realize a heating function.
A thermocouple wire 1s welded to the center of a test piece heating area (a test area of interest), the thermocouple wire is connected to a thermocouple module of a PLC (Programmable Logic Controller) to monitor the temperature of the test piece in real time, and the measured temperature of the test piece is used as a feedback signal in a PLC control system to control the power of the induction heating power supply, thereby realizing a temperature control function.
The metal plate is fixedly arranged on the support frame, so that one side of the metal plate 1s parallel to the test piece, and the other side is parallel to the induction coil.
The support frame is further provided with an induction coil mounting piece, the induction coil mounting piece includes a mounting plate, and both ends of the mounting plate are fixedly mounted on the support frame through fixing members, respectively.
The mounting plate is provided with at least two holes, and two outgoing lines of the induction coil pass through the holes and are connected to the induction heating power supply.
In this embodiment, the electric heating temperature control system uses a CPU (Central Processing Unit) module as the host and expands the thermocouple signal module, and the thermocouple signal module connected to the temperature sensor processes the temperature of the test piece collected by the temperature sensor and transmits the temperature to the CPU. The specific processing process can use the existing method or circuit, and details are not described herein again.
The CPU compares the collected real-time temperature of the test piece with a target temperature to obtain an error value, a control instruction is obtained according to the error value by using a PID control program or algorithm stored in the CPU, the CPU processes the control instruction, the processed control signal is output from an output port of the PLC and converted into a 0-5 V electrical signal, and the electrical signal is transmitted to the low-voltage high-current induction heating power supply in an automatic mode to control the output value of the low-voltage high-current induction heating power supply, thereby realizing a heating temperature control function of the platform.
Of course, in some embodiments, the control instruction can be directly input from an embedded touch display screen to artificially or manually control the heating temperature.
In some other embodiments, the electric heating temperature control system is also accompanied by a safety protection system, which can protect the safety of the system in an emergency.
In some embodiments, the stretching control system includes a tester, a two-way cross stretching device, a scale grating, and a force sensor. The two-way cross stretching device is preferably mechanical, and the two-way cross stretching device provided by the application number
201710187880.1 is available. As shown in FIG. 2, the two-way cross stretching test device includes a cross base 1, trapezoidal block bases 2, trapezoidal blocks 3, a cross pressing assembly 4, clamping components 5, tension sensors 8, a spring 9, scale gratings 10 and grating reading heads 11.
The cross base 1 is provided with a cross groove, so that the cross base 1 forms a cross frame. The trapezoidal block bases 2 are respectively arranged in sub grooves of the cross groove, and the trapezoidal block bases 2 can slide in the sub grooves. The trapezoidal block base 2 slides outward from the center of the cross base 1 or slides from the outside to the center of the cross base I.
A baffle 7 is vertically arranged on the trapezoidal block base 2, and the inner side of the baffle 7 faces the center of the cross base 1. The trapezoidal block 3 is placed on the side of the baffle 7 facing the center of the cross base 1, wherein the bottom of the trapezoidal block 3 leans against the baffle 7. A clamping component 5 is arranged at one end of each of the four trapezoidal block bases 2 close to the center of the cross base I, and a tension sensor 8 is arranged between the clamping component 5 and the trapezoidal block base 2. The tension sensor 8 is fixed to the trapezoidal base 2 by bolt connection, and is fixedly connected to the clamping component 5. For other more details, reference may be made to the specification of the application number
201710187880.1, and details are not described herein again. During use, a top of a pressing head 42 is connected to a movable cross-beam of the commercial tester, and a bottom is connected to the center of a pressing plate 41. By controlling the commercial tester, the movable cross-beam of the commercial tester drives the pressing head 42 and the pressing plate 41 to press down. Four corners of the pressing plate 41 respectively abut against oblique edges of the four trapezoidal blocks 3 through rolling bearings, so that the vertical movement of the pressing plate 41 is converted into the horizontal movement of the four trapezoidal blocks. When the pressing plate 41 is pressed down, the four rolling bearings slide along the oblique edges of the trapezoidal blocks 3, the trapezoidal blocks slide outward in the horizontal direction under the thrust of the pressing head 42, the clamping components 5 are driven to stretch the test piece outward, and the force sensors 8 measure the tensile force of the two-way cross stretching test device on the test piece, and the scale gratings 10 measure the displacements of the test piece in two vertical directions. The trapezoidal block is connected to a bottom plate through a guide rail, a clamping component is arranged at one end of each of the four trapezoidal block bases close to the center of the bottom plate, and a force sensor is arranged between the clamping component and the trapezoidal block. The scale grating reading head is connected to the trapezoidal block, and the scale grating is fixed to the bottom plate. In some embodiments, the strain measuring system is a DIC three-dimensional digital speckle strain gauge, including an adjustable measuring head, a control box and a computer, wherein the adjustable measuring head includes a camera, a laser, an LED and a bracket. As shown in FIG. 3, the control box controls the operations of the camera, the laser and the LED, the computer receives the image captured by the camera, and the distance between the bracket and the two-way cross stretching device/ test piece is adjustable.
Before measurement, random speckles are sprayed to the surface of the test piece with a high-temperature and oxidation resistant spray paint, and then the measurement distance between the adjustable measuring head and the test piece is adjusted according to the breadth parameters of the camera. During measurement, a new project is created on the PC. After the initialization setting of parameters is completed, the cross central line of the camera is corrected to capture an image. After the image is captured, a patch area and seed points are created in a calculation mode, and measurement results are automatically calculated.
The strain measuring system captures a speckle image on the test piece through the camera, matches deformation points on the surface by using a digital image correlation algorithm (DIC), and calculates a strain field of the hot tensile test piece through the changes of three-dimensional coordinates of each point. As an optical non-contact three-dimensional strain measuring system, it has the advantages of rapidness, simplicity, flexibility and high precision, can achieve non-contact measurement and obtain the true strain of the test piece during high-temperature uniaxial tensile test. Based on the above, the platform can perform accurate heating temperature control on the cross test piece, accurately measure the strain field of the test piece, and record the strain, force and displacement development history of the plate during deformation, which helps the characterization of mechanical properties of the plate at high temperatures and the test of forming properties; and the heating equipment of the platform is not restricted by device structures, which provides convenience for the test operation.
Target temperatures of 200°C and 300°C are set through the PLC for heating temperature control test on the test piece, and the temperature field is monitored by using an infrared thermometer to test the temperature uniformity of the heating center area of the test piece. (Note: Due to the precision of the infrared thermometer, there is a certain deviation between the measured temperature and the actual temperature, but it does not affect the verification of the temperature uniformity of the heating area in this test.) As shown in FIG. 4, the temperature difference among three temperature measuring points at 200°C is 0.5°C. The temperatures measured at the three temperature measuring points in the heating center area (30mm 30mm) of the test piece are: 204.9°C, 205.4°C, and 205.0°C.
As shown in FIG. 5, the temperature difference among three temperature measuring points at 300°C tl is 0.2°C. The temperatures measured at the three temperature measuring points in the heating center area (30mm*x30mm) of the test piece are: 344.0°C, 344.2°C, and 344.2°C. Therefore, the heating device can realize uniform heating of the flat plate test piece.
In addition, the uniformity of the temperature gradient in the thickness direction of the plate is further verified (see FIGS. 6 and 7). In FIG. 6, the time center area is a thinning area, the temperature measuring point A is in the thinning area in the center of the test piece, the plate has a thickness of
0.15 mm at this point, and the temperature measurement result of the infrared thermometer is
223.4°C. The temperature measuring point B is in a non-thinning area of the test piece, the plate has a thickness of 2 mm at this point, and the temperature measurement result of the infrared thermometer is 223.4°C. Therefore, it can be obtained that the heating effect of the heating temperature control device in the thickness direction of the plate test piece meets the heating uniformity requirement.
Test piece heating accuracy verification: Target temperatures of 100°C, 200°C, 300°C, and 400°C are set through the PLC for heating temperature control (5 min) test on the test piece, and the temperature measured by the thermocouple wire is monitored and compared. The temperature control effects are as shown in the following table: Target temperature (°C) Minimum temperature Maximum temperature within 5 min within 5 min Therefore, the temperature control effect is obvious, with reliable accuracy and stability, and the requirements of high-temperature mechanical test are met.
After constant control on the temperature, the dual tensile mechanical properties of the plate at different temperatures under equal dual tension and different stretch ratios can be tested, including: stress-strain curve, yield criterion identification and forming limit construction.
Described above are merely preferred embodiments of the present application, and the present application is not limited thereto. Various modifications and variations may be made to the present application for those skilled in the art. Any modification, equivalent substitution, improvement or the like made within the spirit and principle of the present application shall fall into the protection scope of the present application. Although the specific embodiments of the present invention are described above in combination with the accompanying drawing, the protection scope of the present invention is not limited thereto. It should be understood by those skilled in the art that various modifications or variations could be made by those skilled in the art based on the technical solution of the present invention without any creative effort, and these modifications or variations shall fall into the protection scope of the present invention.
10 .

Claims (10)

ConclusiesConclusions 1. Kruisvormig trekproefplatform ter opwarming en karakterisering, omvattende omvattende een temperatuurregelsysteem gebaseerd op een elektrische verwarming, een uitrekkingregelsysteem en een rekmetingsysteem, waarbij: het uitrekkingregelsysteem een proefapparaat, een twee-weg-kruisrekapparaat , een meetschaal en een krachtsensor omvat, het proefapparaat met het twee-weg-kruisrekapparaat verbonden is om druk erop uit te oefenen, het twee-weg-kruisrekapparaat gebruikt wordt om een proefstuk te klemmen en uit te rekken, en de meetschaal en de krachtsensor gebruikt worden om de uitgerokkene lengte en de krachtwaarde van het proefstuk af te lezen; het temperatuurregelsysteem gebaseerd op een elektrische verwarming een metaalplaat, een inductiespoel, een temperatuursensor en een inductieve warmte-energievoeding omvat, de inductieve warmte-energievoeding met de inductiespoel verbonden is, de inductiespoel op één zijde van de metaalplaat opgesteld is, de metaalplaat door de inductiespoel verwarmd is ten einde een warmteomgeving te bieden, de metaalplaat evenwijdig met de bovenzijde van het twee-weg-kruisrekapparaat opgesteld is, en de temperatuur een ingestelde waarde bereikt door de waarde van de stroom in de inductiespoel in te stellen; het rekmetingsysteem een meetkop en een processor omvat die aan elkaar verbonden zijn, de meetkop een camera omvat om een beeld van een uitrekkingsproces op te nemen, en de processor een rekwaarde van het proefstuk tijdens de trekproef op een ingestelde temperatuur volgens het beeld bekomt.A cross-shaped tensile test platform for heating and characterization, comprising a temperature control system based on an electric heater, an extension control system and a strain measurement system, wherein: the extension control system comprises a test apparatus, a two-way cross-stretch apparatus, a measuring scale and a force sensor, the test apparatus having the two-way cross-stretch device is connected to apply pressure to it, the two-way cross-stretch device is used to clamp and stretch a sample, and the scale and force sensor are used to measure the stretched length and force value of the sample to read; the temperature control system based on an electric heating comprises a metal plate, an induction coil, a temperature sensor and an inductive heat energy supply, the inductive heat energy supply is connected to the induction coil, the induction coil is arranged on one side of the metal plate, the metal plate through the induction coil heated to provide a heat environment, the metal sheet is arranged parallel to the top of the two-way cross stretching device, and the temperature reaches a set value by adjusting the value of the current in the induction coil; the strain measurement system comprises a measuring head and a processor connected together, the measuring head comprises a camera to record an image of a stretching process, and the processor obtains a strain value of the test piece during the tensile test at a set temperature according to the image. 2. Kruisvormig trekproefplatform ter opwarming en karakterisering volgens conclusie 1, waarbij de metaalplaat vast op het ondersteuningsframe opgesteld is, zodat een zijde van de metaalplaat evenwijdig met het proefstuk is, en de andere zijde evenwijdig met de inductiespoel loopt.The cross-shaped tensile test platform for heating and characterization according to claim 1, wherein the metal sheet is fixedly arranged on the support frame so that one side of the metal sheet is parallel to the test piece and the other side is parallel to the induction coil. 3. Kruisvormig trekproefplatform ter opwarming en karakterisering volgens conclusie 1, waarbij de inductieve warmte-energievoeding met een programmeerbare logische sturing verbonden is om de uitgevoerde energie van de inductieve warmte-energievoeding te regelen ten einde de temperatuur van het trekproefstuk automatisch in te stellen en te regelen.The cross-shaped tensile test platform for heating and characterization according to claim 1, wherein the inductive heat energy supply is connected to a programmable logic controller to control the output energy of the inductive heat energy supply so as to automatically adjust and control the temperature of the tensile test piece. to arrange. 4. Kruisvormig trekproefplatform ter opwarming en karakterisering volgens conclusie 1, waarbij het ondersteuningsframe verder van een montagestuk voor de inductiespoel voorzien, de inductiespoel een montageplaat omvat, en beide uiteinden van de montageplaat respectievelijk vast op het ondersteuningsframe via bevestigingselementen gemonteerd zijn.The cross-shaped tensile test platform for heating and characterization according to claim 1, wherein the support frame further includes an induction coil mounting piece, the induction coil comprises a mounting plate, and both ends of the mounting plate are respectively fixedly mounted to the support frame via fasteners. 5. Kruisvormig trekproefplatform ter opwarming en karakterisering volgens conclusie 1, waarbij de twee uitgaande elektrische lijnen van de inductiespoel doorheen de montageplaat lopen en met de inductieve warmte-energievoeding verbonden zijn.The cruciform tensile test platform for heating and characterization according to claim 1, wherein the two outgoing electrical lines from the induction coil pass through the mounting plate and are connected to the inductive heat energy supply. 6. Kruisvormig trekproefplatform ter opwarming en karakterisering volgens conclusie 1, waarbij een thermokoppel in de verwarmde zone van het trekproefstuk opgesteld is.The cross-shaped tensile test platform for heating and characterization according to claim 1, wherein a thermocouple is arranged in the heated zone of the tensile test piece. 7. Kruisvormig trekproefplatform ter opwarming en karakterisering volgens conclusie 1, waarbij twee-weg-kruisrekapparaat een kruisvormige basis, trapeziumvormige blokbasissen, trapeziumvormige blokken, een kruisvormig druksamenstel, klemmingscomponenten, spanningsensoren, een veer, meetschalen en leeskoppen; de kruisvormige basis van een kruisvormige groef voorzien is, en de trapeziumvormige blokbasissen respectievelijk in vier deelgroeven van de kruisvormige groef opgesteld zijn en langs de deelgroeven van de kruisvormige groeven glijden; een schot vertikaal op de trapeziumvormige blokbasis opgesteld staat, het trapeziumvormige blok beweegbaar op een binnenzijde van het schot opgesteld is, de klemmingscomponent vast op het uiteinde van de trapeziumvormige blokbasis opgesteld is en tegenover een centraal punt van de kruisvormige basis gelegen is, en de spanningssensor tussen de trapeziumvormige blokbasis en de klemmingscomponent opgesteld is; het kruisvormige druksamenstel een kruisvormige drukarm en een drukkop omvat, de drukkop in het midden van de kruisvormige drukarm opgesteld is, een onderkant van het trapeziumvormige blok tegen het schot leunt, en een hellend oppervlak van het trapeziumvormige tegen een bovenste rol van de kruisvormige drukarm aangrenst; een binnenwand van de kruisvormige basis van een evenwijdige groef voorzien is, de meetschaal in de groef opgesteld 1s, en de leeskop die met de meetschaal overeenstemt op de trapeziumvormige basis opgesteld is; de hoeken tussen de onderranden en de schuine randen van de trapeziumvormige blokken zo ingesteld zijn dat ze verschillende hoeken zijn.The cruciform tensile test platform for heating and characterization according to claim 1, wherein two-way cross stretching apparatus comprises a cruciform base, trapezoidal block bases, trapezoidal blocks, a cruciform compression assembly, clamping components, tension sensors, a spring, scales and read heads; the cross-shaped base is provided with a cross-shaped groove, and the trapezoidal block bases are respectively arranged in four sub-grooves of the cross-shaped groove and slide along the sub-grooves of the cross-shaped grooves; a bulkhead is arranged vertically on the trapezoidal block base, the trapezoidal block is movably arranged on an inner side of the bulkhead, the clamping component is mounted fixedly on the end of the trapezoidal block base and is opposite a central point of the cross-shaped base, and the tension sensor arranged between the trapezoidal block base and the clamping component; the cruciform pressure assembly comprises a cruciform pressure arm and a pressure head, the pressure head is disposed in the center of the cruciform pressure arm, a bottom side of the trapezoidal block rests against the bulkhead, and an inclined surface of the trapezoidal shape abuts an upper roll of the cruciform pressure arm ; an inner wall of the cross-shaped base is provided with a parallel groove, the measuring scale is arranged in the groove, and the reading head corresponding to the measuring scale is arranged on the trapezoidal base; the angles between the bottom edges and the bevels of the trapezoidal blocks are set to be different angles. 8. Kruisvormig trekproefplatform ter opwarming en karakterisering volgens conclusie 1, waarbij een beweegbare dwarsbalk van het proefapparaat de drukkop en de drukplaat van het twee-weg-kruisrekapparaat drijft ten einde neerwaarts te drukken; vier hoeken van de drukplaat tegen de schuine randen van de vier trapeziumvormige randen via rollagers aangrenzen, zodat de verticale beweging van de drukplaat in de horizontale beweging van de vier trapeziumvormige blokken omgezet wordt; het trapeziumvormige blok met een bodemplaat via een geleidingsrail verbonden is; de klemmingscomponent op een uiteinde van elke van de vier trapeziumvormige blokken dicht bij het midden van de bodemplaat opgesteld is, en de krachtsensor tussen de klemmingscomponent en het trapeziumvormige blok opgesteld is.The cruciform tensile test platform for heating and characterization according to claim 1, wherein a movable crossbar of the testing apparatus drives the printing head and the printing plate of the two-way cross stretching apparatus to press downwardly; abut four corners of the pressure plate against the bevels of the four trapezoidal edges via roller bearings, so that the vertical movement of the pressure plate is converted into the horizontal movement of the four trapezoidal blocks; the trapezoidal block is connected to a bottom plate via a guide rail; the clamping component on one end of each of the four trapezoidal blocks is arranged close to the center of the bottom plate, and the force sensor is arranged between the clamping component and the trapezoidal block. 9. Kruisvormig trekproefplatform ter opwarming en karakterisering volgens conclusie 1, waarbij het rekmetingsysteem uit een driedimensionale digitale gespikkelde rekstrook geschikt voor digitale beeldcorrelatie samengesteld is, en een instelbare meetkop en een processor omvat ; de instelbare meetkop een camera, een lichtbron en een steun omvat; de camera en de lichtbron op de steun opgesteld zijn, en de afstand tussen de steun en de klemmingscomponent instelbaar is.The cruciform tensile test platform for heating and characterization according to claim 1, wherein the strain measurement system is composed of a three-dimensional digital speckled strain gauge suitable for digital image correlation, and comprises an adjustable measuring head and a processor; the adjustable measuring head comprises a camera, a light source and a support; the camera and the light source are arranged on the support, and the distance between the support and the clamping component is adjustable. 10. Werkwijze van het proefplatform volgens een van de conclusies 1 tot 9, omvattende de volgende stappen: construeren van een thermische omgeving voor een ingestelde temperatuur door gebruik te maken van het temperatuurregelsysteem gebaseerd op een elektrische verwarming voor de trekproef van het proefstuk, druk uitoefenen op het twee-weg-kruisrekapparaat bij middel van het proefapparaat in deze thermische omgeving, uitrekken van het proefstuk door middel van het twee-weg-kruisrekapparaat, opnemen van een beeld van het ganse rekproces, aflezen van de gerokkene lengte en van de krachtwaarde van het proefstuk, en vervolgens berekenen van het rekveld van het warme trekproefstuk.The method of the test platform according to any one of claims 1 to 9, comprising the steps of: constructing a thermal environment for a set temperature by using the temperature control system based on an electric heater for the tensile test of the test piece, applying pressure on the two-way cross-stretch device by means of the test device in this thermal environment, stretching of the sample by means of the two-way cross-stretch device, recording an image of the entire stretching process, reading of the stretched length and of the force value of the test piece, and then calculating the strain field of the hot tensile test piece.
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