FIELD OF INVENTION

[001] The invention relates to the fixture and method for carrying out wraparound bend testing of high strength-low ductile materials in a Universal Testing Machine (UTM).
BACKGROUND OF THE INVENTION
[002] Bend testing, a test to ensure the integrity of the welds is a requirement to qualify a weld according to any standards. The bend tests can be face & root or side bend depending on the thickness of the test coupons and usually, it is performed using a guided bend test fixture to bend the specimen to an angle of 180° with the mandrel diameter chosen depending on the ductility of the material. However, not all materials especially, in welded condition will have the required ductility to withstand the guided bend test. One such material is Titanium & its alloys, which are in the weldable range. Apart from this, the dissimilar welding, welds with soft fusion zones, etc. are other materials, which may require wraparound bend test. In these materials, the applicable code, recommends a wraparound bend test with a larger diameter (usually 16t, where ‘t’ is the thickness of the specimen) for ensuring the quality of the weld. The wrap around bend test is carried out by holding one end of the specimen and pull the other end to wrap around the fixture. This kind of test require a full-fledged standalone set up/equipment for performing this test. Testing of high strength materials like Titanium will require huge force to carry out the testing and making such equipment will require special tooling. Hence, having a suitable fixture to carry out the testing in the UTM will be beneficial to test high strength materials for wraparound bend ductility. Accordingly, a suitable fixture has been designed and fabricated for wraparound bend testing of such high strength materials and the details are explained.
[003] The US patent US 1975/3906784 relates to a guided bend testing machine which has geared arrangements on both table and the pinion which bends the specimen by a motorized pivot arm. The pivot arm has a cylindrical die mounted concentrically with the circular edge of the table and a pressure roller spaced therefrom, which is selected depending on the thickness of the strips. The machine is more suitable for testing the metal strips with welds.
[004] The US patent US 1986/4573360 relates to apparatus for bend testing on an elongated material or strip such as band saw blade welded to endless shape.
[005] The US patent US 1987/4656872 relates to an apparatus for testing the ductility of a weld formed by using a cylindrical mandrel and roller mounted for rotation along mutually parallel axis. A shoe having a contact surface is used for maintaining the contact with the specimen for bending and the bending is accomplished by providing a rotating force on the mandrel.
[006] All the prior arts mentioned are discussing apparatus for carrying out guided bend test on strips of metal with or without weld especially, on thin sheet materials. None of the prior arts have discussed about wraparound bend testing of high strength materials.
[007] The present invention relates to the design and fabrication of a fixture suitable for carrying out wraparound bend testing of high strength materials in a UTM. The various features of novelty, which characterize the invention are pointed out in the claims
[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.
OBJECTS OF THE INVENTION
[009] The object of the present invention is to design and develop a fixture for wraparound bend testing.
[0010] Second objective of the present invention is to carry out the wraparound bend testing in UTM.
[0011] Third objective of the present invention is to carry out side bend wraparound bend testing of high strength materials.
[0012] Third object of the present invention is to use the fixture for wraparound bend testing of high strength materials like Titanium, Vanadium, Molybdenum, etc.
[0013] 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
[0014] The problem of ovality in pipes is solved using a special fixture arrangement in combination with a hydraulic jack, which can give a direct action by means of cold working on the pipe’s inner diameter at any required axis. The hydraulic jack is fixed to a height adjustable, movable trolley by means of C- Clamps to a stepped rod mounted on two pillow block bearings at the flat top of the trolley. One end of the rod carries a counter weight block to balance the weight of the hydraulic jack mounted on the other end. The components on the apparatus namely the rod, C-Clamp, pillow block bearing and counter weight block can be changed depending on the size of the pipe and capacity of the hydraulic jack required for ovality correction.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
[0015] 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:
Fig. 1 discloses the wrap around bend testing fixture according
to the present invention.
Fig. 2 discloses the perspective view of the fixture according to the present invention
Fig. 3 discloses bend tested specimens according to the present invention.
[0016] 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.
DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE PRESENT INVENTION WITH REFERENCE TO THE ACCOMPANYING DRAWINGS

[0017] 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.
[0018] 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.
[0019] The present subject matter relates to fixture for carrying out wraparound bend testing of high strength-low ductile materials in a Universal Testing Machine (UTM).
[0020] 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. 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.
[0021] 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. The present invention will now be described more specifically with reference to the following specification.
[0022] 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.
[0023] Wraparound bend testing is a test carried to qualify the welds usually in high strength and low ductile materials like titanium, as per structural welding codes. The diameter to which the bend testing is related to the thickness and it is 16t as per AWS D1.9. Depending of the thickness of the test specimens, the bend testing has to be face bend, root bend or side bend test. The material is of very high strength and hence, the testing equipment should be stronger than the material to apply the required load for carrying out the testing, especially for plates of high thickness.
[0024] Universal Testing Machine (UTM), has the capability to apply high loads and is a common machine in any testing laboratory. Use of UTM for wrap around bend testing shall be simpler and easy to adapt compared to fabricating a dedicated apparatus with the loading mechanism for such high strength materials.
[0025] In this development, a suitable fixture has been designed and fabricated for carrying out the wrap around bend testing of such high strength and low ductility materials. The fixture consists of a base plate with the fixing holes at the corners for positioning it firmly in the table of the UTM. The base plate is made of ultra-high strength steel of 30 mm thickness. Over the base plate, two L shaped plates of 20 mm thickness made of ultra-high strength steel with a separation equal to the width of the specimen to be tested are welded along with a segment of a pipe equivalent to the bending radius (16t, where t is the thickness of the test specimen), which is placed between the L shaped plates. The test specimen shall be placed over the pipe segment and the movement shall be locked by thick bolts and nuts equivalent to the diameter of the holes provided in the horizontal rows of the L shaped plates. The mandrel with a diameter of at least 4t shall be used to plunge from the top gradually to bend the specimen over the pipe segment. Once the specimen is half bent, the same shall be removed and the bent side shall be placed in the fixture and locked using the thick bolts and nuts equivalent to the diameter of the holes provided in the rows in the vertical direction. Subsequently, the second half of the specimen shall be bent following the same procedure as mentioned above.

[0026] Referring to fig. 2, a fixture (10) according to the present invention is disclosed. The fixture consists of a base plate made of ultra-high strength steel of constant thickness of 30 mm (1) with two Ø 16 mm holes on each corners for positioning the fixture in the base frame of UTM, a pipe (3) of diameter which is equal to 16t where ‘t’ is the thickness of the test specimen and this pipe (3) is welded to two L shaped plates (2) made of ultra-high strength steel of 20 mm thickness with a separation equal to the thickness of the specimen to be tested. The holes (4) are provided in two rows in the horizontal axis for holding the specimen during the start of the test and holes (5) are provided in vertical axis (one column) for holding the specimen after half bend.
[0027] The process for wrap around bend testing according to the present invention is disclosed below:
[0028] The test specimen (6) is placed over the pipe (3) and movement is locked by bolts and nuts (4) provided in the horizontal axis. The mandrel with a diameter of at least 4t where ‘t’ is the thickness of the specimen (6) to be tested is plunged from the top of the UTM machine (7) gradually to bend the specimen (6) over the pipe (3) segment. Once the specimen (3) is half bent, the same is removed and the bent side is placed in the pipe (3) and locked using the bolts and nuts (5) provided in the vertical axis. Now using the mandrel of the same diameter provided in the UTM machine (7) is plunged as mentioned above. The wrap around bend tested specimen (7) are show in in Figure 3.
[0029] The wraparound bend tested specimens in the developed fixture is shown in Fig.3.
[0030] Although embodiments for the present subject matter have been described in language specific to package 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/device 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.
[0031] 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.”
[0032] 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.
[0033] 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.

WE CLAIM:

1. A fixture (10) for wrap around bend testing of high strength materials, the fixture comprising:
a base plate (B) with two Ø 16 mm holes on each corners for positioning the fixture (10) in the base frame of Universal Testing Machine (7);
a pipe (3) welded onto two L shaped plates (2);
holes (4) are provided in two rows in the horizontal axis for holding a specimen (6) during the start of the test; and
holes (5) are provided in vertical axis (one column) for holding the specimen (6) after half bend.
2. The fixture (10) as claimed in claim 1, wherein the base plate (B) is made of ultra-high strength steel of constant thickness of 30 mm.
3. The fixture (10) as claimed in claim 1, wherein the diameter of the pipe (3) equal to 16t where ‘t’ is the thickness of the test specimen (6).
4. The fixture (10) as claimed in claim 1, wherein the L shaped plates (2) are made of ultra-high strength steel of 20 mm thickness with a gap equal to the thickness of the specimen (6) to be tested.
5. The process for wrap around bend testing of high strength materials comprising steps of:
Placing the test specimen (6) over the pipe (3);
Locking the movement of the test specimen (6) by bolts and nuts (4) provided in the horizontal axis;
a mandrel to be gradually lowered down from the top of the UTM machine (7) to bend the specimen (6) over the pipe (3);
removing the specimen (6) after it is bent in half;
placing the bent side in the pipe (3) and locked using the bolts and nuts (5) provided in the vertical axis; and
using the mandrel of the same diameter provided in the UTM machine (7) is plunged as mentioned above.
6. The process as claimed in claim 5, wherein the diameter of the mandrel is 4t where ‘t’ is the thickness of the specimen (6).