Claims:We claim:
1. An anti-buckling device (100) for a tension-compression cyclic test for evaluating Bauschinger parameter of a thin sheet metal (200), the anti-buckling device (100) comprising of:
two identical plates (101, 102);
an identical obround slot (102a) is provided longitudinally in each of the two identical plates (101, 102); and
plurality of through holes (102b, 102c, 102d, 102e) provided on each of the two identical plates (101, 102) to mount the one identical plate (101) over the other identical plate (102) by a plurality of fasteners (103, 103a).

2. The anti-buckling device (100) as claimed in claim 1, wherein two through holes (102b, 102c) from the four through holes (102b, 102c, 102d, 102e) are provided on top portion (102f) and two through holes (102d, 102e) from the four through holes (102b, 102c, 102d, 102e) are provided on bottom portion (102g) of the two identical plates (101, 102).

3. The anti-buckling device (100) as claimed in claim 2, wherein the two through holes (102b, 102c) provided at the top portion (102f) are longitudinally spaced apart from the two through holes (102d, 102e) provided at the bottom portion (102g).

4. The anti-buckling device (100) as claimed in claim 1, wherein the identical obround slot (102a) is defined along longitudinal central axis (Z) of each of the identical plates (101, 102).

5. The anti-buckling device (100) as claimed in claim 1, wherein the identical obround slot (102a) is defined longitudinally in between the four through holes (102b, 102c, 102d, 102e).

6. The anti-buckling device (100) as claimed in claim 1, wherein the thin metal sheet (200) sandwiched between the two identical plates (101, 102).
7. The anti-buckling device (100) as claimed in claim 1, wherein material of the anti-buckling device (100) is stronger than material of the thin sheet metal (200).

8. The anti-buckling device (100) as claimed in claim 4, wherein the width of the obround slot (102a) is smaller than the width of the thin metal sheet (200) during the tension compression cyclic test.

9. An anti-buckling system (300) for a tension-compression cyclic test for evaluating Bauschinger parameter of a thin sheet metal (200), the anti-buckling system (300) comprising of:
two identical plates (102);
an identical obround slot (102a) provided longitudinally (Y) in each of the two identical plates (101, 102);
four through holes (102b, 102c, 102d, 102e) provided on each of the two identical plates (101, 102) to mount the one identical plate (101) over the other identical plate (102) by a plurality of fasteners (103, 103a);
the thin metal sheet (200) sandwiched between the two identical plates (101, 102); and
an extensometer adapted to sense marks (105) provided on a gauge section of the sandwiched thin metal sheet (200) through the identical obround slot (102a) to obtain stress strain data during the tension-compression cyclic test.

10. The anti-buckling system (300) as claimed in claim 9, wherein the identical obround slot (102a) is defined along longitudinal central axis (Z) of each of the identical plates (101, 102).

11. The anti-buckling system (300) as claimed in claim 9, wherein the extensometer is video extensometer.
, Description:ANTI-BUCKLING DEVICE (ABD) FOR TENSION-COMPRESSION CYCLIC TEST OF THIN SHEETS
FIELD OF INVENTION:
[001] The present subject matter described herein, relates to metal fatigue testing technology to test mechanical properties of thin sheets and, in particularly, to anti-buckling device (ABD) in tension-compression cyclic test of thin metal sheets to buckle under tension compression test.
BACKGROUND AND PRIOR ART AND PROBLEM IN PRIOR ART:
[002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[003] In current modern world, thin metal sheets are used at many places, such as automobile bodies (commercial as well as personal), airplane fuselages and wings, medical tables, roofs for buildings (architecture) and many other applications. In the automobile industry, safety and reliability of the automobile is prime concern where material fatigue performance of the metal sheet plays important role for safety and reliability of the automobile. Therefore, tension-compression cycle testing of the metal sheet at high strain identifies the strength of the sheet metal for safety and reliability of the automobile or different applications.
[004] In the tension-compression cyclic test of thin metal sheet, buckling of sheet is the major technical problem in the testing apparatus. Buckling of the thin metal sheet in the tension-compression cyclic test impacts the stress strain data and creates hurdle in completion of tests and the testing fails.
[005] In the existing anti-buckling device, there are several challenges and dis-advantages. The existing anti-buckling device, as shown in Fig. 4, requires large number of parts which need to be join with each other by a plurality of nuts and bolts. Assembly of large number of parts increases cost, weight of device and time of assembly, further, there are high chances of failure of any part during use, accordingly, the existing anti-buckling device has less durability and high serviceability. Also, the device does not have the provision of clamping it on one of the surfaces of the sheet at the gauge section and get the strain of the sample during the test. Fig. 5 shows double-shear clamp for testing shearing strength of material. Anti buckling device shown in Fig. 6, holds a metal specimen which is subjected to compression and to rapid cyclical heating and cooling while permitting visual observation. However, for simple tensile and compression test, the design proves to be complicated.
[006]
[007] However, the design referenced, lack the features to monitor the gauge section during the test using an external scanner or through video extensometer or are complicated in design. It would, therefore desirable to develop an Anti-buckling device which can be used for tension-compression cyclic test of thin metal sheet by overcoming the above-mentioned technical problems. Therefore, there is a need in the art to have a structured Anti-buckling device which is cost effective and simple in structure to avoid buckling of thin sheet in the tension compression cyclic test for evaluating Bauchinger parameter.

[008] The information disclosed in this background of the disclosure section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.
[009] OBJECTS OF THE INVENTION:
[0010] It is therefore the object of the invention to overcome the aforementioned and other drawbacks in prior device/system/apparatus.
[0011] The principal objective of the present invention is to provide an anti-buckling device to be used for tension-compression cycle test as well as allows to get scanned for the strain measurements for evaluating the Bauschinger parameters of thin metal sheet. This anti-buckling device prevents buckling of the thin sheet sample during the compression mode of a tension compression cyclic test..
[0012] Another object of the present invention is to provide the anti-buckling device with rectangular shape structure.
[0013] Yet another object of the present invention is to provide the anti-buckling device which is cost efficient, easy to manufacture, lesser number of parts, and avoids buckling of thin metal sheet during tension compression cyclic test.
[0014] These and other objects and advantages of the present subject matter will be apparent to a person skilled in the art after consideration of the following detailed description taken into consideration with accompanying drawings in which preferred embodiments of the present subject matter are illustrated.
SUMMARY OF THE INVENTION:
[0015] One or more drawbacks of conventional anti-buckling device for tension-compression cyclic test of thin metal sheet are overcome, and additional advantages are provided through the anti-buckling device as claimed in the present disclosure. Additional features and advantages are realized through the technicalities of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered to be a part of the claimed disclosure.
[0016] The present subject matter relates to an anti-buckling device for a tension-compression cycle testing of thin sheet metal under tension compression mode. The anti-buckling device comprises of two identical plates where each of the two identical plates has an identical obround slot which is provided longitudinally (Y). Four through holes are provided on each of the two identical plates to mount the one identical plate over the other identical plate by a plurality of fasteners. From the four through holes, two through holes are provided closer to the top surface or at the top portion and other two through holes are provided closer to the bottom surface of the identical plate or at the bottom portion. The two through holes that are provided at the top portion are longitudinally spaced apart from the two through holes that are provided at the bottom portion.
[0017] In an embodiment, material of the anti-buckling device is stronger than the thin sheet metal to be tested for the tension-compression cyclic test.
[0018] In an embodiment, the identical obround slot is defined along longitudinal central axis (Z) of each of the identical plates.
[0019] In yet another embodiment of the present subject matter, a video extensometer is adapted to detect marks provided on a gauge section of the thin metal sheet that is sandwiched in between the anti-buckling device through the identical obround slot to obtain stress-strain data during the tension-compression cyclic test.
[0020] It is to be understood that the aspects and embodiments of the disclosure described above may be used in any combination with each other. Several of the aspects and embodiments may be combined to form a further embodiment of the disclosure.
[0021] The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] It is to be noted, however, that the appended drawings illustrate only typical embodiments of the present subject matter and are therefore not to be considered for limiting of its scope, for the invention may admit to other equally effective embodiments. The detailed description is described with reference to the accompanying figures. In the figures, a reference number identifies the figure in which the reference number first appears. The same numbers are used throughout the figures to reference like features and components. Some embodiments of system or methods or structure in accordance with embodiments of the present subject matter are now described, by way of example, and with reference to the accompanying figures, in which:
[0023] Fig. 1 illustrates structure of anti-buckling device for tension-compression cyclic test of thin metal sheet, in accordance with an embodiment of the present subject matter;
[0024] Fig. 2 illustrates front view of the anti-buckling device as illustrated in figure 1, in accordance with an embodiment of the present subject matter; and
[0025] Fig. 3 illustrates rectangular plate structure of the anti-buckling device as shown in the figure 1, in accordance with an embodiment of the present subject matter.
[0026] The figures depict embodiments of the present subject matter for the purposes of illustration only. A person skilled in the art will easily recognize from the following description that alternative embodiments of the structures and methods illustrated herein may be employed without departing from the principles of the disclosure described herein.
DESCRIPTION OF THE PREFERRED EMBODIMENTS:
[0027] While the embodiments of the disclosure are subject to various modifications and alternative forms, specific embodiment thereof have been shown by way of example in the figures and will be described below. It should be understood, however, that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the scope of the disclosure.
[0028] The terms “comprises”, “comprising”, or any other variations thereof used in the disclosure, are intended to cover a non-exclusive inclusion, such that a device, system, assembly that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such system, or assembly, or device. In other words, one or more elements in a system or device proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or device.
[0029] The present subject matter relates to an anti-buckling device for a tension-compression cycle testing of thin sheet metal under tension compression mode. The anti-buckling device comprises of two identical plates and an identical obround slot that is provided longitudinally (Y) in each of the two identical plates. Four through holes are provided on each of the two identical plates to mount the one identical plate over the other identical plate by a plurality of fasteners. Where the two through holes that are provided at a top portion are longitudinally spaced apart from the two through holes that are provided at a bottom portion.
[0030] It should be noted that the description and figures merely illustrate the principles of the present subject matter. It should be appreciated by those skilled in the art that conception and specific embodiment disclosed may be readily utilized as a basis for modifying or designing other structures for carrying out the same purposes of the present subject matter. It should also be appreciated by those skilled in the art that by devising various arrangements that, although not explicitly described or shown herein, embody the principles of the present subject matter and are included within its spirit and scope. Furthermore, all examples recited herein are principally intended expressly to be for pedagogical purposes to aid the reader in understanding the principles of the present subject matter and the concepts contributed by the inventor(s) to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. The novel features which are believed to be characteristic of the present subject matter, both as to its organization and method of operation, together with further objects and advantages will be better understood from the following description when considered in connection with the accompanying figures.
[0031] These and other advantages of the present subject matter would be described in greater detail with reference to the following figures. It should be noted that the description merely illustrates the principles of the present subject matter. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described herein, embody the principles of the present subject matter and are included within its scope.
[0032] In the present specification, arrow marked with Y indicates Longitudinal direction and arrow marked with X indicates transverse direction, and dotted line marked with ZZ passes through the center of the plates in longitudinal direction indicates the longitudinal central axis of the plates.
[0033] Fig. 1 illustrates a structure of anti-buckling device to be used for bigger samples in tension-compression cyclic test of thin metal sheet to prevent buckling during tension compression cyclic test, in accordance with an embodiment of the present subject matter. The anti-buckling device 100 comprises of two identical plates 101, 102, and an identical obround slot 102a. The identical obround slot 102a is provided longitudinally axis (Y) in each of the two identical plates 101, 102. Further, each identical plate has four through holes 102b, 102c, 102d, 102e that are provided to mount the one identical plate 101 over the other identical plate 102 by a plurality of fasteners 103, 103a, such as bolts and nuts. Referring to figure 1 and 2, the bolts can be either of Allen head or normal such that it can just pass through the holes present on the identical plates 101, 102.
[0034] Referring to figure 3, from the four through holes 102b, 102c, 102d, 102e, the two through holes 102b, 102c are provided closer to top surface 102f of the two identical plate. Similarly, the other two through holes 102d, 102e are provided closer to bottom surface 102g of the two identical plate. In other words position of the four through holes can be understood that the two through holes 102b, 102c are provided at top portion 102f and other two through holes 102d, 102e are provided at bottom portion 102g. In other configuration, position of the four through holes can be understood that each through hole is provided closer to corner of the rectangular identical plates 101, 102. The two through holes 102b, 102c that are provided at the top portion 102f are longitudinally spaced apart from the two through holes 102d, 102e that are provided at the bottom portion 102g. As shown in the figure 3, the obround slot 102a is defined along longitudinal central axis (Z) of each of the identical plates 101, 102. Further, one obround end of the obround slot 102a is provided closer to the top surface 102f and other obround end of the obround slot 102a is provided closer to the bottom surface 102g.
[0035] Again referring to figure 1 and 2, the thin metal sheet 200 is sandwiched in between the two identical plates 101, 102 to prevent buckling during testing. The identical obround slot 102a is in each plate 101, 102 as shown in figure 2, whose width is smaller than the width of the thin metal sheet 200, thereby preventing the thin metal sheet 200 from buckling and going out of plane. The width of the sample should always be greater than the width of the obround slot at all times during the test. Since each identical plate 101, 102 is present on either side of the thin metal sheet 200 such that the thin metal sheet 200 is prevented from buckling from both the sides.
[0036] In an embodiment, the material of construction of anti-buckling device 100 is stronger than the thin metal sheet 200 to be tested. The material of anti-buckling device 100 should be strong enough to overcome the force exerted by the thin metal sheet 200 on the plates 101, 102 of anti-buckling device 100, as shown in Figure 2, during compression load mode or buckling action to prevent buckling of the experimental thin metal sheet 200.
[0037] As shown in the figure 1 and 2, the thin metal sheet 200 which is to be tested on the tension-compression cyclic test machine is sandwiched between two identical plates 101, 102. The identical plates 101, 102 are kept in such a way that their identical profile gets superimposed or matches over each other. The identical plates 101, 102 are fastened with the help of the plurality of fasteners, such as bolt 103 and nut 103a in such a way that the bolt and nut can be easily unclamped through hand without using any tool. The identical plates 101, 102 should not be fastened loose or tight. For experimental/testing result, proper fastening of the identical plates 101, 102 is very essential.
[0038] After sandwiched in between the two identical plates 101, 102, reference marks 105 (two marks) may be provided on visible portion which can be referred as gauge section of the thin metal sheet 200 through the obround slot 102a. The reference marks 105 are longitudinally spaced apart from each other in longitudinal direction Y. In other words, one mark 105 is provided closer to one obround end of the obround slot 102a and other mark is provided closer to other obround end of the obround slot 102a. The obround slot 102a present on the identical plates 101, 102 facilitates the marks 105 on the gauge section of the thin metal sheet 200 get sensed or scanned or detected by the video extensometer. Further, the video extensometer can be placed at in-line distance away from the anti-buckling device, specifically, from the obround slot 102a. The marks 105 on the thin metal sheet 200 move away from each other during tensile mode of testing, and the marks 105 come closer to each other during compression mode of testing. The change in the distance between the marks 105 during testing is captured by the video extensometer, thereby capturing the strain on the thin metal sheet 200. In the present embodiment, distance detected by the video extensometer is sent to coupled processing system for calculating and determining the Bauschinger parameter of the thin metal sheet 200. The detected distance between the two marks 105 is used to get the stress-strain curve during tensile and compression mode of testing which eventually is used to evaluate Bauschinger parameter of the thin metal sheet 200 in a processing system.
[0039] Testing condition:
[0040] The tension-compression cyclic test machine grips the thin metal sheet 200 just near the anti-buckling device 100 leaving a gap of about 1 to 2mm between the anti-buckling device 100 and the grip of the tension-compression cyclic test machine at both ends. The tension-compression cyclic test is carried out in stress control mode oscillating between tension and compression mode. Tensile load is subjected to the thin metal sheet 200, up to certain strain through the grips of the machine then compression load is subjected to the thin metal sheet 200 till certain strain. The stress strain data is captured by the machine through the extensometer and load cell helps in evaluating the Bauschinger parameter of the thin metal sheet 200. During compression mode, anti-buckling device 100 prevents the thin metal sheet 200 from buckling as the width of the obround slot 102a in the anti-buckling device 100 device is smaller than the width of the thin sheet metal 200 thereby not allowing the gauge section of the thin metal sheet 200 to go out of plane or buckle, eliminating the possibility of buckling of the thin metal sheet 200.
[0041] Referring to figure 1 which illustrates a structure of the anti-bucking system 300. The anti-buckling system 300 comprises an anti-buckling device 100, a thin metal sheet 200 and a video extensometer. The anti-buckling device 100 is configured to sandwiched the thin metal sheet 200 evaluating Bauschinger parameter under tension-compression cyclic test. For the sake of brevity and to avoid ambiguity, structure of anti-buckling device is not explained in detailed here. The anti-buckling device 100 has two identical plates 101, 102 and an identical obround slot 102a that is provided longitudinally (Y) in each of the two identical plates 101, 102. Further, the anti-buckling device 100 has four through holes 102b, 102c, 102d, 102e that are provided on each of the two identical plates 101, 102 to mount the one identical plate 101 over the other identical plate 102 by a plurality of fasteners 103, 103a. The width of the obround slot 102a in each plate 101, 102 is less than the width of the thin metal sheet 200 to prevent the thin metal sheet 200 from buckling during testing.
[0042] In an embodiment, the material of construction of anti-buckling device 100 is stronger than the thin metal sheet 200 to be tested. The material of anti-buckling device 100 should be strong enough to overcome the force exerted by the thin metal sheet 200 on the plates 101, 102 of anti-buckling device 100, as shown in Figure 2, during compression load mode or buckling action to prevent buckling of the experimental thin metal sheet 200.
[0043] During testing, it is mandatory to put the marks 105 on the gauge section of the thin metal sheet 200 which is sensed or scanned by the extensometer to get the experimental data.
[0044] The system 300 has a video extensometer (which is not shown in the figures) adapted to sense/detect marks 105 provided on the gauge section of the sandwiched thin metal sheet 200 through the identical obround slot 102a to obtain stress strain data during the tension-compression cyclic test. Further, the video extensometer is coupled with a processing system to evaluate Bauschinger parameter based on the obtained stress-strain data.
Advantages of the Invention over prior art:
[0045] The present structure of Anti-buckling device prevents buckling of thin metal sheet during tension compression experiments and facilitates the marks on the gauge section of the thin metal sheet to get sensed or scanned or detected by the video extensometer.
[0046] It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as “open” terms (e.g., the term “including” should be interpreted as “including but not limited to,” the term “having” should be interpreted as “having at least,” the term “includes” should be interpreted as “includes but is not limited to,” etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases “at least one” and “one or more” to introduce claim recitations. However, the use of such phrases should not be construed to imply that the introduction of a claim recitation by the indefinite articles “a” or “an” limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases “one or more” or “at least one” and indefinite articles such as “a” or “an” (e.g., “a” and/or “an” should typically be interpreted to mean “at least one” or “one or more”); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of “two recitations,” without other modifiers, typically means at least two recitations, or two or more recitations). Furthermore, in those instances where a convention analogous to “at least one of A, B, and C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, and C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances where a convention analogous to “at least one of A, B, or C, etc.” is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., “a system having at least one of A, B, or C” would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms, or both terms. For example, the phrase “A or B” will be understood to include the possibilities of “A” or “B” or “A and B.”
[0047] It will be further appreciated that functions or structures of a plurality of components or steps may be combined into a single component or step, or the functions or structures of one-step or component may be split among plural steps or components. The present invention contemplates all of these combinations. Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention. The present invention also encompasses intermediate and end products resulting from the practice of the methods herein. The use of “comprising” or “including” also contemplates embodiments that “consist essentially of” or “consist of” the recited feature.
[0048] Although embodiments for the present subject matter have been described in language specific to structural features, it is to be understood that the present subject matter is not necessarily limited to the specific features described. Rather, the specific features and methods are disclosed as embodiments for the present subject matter. Numerous modifications and adaptations of the system/component of the present invention will be apparent to those skilled in the art, and thus it is intended by the appended claims to cover all such modifications and adaptations which fall within the scope of the present subject matter.