KR101811619B1 - Jig for Thin Sheet Specimen Fatigue Test having Anti-Buckling Function - Google Patents

Abstract

The present invention discloses a jig to test fatigue of a thin-film specimen wherein the jig includes a first jig unit and a second jig unit to support one side surface and the other side surface of the thin-film specimen respectively, wherein the first jig unit forms an unconstrained area on an upper region than a center line based on a longitudinal direction of the thin-film specimen on one side of the thin-film specimen, wherein the second jig unit forms an unconstrained area on a lower region than the center line on the other side of the thin-film specimen.

Description

{Jig for Thin Sheet Specimen Fatigue Test Having Anti-Buckling Function}

The present invention relates to a jig for fatigue test of a thin plate specimen having a buckling prevention function.

Structures made of steel materials such as ships, offshore, and bridges can not avoid the occurrence and growth of cracks. Damage and destruction of structures caused by this cause damage to people and property. Fatigue is a phenomenon in which a metallic material receives a repeated load even if it has sufficient strength at a static load. The fatigue test measures the number of repetitions until the metal material is destroyed by applying repeated loads of various shapes and sizes to the material. The relationship between the stress (S) and the number of repetitions (N) is shown in the logarithmic scale as an S-N curve. The obtained S-N curve predicts the degree of fatigue of the structure designed using the material.

Standards for fatigue testing of metallic materials are provided by organizations such as ISO, ASTM, etc. and are designed to prevent buckling of thin specimens to perform fatigue tests on thin specimens. Buckling is a phenomenon in which when the length of the thin plate specimen is larger than the thickness of the cross section, it suddenly collapses below the yield strength due to the compressive load applied in the longitudinal direction at both ends. Since the area of the transverse section perpendicular to the longitudinal direction to which the repeated load is applied is relatively small, it is not easy to prevent buckling in a state in which repeated loads are applied in the fatigue test process.

An object of the present invention is to provide a jig for fatigue test of a thin plate specimen which can prevent buckling of a thin plate specimen which may occur in a fatigue test of a thin plate specimen.

The jig for thin plate specimen fatigue testing according to the present invention comprises a first jig unit and a second jig unit for respectively supporting one side surface and the other side surface of the thin plate specimen and the first jig unit is provided on one side of the thin plate specimen, And the second jig unit forms an unconstrained region in a lower region than the center line on the other side of the thin plate specimen.

The first jig unit and the second jig unit are formed to be point-symmetric with respect to a center point of the thin plate specimen. The first fixing unit fixes a lower region of one side of the thin plate specimen A first grip portion for supporting and fixing an upper region of one side surface of the thin plate specimen, and a second grip portion located at a lower portion of the first grip portion and having a lower end fixed to the upper end of the first fixing portion, And a first guide part spaced apart from the center of the thin plate specimen and forming the unconstrained area in an upper area than the center line of the thin plate specimen, the second fixing part fixing the upper area of the other side of the thin plate specimen, A second grip portion for supporting and fixing the lower region of the other side surface of the thin plate specimen, and a second grip portion located at the lower portion of the second grip portion, 2 and is spaced apart from the bottom of the state can be formed, including a second guide portion that forms the non-binding region to a lower region than the center line of the sheet specimen.

The first fixing part is formed to have a saw-like shape at an upper end thereof, and the lower end of the first guide part is formed in a sawtooth shape in which it is staggered with the tooth shape of the upper end of the first fixing part, The second fixing portion is formed to have a serrated shape at the lower end thereof, and the upper portion of the second guide portion is formed in an upper portion of the center line in a zigzag shape or irregular shape in a nonlinear shape along the width direction, The non-restrained region is formed in a zigzag or irregular shape having a non-linear shape along the width direction in the lower region of the center line from the other side of the thin plate specimen .

The first fixing portion may include a first fixing body formed in a block shape, a first fixing groove formed on an inner surface of the first fixing body to insert a lower portion of the thin plate specimen, A first slip groove formed in the first slip groove, and a first fixed slip inserted in the first slip groove, the inner side of which is flush with the inner side face of the first fixing groove and the coefficient of friction is lower than that of the first fixing body, Wherein the first grip portion includes a first grip portion formed in a block shape and a second grip portion formed on the first grip portion in such a manner that the inner surface of the first grip portion is flush with the inner surface of the first fixing body when the thin plate specimen is supported, And a first grip portion protruding from an inner surface of the grip body, wherein the first guide portion is located at a lower portion of the first grip body, A first guide body coupled to the first guide body and an inner surface of the first guide body and having an inner surface coplanar with an inner surface of the first grip protrusion, A first fixing groove formed on an inner surface of the second fixing body and having an upper portion inserted therein and a second fixing groove formed on an inner surface of the second fixing body, A second slip groove formed in a lower portion of the groove and a second slip groove formed in the second slip groove so that an inner side surface of the second slip groove is flush with an inner side surface of the second fixing groove and a coefficient of friction is lower than that of the second fixing body Wherein the second grip portion includes a second grip portion formed in a block shape and an inner side surface of the second grip portion when the thin plate specimen is supported with the second fixing portion, And a second grip projection protruding from an inner surface of the second grip body so as to be flush with the inner surface of the second grip body, wherein the second guide portion is located at an upper portion of the second grip body, A second guide body spaced apart from the second guide body, and a second guide body coupled to an inner surface of the second guide body and having an inner surface coplanar with an inner surface of the second grip protrusion, 2 guide slip pads.

The first fixed body and the first fixed slip pad are formed to have a saw-like shape at the upper end, and the lower ends of the first guide body and the first guide slip pad are connected to the first fixed body and the first fixed slip pad, The second fixed body and the second fixed slip pad are formed so that the lower end thereof has a serrated shape and the second fixed body and the second fixed slip pad are formed such that the lower ends of the second fixed body and the second fixed slip pads form a saw- The pad may be formed in a sawtooth shape in which the upper end is staggered with the lower end of the second fixed body and the second fixed slip pad.

The inner surface of the first fixing groove, the inner surface of the first grip projection, the inner surface of the second fixing groove, and the inner surface of the second grip projection may be formed by knurling.

The jig for fatigue test of the thin plate specimen of the present invention has the effect of minimizing the non-restraint area which is not in contact with the thin plate specimen, thereby reducing the buckling mainly occurring in the non-restraint area.

The fatigue test jig for a thin plate specimen according to the present invention is characterized in that a non-constrained region is formed in a nonlinear shape along a width direction in a lower region on one side and an upper region on the other side with reference to a central region of the thin plate specimen, It has the effect of reducing the buckling while freely implementing tension and compression of the thin plate specimen.

Further, the jig for fatigue test of thin plate specimen of the present invention has the effect of matching the longitudinal center axis of the thin plate specimen with the load acting axis of the fatigue tester regardless of the thickness change of the thin plate specimen, by supporting both sides of the thin plate specimen in point symmetry.

In addition, the jig for testing a thin plate specimen of the present invention has a fixing groove for receiving the thin plate specimen and a protrusion for pressing the thin plate specimen while being coupled to the fixing groove, thereby facilitating alignment and fixation of the specimen during mounting.

Further, the jig for fatigue test of the thin plate specimen of the present invention has an effect of fixing the thin plate specimen at a proper pressure by adjusting the bolt tightening force by contacting the guide portion with the thin plate specimen and fixing it with bolts.

The jig for fatigue test of a thin plate specimen according to the present invention is provided with a slip pad having a low coefficient of friction in a region guiding in contact with the thin plate specimen so as to minimize the influence of frictional force upon contact and smoothly apply a repeated load in the longitudinal direction of the thin specimen .

1 is a side view of a fatigue testing machine equipped with a jig for fatigue test of a thin plate specimen according to an embodiment of the present invention.
2 is a perspective view of a jig for fatigue test of thin specimen according to an embodiment of the present invention.
Fig. 3 is a perspective view of the first and second jig units of Fig. 2;
Fig. 4 is a partially exploded perspective view of the jig for fatigue test of the thin plate specimen of Fig. 2;
5 is an exploded perspective view of the jig for fatigue test of the thin plate specimen of FIG.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a jig for testing a thin specimen fatigue of the present invention will be described in detail with reference to the accompanying drawings and embodiments.

The embodiments of the present invention are described in order to more fully explain the present invention to those skilled in the art, and the following embodiments may be modified into various other forms, It is not limited to the embodiment. Rather, these embodiments are provided so that this disclosure will be more faithful and complete, and will fully convey the scope of the invention to those skilled in the art.

In the following drawings, thickness and size of each layer are exaggerated for convenience and clarity of description, and the same reference numerals denote the same elements in the drawings. As used herein, the term "and / or" includes any and all combinations of one or more of the listed items. The term "coupled or connected" in this specification means not only the case where the first member and the second member are directly coupled or connected but also the case where the third member is interposed between the first member and the second member, But also the case where the member and the second member are indirectly coupled or connected.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a," "an," and "the" include singular forms unless the context clearly dictates otherwise. Also, " comprise, include, " and / or "comprising, " when used in this specification are intended to include the structures, shapes, numbers, To specify the presence of these groups and not to preclude the presence or addition of one or more other structures, shapes, numbers, operations, elements, elements and / or groups.

Although the terms first, second, etc. are used herein to describe various elements, components, regions, layers and / or portions, these members, components, regions, layers and / It is obvious that no. These terms are only used to distinguish one member, component, region, layer or section from another region, layer or section. Thus, a first member, component, region, layer or section described below may refer to a second member, component, region, layer or section without departing from the teachings of the present invention.

It should also be understood that the terms related to space such as horizontal, vertical, vertical, horizontal, top, bottom, top, bottom, front, back, left, right, Can be used. Terms related to such a space are for easy understanding of the present invention according to various installation states, placement states, mounting states, use states or process states of the present invention, and are not intended to limit the present invention. For example, when the elements or features of the drawings are rotated or the direction of viewing is changed, the configurations or features of the horizontal, vertical, vertical, horizontal, top, bottom, Therefore, the present invention should not be interpreted as being limited to terms related to such space.

First, the structure of a jig for fatigue test of a thin plate specimen of the present invention will be described.

1 is a side view of a fatigue testing machine equipped with a jig for fatigue test of a thin plate specimen according to an embodiment of the present invention. 2 is a perspective view of a jig for fatigue test of thin specimen according to an embodiment of the present invention. Fig. 3 is a perspective view of the first and second jig units of Fig. 2; Fig. 4 is a partially exploded perspective view of the jig for fatigue test of the thin plate specimen of Fig. 2; 5 is an exploded perspective view of the jig for fatigue test of the thin plate specimen of FIG.

1 to 5, the jig 100 for thin plate specimen fatigue testing according to the present invention is formed with a first jig unit 100a and a second jig unit 100b.

In the following description, the inner side or inner side surface refers to mutually facing directions or surfaces of the first jig unit 100a and the second jig unit 100b in Fig. 1, and the outer side or outer side surface is the opposite direction or the opposite side it means. The front side and the rear side mean the + y direction and the -y direction, respectively. The upper side and the lower side mean the + z direction and the -z direction, respectively, and the upper side and the lower side mean the + Means the + z and -z directions. The longitudinal direction of the thin plate specimen (a) refers to the up-and-down direction based on the state where the thin plate specimen (a) is bonded to the jig for testing the thin plate specimen fatigue. The width direction is parallel to one side or the other side It means one direction.

1, the first jig unit 100a located on one side of the thin plate specimen (a) and the second jig unit 100b located on the other side of the thin plate specimen (a) Supports one side and the other side of the specimen (a), fixing the upper side and the lower side. The first jig unit 100a and the second jig unit 100b are formed in the same shape and are point-symmetrically joined with respect to the center of the thin plate specimen a. The first jig unit 100a and the second jig unit 100b are fastened and coupled by appropriate fastening bolts 200 with appropriate pressure.

The thin plate specimen (a) is always mounted on the thin plate specimen fatigue testing jig (100) so that it always coincides with the load acting axis center of the fatigue tester regardless of the specimen thickness. The thin plate specimen (a) is formed of a thin plate having a predetermined length and width, and is formed into a shape having a length greater than the width and extending in the longitudinal direction. The thin plate specimen (a) generally has a thickness of 0.5 mm or less and has a relatively high thickness at which the buckling is likely to occur during the fatigue test. The thin plate specimen (a) is defined as a virtual center line located in the middle in the width direction at the center in the longitudinal direction, and the upper portion is defined as the upper region and the lower portion is defined as the lower region.

The first jig unit 100a and the second jig unit 100b support the thin plate specimen a as a whole and form an unconstrained area in a partial area. The non-restrained area means an area exposed to the outside without contact or support by the first jig unit 100a or the second jig unit 100b. The unconstrained area is a necessary area for the thin plate specimen (a) to be compressed or tensioned when a repeated load is applied to the thin plate specimen (a). The unconstrained area is formed on one side surface and the other side surface of the thin plate specimen (a), respectively. The first jig unit 100a forms an unconstrained area in a region above the center line with respect to the longitudinal direction of the thin plate specimen a on one side of the thin plate specimen a, In the other side of the specimen (a), an unconstrained region is formed in the lower region than the center line. Therefore, since the jig 100 for testing a thin specimen fatigue supports one side or the other side at all positions with respect to the longitudinal direction of the thin specimen a, one side and the other side of the thin specimen a are not constrained simultaneously It is possible to reduce the possibility of local buckling which may occur in an unfavorable region.

The first jig unit 100a and the second jig unit 100b are provided with non-slip means such as knurling at a portion where the thin plate specimen a is fixed, and the remaining portion, which contacts and supports the thin plate specimen a, Is formed of a material having a low coefficient of friction so as to reduce frictional force with the thin plate specimen (a).

The upper side and the lower side of the jig 100 for testing the thin specimen fatigue are respectively coupled and fixed to the grips 11a and 11b of the fatigue tester 10 together with the grip wedges 13a and 13b. The jig 100 for testing a thin specimen fatigue applies a compressive force and a tensile force to the thin plate specimen a according to the vertical movement of the upper grip 11a and the lower grip 11b. The thin plate specimen a is not coupled to the grip wedges 13a and 13b of the direct fatigue tester 10 but is coupled to the grip wedges 13a and 13b in a state of being mounted on the thin plate specimen fatigue testing jig 100, The occurrence of buckling is reduced with repeated loads.

The first jig unit 100a includes a first fixing part 110a, a first grip part 120a, and a first guide part 130a. The first jig unit 100a contacts and supports one side of the thin plate specimen (a), and fixes the upper region and the lower region of the thin plate specimen (a), respectively.

The first fixing part 110a includes a first fixing body 111a and a first fixing groove 112a and a first slip groove 113a and a first fixing slip pad 114a. In addition, the first fixing portion 110a may further include a first stepped groove 115a. The first fixing part 110a is located at a relatively lower position in the first jig unit 100a and fixes the lower area of one side of the thin plate specimen a and supports a part of the upper area. The first fixing part 110a is formed to have a saw-like shape at the upper end. The first fixing part 110a may be formed in such a shape that the upper end is regularly or irregularly repeated triangular protrusions. Here, the triangular protrusion has a shape when viewed from the inner side or outer side of the first fixing portion 110a.

The first fixing body 111a extends in the vertical direction and is formed into a block shape having a predetermined length and a predetermined width. The first fixing body 111a is formed to have a width larger than the width of the thin plate specimen a. The first fixing body 111a is formed to have a length longer than half the length of the thin plate specimen (a). That is, the upper end of the first fixing body 111a is located in the upper region with respect to the longitudinal direction than the center line of the thin plate specimen (a).

The first fixing body 111a is formed to have a saw-like shape at its upper end. That is, the first fixing body 111a may be formed such that the upper end of the first fixing body 111a is regularly or irregularly repeated. The first fixing body 111a forms an unconstrained area in a region above the center line at one side of the thin plate specimen (a). The unconstrained area is formed in a zigzag shape or an irregular shape that is nonlinear along the width direction at one side of the thin plate specimen (a).

The first fixing groove 112a is formed in a groove shape having a predetermined width and depth on the inner surface of the first fixing body 111a and extends upward and downward and is opened upward. The first fixing groove 112a may be opened downward. The first fixing groove 112a is formed to have a predetermined fixed length required to fix the thin plate specimen a. For example, the first fixing groove 112a may have a length corresponding to half the length of the first fixing body 111a. The first fixing groove 112a is formed to have a width corresponding to the width of the thin plate specimen a. The thin plate specimen (a) is inserted and fixed so that one side is in contact with the inner side. The inner surface of the first fixing groove 112a is knurled so that the thin plate specimen a can be fixed more securely.

The first slip groove 113a is formed as a groove having a predetermined depth on the upper side of the first fixing groove 112a on the inner surface of the first fixing body 111a and is formed to open upward. The first slip groove 113a is formed to have the same width as the first fixing groove 112a. The first slip groove 113a is formed at a depth deeper than the first fixing groove 112a from the inner side of the first fixing body 111a. That is, the first slip groove 113a is formed so as to be stepped outwardly from the inner side surface of the first fixing groove 112a at a predetermined step height.

The first fixed slip pad 114a is formed in a plate shape and has a plate shape corresponding to the first slip groove 113a. The first fixed slip pad 114a has a thickness corresponding to a depth difference between the first slip groove 113a and the first fixing groove 112a. That is, the first fixed slip pad 114a has a thickness corresponding to the step height of the first slip groove 113a. The first fixed slip pad 114a is inserted and fixed in the first slip groove 113a and the inner side surface of the first fixed slip pad 114a is flush with the inner side surface of the first fixing groove 112a. The first fixed slip pad 114a may be bonded to the first slip groove 113a by a separate adhesive.

The first fixed slip pad 114a is formed to have a saw-like shape with an upper end having the same shape as the first fixed body 111a. The first fixed slip pad 114a forms an unconstrained area in a region above the center line at one side of the thin plate specimen a like the first fixing body 111a.

The first fixed slip pad 114a is formed of a resin material having a lower friction coefficient than the first fixed body 111a. The first fixed slip pad 114a may be formed of a resin material such as polytetrafluoroethylene (PTFE). The inner surface of the first fixed slip pad 114a is formed in a flat surface and is not knurled unlike the inner surface of the first fixing groove 112a. The first fixed slip pad 114a supports the inner surface of the first fixed slip pad 114 in contact with one side of the thin plate specimen a while minimizing frictional force with one side of the thin plate specimen a which is tensionally compressed in the up and down direction. The first fixed slip pad 114a allows the repeated load applied by the fatigue tester 10 to be fully transferred to the thin plate specimen a without loss due to frictional force.

The first stepped groove 115a is formed to be stepped to a predetermined depth from the front side and the rear side of the first fixing body 111a. The first stepped groove 115a is formed to open to the inside, the outside, and the upper side of the first fixing body 111a. The first stepped groove 115a exposes a part of the front and rear sides of the central region of the thin plate specimen (a) to be fixed to the outside. The lower side of the first slip groove 113a may be opened and the shape of the first fixed slip pad 114a may be changed as well.

The first grip portion 120a is formed with a first grip body 121a and a first grip projection 122a. The first grip portion 120a is located at an upper portion of the first jig unit 100a and supports and fixes the upper region on one side of the thin plate specimen a. The first grip body 121a and the first grip protrusion 122a may be integrally formed by machining one block.

The first grip body 121a extends in the vertical direction and is formed into a block shape having a predetermined length and a predetermined width. The first grip body 121a is formed to have a width larger than the width of the thin plate specimen (a). The first grip body 121a has a width corresponding to the width of the first fixed body 111a. The first grip body 121a is formed to have a length corresponding to the length of the first fixing groove 112a of the first fixing body 111a.

The first grip projection 122a protrudes from the inner surface of the first grip body 121a with a predetermined width and height and extends in the vertical direction. The first grip projection 122a protrudes to a predetermined height so that the inner surface of the first grip protrusion 122a is flush with the inner surface of the first fixing body 111a when the thin plate specimen a is supported with the first fixing portion 110a . The first grip protrusion 122a may have a width and a length corresponding to the first fixing groove 112a. That is, the first grip projection 122a is formed to have a width corresponding to the width of the thin plate specimen a. The first grip projection 122a is formed to have a fixed length necessary to fix the upper side of the thin plate specimen a.

The first grip projection 122a is in contact with one side of the thin plate specimen (a) and supports and fixes the thin plate specimen (a). The first grip projection 122a is knurled on the inner side so that the thin plate specimen a can be fixed more securely.

The first guide part 130a includes a first guide body 131a and a first guide slip pad 132a. The first guide portion 130a is positioned between the first fixing portion 110a and the first grip portion 120a and supports the upper region of one side of the thin plate specimen a. The first guide part 130a is positioned below the first grip part 120a and the lower end of the first guide part 130a is spaced apart from the upper end of the first fixing part 110a so that the first fixing part 110a to form an unconstrained area. Meanwhile, the first guide part 130a may be formed such that its upper end is in contact with the lower end of the first grip part 120a. The first guide part 130a has a sawtooth shape in which the lower end of the first guide part 130a is inserted into the sawtooth shape of the upper end of the first fixing part 110a. The unconstrained area is formed in a zigzag or irregular shape in a nonlinear shape along the width direction on the upper region of the center line on one side of the thin plate specimen (a). The first guide part 130a forms a non-constrained area together with the first fixing part 110a in a shape other than a straight line to reduce the possibility of buckling in the fatigue test process.

The first guide portion 130a is fastened to the second fixing portion 110b by a fastening bolt 200.

The first guide body 131a is formed in a block shape having a predetermined length and a predetermined width. (The first guide body 131a) is formed to have a width larger than the width of the thin plate specimen (a). The first guide body 131a may have the same width as the first grip body 121a. The first guide body 131a may have a length corresponding to the length between the first fixing groove 112a and the first stepped groove 115a in the first fixing body 111a. The first guide body 131a is located below the first grip body 121a and the lower end surface of the first guide body 131a is spaced apart from the upper surface of the first fixing body 111a. The upper surface of the first guide body 131a may be in contact with the lower portion of the first grip body 121a.

The first guide body 131a) is formed so that the lower end thereof has a serrated shape. That is, the lower end of the first guide body 131a may be formed in a shape in which triangular protrusions are regularly or irregularly repeated in the width direction. The lower end of the first guide body 131a is formed in a sawtooth shape in which teeth are formed at the upper end of the first fixing body 111a and is spaced apart from the upper end of the first fixing body 111a, Thereby forming an unconstrained area.

The first guide main body 131a is fastened to the second fixing body 111b by a fastening bolt 200 and the first guide slip pad 132a is fastened to the thin plate 120 by the tightening force of the fastening bolt 200. [ Allow the pressure in contact with the specimen (a) to be adjusted.

The first guide slip pad 132a is formed in a plate shape and has a shape corresponding to the width of the first fixed slip pad 132a and the length of the first guide body 131a. The first guide slip pad 132a has a thickness such that an inner surface of the first guide slip pad 132a is flush with an inner surface of the first grip projection 122a. When the first guide slip pad 132a is engaged with the first guide main body 131a, the inner surface of the first guide slip pad 132a is flush with the inner surface of the first grip protrusion 122a coupled to the first grip main body 121a Respectively. The first guide slip pad 132a may be bonded to the inner surface of the first guide body 131a by a separate adhesive.

The first guide slip pad 132a is formed to have a serrated shape in the same shape as that of the first guide main body 131a. That is, the lower ends of the first guide slip pads 132a are serrated formed at the upper end of the first fixed slip pad 114a and are serrated to be staggered with each other, So as to form an unconstrained area.

The first guide slip pad 132a is formed of a resin material having a lower friction coefficient than the first guide body 131a. The first guide slip pad 132a is formed of a resin material having a low friction coefficient such as PTFE (polytetrafluoroethylene) in the same manner as the first fixed slip pad 114a. The inner surface of the first fixed slip pad 114a is formed in a plane to lower the friction coefficient and is not knurled unlike the inner surface of the first fixing groove 112a. The first guide slip pad 132a supports the inner surface of the first guide slip pad 132 in contact with one side surface of the thin plate specimen a while minimizing frictional force with one side surface of the thin plate specimen a which is tensionally compressed in the up and down direction. The first guide slip pad 132a allows the repeated load applied by the fatigue tester 10 to be transferred to the thin plate specimen a without loss by frictional force.

The second jig unit 100b includes a second fixing portion 110b, a second grip portion 120b, and a second guide portion 130a. The second jig unit 100b supports the other side of the thin plate specimen a and fixes the upper side and the lower side of the thin plate specimen a together with the first jig unit 100a. The second jig unit 100b is formed in the same manner as the first jig unit 100a and is formed to be point-symmetric with respect to the center point of the thin plate specimen a.

The second fixing portion 110b includes a second fixing body 111b, a second fixing groove 112b, a second slip groove 113b, and a second fixing slip pad 114b. In addition, the second fixing portion 110b may further include a second stepped groove 115b. The second fixing portion 110b is located at a relatively upper portion in the second jig unit 100b. The second fixing part 110b fixes the upper area of the other side of the thin plate specimen a and supports a part of the lower area. The second fixing portion 110b is formed such that the lower end thereof has a serrated shape. The second fixing part 110b may be formed in such a shape that the lower end of the second fixing part 110b is regularly or irregularly repeated.

The second fixing body 111b is formed in the same shape as the first fixing body 111a. The lower end of the second fixing body 111b is located below the center line of the thin plate specimen a.

The second fixing body 111b is formed so that the lower end thereof has a serrated shape. That is, the second fixing body 111b may be formed such that the lower end of the second fixing body 111b is regularly or irregularly repeated. The second fixing body 111b forms an unconstrained area below the center line at the other side of the thin plate specimen (a). The non-restrained region is formed in a zigzag shape or a non-regular shape in a nonlinear shape along the width direction at the other side of the thin plate specimen (a).

The second fixing groove 112b is formed on the inner surface of the second fixing body 111b. The second fixing groove 112b is formed in the same shape as the first fixing groove 112a. The second fixing groove 112b is formed to open upward. The second fixing groove 112b may be formed to open downward. The thin plate specimen (a) is inserted and fixed so that its other side is in contact with the inner side surface of the second fixing groove 112b. The second fixing groove 112b is formed by knurling the inner surface so that the thin plate specimen a can be fixed more securely.

The second slip groove 113b is formed on the inner surface of the second fixing body 111b as a groove having a predetermined depth below the second fixing groove 112b. The second slip groove 113b is formed in the same shape as the first slip groove 113a. The second slip groove 113b is formed downward from the second fixing groove 112b and is formed to open downward. The second slip groove 113b is formed at a depth deeper than the second fixing groove 112b from the inner surface of the second fixing body 111b. That is, the second slip groove 113b is formed to step outward from the inner side surface of the second fixing groove 112b at a predetermined height.

The second fixed slip pad 114b is formed in a plate shape and has a plate shape corresponding to the second slip groove 113b. The second fixed slip pad 114b has a thickness corresponding to a depth difference between the second slip groove 113b and the second fixing groove 112b. That is, the second fixed slip pad 114b has a thickness corresponding to the step height of the second slip groove 113b. The second fixed slip pad 114b may have the same shape as the first fixed slip pad 114a. The second fixed slip pad 114b is inserted and fixed in the second slip groove 113b and the inner side surface of the second fixed slip pad 114b is flush with the inner side surface of the second fixing groove 112b. The second fixed slip pad 114b may be adhered to the second slip groove 113b by a separate adhesive.

The lower end of the second fixed slip pad 114b is formed to have a serrated shape in the same shape as the second fixed body 111b. The second fixed slip pad 114b forms an unconstrained area in the upper region of the other side of the thin plate specimen a than the center line as the second fixed body 111b.

The second fixed slip pad 114b is formed of the same material as the first fixed slip pad 114a. That is, the second fixed slip pad 114b is formed of a resin material having a lower friction coefficient than the second fixed body 111b. The second fixed slip pad 114b may be formed of a resin material such as polytetrafluoroethylene (PTFE). The inner surface of the second fixed slip pad 114b is formed in a plane to lower the coefficient of friction and is not knurled unlike the inner surface of the second fixing groove 112b. The second fixed slip pad 114b is supported while being in contact with the other side of the thin plate specimen a so that the frictional force between the second fixed slip pad 114b and the other side of the thin plate specimen a which is tensionally compressed in the up and down direction is minimized. The second fixed slip pad 114b allows the repeated load applied by the fatigue tester 10 to be transferred to the thin plate specimen a without loss by frictional force.

The second stepped groove 115b is formed to be stepped to a predetermined depth from the front side and the rear side of the second fixing body 111b. The second stepped groove 115b is formed in the same manner as the first stepped groove 115a. The second stepped groove 115b allows a part of the front and rear sides of the unrestricted area of the thin plate specimen (a) to be fixed to be exposed to the outside. The lower side of the second slip groove 113b may be opened and the shape of the second fixed slip pad 114b may be changed as well.

The second grip portion 120b is formed with a second grip body 121b and a second grip projection 122b. The second grip portion 120b is located at a lower portion of the second jig unit 100b and supports and fixes the lower region at the other side of the thin plate specimen a. The second grip portion 120b may be formed in the same manner as the first grip portion 120a.

The second grip body 121b is formed in a block shape extending in the vertical direction and having a predetermined length and a predetermined width. The second grip body 121b is formed in the same shape as the first grip body 121a. The second grip body 121b is formed to have a length corresponding to the length of the second fixing groove 112b of the second fixing body 111b.

The second grip protrusion 122b protrudes from the inner surface of the second grip body 121b with a predetermined width and height, and is formed to extend in the vertical direction. The second grip projection 122b protrudes to a predetermined height so that the inner surface of the second grip protrusion 122b is flush with the inner surface of the second fixing body 111b when the thin plate specimen a is supported with the second fixing portion 110b . The second grip projection 122b may have the same shape as the first grip projection 122a. The second grip projection 122b is formed with a fixed length necessary to fix the underside of the thin plate specimen a. The inner surface of the second grip projection 122b is in contact with the other side surface of the thin plate specimen (a), and the lower surface of the thin plate specimen (a) is contacted and fixed. The second grip projection 122b is knurled on the inner surface so that the thin plate specimen a can be fixed more securely.

The second guide portion 130b includes a second guide body 131b and a second guide slip pad 132b. The second guide portion 130a is positioned between the second fixing portion 110b and the second grip portion 120b to support and support the lower area of the other side of the thin plate specimen a. The second guide part 130b is located on the upper part of the second grip part 120b and the upper part is spaced apart from the lower end of the second fixing part 110b so that the second fixing part 110b to form an unconstrained area. At this time, the second guide part 130a may be formed such that the lower end of the second guide part 130a contacts the upper end of the second grip part 120b. The non-constrained region is formed in a non-linear shape in a zigzag shape along the width direction in the lower region of the center line from the other side of the thin plate specimen (a). The unconstrained area formed in the lower area of the other side of the thin plate specimen (a) is a point-symmetric area defined by the unconstrained area formed on the upper area of one side of the thin plate specimen (a) . Therefore, the thin plate specimen (a) is less likely to buckle during the fatigue test.

The second guide portion 130a is fastened to the first fixing portion 110a by a fastening bolt 200.

The second guide body 131b is formed in a block shape having a predetermined length and a predetermined width. The second guide body 131b is formed in the same shape as the first guide body 131a. The lower end surface of the second guide main body 131b is in contact with the upper end of the second grip main body 121b and the upper end surface of the second guide main body 131b is spaced apart from the lower end surface of the second fixed main body 111b.

The second guide body 131b is formed so that the upper end thereof has a sawtooth shape. That is, the upper end of the second guide body 131b may be formed in a shape in which triangular protrusions are regularly or irregularly repeated in the width direction. The upper end of the second guide main body 131b forms a non-restrained area while being offset from the saw-tooth formed at the lower end of the second fixed body 111b.

The second guide body 131b is fastened to the first fixing body 111a by the fastening bolts 200 and the second guide slip pad 132b is fastened to the thin plate specimen so that the pressure in contact with a) is regulated.

The second guide slip pad 132b is formed in a plate shape and has a width corresponding to the second slip pad and a length corresponding to the length of the second guide main body 131b. The second guide slip pad 132b is formed to have a thickness such that an inner surface of the second guide slip pad 132b is coplanar with an inner surface of the second grip projection 122b. That is, when the second guide slip pad 132b is coupled to the second guide main body 131b, the inner surface is flush with the inner surface of the second grip protrusion 122b coupled to the second grip body 121b Respectively. The second guide slip pad 132b may be adhered to the inner surface of the second guide body 131b by a separate adhesive.

The second guide slip pad 132b is formed so that its upper end has a saw-like shape in the same shape as the second guide main body 131b. The upper end of the second guide slip pad 132b is formed in a serrated shape formed at the lower end of the second fixed slip pad 114b and inserted into the second fixed slip pad 114b and is spaced apart from the lower end of the second fixed body 111b Thereby forming an unconstrained area.

The second guide slip pad 132b is formed of a resin material having a low friction coefficient such as PTFE (polytetrafluoroethylene) in the same manner as the second fixed slip pad 114b. The inner surface of the second fixed slip pad 114b is formed in a plane to lower the coefficient of friction and is not knurled unlike the inner surface of the second fixing groove 112b. The second guide slip pad 132b supports the inner surface of the second guide slip pad 132 in contact with the other side surface of the thin plate specimen a while minimizing the frictional force with the other side of the thin plate specimen a that is tensionally compressed in the up and down direction. The second guide slip pad 132b allows the repeated load applied by the fatigue testing machine 10 to be fully transferred to the thin plate specimen a without loss due to frictional force.

Next, the operation of the jig for fatigue test of the thin plate specimen of the present invention will be described.

The thin plate specimen (a) is joined such that the lower region of one side is seated in the first fixing groove 112a of the first fixing portion 110a. At this time, the first fixed slip pad 114a is mounted and fixed to the first slip groove 113a of the first fixing body 111a. The first fixed slip pad 114a is in contact with one side of the thin plate specimen (a) to an area above the center line and supports the thin plate specimen (a). The second fixing portion 110b is coupled to the thin plate specimen a such that the upper side of the other side of the thin plate specimen a is seated in the second fixing groove 112b. At this time, the second fixed slip pad 114b is fixed to the second slip groove 113b of the second fixed body 111b. The second fixed slip pad 114b is contacted from the other side of the thin plate specimen (a) to the lower region than the center line, and supports the thin plate specimen (a).

The second grip body 121b is engaged with the second grip protrusion 122b to be inserted into the first fixing groove 112a. At this time, the inner surface of the second grip projection 122b is in contact with the lower area of the other side of the thin plate specimen (a). In addition, the first grip body 121a is engaged with the first grip protrusion 122a to be inserted into the second fixing groove 112b. The inner surface of the first grip projection 122a is in contact with the upper area of one side of the thin plate specimen (a). The thin plate specimen a is configured such that the lower region of the thin plate specimen a is inserted into the first fixing groove 112a of the first fixing portion 110a and the second grip projection portion 122b of the second grip portion 120b is inserted into the first fixing groove 112a of the first fixing portion 110a, And the upper region is inserted into the second fixing groove 112b of the second fixing portion 110b and fixed while inserting the first grip projection 122a of the first grip portion 120a. Therefore, the jig 100 for testing a thin specimen fatigue can easily align and fix the thin specimen (a).

 The first fixing part 110a and the second grip part 120b are fastened by separate fastening bolts 200 to fix the lower area of the thin plate specimen a. The second fixing part 110b and the first grip part 120a are fastened by separate fixing bolts 200 to fix the upper area of the thin plate specimen a. The lower surface of the thin plate specimen a is fixed by the first fixing body 111a and the second grip body 121b and one side is in contact with the upper region than the center line by the first fixing slip pad 114a . The upper portion of the thin plate test piece (a) is fixed by the second fixing body 111b and the first grip body 121a and the other side is brought into contact with the lower portion of the center line by the second fixed slip pad 114b .

The first guide part 130a is in contact with one side of the thin plate specimen a such that the lower end between the first fixing part 110a and the first grip part 120a is spaced apart from the upper end of the first fixing part 110a . The first guide part 130a is fastened to the second fixing part 110b by a separate fastening bolt 200. The first guide part 130a together with the first fixing part 110a forms an unconstrained area in a region above the center line at one side of the thin plate specimen a. A serration formed on the lower ends of the first guide slip pads 132a and the serrations formed on the upper ends of the first fixed body 111a and the first fixed slip pads 114a) The non-constrained regions are formed in a non-linear zigzag shape. The first guide part 130a is fastened to the second fixing part 110b with appropriate pressure by the fastening bolts 200 to support and support the thin plate specimen a.

The second guide portion 130b is brought into contact with the other side of the thin plate specimen a such that the upper end between the second fixing portion 110b and the second grip portion 120b is spaced apart from the lower end of the second fixing portion 110b . The second guide portion 130b is fastened to the first fixing portion 110a by a separate fastening bolt 200. The second guide part 130b together with the second fixing part 110b forms an unconstrained area in the lower area than the center line at the other side of the thin plate specimen (a). The teeth formed on the lower ends of the second fixed body 111b and the second fixed slip pad 114b and the teeth formed on the upper ends of the second guide body 131b and the second guide slip pad 132b The unconstrained area is formed in a non-linear zigzag shape. The second guide portions 130b are respectively fastened to the first fixing portions 110a with proper pressure by the fastening bolts 200 to support and support the thin plate specimen a.

The thin plate specimen (a) is supported by the inner surface of the first fixing body 111a and the first fixing slip pad 114a, and the upper region is supported by the first grip body 121a and the first Is supported by the guide slip pad 132a and the unconstrained area is formed in an area above the center line. The upper portion of the other side of the thin plate specimen (a) is supported by the inner surface of the second fixed body 111b and the second fixed slip pad 114b, and the lower portion is supported by the second grip body 121b Is supported by the second guide slip pad 132b and the unconstrained area is formed in the lower area than the center line. Since the thin plate specimen (a) is supported while forming an unconstrained region in the upper region and the lower region on the other side, one side or the other side is supported at all positions when viewed from the longitudinal direction in which the repeated load is applied . Further, the unconstrained area is formed in a zigzag shape that is nonlinear along the width direction of the thin plate specimen (a). Therefore, the jig 100 for thin-film specimen fatigue test minimizes the deformation or buckling of the thin specimen (a) while normally applying the cyclic load to the thin specimen (a) during the fatigue testing process.

The jig 100 for testing the thin plate specimen fatigue is disposed on one side and the other side of the thin plate specimen a so as to support the thin plate specimen a in its entirety. So that the longitudinal center axis of the thin plate specimen a coincides with the central axis of the grips 11a and 11b of the fatigue tester 10 even after being mounted on the grip wedges 13a and 13b.

The jig 100 for thin specimen fatigue testing supports the lower region of the thin plate specimen a by the first fixed slip pad 114a and the second guide slip pad 132b and the second fixed slip pad 114b The first guide slip pad 132a and the first guide slip pad 132a reduce the frictional force of the thin plate specimen a and reduce the repeated load applied to the thin plate specimen a by the fatigue tester 10, Without any possible loss. The jig 100 for testing the thin plate specimen fatigue has an inner surface of the first fixing groove 112a, an inner surface of the first grip projection 122a, an inner surface of the second fixing groove 112b, 122b are formed by knurling, the thin plate specimen (a) can be more firmly fixed.

It should be noted that the present invention is not limited to the above-described embodiments, and various modifications and variations of the present invention are possible in light of the above teachings. It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.

100: Jig for fatigue test of thin plate specimen
100a: first jig unit
110a:
111a: first fixing body 112a: first fixing groove
113a: first slip groove 114a: first fixed slip pad
115a: 1st step groove
120a: first grip portion
121a: first grip body 122a: first grip projection
130a: first guide portion
131a: first guide body 132a: first guide slip pad
100b: second jig unit
110b: second fixing portion
111b: second fixing body 112b: second fixing groove
113b: second slip groove 114b: second fixed slip pad
115b: second step groove
120b: second grip portion
121b: second grip body 122b: second grip projection
130b: second guide portion
131b: second guide body 132b: second guide slip pad

Claims (6)

A first jig unit and a second jig unit for respectively supporting one side surface and the other side surface of the thin plate specimen,
Wherein the first jig unit forms an unconstrained area in an upper region than a center line with respect to a longitudinal direction of the thin plate specimen on one side of the thin plate specimen, Forming an unconstrained region in the region,
The first jig unit and the second jig unit are formed to be point-symmetric with respect to the center point of the thin plate specimen,
The first jig unit
A first fixing part fixing the lower area of one side of the thin plate specimen and supporting a part of the upper area,
A first grip portion for supporting and fixing an upper region on one side of the thin plate specimen,
And a first guide portion located at a lower portion of the first grip portion and spaced apart from an upper end of the first fixing portion at a lower end to form the unconstrained region in an upper region than a center line of the thin plate specimen,
The second jig unit
A second fixing part fixing the upper area of the other side of the thin plate specimen and supporting a part of the lower area,
A second grip portion for supporting and fixing a lower region of the other side of the thin plate specimen,
And a second guide portion located at a lower portion of the second grip portion and spaced apart from a lower end of the second fixing portion at an upper end thereof to form the unconstrained region in a lower region than a center line of the thin plate specimen,
The first fixing part includes a first fixing body formed in a block shape, a first fixing groove formed on an inner surface of the first fixing body and inserted into a lower portion of the thin plate specimen, A first slip groove and a first fixed slip pad inserted in the first slip groove and having an inner side surface flush with the inner side surface of the first fixing groove and having a coefficient of friction lower than that of the first fixing body, ≪ / RTI &
The first grip portion includes a first grip body formed in a block shape and a second grip portion formed on the inner side surface of the first grip body so that an inner side surface thereof is flush with an inner side surface of the first fixed body when the thin plate specimen is supported, And a second grip projection projecting from the first grip projection,
Wherein the first guide portion is disposed at a lower portion of the first grip body and has a lower end connected to an inner surface of the first guide body and spaced apart from an upper end of the first fixed body, And a first guide slip pad formed flush with the inner surface of the grip projection and formed of the same material as the first fixed slip pad,
The second fixing part includes a second fixing body formed in a block shape, a second fixing groove formed on an inner surface of the second fixing body to insert an upper portion of the thin plate specimen, 2 slip grooves and a second fixed slip pad inserted in the second slip grooves and having an inner side surface flush with the inner side surface of the second fixing groove and having a coefficient of friction lower than that of the second fixing body In addition,
Wherein the second grip portion includes a second grip body formed in a block shape and an inner side surface of the second grip body so that the inner side surface of the second grip body is flush with the inner side surface of the second fixed body when the thin plate specimen is supported, And a second grip protrusion protruding from the first grip protrusion,
Wherein the second guide portion is coupled to an inner surface of the second guide body and an upper surface of the second guide body is positioned at an upper portion of the second grip body and spaced apart from a lower end of the second fixed body, And a second guide slip pad which is flush with an inner surface of the grip protrusion and is made of the same material as the second fixed slip pad. delete delete delete The method according to claim 1,
The first fixed body and the first fixed slip pad are formed to have a saw-like shape at an upper end thereof. The lower ends of the first guide body and the first guide slip pad are connected to the first fixed body and the first fixed slip pad And is formed in a serrated shape which is interlaced with the top serrations,
The second fixed body and the second fixed slip pad are formed to have a sawtooth shape at the lower end, and the second guide body and the second guide slip pad have an upper end fixed to the second fixed body and the second fixed slip pad And a jig for jigging the thin plate specimen. The method according to claim 1,
Wherein the inner surface of the first fixing groove, the inner surface of the first grip projection, the inner surface of the second fixing groove, and the inner surface of the second grip projection are knurled.

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