CN105758728A - Variable-temperature composite load in-situ testing platform - Google Patents

Abstract

The invention relates to an in-situ mechanical test platform for variable temperature composite load, which belongs to the field of material micromechanical performance testing. The test platform integrates a variable temperature module, a composite loading module, and an in-situ observation module. Composed of a thermostat and a thermocouple temperature sensor, it can precisely control the test temperature. The composite loading module is composed of a drive unit, a transmission unit and a signal acquisition unit. The composite loading form is realized by a new ring fixture. The temperature variable module and the composite loading module are compact in structure. It is easy to integrate the current mainstream optical microscope and electron microscope to monitor the evolution process of the internal structure of the material when the crack initiation, propagation and destruction of the material are under the combined action of temperature and composite load. It provides a brand-new testing means and method for revealing the mechanical behavior of materials under the joint action of temperature field and composite load.

Description

Variable temperature compound load in-situ mechanical test platform

technical field

The invention relates to an in-situ mechanical testing platform for variable temperature composite load, which belongs to the field of material micromechanical performance testing. The testing platform integrates a variable temperature module, a composite loading module and an in-situ observation module. The composite loading module is composed of a drive unit, a transmission unit and a signal acquisition unit. The composite loading form is realized by a new type of ring fixture. With the help of a high-precision digital goniometer, the axial direction and the tensile direction of the tested piece can be formed at different test angles to construct Different stress states are produced, so that the stress state of the specimen is closer to the real service state. The variable temperature module is composed of a built-in sensor super heat gun, a digital thermostat, and a thermocouple temperature sensor, which can accurately control the test temperature. The variable temperature module and the composite loading module are compact in structure, which is convenient for integrating the current mainstream optical microscope and electron microscope to monitor the evolution process of the internal structure of the material when the crack initiation, propagation and destruction of the material are under the joint action of different temperatures and composite loads. The microscopic nature of material properties, understanding the macroscopic laws of materials, and revealing the mechanical behavior of materials under the combined action of temperature field and composite load provide brand-new testing means and methods.

Background technique

The research and development and application of new materials and new processes are the basis of industrial development, and the continuous development of material testing technology is an important means of researching and manufacturing new materials and in-depth exploration of the properties of existing materials. Material mechanical performance testing technology is mainly to obtain macro mechanical parameters such as elastic modulus, shear modulus, yield limit and strength limit of materials. With the rapid development of material technology, various new materials are constantly emerging, and for these The testing and analysis of the specificity of new materials has become a hot research topic at home and abroad. The traditional methods of testing the mechanical properties of materials can no longer keep up with the urgent needs of researchers to explore the microscopic nature of material properties. Therefore, there is an urgent need for testing technologies and methods based on new principles and methods. The appearance of the instrument provides a brand-new testing method and method for in-depth understanding of the microscopic nature of material properties, understanding of the macroscopic laws of materials, and revealing the mechanical behavior of materials under the joint action of temperature field and composite load.

With the development of precision manufacturing technology and microscopic imaging technology, in-situ testing technology based on miniaturization has emerged. Through the method of in-situ monitoring, the complete process of microstructural morphology changes of materials under load can be obtained, which fully explains The corresponding relationship between microstructure and performance, the research on in-situ mechanical testing technology abroad is relatively early at present, and in response to the demand for in-situ testing devices in the scientific research field, Kammrath&Weiss in Germany, Deben in the United Kingdom and MTIInstruments in the United States have launched several The miniaturized in-situ test device has promoted the development of in-situ test technology for materials, but domestic research on in-situ test technology started relatively late, and the test of mechanical properties of materials still relies on traditional test methods. The development of this kind of in-situ testing method and instrument is relatively backward, coupled with foreign technology secrecy and the cost of in-situ testing equipment, domestic research institutions using this new type of in-situ testing method and equipment are rare, which requires domestic independent research and development and manufacturing of new In-situ mechanical performance testing instruments, most of the testing instruments currently focus on a single load. In actual working conditions, the loading form of many components is not a single load, and the service environment is not in a very high temperature state, but a combination of multiple load forms and variable temperature conditions. The damage and failure behavior of materials under the influence of combined load and temperature are quite different from those under the action of single load at normal temperature. Therefore, the in-situ mechanical test platform of variable temperature combined load mode is of great significance for in-depth research on material performance evolution and failure damage mechanism. .

Contents of the invention

The test platform integrates variable temperature modules, composite loading modules, and in-situ observation modules. The composite loading module is composed of a drive unit, a transmission unit and a signal acquisition unit. The composite loading form is realized by a new type of ring fixture. With the help of a high-precision digital goniometer, the axial direction and the tensile direction of the tested piece can be formed at different test angles to construct Different stress states are produced, so that the stress state of the specimen is closer to the real service state. The variable temperature module is composed of a sensor built-in super heat gun, a temperature regulator, and a thermocouple temperature sensor, which can accurately control the test temperature. The test platform provides an effective test method for studying the influence of temperature on the mechanical properties of materials and the changes in the microstructure and organization of materials. The test platform can not only study the mechanical properties of materials under different temperature gradients, but also explore temperature-sensitive materials such as phase change materials. Before the test, adjust the digital thermostat to control the hot air within the phase transition temperature range of the specimen, then rotate the fixture to determine the composite loading form, and use the in-situ observation device to monitor the micro-mechanical behavior of the material in real time during the test. While observing in situ, the magnetic scale transmits the detected displacement signal and the load signal detected by the precision force sensor to the computer through the acquisition card, and draws the stress-strain curve in real time.

The above purpose of the testing platform is achieved through the following technical solutions: The invention relates to an in-situ mechanical testing platform with variable temperature and composite load, which belongs to the field of testing the microscopic mechanical properties of materials. The test platform integrates variable temperature modules, composite loading modules, and in-situ observation modules. The composite loading module is composed of a drive unit, a transmission unit and a signal acquisition unit. Among them, the composite loading module and the variable temperature module are fixed on the base of the test platform through bolt connection. Since the size of the heating specimen is relatively small, the heating device selects a super heat gun with a built-in sensor. The maximum temperature can reach 800°C, which meets the general heating test conditions. The in-situ observation module can be integrated with the current mainstream optical microscope, or placed in the scanning electron microscope.

The composite loading module is composed of a drive unit, a transmission unit and a signal acquisition unit. The drive unit is composed of a telescopic hot air steering tube 28 installed on the front end of the heat gun to ensure that the hot air port is facing the gauge length of the test piece. During the test, the heat gun Although point-to-point heating with a caliber of 2mm can be achieved, the heat will inevitably be transferred to the clamp body (15), the clamp pressure plate (25) and even the connection plate. In order to avoid high temperature damage to the test device and affect the test data, high temperature resistant materials In addition to processing the above parts, heat insulation tape is used to insulate layers of parts that are easily affected by high temperature, such as clamp bodies, to minimize heat transfer. The in-situ observation module can be integrated with the current mainstream optical microscope, and the test platform can also be placed in the scanning electron microscope.

The beneficial effect of this test device is that most of the test instruments are mainly based on a single load at present. In actual working conditions, the loading form of many components is not a single load, and the service environment is not in a very high temperature state, but a combination of various load forms and variable temperature conditions. Together, the damage and failure behaviors of materials under the influence of combined load and temperature are quite different from those under the action of a single load at room temperature. Therefore, in-situ mechanical testing of variable temperature combined load mode is of great significance for in-depth research on material performance evolution and failure mechanisms. . This test platform integrates a composite loading module, a variable temperature module, and an in-situ observation module. It has a compact structure, a reasonable layout, and high testing accuracy. This test platform provides an effective test method for studying the influence of temperature on the mechanical properties of materials and the changes in material microstructure and organization. The test platform can not only study the mechanical properties of materials under different temperature gradients, but also explore temperature-sensitive materials such as phase change materials. For the mechanical properties of the material, adjust the digital thermostat before the test to control the hot air within the phase transition temperature range of the specimen, then rotate the fixture to determine the composite loading form, and use the in-situ observation device to monitor the micro-mechanical behavior of the material in real time during the test. While observing in situ, the magnetic scale will transmit the detected displacement signal and the load signal detected by the precision force sensor to the computer through the acquisition card, and use the LABVIEW software to automatically fit and generate the stress-strain curve under the compound load.

Description of drawings

Figure 1 is a schematic diagram of the overall appearance and structure of the test platform.

Figure 2 is a schematic top view of the test platform.

Figure 3 is a schematic left view of the test platform.

Figure 4 is a schematic diagram of the ring fixture of the test platform.

Figure 5 is a schematic diagram of the heating of the test platform.

Figure 6 is a schematic diagram of the composite load loading of the test platform.

In the figure: 1. Motor flange; 2. Primary worm I; 3. Primary turbine; 4. Secondary worm support seat; 5. Secondary worm bearing; 6. Precision ball screw support seat; 7. Secondary Worm; 8. Two-stage turbine; 9. Precision two-way ball screw; 10. Heat gun support seat; 11. Heat gun; 12. Connecting plate Ⅰ; 13. Magnetic scale; 14. Magnetic scale; 15. Ring clamp body ;16. Fixture bolts; 17. Precision guide rail slider; 18. Precision guide rail Ⅰ; 19. Precision force sensor; 20. Precision guide rail Ⅱ; 21. Marble bottom plate; 22. Connecting plate Ⅱ; , precision DC servo motor; 25, fixture pressure plate; 26, planetary gear reducer; 27, in-situ observation microscope; 28, telescopic hot air steering tube;

specific implementation plan

The detailed content of the present invention and its specific implementation will be further described below in conjunction with the accompanying drawings.

Referring to Fig. 1 to Fig. 6, the present invention relates to an in-situ mechanical testing platform with variable temperature composite load, which belongs to the field of material micromechanical performance testing. The test platform integrates a variable temperature module, a composite loading module, and an in-situ observation module. The composite loading module is composed of a drive unit, a transmission unit and a signal acquisition unit. Among them, the composite loading module and the temperature changing module are fixed on the marble base plate through bolt connection. Since the size of the heating specimen is relatively small, the heating device chooses a super hot air gun with a built-in sensor. Up to 800°C, meeting the general heating test conditions. The in-situ observation module can be integrated with the current mainstream optical microscope, or placed in the scanning electron microscope. The composite loading module is composed of a drive unit, a transmission unit and a signal acquisition unit. The drive unit is composed of a precision DC servo motor 24 , a planetary gear reducer 26 and a motor flange 1 . Their connection mode is that the DC servo motor and the planetary gear reducer are installed together, and the whole is connected with the motor flange 1 by bolts and fixed on the test platform base 21 . The transmission unit adopts the method of two-stage worm gear deceleration and torque increase. The first-stage turbine 3 and the first-stage worm 2 mesh with each other to reduce the output speed of the motor 24 through the planetary gear reducer 26 for the first time. The second-stage worm 7 passes through the second-stage worm bearing. 5 and the secondary worm bearing support 4 are installed on the test platform base 21 with screws, and the rotational motion is converted into the linear reciprocating motion of the precision two-way ball screw 9 through the speed regulation of the two-stage worm gear. The two-way ball screw 9 is fixedly connected to the base 21 of the test platform by the matching precision ball screw support seat, and the ball screw nut pair will connect the connecting plate I12 and connecting plate II22 that produce relative displacement to the precision guide rail slider On 17, the precision guide rail I18 and the precision guide rail II20 are fixed on the test platform base 21 with hexagon socket bolts, and the linear reciprocating motion of the precision bidirectional ball screw 9 simultaneously drives the connecting plate I12 and the connecting plate II22 to move relative to each other. The annular clamp body 15 is respectively fixed on the connection plate I12 and the connection plate II22 by the clamp fastening bolts 16 through the clamp body annular groove. Before the test, the precision digital goniometer is used to determine the test angle and then the clamp fastening bolts 16 are tightened. Then the test piece 23 is installed, and the clamp pressing plate 25 is pressed on the test piece 23 to lock it, so as to realize the test research under different stress states. The signal acquisition unit is composed of a magnetic scale 13 for detecting displacement and a precision force sensor 19 for the magnetic scale 14. Their connection mode is that the reading head of the magnetic scale 13 is fixed on the side of the connecting plate Ⅰ12, and directly measures the relative displacement at the fixture. 14 is a self-adhesive steel strip on the back. The front of the steel strip is uniformly magnetized and can be directly pasted and fixed on the test platform base 21. One end of the precision force sensor 19 is threaded with the connection plate II 22 and the other end is connected with the straight plate at the end of the base for use. The nuts are locked, and when the connecting plate I12 and the connecting plate II22 move relative to each other during the test, the precision force sensor 19 is squeezed to collect the value of the load in real time.

The temperature changing module is composed of a heat gun 11 , a heat gun support base 10 , and a telescopic hot air steering pipe 28 . The heat gun support base 10 is fixedly connected with the test platform base 21, and the heat gun 11 passes through the two heat gun support bases 10 and is fixed with a locking nut. Install the telescopic hot air steering pipe 28 on the front end of the heat gun to ensure that the hot air outlet is facing the gauge length of the test piece. Although the heat gun can achieve point-to-point heating with a diameter of 2mm during the test, the heat will inevitably be transferred to the clamp body 15 and the fixture The pressure plate 25 and even the connection plate, in order to avoid high temperature damage to the test device and affect the test data, in addition to selecting high temperature resistant materials to make the above parts, heat insulating tape is used to insulate the clamp body and other parts that are easily affected by high temperature. Minimize heat transfer. The in-situ observation module can be integrated with the current mainstream optical microscope, and the test platform can also be placed in the scanning electron microscope.

Referring to Fig. 1 to Fig. 6, the present invention relates to an in-situ mechanical testing platform with variable temperature composite load, which belongs to the field of material micromechanical performance testing. The test platform integrates a variable temperature module, a composite loading module, and an in-situ observation module. The composite loading module is composed of a drive unit, a transmission unit and a signal acquisition unit. The components and specific models involved are: DC servo motor 24 (model maxonA-max26 graphite brush 6W), planetary gearbox 26 (maxonGP26A), magnetic scale 13 (MSK5000 produced by German Siko company), precision Force sensor 19 (CF40603-200kg), sensor built-in super heat gun 11 (SEN-220V-440W-BS), digital thermostat (DAC-8D), thermocouple temperature sensor (5TC-GG-K-36- 36) Linear guide (THKSRS12M), worm gear (KHKBG1-20R1SW1-R1), ball screw (Jinwangda SFK01002).

In the specific test process of this test platform, use CAD to draw the two-dimensional picture of the test piece 23 and import it into the wire cutting control software to obtain the test piece 23 through wire cutting. In order to clearly observe the destruction process of the test piece under the microscope, The surface of the test piece needs to be treated. Use a polishing machine to grind and polish the surface of the test piece to remove obvious scratches on the surface of the material. If necessary, use chemical reagents to corrode the material to obtain the metallographic structure of the material. Before the test, use a digital goniometer to determine the tension-shear angle, and use the ring clamp body to construct a composite loading mode at any angle between 0°-90°. After determining the test angle, tighten the clamp fastening bolt 16 to secure the clamp body 15 to the connecting plate I12 and the connecting plate II22, and then install the test piece 23, and use the clamp pressure plate 25 to press the cover on the test piece for locking. Then turn on the heat gun 11 to regulate the test temperature. The test temperature is controlled by the digital thermostat matched with the super heat gun. By changing the temperature and flow, the increase or decrease of heat can be easily controlled. The thermocouple temperature sensor is used to monitor the test temperature in real time. The coordinated use of the temperature regulator and the thermocouple temperature sensor can obtain a suitable test temperature. When the test temperature is stable, open the control software of the test platform, start the DC servo motor 24, and decelerate through the planetary gear reducer 26 and the two-stage worm gear. , convert the rotational motion of the motor into the linear reciprocating motion of the precision two-way ball screw 9 to drive the connecting plate I12 and the connecting plate II22 to perform relative motion, and apply load to the test piece. Since the planetary gear reducer is 19:1, the two-stage worm gear decelerates The ratio is 400:1, so it is basically a quasi-static output, which is convenient for in-situ observation and analysis of crack initiation and expansion forms. During the test, when the reading head of the magnetic scale 13 moves, it reads the changes of S pole and N pole on the magnetic scale 14 and subdivides this signal into AB phase signal output, because the magnetic scale measures digital signals, which can be directly The digital interface transmitted to the acquisition card is read by the host computer software, and the displacement resolution can reach 1um. One end of the precision force sensor 19 is threaded with the connection plate II 22, and the other end is connected with the straight plate at the end of the base and locked with a nut. During the test When the connecting plate I12 and the connecting plate II22 move relative to each other, the precision force sensor 19 will collect the value of the load in real time when it is squeezed. The load signal detected by the precision force sensor is sent to the computer through the acquisition card, and the LABVIEW software is used to automatically fit and generate the load value under the action of the load. the stress-strain curve.

The in-situ observation module can be integrated with the current mainstream optical microscope, or placed in the scanning electron microscope. The invention is compact in size, convenient in situ, combined with optical microscope and electron microscope, can dynamically monitor the evolution process of the internal structure of the material when the crack initiation, expansion and destruction of the material are under the joint action of different temperatures and compound loads. It provides a brand-new testing method and method for in-depth understanding of the microscopic nature of material properties, understanding of the macroscopic laws of materials, and revealing the mechanical behavior of materials under the joint action of temperature field and composite load.

Claims (4)

1. an alternating temperature combined load in-situ mechanical test platform, it is characterized in that: test platform is integrated with alternating temperature module, Combined Loading module and in-situ observation module three part, when applying combined load, test temperature can be changed, and in-situ observation microcosmic evolved behavior of material under combined load and temperature combined effect, such as crack initiation, extension and fracture mode etc.；

Described alternating temperature module is that heat gun supporting seat (10) is connected with test platform pedestal (21), heat gun (11) passes the locking hole of two heat gun supporting seats (10) and locks with locking nut, telescopic hot blast steering tube (28) is threaded connection and is arranged on heat gun front end, it is ensured that hot-air mouth is just to specimen equidistance line marking place；

Described Combined Loading module is by driver element, gear unit and signal gathering unit composition.Described driver element is DC servo motor (24) and planetary gear reduction box (26) supporting installation, entirety and motor flange (1) bolt is connected and fixed on test platform pedestal (21)；Described gear unit is that first turbine (3) engages each other with one-level worm screw (2), motor (24) is carried out first time deceleration through the rotating speed that planetary gear reduction box (26) exports, second-stage worm (7) is supportted seat (4) by second-stage worm bearing (5) and second-stage worm bearing and fixes and be arranged on test platform pedestal (21) with screw, the two-way ball-screw (9) pedestal (21) with precision ball screw supporting seat (6) supporting installation and with test platform is connected, the connecting plate I (12) and connecting plate II (22) that produce relative displacement are rigidly connected by ball guide screw nat with precise guide rail slide block (17), precise guide rail I (18), precise guide rail II (20) is connected with test platform pedestal (21).Described marmon clamp concrete (15) is separately fixed on connecting plate I (12) and connecting plate II (22) through clamp body cannelure by clamp bolt (16)；Described signal gathering unit is the side that magnetic railings ruler (13) read head is fixed on connecting plate I (12), the relative displacement at direct measured material place, magnetic scale (14) is that a back is from adhesive steel band, steel band front is magnetized uniformly, can directly pasting and be fixed on test platform pedestal (21), precision force transducer (19) one end is connected with the threaded one end of connecting plate II (22) with the straight plate of base ends and uses nut check.

2. an alternating temperature combined load in-situ mechanical test platform, it is characterized in that: require that described test platform is that the impact of material mechanical performance is provided effective means of testing with the change of material microstructure and tissue by research temperature according to right 1, examination platform can not only study the mechanical property of material under different temperatures gradient, the mechanical property of phase-change material equitemperature sensitive material can also be probed into, regulating numeral temperature before test adjusts device to be controlled by hot blast in test specimen transition temperature range, then rotating clamp specifically determines Combined Loading form, in-situ observation device is utilized to monitor material Micromechanics behavior in real time during test.

3. an alternating temperature combined load in-situ mechanical test platform, it is characterized in that: require that described test platform adopts annular test fixture according to right 1, the Combined Loading of different stress is realized by rotary annular fixture (15), the axis direction of test specimen can be made with draw direction to become different tests angle by high accuracy number clinometer, thus constructing different stress states, the stress of test specimen is made to be more nearly real service state.Annular holder is made up of jig main body (15) and clamp platen (25), design a cannelure for stationary fixture and change test angle in annular holder body rim, during design, make the gauge length center superposition of circular clamp body, the cannelure geometry center of circle and test specimen.

null4. an alternating temperature combined load in-situ mechanical test platform，It is characterized in that: according to right 2 requires，This test platform can complete in-situ mechanical testing experiment under combined load and temperature combined effect，Heater is integrated on test instrunment，In order to facilitate in-situ observation，Heater is positioned over underside just gauge length center to test specimen (23)，Loading procedure guaranteeing, heating location is in test specimen center all the time，Heater adopts the built-in super-hot air pressure gun of sensor，Point-to-point heating can be realized，Test temperature is adjusted device to control by the numeral temperature supporting with super-hot air pressure gun，By changing temperature、Flow，The increase and decrease of heat can be controlled easily，Adopt the real-time monitoring test temperature of thermocouple temperature sensor，Used by the coordination of thermoregulator and thermocouple temperature sensor and can obtain suitable test temperature.