Composite pultrusion profile test sample and clamp

Abstract

The invention discloses a composite material pultrusion profile test sample and a clamp, the composite material pultrusion profile test sample comprises a profile body, the profile body is provided with a test section and clamping sections located at the two sides of the test section in the length direction, the clamping sections comprise a single conical clamping section close to the test section and a rectangular clamping section far away from the test section, the width of the single-cone-shaped clamping section is gradually reduced in the direction away from the test section to the direction close to the test section, and the thickness of the single-cone-shaped clamping section is smaller than that of the rectangular clamping section, so that the single-cone-shaped clamping section and the rectangular clamping section form a step-shaped structure in the thickness direction. A friction force and pressure coupled stress mode is formed through the rectangular clamping section and the single conical clamping section, and the tensile properties, including the tensile strength, the tensile elastic modulus and the Poisson's ratio, of the pultrusion profile can be effectively measured.

Description

Technical Field

[0001] The invention relates to the technical field of material engineering, and in particular to a composite material pultrusion profile test specimen. Background Art

[0002] Fiber-reinforced composite pultruded profiles have high production efficiency and stable mechanical properties. They are important composite products for realizing large-scale all-composite structures and are also one of the most promising composite materials. With the development of high-strength and high-modulus glass fibers, the longitudinal tensile strength of composite pultruded profiles has reached 1500MPa, the elastic modulus has exceeded 60GPa, and the wall thickness of pultruded profiles has reached more than 20mm as the structure has become larger.

[0003] In the relevant technology, the tensile performance testing standards have exposed failure modes such as insufficient friction in the end anchoring area or local crushing, making it difficult to measure the tensile strength of the pultruded profile. The longitudinal tensile strength of the pultruded profile is an essential parameter in its structural analysis and design, which directly affects the accuracy of the prediction of the failure strength of the pultruded profile structure. Summary of the invention

[0004] The present invention aims to solve one of the technical problems in the related art at least to a certain extent.

[0005] To this end, an embodiment of the present invention provides a composite material pultruded profile test specimen to meet the demand for testing the tensile properties of pultruded profile structural parts.

[0006] The composite pultruded profile test specimen of the embodiment of the present invention includes a profile body, wherein the profile body has a test section and clamping sections located on both sides of the test section in the length direction, the clamping sections include a single-conical clamping section close to the test section and a rectangular clamping section away from the test section, the width of the single-conical clamping section gradually decreases in the direction away from the test section toward the test section, and the thickness of the single-conical clamping section is less than the thickness of the rectangular clamping section, so that the single-conical clamping section and the rectangular clamping section form a step-like structure in the thickness direction.

[0007] The composite pultruded profile test specimen of the embodiment of the present invention has an end face of the rectangular clamping section in the thickness direction and an end face of the single-cone clamping section in the thickness direction that provide a plane for applying friction for the test fixture. There is a section between the single-cone clamping section and the rectangular clamping section, which is also the riser surface of the step. The section provides a plane for applying pressure for the test fixture, thereby forming a force mode of coupling friction and pressure to improve the anchoring strength of the specimen end, thereby effectively measuring the tensile properties of the pultruded profile, including tensile strength, tensile elastic modulus and Poisson's ratio.

[0008] In some embodiments, center lines of the single-tapered clamping section and the rectangular clamping section in the length direction are collinear, so that the single-tapered clamping section and the rectangular clamping section form two steps in the thickness direction.

[0009] In some embodiments, there is a double-conical transition section between the single-conical clamping section and the test section, and the width of the double-conical transition section gradually decreases in the direction away from the test section toward the test section, and the thickness of the double-conical transition section gradually decreases in the direction away from the test section toward the test section.

[0010] An embodiment of the present invention further provides a fixture, which is used for testing a composite material pultruded profile specimen described in any one of the above embodiments.

[0011] The clamp of the embodiment of the present invention comprises:

[0012] A top connecting member, the top connecting member comprising a top plate, the top plate being used to be arranged on a side of the rectangular clamping section away from the testing section;

[0013] A middle connecting piece, the middle connecting piece comprising two middle plates connected to the top plate, the two middle plates being respectively arranged on both sides of the rectangular clamping section in the thickness direction, and the middle plates being in contact with the end surface of the rectangular clamping section in the thickness direction, so that the two middle plates clamp the rectangular clamping section together;

[0014] A bottom connecting member, wherein the bottom connecting member includes a bottom plate, wherein the bottom plate is connected to the middle plate, and wherein the bottom plate is arranged on one side in the thickness direction of the single-conical clamping section, and wherein the end surface of the bottom plate away from the test section contacts the end surface of the rectangular clamping section close to the test section.

[0015] The clamp of the embodiment of the present invention can overcome the problem of insufficient friction force in the end anchoring area existing in the related art by being clamped at the end of the sample.

[0016] In some embodiments, the middle plate is movable along the thickness direction of the rectangular clamping section to adjust the clamping force of the two middle plates on the rectangular clamping section. A first slide is provided on the end surface of the top plate close to the test section, and a first slider engaged in the first slide is provided on the end surface of the middle plate away from the test section.

[0017] In some embodiments, the middle connecting member also includes a middle bolt, which is sequentially assembled on the two middle plates along the thickness direction of the rectangular clamping section, so that the clamping force of the two middle plates on the rectangular clamping section can be adjusted by screwing the middle bolt.

[0018] In some embodiments, there are two bottom plates, which correspond to and are connected to the two middle plates one by one. The two bottom plates are respectively arranged on both sides of the single conical clamping section in the thickness direction, and the bottom plates are in contact with the end faces of the single conical clamping section in the thickness direction, so that the two bottom plates can clamp the single conical clamping section together.

[0019] In some embodiments, the base plate is movable along the thickness direction of the single-conical clamping section to adjust the clamping force of the two base plates on the single-conical clamping section. A second slide is provided on the end surface of the base plate away from the test section, and a second slider is provided on the end surface of the middle plate close to the test section and fits in the second slide.

[0020] In some embodiments, the bottom connecting member also includes a bottom bolt, which is sequentially assembled on the two bottom plates along the thickness direction of the single-conical clamping section, so that the clamping force of the two bottom plates on the single-conical clamping section can be adjusted by screwing the bottom bolt.

[0021] In some embodiments, the top connector further comprises a top bolt, wherein the top bolt is disposed on an end surface of the top plate away from the test section, and a central axis of the top bolt is colinear with a central line of the test section in a length direction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the three-dimensional structure of a composite material pultruded profile test specimen according to an embodiment of the present invention.

[0023] Figure 2 1 is a first schematic diagram of a composite pultruded profile test specimen according to an embodiment of the present invention.

[0024] Figure 3 4 is a second schematic diagram of a composite pultruded profile test specimen according to an embodiment of the present invention.

[0025] Figure 4 It is a schematic diagram of the three-dimensional structure of the clamp according to an embodiment of the present invention.

[0026] Figure 5 is a first schematic diagram of a clamp according to an embodiment of the present invention.

[0027] Figure 6 is a second schematic diagram of the clamp according to an embodiment of the present invention.

[0028] Reference numerals:

[0029] 1- specimen, 11- rectangular clamping section, 12- single-cone clamping section, 13- double-cone transition section, 14- test section, 2- fixture, 21- top bolt, 22- top plate, 23- middle bolt, 24- middle plate, 25- bottom bolt, 26- bottom plate. DETAILED DESCRIPTION

[0030] Embodiments of the present invention are described in detail below, and examples of the embodiments are shown in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to be used to explain the present invention, but should not be understood as limiting the present invention.

[0031] The composite pultruded profile test sample 1 according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0032] The composite material pultruded profile test specimen 1 of the embodiment of the present invention is sampled and processed from a fiber-reinforced composite material pultruded profile of any cross section.

[0033] For example, Figures 1 to 3 As shown, the composite material pultruded profile test specimen 1 of the embodiment of the present invention comprises a profile body, and the cross-section of the profile body is rectangular.

[0034] The profile body has a test section 14 and clamping sections located on both sides of the length direction of the test section 14, that is, the profile body has a test section 14 located in the middle and clamping sections located at both ends thereof. The two clamping sections at the ends of the sample 1 are clamped by the test fixture 2, and then the sample 1 is longitudinally stretched, and the cross-sectional area of ​​the test section 14 is calculated, thereby measuring the ultimate tensile strength of the sample 1.

[0035] Since the related art has the problem of insufficient friction in the end anchoring area, the clamping section of the sample 1 in the embodiment of the present invention adopts a two-section structure to form a force mode of friction and pressure coupling in the clamping section, thereby effectively improving the clamping force of the sample 1.

[0036] like Figures 1 to 3 As shown, the clamping section includes a single-cone clamping section 12 close to the test section 14 and a rectangular clamping section 11 away from the test section 14. The width of the single-cone clamping section 12 gradually decreases in the direction from away from the test section 14 to close to the test section 14, and the thickness of the single-cone clamping section 12 does not change in the direction from away from the test section 14 to close to the test section 14. The width of the end of the single-cone clamping section 12 away from the test section 14 is consistent with the width of the rectangular clamping section 11, and the thickness of the single-cone clamping section 12 is less than the thickness of the rectangular clamping section 11, so that the single-cone clamping section 12 and the rectangular clamping section 11 form a step-like structure in the thickness direction.

[0037] Therefore, in the composite pultruded profile test specimen 1 of the embodiment of the present invention, the end face of the rectangular clamping section 11 in the thickness direction and the end face of the single-cone clamping section 12 in the thickness direction provide a plane for applying friction for the test fixture 2, and there is a section between the single-cone clamping section 12 and the rectangular clamping section 11, which is also the riser surface of the step, and provides a plane for applying pressure for the test fixture 2, thereby forming a force mode of friction and pressure coupling to improve the anchoring strength of the end of the specimen 1, and then the tensile properties of the pultruded profile, including tensile strength, tensile elastic modulus and Poisson's ratio, can be effectively measured.

[0038] Furthermore, if Figures 1 to 3 As shown, the center lines of the single-cone clamping section 12 and the rectangular clamping section 11 in the length direction are collinear, so that the single-cone clamping section 12 and the rectangular clamping section 11 form two steps in the thickness direction.

[0039] In other words, there are two sections between the single-cone clamping section 12 and the rectangular clamping section 11, and the two sections are arranged opposite to each other, thereby improving the uniformity of the applied pressure and further improving the stability of the tensile test.

[0040] In some embodiments, Figures 1 to 3 As shown, there is a double-conical transition section 13 between the single-conical clamping section 12 and the test section 14, and the width of the double-conical transition section 13 gradually decreases in the direction away from the test section 14 toward the test section 14, and the thickness of the double-conical transition section 13 gradually decreases in the direction away from the test section 14 toward the test section 14.

[0041] It can be understood that the cross-sectional area of ​​the clamping section is larger than the cross-sectional area of ​​the test section 14. By setting a double-conical transition section 13 between the two, the width and thickness of the sample 1 are reduced at the same time, so that the clamping section can smoothly transition to the test section 14, reducing stress concentration and reducing the impact on the test results.

[0042] The following describes a fixture 2 according to an embodiment of the present invention in conjunction with the accompanying drawings. The fixture 2 is applicable to a composite material pultruded profile test specimen 1 in any of the above embodiments.

[0043] like Figures 4 to 6 As shown, the clamp 2 according to the embodiment of the present invention includes: a top connecting piece, a middle connecting piece and a bottom connecting piece.

[0044] The top connecting member includes a top plate 22 . The top plate 22 is disposed on a side of the rectangular clamping section 11 away from the testing section 14 . The top plate 22 is used to be connected to a testing machine.

[0045] The middle connecting member includes two middle plates 24, and the end of the middle plate 24 away from the test section 14 is connected to the end surface of the top plate 22 close to the test section 14. The two middle plates 24 are respectively arranged on both sides of the rectangular clamping section 11 in the thickness direction, and the middle plates 24 are in close contact with the end surface of the rectangular clamping section 11 in the thickness direction, so that the two middle plates 24 clamp the rectangular clamping section 11 together to provide a friction type clamping force for the sample 1.

[0046] The bottom connecting member includes a bottom plate 26, the end surface of the bottom plate 26 away from the test section 14 is connected to the end of the middle plate 24 close to the test section 14, the bottom plate 26 is arranged on one side of the thickness direction of the single cone clamping section 12, and the end surface of the bottom plate 26 away from the test section 14 is in close contact with the end surface of the rectangular clamping section 11 close to the test section 14, providing a push-type clamping force (i.e., pressure) for the specimen 1.

[0047] Therefore, two clamps 2 according to the embodiments of the present invention are used and clamped at the two ends of the sample 1 respectively. The clamps 2 are connected to the testing machine. A force mode of friction and pressure coupling is formed between the clamps 2 and the sample 1, which can overcome the problem of insufficient friction in the end anchoring area existing in the related technology.

[0048] In some embodiments, Figures 4 to 6 As shown, the middle plates 24 are movable along the thickness direction of the rectangular clamping section 11 to adjust the clamping force of the two middle plates 24 on the rectangular clamping section 11 .

[0049] Alternatively, if Figures 4 to 6 As shown, a first slideway is provided on the end surface of the top plate 22 close to the test section 14, and a first slider matched in the first slideway is provided on the end surface of the middle plate 24 away from the test section 14. Moreover, the first slideway and the first slider are L-shaped, and the middle plate 24 and the top plate 22 are slidably connected by the cooperation of the two.

[0050] Furthermore, if Figures 4 to 6 As shown, the middle connecting member also includes a middle bolt 23, which is sequentially assembled on two middle plates 24 along the thickness direction of the rectangular clamping section 11, so that the clamping force of the two middle plates 24 on the rectangular clamping section 11 can be adjusted by screwing the middle bolt 23.

[0051] In some embodiments, Figures 4 to 6 As shown, there are two bottom plates 26, which correspond to and are connected to the two middle plates 24 one by one. The two bottom plates 26 are used to be respectively arranged on both sides of the single-cone clamping section 12 in the thickness direction, and the bottom plates 26 are in contact with the end surface of the single-cone clamping section 12 in the thickness direction, so that the two bottom plates 26 clamp the single-cone clamping section 12 together to provide friction clamping force for the sample 1.

[0052] Similarly, the bottom plates 26 are movable along the thickness direction of the single-cone clamping section 12 to adjust the clamping force of the two bottom plates 26 on the single-cone clamping section 12 .

[0053] Alternatively, if Figures 4 to 6 As shown, a second slideway is provided on the end surface of the bottom plate 26 away from the test section 14, and a second slider matched in the second slideway is provided on the end surface of the middle plate 24 close to the test section 14. Moreover, the second slideway and the second slider are L-shaped, and the middle plate 24 and the bottom plate 26 are slidably connected by the cooperation of the two.

[0054] Furthermore, if Figures 4 to 6 As shown, the bottom connecting member also includes a bottom bolt 25, which is sequentially assembled on two bottom plates 26 along the thickness direction of the single-cone clamping section 12, so that the clamping force of the two bottom plates 26 on the single-cone clamping section 12 can be adjusted by screwing the bottom bolt 25.

[0055] In some embodiments, Figures 4 to 6 As shown, the top connecting member further includes a top bolt 21 , which is disposed on the end surface of the top plate 22 away from the test section 14 , so that the top plate 22 is connected to the testing machine through the top bolt 21 .

[0056] Furthermore, the central axis of the top bolt 21 is colinear with the central line of the test section 14 in the length direction, and a tensile force is applied along the axial direction of the sample 1 to improve the accuracy of the test.

[0057] In summary, during the test, as the applied tension gradually increases, the clamping force of the fixture 2 is further increased by screwing the bolts, and the two forces are proportional, thereby ensuring the safety of the test. For example, a drive motor is provided, and a screwing tool is installed on the output shaft of the drive motor to form an automatic screwing device. The test machine and the automatic screwing device are combined into a control system, and the change signal of the output force of the test machine is transmitted to the automatic screwing device, and timely adjustment is made to ensure the appropriate clamping force.

[0058] In the description of the present invention, it is to be understood that the terms “center”, “longitudinal”, “lateral”, “length”, “width”, “thickness”, “up”, “down”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inside”, “outside”, “clockwise”, “counterclockwise”, “axial”, “radial”, “circumferential”, etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0059] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In the description of the present invention, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0060] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection, an electrical connection, or communication with each other; it can be a direct connection, or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0061] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or the first and second features are in indirect contact through an intermediate medium. Moreover, a first feature being "above", "above" or "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below", "below" or "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0062] In the present invention, the terms "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, without contradiction.

[0063] Although the above embodiments have been shown and described, it is to be understood that the above embodiments are exemplary and are not to be construed as limitations on the present invention. Changes, modifications, substitutions and variations of the above embodiments by those of ordinary skill in the art are all within the scope of protection of the present invention.

Claims

1. A composite material pultrusion profile test specimen, characterized in that: The invention comprises a profile body, wherein the profile body comprises a test section and clamping sections located on both sides of the test section in the length direction, wherein the clamping sections comprise a single conical clamping section close to the test section and a rectangular clamping section away from the test section, wherein the width of the single conical clamping section gradually decreases in the direction away from the test section toward the test section, and the thickness of the single conical clamping section is less than the thickness of the rectangular clamping section, so that the single conical clamping section and the rectangular clamping section form a step-like structure in the thickness direction.

2. The composite pultruded profile test specimen according to claim 1, characterized in that: The center lines of the single-cone clamping section and the rectangular clamping section in the length direction are collinear, so that the single-cone clamping section and the rectangular clamping section form two steps in the thickness direction.

3. The composite pultruded profile test specimen according to claim 1, characterized in that: A double-conical transition section is provided between the single-conical clamping section and the test section, wherein the width of the double-conical transition section gradually decreases in a direction away from the test section toward the test section, and the thickness of the double-conical transition section gradually decreases in a direction away from the test section toward the test section.

4. A clamp, characterized in that: The fixture is used for testing a composite pultruded profile specimen according to any one of claims 1 to 3, and the fixture comprises: A top connecting member, the top connecting member comprising a top plate, the top plate being used to be arranged on a side of the rectangular clamping section away from the testing section; A middle connecting piece, the middle connecting piece comprising two middle plates connected to the top plate, the two middle plates being respectively arranged on both sides of the rectangular clamping section in the thickness direction, and the middle plates being in contact with the end surface of the rectangular clamping section in the thickness direction, so that the two middle plates clamp the rectangular clamping section together; A bottom connecting member, wherein the bottom connecting member includes a bottom plate, wherein the bottom plate is connected to the middle plate, and wherein the bottom plate is arranged on one side in the thickness direction of the single-conical clamping section, and wherein the end surface of the bottom plate away from the test section contacts the end surface of the rectangular clamping section close to the test section.

5. The clamp according to claim 4, characterized in that: The middle plate is movable along the thickness direction of the rectangular clamping section to adjust the clamping force of the two middle plates on the rectangular clamping section. A first slide is provided on the end surface of the top plate close to the test section, and a first slider fitted in the first slide is provided on the end surface of the middle plate away from the test section.

6. The clamp according to claim 5, characterized in that: The middle connecting member also includes a middle bolt, which is sequentially assembled on the two middle plates along the thickness direction of the rectangular clamping section, so that the clamping force of the two middle plates on the rectangular clamping section can be adjusted by screwing the middle bolt.

7. The clamp according to claim 4, characterized in that: There are two bottom plates, which correspond to and are connected to the two middle plates one by one. The two bottom plates are respectively arranged on both sides of the single-conical clamping section in the thickness direction, and the bottom plates are in contact with the end faces of the single-conical clamping section in the thickness direction, so that the two bottom plates clamp the single-conical clamping section together.

8. The clamp according to claim 7, characterized in that: The bottom plate is movable along the thickness direction of the single-cone clamping section to adjust the clamping force of the two bottom plates on the single-cone clamping section. A second slide is provided on the end surface of the bottom plate away from the test section, and a second slider fitted in the second slide is provided on the end surface of the middle plate close to the test section.

9. The clamp according to claim 8, characterized in that The bottom connecting member also includes a bottom bolt, which is sequentially assembled on the two bottom plates along the thickness direction of the single-cone clamping section, so that the clamping force of the two bottom plates on the single-cone clamping section can be adjusted by screwing the bottom bolt.

10. The clamp according to claim 4, characterized in that The top connecting member further comprises a top bolt, which is arranged on an end surface of the top plate away from the test section, and a central axis of the top bolt is colinear with a central line of the test section in a length direction.

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