LU102139B1 - 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
LU102139B1
LU102139B1 LU102139A LU102139A LU102139B1 LU 102139 B1 LU102139 B1 LU 102139B1 LU 102139 A LU102139 A LU 102139A LU 102139 A LU102139 A LU 102139A LU 102139 B1 LU102139 B1 LU 102139B1
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Luxembourg
Prior art keywords
cross
induction coil
test piece
trapezoidal block
test platform
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LU102139A
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French (fr)
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LU102139A1 (en
Inventor
Jun Gao
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Univ Shandong
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    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • G01N3/18Performing tests at high or low temperatures
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/02Details
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N3/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N3/08Investigating strength properties of solid materials by application of mechanical stress by applying steady tensile or compressive forces
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0014Type of force applied
    • G01N2203/0016Tensile or compressive
    • G01N2203/0017Tensile
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/0058Kind of property studied
    • G01N2203/0069Fatigue, creep, strain-stress relations or elastic constants
    • G01N2203/0075Strain-stress relations or elastic constants
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/022Environment of the test
    • G01N2203/0222Temperature
    • G01N2203/0226High temperature; Heating means
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/026Specifications of the specimen
    • G01N2203/0262Shape of the specimen
    • G01N2203/0272Cruciform specimens
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/06Indicating or recording means; Sensing means
    • G01N2203/0605Mechanical indicating, recording or sensing means
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/06Indicating or recording means; Sensing means
    • G01N2203/0641Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/06Indicating or recording means; Sensing means
    • G01N2203/0641Indicating or recording means; Sensing means using optical, X-ray, ultraviolet, infrared or similar detectors
    • G01N2203/0647Image analysis
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/06Indicating or recording means; Sensing means
    • G01N2203/067Parameter measured for estimating the property
    • G01N2203/0676Force, weight, load, energy, speed or acceleration
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/06Indicating or recording means; Sensing means
    • G01N2203/067Parameter measured for estimating the property
    • G01N2203/0682Spatial dimension, e.g. length, area, angle
    • GPHYSICS
    • G01MEASURING; TESTING
    • G01NINVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N2203/00Investigating strength properties of solid materials by application of mechanical stress
    • G01N2203/02Details not specific for a particular testing method
    • G01N2203/06Indicating or recording means; Sensing means
    • G01N2203/067Parameter measured for estimating the property
    • G01N2203/0694Temperature

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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 present disclosure provides a cruciform tensile characterization heating test platform and method. The test platform comprises an induction heating temperature control system, a stretching control system 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 device, and the temperature reaches a set value by adjusting the current value in the induction coil. The present disclosure can accurately test the mechanical properties and forming properties of the plate at high temperatures under equal dual tension and different loading ratios.

Description

CRUCIFORM TENSILE CHARACTERIZATION HEATING TEST PLATFORM AND ps
METHOD Field of the Invention The present disclosure 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 disclosure, 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 disclosure 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 disclosure 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 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, 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. (0108138 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 disclosure 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 disclosure 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. pts Brief Description of the Drawings The accompanying drawings constituting a part of the present disclosure are used for providing a 5 further understanding of the present disclosure, and the schematic embodiments of the present disclosure and the descriptions thereof are used for interpreting the present disclosure, rather than constituting improper limitations to the present disclosure.
FIG. 1 is a schematic structural diagram of a test platform according to the present disclosure; FIG. 2 is a schematic diagram of a two-way cross stretching device according to the present disclosure; FIG. 3 is a schematic structural diagram of a strain measuring system according to the present disclosure; 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, 1-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, 11-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 disclosure 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 disclosure.
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
| BN 6 LU102139 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 disclosure, 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 disclosure, but do not specify any component or element in the present disclosure, and cannot be understood as limitations to the present disclosure.
In the present disclosure, 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 disclosure may be determined according to specific circumstances, and cannot be understood as limitations to the present disclosure.
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.
À thermocouple wire is 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 is 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 1.
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 1, 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 (30mmx30mm) 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
| 11 LU102139 is 0.2°C. The temperatures measured at the three temperature measuring points in the heating center area (30mmx30mm) 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
| ; LU102139 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 disclosure are described above in combination with the accompanying drawing, the protection scope of the present disclosure 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 disclosure without any creative effort, and these modifications or variations shall fall into the protection scope of the present disclosure. 10 .

Claims (10)

TEESE... 13 LU102139 Claims
1. A cruciform tensile characterization heating test platform, comprising an electric heating temperature control system, a stretching control system and a strain measuring | system, wherein: the stretching control system comprises 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 comprises 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, 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 comprises a measuring head and a processor connected to each other, the measuring head comprises 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.
2. The cruciform tensile characterization heating test platform according to claim 1, wherein the metal plate is fixedly arranged on the 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.
3. The cruciform tensile characterization heating test platform according to claim 1, wherein 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.
4. The cruciform tensile characterization heating test platform according to claim 1,
EE. 14 LU102139 wherein the support frame is further provided with an induction coil mounting piece, the induction coil mounting piece comprises a mounting plate, and both ends of the mounting plate are fixedly mounted on the support frame through fixing members, | respectively.
5. The cruciform tensile characterization heating test platform according to claim 1, wherein two outgoing lines of the induction coil pass through the mounting plate and are connected to the induction heating power supply.
6. The cruciform tensile characterization heating test platform according to claim 1, wherein a thermocouple wire is arranged in the heated area of the tensile test piece.
7. The cruciform tensile characterization heating test platform according to claim 1, wherein the two-way cross stretching device comprises 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 comprises 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.
8. The cruciform tensile characterization heating test platform according to claim 1,
wherein a movable cross-beam of the tester drives the pressing head and the pressing HU102139 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.
9. The cruciform tensile characterization heating test platform according to claim 1, wherein the strain measuring system is composed of a DIC three-dimensional digital speckle strain gauge, comprising an adjustable measuring head and a processor; the adjustable measuring head comprises 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.
10. A working method of the test platform according to any one of claims 1-9, comprising: 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. | |
LU102139A 2019-10-17 2020-10-15 Cruciform tensile characterization heating test platform and method LU102139B1 (en)

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CN201910990016.4A CN110672426A (en) 2019-10-17 2019-10-17 Cross double-pull characterization heating test platform and method

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CN111751217B (en) * 2020-06-29 2023-07-21 西安建筑科技大学 Horizontal concrete uniaxial tension test device and application method thereof
CN115931560B (en) * 2022-12-19 2023-10-03 武汉泰科生物技术有限公司 Agar gel strength detection device

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ATE161381T1 (en) * 1992-09-03 1998-01-15 Hidec Corp Ltd ELECTROMAGNETIC INDUCTION RADIATOR
CN201945504U (en) * 2010-07-08 2011-08-24 宁波东升包装材料有限公司 Electromagnetic induction heating type strain gauge for thermal shrinkage stress of plastic sheet
CN101865526A (en) * 2010-07-13 2010-10-20 吴德滨 High-frequency electromagnetic induction water heater
CN103561494A (en) * 2013-11-12 2014-02-05 顾晓烨 Heating method with heat stored in electromagnetic induction heating mode and heat released slowly
CN106908319B (en) * 2017-03-27 2019-11-19 山东大学 A kind of two-way cross tensile test device
CN108114980B (en) * 2017-12-21 2019-04-23 燕山大学 The method for preparing titanium-magnesium composition plate using the straight rolling of the different temperature of electromagnetic induction heating
CN208140498U (en) * 2018-01-26 2018-11-23 吉林大学 High temperature multi-load loads in-situ testing device

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