CN115046850A

CN115046850A - Sample and test device for uniaxial in-plane compression test of sheet material at high temperature

Info

Publication number: CN115046850A
Application number: CN202210605335.0A
Authority: CN
Inventors: 周平
Original assignee: Southwest University
Current assignee: Southwest University
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2022-09-13

Abstract

The invention provides a test sample and a test device for a uniaxial in-plane compression test of a sheet material at high temperature, wherein the test sample is a dog-bone-shaped test sample, and a parallel section in the middle of the test sample comprises a groove positioned on the front side surface and transition regions positioned at the upper end and the lower end of the groove; the test device adopts the test sample and also comprises a clamp; the clamp comprises a front anti-buckling plate and a rear anti-buckling plate, and the sample is clamped between the front anti-buckling plate and the rear anti-buckling plate; the front buckling-preventing plate is mounted on the rear buckling-preventing plate through a guide pin and a spring pressing device, and the spring pressing device comprises a belleville spring washer combination body; the front buckling-restrained plate is provided with positioning pins for limiting the left side and the right side of the sample. The sample and the test device provided by the invention are simple and convenient to operate when used for carrying out the in-plane compression test, and can improve the test precision and the maximum measurable compression strain.

Description

Sample and test device for uniaxial in-plane compression test of sheet material at high temperature

Technical Field

The invention relates to the technical field of material mechanical property testing, in particular to a test sample and a test device for a uniaxial in-plane compression test of a sheet material at a high temperature.

Background

Due to the tension-compression asymmetry and the bauschinger effect of many lightweight materials, characterization of the mechanical properties of the materials under compressive load is gaining increasing importance. The pull-press asymmetry is a significant constitutive behavior of Hexagonal Close Packed (HCP) metals, porous materials, and carbon fiber reinforced composites. The bauschinger effect is a common phenomenon in most polycrystalline metals, and part of the material fibers layered in the thickness direction of the sheet are usually inevitably subjected to in-plane compression or cyclic stretch-compression during sheet forming and impact. Therefore, it is important to develop a test method to characterize the mechanical properties of a material under monotonic compression or cyclic tension-compression in the plane. However, it has long been a challenge to determine the compressive properties of sheet materials because sheet materials tend to buckle when a compressive load is applied before substantial compressive failure occurs.

The high slenderness of the sheet specimen and the eccentric load during the in-plane compression test may cause the specimen to buckle, thereby causing premature specimen failure. In addition to buckling, small slenderness ratios and inadequate boundary constraints may lead to barrelling of the specimen, leading to non-uniform strain distributions and non-uniaxial stress states. Therefore, a reliable in-plane compression test method should be able to suppress buckling and barreling of the specimen. To meet these standards, various in-plane compression testing methods for sheet, plastic and composite materials have been developed, which can be classified into three categories depending on the manner in which the load is applied and the geometry of the specimen: shear loading, end loading, and compound loading.

The shear loading method introduces the load into the sample through the shearing action of the clamp, while the end loading method introduces the load through two end faces of the sample, and the combined loading compression method integrates the advantages of the former two methods. These three methods have all been used for different test standards. For plastics, ASTM D695 employs an end-loading method; for the composite material, ASTM D3410, boeing-improved ASTM D695 and ASTM D6641 respectively adopt the above three methods; for metals, room temperature test standard ASTM E9 and high temperature test standard ASTM E209 employ shear loading and end loading methods, respectively. This method is commonly used in cyclic tension-compression testing because of the better compatibility of the shear loading method with tensile testing.

Two types of test methods are mainly proposed depending on the specimen geometry, the first being called the stacking method, proposed by airchison and tuckrman, and as shown in fig. 1(a), by adhesively stacking a plurality of thin plate layers, a small slenderness ratio can be obtained, and thus the specimen buckling can be suppressed, and in recent years, such test methods have been successfully applied to AZ31, ZE10 and ZEK100 magnesium alloys at high temperature and high strain rate. Although this method can measure strain using Digital Image Correlation (DIC) technique is another great advantage, it is easy to soften the gel layer at high temperature, long and costly in sample preparation; furthermore, the barrel effect is inevitable in large compression set due to the small slenderness ratio and frictional forces acting at the ends. As shown in fig. 1(b), the second test method is to use a single thin plate test piece in a rectangular or dog-bone shape and to apply lateral support to the wide side of the test piece using a buckling-resistant jig to prevent the test piece from bending in the thickness direction, and such test methods have been widely used in some in-plane monotonic compression test standards, such as ASTM D3410, boeing-modified ASTM D695, ASTM D6641, ASTM E9, and ASTM E209. However, in this test method, the maximum compressive strain attainable before buckling of the test piece is generally less than 0.1.

Over the past two decades, as the need for the study of the bauschinger effect during sheet forming and impact has increased, many innovative studies have been conducted to develop a continuous cyclic tensile-compressive test method under complex, high strain conditions. Yoshida et al used a different stacking method of bonding five dog bone shaped coupons together and applying broad side lateral support that measured compressive strain of low carbon steel up to 0.25 and high strength steel up to 0.13, but this method had the same disadvantages as the stacking method. Boger et al supported an enlarged dog bone specimen under cyclic tension-compression loading using a hydraulic clamping system with solid side plates. This method can measure the compression strain of the aluminum alloy as high as 0.15. However, the maximum compressive strain achievable with this method is highly dependent on the length of the unsupported section and the specimen and loading axis must be aligned, so this method may not be suitable for very thin specimens.

In order to eliminate the problem of interference between the longitudinal press plate and the transverse support clamp, Kuwabara et al developed an integrated test apparatus for continuous cycle tension-compression based on a comb-shaped buckling-resistant clamp, using which a compressive strain of 0.15-0.20 could be measured even though the test specimen was very thin, but due to the size limitation of the comb-shaped buckling-resistant clamp, a longer test specimen was required, and therefore it was difficult to ensure the centering of the loading axis and the test specimen axis; the neutral misalignment results in a reduction in the maximum compressive strain before buckling, which can be increased by increasing the clamping force, but the greater biaxial stress and friction effects reduce the measurement accuracy. Using a similar principle, Cao et al developed a novel anti-buckling fixture that used 4 wedges to cover the entire broad face of a dog-bone specimen and was able to move freely with the specimen during testing, which was able to measure the maximum compressive strain of steel and aluminum alloys to about 0.1.

It has been difficult to measure strain using the second method since the anti-buckling means obscures the broad face of the sample. Some common methods measure strain on the thick-side of the sample using foil strain gauges, laser extensometers, and DIC techniques. These methods are not always feasible, however, such as with very thin specimens, where great difficulty is encountered using strain gage or DIC measurement techniques.

In summary, the existing testing technology still cannot meet the increasing testing requirements, and a more effective testing method is urgently needed, so that not only can more accurate strain measurement be ensured, but also higher maximum compressive strain can be achieved.

Disclosure of Invention

In view of the above-mentioned technical problems of the conventional in-plane compression test method for sheet materials, a sample and a device for uniaxial in-plane compression test of sheet materials at high temperature are provided.

The technical means adopted by the invention are as follows:

a test sample for a uniaxial in-plane compression test of a sheet material at high temperature is a dog-bone-shaped test sample, and a parallel section in the middle of the test sample comprises a groove positioned on the front side surface and transition regions positioned at the upper end and the lower end of the groove.

Further, the ratio of the groove length to the parallel segment length is 1/3-3/4; the ratio of the depth of the groove to the thickness of the part of the sample except the groove is 0.025-0.1.

The invention also provides a device for testing the uniaxial in-plane compression of the sheet material at high temperature, which adopts the test sample and also comprises a clamp; the clamp comprises a front anti-buckling plate and a rear anti-buckling plate, and the sample is clamped between the front anti-buckling plate and the rear anti-buckling plate; the front buckling-preventing plate is mounted on the rear buckling-preventing plate through a guide pin and a spring pressing device, and the spring pressing device comprises a belleville spring washer combination body; the front buckling-restrained plate is provided with positioning pins for limiting the left side and the right side of the sample.

Further, the spring pressing device further comprises a bolt and a nut, the bolt penetrates through the front buckling preventing plate and the rear buckling preventing plate and is fixed through the nut, and the butterfly spring washer combination body is sleeved on the bolt and is located between the bolt head and the front buckling preventing plate.

Further, the front anti-buckling plate comprises a front upper anti-buckling plate and a front lower anti-buckling plate which are arranged up and down; the lower surface of the sample is flush with the upper surface of the base; the front upper buckling-restrained plate and the front lower buckling-restrained plate are respectively installed on the rear buckling-restrained plate through the guide pin and the spring pressing device.

Further, the front upper buckling-restrained plate and the front lower buckling-restrained plate are respectively provided with two positioning pins.

Furthermore, the belleville spring washer assembly comprises a plurality of belleville spring washers, and the rigidity coefficient and the maximum deformation of the belleville spring washer assembly are adjusted by adjusting the number and the combination mode of the belleville spring washers.

Furthermore, the front buckling-restrained plate is provided with a data acquisition opening for exposing the groove.

Compared with the prior art, the invention has the following advantages:

1. the invention provides a sample for a uniaxial in-plane compression test of a sheet material at high temperature, and designs a novel dog-bone-shaped sample, wherein the sample is provided with a transition region at the upper end and the lower end of a groove at a parallel section respectively, so that on one hand, the barrel effect of a sample measurement region can be inhibited, and on the other hand, the buckling failure of the sample can be delayed, namely, the maximum measurable compression deformation is improved, so that the target that the maximum compression strain exceeds 0.2 before the sample buckles is achieved.

2. The invention provides a single-axis in-plane compression test device for a sheet material at a high temperature, which is characterized in that a buckling-resistant clamp capable of allowing a sample to expand or extend along the thickness direction is designed to inhibit buckling of the sample, and the test device is adopted to carry out a single-axis in-plane compression test, so that higher precision can be obtained without biaxial stress effect correction and friction effect correction.

Based on the reason, the invention can be widely popularized in the field of mechanical property testing of materials.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, and it is obvious that the drawings in the following description are some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to these drawings without creative efforts.

FIG. 1 is a schematic diagram of two in-plane compression test methods in the background art.

FIG. 2 is a schematic view of the structure of a sample according to the present invention.

Fig. 3 is a schematic side view of the groove structure.

FIG. 4 is a schematic structural diagram of the testing apparatus according to the present invention.

FIG. 5 is a schematic front view of the test apparatus of the present invention.

Fig. 6 is a sectional view taken in the direction of fig. 5A-a.

Fig. 7 is an enlarged view of a portion B in fig. 6.

Fig. 8 is a schematic view of the combination type of belleville spring washers according to the present invention.

In the figure: 1. pressing a plate; 2. a rear buckling prevention plate; 3. a front upper anti-buckling plate; 4. a front lower anti-buckling plate; 5. a sample; 51. a support section; 52. a free section; 53. a parallel segment; 54. a groove; 55. a transition zone; 6. a base; 7. a guide pin; 8. a high temperature shaft sleeve; 9. a bolt; 10. a belleville spring washer assembly; 11. and positioning pins.

Detailed Description

It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict. The present invention will be described in detail below with reference to the embodiments with reference to the attached drawings.

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The following description of at least one exemplary embodiment is merely illustrative in nature and is in no way intended to limit the invention, its application, or uses. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

It is noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, and it should be understood that when the terms "comprises" and/or "comprising" are used in this specification, they specify the presence of stated features, steps, operations, devices, components, and/or combinations thereof, unless the context clearly indicates otherwise.

The relative arrangement of the components and steps, the numerical expressions and numerical values set forth in these embodiments do not limit the scope of the present invention unless specifically stated otherwise. Meanwhile, it should be understood that the sizes of the respective portions shown in the drawings are not drawn in an actual proportional relationship for the convenience of description. Techniques, methods, and apparatus known to those of ordinary skill in the relevant art may not be discussed in detail but are intended to be part of the specification where appropriate. In all examples shown and discussed herein, any particular value should be construed as exemplary only and not as limiting. Thus, other examples of the exemplary embodiments may have different values. It should be noted that: like reference numbers and letters refer to like items in the following figures, and thus, once an item is defined in one figure, further discussion thereof is not required in subsequent figures.

In the description of the present invention, it is to be understood that the directions or positional relationships indicated by the directional terms such as "front, rear, upper, lower, left, right", "lateral, vertical, horizontal" and "top, bottom", etc., are generally based on the directions or positional relationships shown in the drawings, and are only for convenience of description and simplicity of description, and in the case of no relative description, these directional terms do not indicate and imply that the device or element being referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore, should not be taken as limiting the scope of the present invention: the terms "inner and outer" refer to the inner and outer relative to the profile of the respective component itself.

Spatially relative terms, such as "above … …", "above … …", "above … …, on a surface", "above", and the like, may be used herein for ease of description to describe one device or feature's spatial relationship to another device or feature as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if a device in the figures is turned over, devices described as "above" or "on" other devices or configurations would then be oriented "below" or "under" the other devices or configurations. Thus, the exemplary term "above … …" can include both an orientation of "above … …" and "below … …". The device may be otherwise variously oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

It should be noted that the terms "first", "second", and the like are used to define the components, and are only used for convenience of distinguishing the corresponding components, and the terms have no special meanings unless otherwise stated, and therefore, the scope of the present invention should not be construed as being limited.

Example 1

As shown in FIGS. 2 to 3, the invention provides a sample for uniaxial in-plane compression test of a thin plate material at high temperature, the sample 5 is a dog bone-shaped sample, and a parallel section 53 in the middle of the sample 5 comprises a groove 54 on the front side surface and transition regions 55 on the upper end and the lower end of the groove 54.

Further, the ratio of the length of the groove 54 to the length of the parallel section 53 is 1/3-3/4; the ratio of the depth of the groove 54 to the thickness of the sample 5 excluding the groove 54 is 0.025 to 0.1.

Further, the junction between the transition region 55 and the groove 54 may be a rounded corner or a right-angled corner with a radius R2, which is determined by the tool selected during machining.

As shown in fig. 4-7, the present invention further provides a device for testing uniaxial in-plane compression of a sheet material at high temperature, which uses the above-mentioned test sample 5, and further comprises a clamp; the clamp comprises a front buckling-preventing plate and a rear buckling-preventing plate 2, and the test sample 5 is clamped between the front buckling-preventing plate and the rear buckling-preventing plate 2; the front buckling-restrained plate is arranged on the rear buckling-restrained plate 2 through a guide pin 7 with the diameter of 5mm and a spring pressing device, and the spring pressing device comprises a belleville spring washer combination 10; the front buckling-restrained plate is provided with a positioning pin 11 used for limiting the left side and the right side of the sample.

Further, the spring pressing device further comprises a bolt 9 and a nut, the bolt 9 penetrates through the front buckling-preventing plate and the rear buckling-preventing plate 2 and is fixed through the nut, and the belleville spring washer assembly 10 is sleeved on the bolt 9 and is located between the head of the bolt 9 and the front buckling-preventing plate.

Further, the front anti-buckling plate comprises a front upper anti-buckling plate 3 and a front lower anti-buckling plate 4 which are arranged up and down; the lower surface of the sample is flush with the upper surface of the base; the front upper buckling-restrained plate 3 and the front lower buckling-restrained plate 4 are respectively installed on the rear buckling-restrained plate 2 through the guide pin 7 and the spring pressing device.

Furthermore, the front upper buckling-restrained plate 3 and the front lower buckling-restrained plate 4 are respectively provided with two positioning pins 11 with phi of 2mm, and the positioning pins are used for limiting the left side and the right side of the sample 5 and ensuring that the sample 5 is located in the middle of the clamp; the positioning pin 11 can play a role in quick positioning, and meanwhile, the positioning pin 11 ensures that the test sample 5 is positioned in the middle of the clamp, so that the longitudinal center line of the test sample 5 can be further ensured to be consistent with the load center line, and the risk of eccentric load is eliminated.

Further, the belleville spring washer assembly 10 includes a plurality of belleville spring washers, and the adjustment of the stiffness coefficient and the maximum deformation of the belleville spring washer assembly 10 is realized by adjusting the number and the combination mode of the belleville spring washers, for example, as shown in fig. 8, the combination type of three belleville spring washers is:

(1) the belleville spring washers are installed in the same direction, the rigidity coefficient of the combined spring can be improved by increasing the number of the belleville spring washers 10, and meanwhile, the maximum deformation amount is kept;

(2) the adjacent belleville spring washers are reversely installed, the rigidity coefficient of the combined spring can be reduced by increasing the number of the belleville spring washers 10, and meanwhile, the maximum deformation amount is improved;

(3) the adjacent belleville spring washers are installed in the same direction or in the opposite direction, namely, the combined combination is realized, and the specific combined spring stiffness coefficient and the maximum deformation can be flexibly designed by changing the number and the combination type of the belleville spring washers;

according to combinatory theory, the number of different combination configurations increases sharply with increasing number of shims, allowing fine tuning of the spring rate and maximum deflection as required.

Further, the clamp further comprises a pressure plate 1 and a base 6; the front and rear anti-buckling plates 2 are located between the pressure plate 1 and the base 6; the rear buckling-preventing plate 2 is fixedly installed on the base 6.

Furthermore, the surfaces of the sample 5 and the clamp are lubricated by adopting a polytetrafluoroethylene spray lubricant, so that the friction force between the sample 5 and the clamp can be reduced to the maximum extent, and the friction coefficient of a contact interface after the lubrication treatment can be reduced to about 0.05.

Further, the front buckling-restrained plate is provided with a data acquisition opening for exposing the groove 54, so that the groove 54 can be seen in the whole process of the test.

Further, the front upper buckling-restrained plate 3 and the front lower buckling-restrained plate 4 are respectively provided with the data acquisition opening.

Further, as shown in fig. 2 to 3, the wide surface portions of the upper and lower ends of the parallel section 53 of the test sample 5 are support sections 51, the support sections 51 are connected to the parallel section 53 through circular arc-shaped transition sections, the support section 51 at the lower end of the parallel section 53 is clamped by the front lower anti-buckling plate 4 and the rear anti-buckling plate 2, the lower portion of the support section 51 at the upper end of the parallel section 53 is clamped by the front upper anti-buckling plate 3 and the rear anti-buckling plate 2, and the upper portion is a free section 52 for contacting the pressure plate 1 during the compression test.

Further, the total length L of the test piece 5 is 31 mm; the length Lf of the free section 52 is 5 mm; the length Lp of the parallel section 53 is 12 mm; the width W of the support section 51 is 16 mm; the length Lg of the groove 54 is 6 mm; the width Wg of the groove 54 is 5 mm.

When the sample and the test device provided by the invention are used for a compression test, the front buckling-restrained plate can move along the thickness direction of the sample 5 along with the change of the thickness of the sample 5 after being pressed, the guide pin 7 is arranged on the front buckling-restrained plate through the high-temperature shaft sleeve 8, when the front buckling-restrained plate moves along the thickness direction of the sample 5, the guide pin 7 is used for positioning and guiding the movement direction of the front buckling-restrained plate with high precision, and meanwhile, the spring pressing device is used for controlling the pressing force between the front buckling-restrained plate and the rear buckling-restrained plate 2 through the belleville spring washer assembly 10, so that the clamp can clamp the sample 5.

The groove 54 can solve the problem that the test sample 5 can be bent early in the thickness direction when the test sample 5 is subjected to a compressive load in the longitudinal direction, and the upper end and the lower end of the groove of the parallel section of the test sample 5 are respectively provided with the transition regions 55, so that on one hand, the deformation uniformity of a test sample measurement region can be improved, the barrel effect (which is a negative effect and can change the stress state and reduce the test precision) of the test sample measurement region is inhibited, and on the other hand, the bending failure of the test sample can be delayed, namely, the maximum measurable compressive deformation is improved.

When the test sample undergoes plane compression deformation, the test sample can expand or stretch along the thickness direction, the front upper buckling-proof plate and the front lower buckling-proof plate can have the capability of allowing the test sample to freely stretch in the thickness direction through the guide pin and the spring pressing device which are arranged in the test device, so that the precision of a test result is ensured, meanwhile, the front buckling-proof plate is designed into a split structure comprising the front upper buckling-proof plate and the front lower buckling-proof plate, and is respectively arranged on the rear buckling-proof plate through the guide pin and the spring pressing device, so that the adjustment can be performed according to the change degree of the thickness of the upper end and the lower end of the test sample after being pressed, and the test precision is further improved; if the clamp prevents the deformation of the sample in the thickness direction, a very large thickness direction stress is caused, so that the sample is in a two-way compressive stress state rather than an expected one-way compressive stress state, on the other hand, the thickness direction pressure is increased, so that the friction force is inevitably increased, the load measured by the testing machine sensor comprises two parts, namely the sample deformation resistance and the friction force between the sample and the clamp, when the friction force is large, the friction force needs to be deducted from the total load to ensure the measurement accuracy of the sample deformation resistance, however, the friction force is difficult to measure, the traditional one-way compression test method has two-way stress effect and friction force effect, so that the two-way stress correction and friction force compensation are needed, and when the sample and the testing device provided by the invention are used for compression test, when the sample is compressed and deformed, the thickness increase amount of the supporting section clamped by the clamp for the sample is small, the thickness increase amount of the parallel section is large, the pressing force of the belleville spring washer assembly cannot be influenced by the thickness increase because the parallel section is not in contact with the front buckling-restrained plate, therefore, the pressing force passively applied by the belleville spring washer assembly due to the thickness increase of the sample is small, the friction coefficient is small, the friction force is small and can be ignored, and the test device provided by the invention can obtain high measurement precision without bidirectional stress correction and friction force compensation.

In the compression test, a universal material testing machine MTS with an internal load sensor can be adopted

The maximum measurable load is 100kN, an end loading method is adopted, namely, compressive loads are applied to two end faces of a sample, a pressure plate and a base of the testing device are respectively arranged on an upper chuck and a lower chuck of the testing machine, and in order to reduce the load eccentricity to the maximum extent, the testing machine can be subjected to careful centering treatment by using an electronic angle meter before testing. For the high temperature environment, the environmental temperature of the sample was controlled using MTS 651 type environmental chamber.

When the experimental device provided by the invention is used for strain measurement, a digital image correlation method-based method can be adopted

The system performs a full field strain distribution measurement of the grooved surface area of the sample using a Point Grey Research GRAS-50S5M-C industrial camera with a Tamron AF 180mm f/3.5 macro lens; the strain analysis parameters of the strain measurement process are as follows: the size of the subset is 31 pixels, the step size is 4, the size of the strain filter is 9 pixels, and the consistent resolution of 0.016 mm/pixel is achieved; three longitudinal and three transverse virtual extensometers were set up to measure the average strain of the specimen in the length and width directions, respectively.

In order to evaluate the performance of the test apparatus of the present invention, four commercial-grade metal plates were selected as the study materials, including DP600 steel with a nominal thickness of 1.5mm, AA5182-O aluminum alloy with a thickness of 1.5mm, AA7075-T6 aluminum alloy with a nominal thickness of 2.0mm, and ZEK100-F magnesium alloy with a thickness of 1.6mm, and numerous studies showed that the tensile true stress-strain curves and the compressive true stress-strain curves of DP600 steel, AA5182-O, and AA7075-T6 aluminum alloys under monotonic load conditions had good agreement, and thus were useful for evaluating the accuracy of the compression test results; in evaluating the performance of the test apparatus using the above four kinds of metal plates, all the samples were subjected to a compression test of the samples at a temperature of 23 to 200 ℃ in the rolling direction of the plate, and the actual sample temperature at the groove position was measured using a K-type thermocouple at each temperature condition.

The result shows that the true stress-strain curves of the steel and aluminum alloy plates under the tensile and compression working conditions have good consistency, and the test device has higher precision; in addition, most tests achieved a maximum compressive strain of greater than 0.2 before buckling of the test specimen.

The ZEK100-F magnesium alloy plate is tested in the temperature range of 23-200 ℃, and when the temperature reaches 175 ℃, a compression true stress-strain curve presents a special S shape, which shows that twin crystals exist, and dislocation slip dominates plastic deformation at higher temperature; at 200 c, the compression curve returns to the typical concave shape.

The test results prove the effectiveness and feasibility of the test device.

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. The test sample for the uniaxial in-plane compression test of the sheet material at high temperature is characterized in that the test sample is a dog-bone-shaped test sample, and the parallel section in the middle of the test sample comprises a groove positioned on the front side surface and transition regions positioned at the upper end and the lower end of the groove.

2. The sheet material specimen for uniaxial in-plane compression test at high temperature according to claim 1, wherein the ratio of the groove length to the parallel segment length is 1/3 to 3/4; the ratio of the depth of the groove to the thickness of the part of the sample except the groove is 0.025-0.1.

3. A sheet material uniaxial in-plane compression test device at high temperature, which adopts the sample of claim 1 or 2, and is characterized by further comprising a clamp; the clamp comprises a front anti-buckling plate and a rear anti-buckling plate, and the sample is clamped between the front anti-buckling plate and the rear anti-buckling plate; the front buckling-preventing plate is mounted on the rear buckling-preventing plate through a guide pin and a spring pressing device, and the spring pressing device comprises a belleville spring washer combination body; the front buckling-restrained plate is provided with positioning pins for limiting the left side and the right side of the sample.

4. The apparatus for testing uniaxial in-plane compression of thin sheet material at high temperature of claim 3, wherein the spring pressing device further comprises a bolt and a nut, the bolt passes through the front buckling-preventing plate and the rear buckling-preventing plate and is fixed by the nut, and the belleville spring washer combination is sleeved on the bolt and is located between the bolt head and the front buckling-preventing plate.

5. The apparatus for uniaxial in-plane compression testing at high temperature of sheet material as claimed in claim 3, wherein said front buckling restrained panel comprises upper and lower front buckling restrained panels disposed one above the other; the lower surface of the sample is flush with the upper surface of the base; the front upper buckling-restrained plate and the front lower buckling-restrained plate are respectively installed on the rear buckling-restrained plate through the guide pin and the spring pressing device.

6. The apparatus for uniaxial in-plane compression testing at high temperature of sheet material as claimed in claim 5, wherein the front upper buckling restrained plate and the front lower buckling restrained plate are respectively provided with two of the positioning pins.

7. The device for testing uniaxial in-plane compression of thin-plate materials at high temperature according to claim 3, wherein the belleville spring washer combination comprises a plurality of belleville spring washers, and the stiffness coefficient and the maximum deformation of the belleville spring washer combination are adjusted by adjusting the number and the combination mode of the belleville spring washers.

8. The sheet material uniaxial in-plane compression test device at high temperature of claim 3, wherein the front buckling restrained plate is provided with a data acquisition opening for exposing the groove.