JP2013181792A - Fracture mechanics parameter measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for measuring a fracture mechanics parameter in a mixed mode by using a sample with a plurality of members adhered thereto.SOLUTION: In a sample 1 in which a defect 4 in a predetermined size is introduced to an interlayer between a first member 2 and a second member 3, the thicknesses of the first member 2 and the second member 3, the elastic moduli of the first member 2 and the second member 3, the length of the second member 3, the width of an inclined part of the second member 3, and the length of the defect 4 are set to optional values. A fracture mechanics parameter measuring method detects fracture mechanics parameters of a mode I and a mode II at the defect 4, and calculates a mixture ratio G/Gof the fracture mechanics parameters between the mode I and the mode II when a tensile load is given in the length direction of the second member 3 with the first member 2 of the sample 1 having the set parameters fixed.

Description

  The present invention relates to a method for measuring fracture mechanics parameters under mixed mode.

As a composite material, for example, there is a resin-based composite material manufactured by laminating resin sheets reinforced with fibers such as carbon fibers. Resin-based composite materials are widely used as structural members for aircraft, automobiles, ships, and the like because they are lightweight and have high strength.
For example, in an aircraft structural member, a plurality of resin matrix composites are bonded together to increase the thickness of the member. Thus, when a foreign material mixes in bonding a plurality of resin matrix composites, the strength is lowered and becomes a starting point of damage. For this reason, the aircraft is designed to allow such damage to some extent. In that case, the strength design may be performed using the interlaminar fracture toughness of the composite material to determine the allowable damage dimensions.

  In JIS K 7086 (Non-Patent Document 1), mode I (opening type) and mode II (in-plane shearing type) deformation modes are applied to flat carbon fiber reinforced plastic with defects introduced between layers. A method for measuring the fracture toughness value of is specified.

  In the measurement method disclosed in ASTM D6671 (Non-patent Document 2), an interlayer delamination defect is formed at one end of a test piece to be a flat fiber-reinforced plastic substrate. While supporting both ends of the test piece, a load is applied to the center of the test piece and a force for peeling off the peeling defect portion is applied. The fracture toughness value in the mixed mode of mode I and mode II is measured by measuring the peeling force when the defect grows.

  In the delamination fracture toughness test method disclosed in Patent Document 1, a specimen having an artificial exfoliation defect formed at one end and a lower part of the defect is shortened is used. Supporting the upper part and multiple ends of the artificial exfoliation defect of this specimen, applying a load to the central part, measuring the load load when the artificial exfoliation defect grows, in the mixed mode of mode I and mode II Fracture toughness value is measured.

Japanese Industrial Standard JIS K 7086 "Test Method for Interlaminar Fracture Toughness of Carbon Fiber Reinforced Plastics" American Standards for Materials Testing ASTM D6671 “Standard Test Method for Mixed Mode I-Mode II Interlaminar Fracture Toughness of Unidirectional Fiber Reinforced Polymer Matrix Composites”

JP-A-4-343042 (Claim 1, paragraphs [0008] to [0012], FIGS. 1 to 4)

  In the test methods of Non-Patent Document 2 and Patent Document 1, since the load condition setting and the jig setting are complicated, the test cannot be easily performed. In addition, the specimen used for the test of Patent Document 1 has a complicated manufacturing process and does not simulate the stacking condition applied to an actual structure.

  An object of this invention is to provide the method of measuring the fracture mechanics parameter in a mixed mode using the test body which adhere | attached the some member.

In order to solve the above-mentioned problems, the present invention has a plate-like first member extending in a first direction and a pair of opposing sides that are smaller than the first member and processed into a vertical or inclined shape. A plate-like second member, and the first member includes a first planar portion so that a defect having a predetermined size is introduced into a contact surface between the first member and the second member. A molded body in which one plane portion of the two members is arranged and bonded in a direction in which the pair of sides intersects the first direction is a specimen, and the specimen parameters of the specimen are the specimen parameters of the first member. A thickness, a thickness of the second member, an elastic modulus of the first member, an elastic modulus of the second member, and the first portion of the planar portion of the second member bonded to the first member. A length of a pair of sides extending in a direction, a width of the defect in the first direction, and the first of the inclined shape Specimen parameter setting step in which the width in the direction is set to an arbitrary value, and both ends in the first direction of the first member in the specimen having the set specimen parameter are fixed, when a predetermined tensile load is applied to said first direction with respect to the specimen, fracture mechanics parameters G _II of fracture mechanics parameters G _I and mode II mode I in the defect, by using FEM analysis From the fracture mechanics parameter calculation step calculated and the fracture mechanics parameter calculated in the first fracture mechanics parameter calculation step, the mode I and mode II fractures at the set specimen parameter and the load are performed. There is provided a fracture mechanics parameter measurement method comprising a mixing ratio calculation step in which a mixing ratio G _I / G _{II of a} mechanical parameter is calculated.

  According to the present invention, the thickness of the first member, the thickness of the second member, the elastic modulus of the first member, the second thickness, and the thickness of the specimen that is increased by bonding the first member and the second member. By changing the elastic modulus of the member, the length of the second member, the width of the inclined portion of the second member, and the length of the defect, the mixing ratio of the fracture mechanics parameters in various mixing modes can be obtained. This mixing ratio can be used for the design of structural members in which members such as resin matrix composites and metal plates are laminated.

In the above invention, both end portions in the first direction of the first member in the specimen having the set specimen parameters are fixed, and a tensile load is applied to the specimen in the first direction. And a delamination strength measurement step in which the value of the tensile load when the fracture starts from the defect is acquired, and in the fracture mechanics parameter calculation step, the acquired in the strength measurement step Using the tensile load value, the mode I fracture mechanics parameter G _Id and the mode II fracture mechanics parameter G _IId when fracture starts from the defect are calculated, and in the mixing ratio calculation step, the calculation is performed. From the fracture mechanics parameters, the mixing ratio G _Id / G _IId when the fracture starts from the defect may be calculated.

  By doing so, it is possible to obtain the mixing ratio when the destruction starts from the defect in various mixing modes. As a result, the correlation peel strength of the defect portion introduced into the specimen in each mixed mode can be obtained.

  In the above invention, a first presser jig having a shape following the shape of the second member is installed on the surface of the specimen on the side where the second member is provided, and the first presser of the specimen is provided. A second presser jig following the shape of the first member may be installed on the surface opposite to the surface on which the jig is installed.

  In the above invention, two molded bodies having the same shape in which the other planar portions of the first member are in contact with each other may be used as the specimen.

  In the above invention, a molded body in which the second member is brought into contact with the other planar portion of the first member of the molded body may be used as the specimen.

  When the specimens having the above-described configurations are used, the specimen is not deformed while a tensile load is applied, so that the fracture mechanics parameters can be obtained more accurately. Therefore, the accuracy of the obtained mixing ratio can be improved.

  According to the present invention, fracture mechanics parameters at various mixing ratios can be measured for a member to which a composite material or a metal plate is bonded. If this invention is used, the load at the time of a fracture | rupture start from a defect in each mixing ratio is acquirable. By using this mixing ratio, it is possible to acquire the strength of a member that is broken in the mixed mode and to design a member for preventing the breakage from starting.

It is the schematic of the test body of 1st Embodiment. It is the schematic explaining the introduction example of a defect. It is the schematic which shows another example of the test body of 1st Embodiment. It is the schematic explaining the measuring method which concerns on 1st Embodiment. It is a graph which shows the mixing ratio when changing a taper ratio and a defect ratio. It is a graph which shows a mixing ratio when changing a taper ratio and an elastic modulus ratio. It is the schematic explaining the measuring method which concerns on 2nd Embodiment. It is a graph showing the change of the mixing ratio by the presence or absence of a pressing jig. It is the schematic of the specimen of 3rd Embodiment. It is the schematic of the test body of 4th Embodiment.

<First Embodiment>
FIG. 1 is a schematic view of a specimen used for the fracture mechanics parameter measurement method according to the first embodiment. FIG. 1A is a side view, and FIG. 1B is a plan view.
1 has a shape in which a first member 2 and a second member 3 are bonded. The first member 2 and the second member 3 are, for example, a resin-based composite material formed by laminating a plurality of fiber reinforced resin sheets (prepregs) in which fibers such as carbon fibers and glass fibers are fixed with an epoxy resin, or a metal plate It is said. The first member 2 and the second member 3 may be bonded by an adhesive or the like, or may be cured and bonded simultaneously after the first member 2 and the second member 3 are laminated.

  The first member 2 is plate-shaped. In FIG.1 (b), the 1st member 2 is made into strip shape, and has the long side and short side which are extended in a 1st direction. In addition, the 1st member 2 may be processed into the shape by which the corner | angular part of the strip was processed into the shape of a straight line or a curve, or the edge part of the long side of a strip was processed into the shape of a curve.

  The second member 3 has a plate shape. As shown in FIG. 1, the second member 3 is preferably rectangular. Alternatively, the second member 3 may be square. As shown in FIG. 1A, the second member 3 is smaller than the first member 2. The length of the long side of the second member 3 is shorter than the length of the long side of the first member 2.

The second member 3 is disposed at the center of the long side of the first member 2. The second member 3 is preferably arranged so as to be symmetric with respect to the central axis of the first member 2 in a direction perpendicular to the first direction.
In this embodiment, the 2nd member 3 is arrange | positioned so that a short side may become a direction which cross | intersects a 1st direction. The short side of the second member 3 is preferably substantially perpendicular to the first direction as shown in FIG. However, the present embodiment is not limited to this, and the second member 3 may be arranged so as to rotate with respect to the arrangement of FIG.
As described above, when the second member 3 is arranged so as to be symmetric with respect to the central axis and the short side of the second member 3 is arranged so as to be substantially perpendicular to the first direction, the fracture mechanics parameter described later is obtained. Calculation becomes easy.

The second member 3 in FIG. 1 has a pair of sides (short sides in FIG. 1B) intersecting in the first direction processed into an inclined shape. The inclined shape may be a linear notch shape or a curved shape as shown in FIG.
In FIG. 1, the short side of the first member 2 and the short side of the second member 3 have the same length, but the short side of the second member 3 may be smaller than the short side of the first member 2. good.

  The larger one of the upper and lower planar portions of the second member 3 is in contact with one of the planar portions of the first member 2. The contact surfaces of the first member 2 and the second member 3 are bonded.

In the specimen 1 of FIG. 1, a defect 4 having a predetermined size is introduced into the contact surface between the first member 2 and the second member 3. The defect 4 is a peeling defect in which the first member 2 and the second member 3 are not bonded. In FIG. 1B, the defect 4 has a rectangular shape when viewed in a plane.
In FIG. 1B, the defect 4 is one of the sides processed into the inclined shape of the second member 3, that is, the short side of the second member 3 on the contact surface between the first member 2 and the second member 3. It is provided on one side. The defect 4 is preferably introduced into the entire short side direction of the second member 3 as shown in FIG. 1B, but the first defect is not introduced at the end of the long side of the second member. The member 2 and the second member 3 may be bonded.

The defect 4 may be introduced into the central portion of the contact surface between the first member 2 and the second member 3. FIG. 2 is a schematic diagram for explaining another example of introducing defects. FIG. 2 is a view as seen from the same direction as FIG.
The defect 4 in FIG. 2A is provided such that the first member 2 and the second member 3 around the defect 4 are bonded. The shape of the defect 4 is not particularly limited, and may be a square or a rectangle.
The defect 4 in FIG. 2B extends in a direction substantially perpendicular to the first direction at the center portion of the contact surface, and the first member 2 and the first member 2 on the end side located on the long side of the first member 2. It is provided so as to penetrate the contact surface with the second member 3.
The defect 4 in FIG. 2C extends in the long side direction (a direction substantially parallel to the first direction) of the first member 2 at the center portion of the contact surface, and both end portions (second portions) of the first member 2. It is provided so as to penetrate the contact surface between the first member 2 and the second member 3 at the processed side of the member 3.

FIG. 3 is a schematic view showing another example of a specimen used for the measurement method according to the first embodiment. FIG. 3A is a side view, and FIG. 3B is a plan view.
In the specimen 1 of FIG. 3, the second member 3 is not cut. For this reason, a pair of sides (short sides) of the second member 3 intersecting with the first direction are processed so as to be perpendicular to the first member 2.

The fracture mechanics parameter measurement method of the first embodiment will be described below.
(1) Setting of specimen parameters The parameters of the specimen 1 shown in FIG. 1 or 3 are set. Here parameters set, the thickness _{t 1} of the first member 2, the thickness _{t 2} of the second member 3, an elastic modulus _{E 1} of the first member 2, the elastic modulus _{E 2} of the second member 3, the second The length W of the member 3, the width L of the inclined portion of the second member 3, and the length a of the defect 4. The length W of the second member 3 is the length of the side that is substantially parallel to the first direction in the plane portion that contacts the first member. The length a of the defect 4 is a length in a direction substantially parallel to the first direction. The width L of the inclined portion is a width in a direction substantially parallel to the first direction.

  Each parameter is set to an arbitrary value, for example, by simulating the material and shape of a structural member of an aircraft. The length a of the defect 4 is set to a value smaller than the length W of the second member 3. In the case of the specimen 1 of FIG. 3, the width L of the inclined portion of the second member 3 is set to zero.

(2) Calculation of Fracture Mechanics Parameters Fracture mechanics parameters of the specimen 1 shown in FIG. 1 or FIG. 3 given arbitrary specimen parameters are calculated by FEM analysis.

The following assumptions are made in the calculation.
FIG. 4 is a schematic diagram for explaining a situation in which a load is applied to the specimen of FIG. Both ends in the first direction of the first member 2 of the specimen 1 are sandwiched by the gripping jig 5. At this time, the second member 3 is not brought into contact with the gripping jig 5.

  A predetermined tensile load is applied to the first member 2 in the long side direction (first direction) via the gripping jig 5. In the calculation, the tensile load is a load or a displacement in the first direction. At this time, since the center axis of the specimen and the axis C in the tensile direction are deviated, the first member 2 is given a tensile force and a bending force to bend toward the side where the second member is not provided. . Since the second member 3 is bonded to the first member 2, a tensile force and a bending force are applied. As a result, at the tip of the defect 4, a mode I deformation in which a crack (peeling) opens in the thickness direction of FIG. 4 and a mode II deformation in which the crack shifts in the first member long side direction of FIG. .

Mode I when a predetermined tensile load is applied by FEM analysis using the above-mentioned t ₁ , t ₂ , E ₁ , E ₂ , W, L, a and the magnitude of the tensile load as parameters. The fracture mechanics parameter G _I of mode II and the fracture mechanics parameter G _{II of} mode _II are calculated.

(3) Calculation of mixing ratio From the fracture mechanics parameters G _I and G _II obtained by FEM analysis, the mixing ratio of mode I and mode II at each tensile load is calculated. In the present embodiment, the mixing ratio is defined as G _I / G _II . The calculated mixing ratio value is a value between 0 and ∞.

In the present embodiment, the taper ratio (t ₂ / L), the defect ratio (a / W), the elastic modulus ratio (E ₁ / E ₂ ) of the notch portion, and the plate thickness ratio (t By changing ₂ / t ₁ ), the ratio between the fracture mechanics parameter GI of mode _I and the fracture mechanics parameter G _II of mode II can be changed.

FIG. 5 is a graph showing the mixing ratio when the taper ratio and the defect ratio are changed. In the figure, the horizontal axis is the taper ratio (t ₂ / L), and the vertical axis is the mixing ratio (G _I / G _II ). When the taper ratio is the same, the mixing ratio decreases as the defect ratio a / W increases. That is, when the defect length increases, the mode II deformation becomes dominant.

FIG. 6 is a graph showing the mixing ratio when the taper ratio and the elastic modulus ratio are changed. In the figure, the horizontal axis is the taper ratio (t ₂ / L), and the vertical axis is the mixing ratio (G _I / G _II ). In the case of the same taper ratio, the mixing ratio increases as the elastic modulus ratio (E ₁ / E ₂ ) increases.

Referring to FIGS. 5 and 6, when the defect ratio or the elastic modulus ratio is the same, the mixing ratio tends to decrease as the taper ratio t ₂ / L increases. That is, when the second member has a predetermined thickness, the mode II deformation becomes more dominant as the inclined portion approaches vertical (in the case of vertical, t ₂ / L becomes infinite).

Using the above measurement method, the mixing ratio of fracture mechanics parameters when fracture starts from a defect can be acquired.
(1 ′) Strength measurement The specimen 1 shown in FIG. 1 or FIG. 3 is produced. In the production of the specimen 1, the first member 2 and the second member 3 are bonded after inserting delamination between the first member 2 and the second member 3. As a method of bonding, the first member and the second member are bonded with an epoxy adhesive or the like. Alternatively, when the first member and the second member are resin-based composite materials, the prepreg is simultaneously cured and molded. However, the first member 2 and the second member 3 are not bonded at the portion where the defect 4 is introduced. The delamination is simulated by a Teflon film or the like according to JIS K7086.

  As shown in FIG. 4, both ends of the first member 2 in the first direction of the specimen 1 are sandwiched by the holding jig 5. The gripping jig 5 is fixed to a tensile test apparatus (not shown). A tensile load in the first direction is applied to the specimen 1 by the test device. From the tip of the defect 4, the magnitude of the tensile load when the first member 2 and the second member 3 are separated from each other is started. The magnitude of this tensile load corresponds to the delamination strength.

Next, in the above step (2), t ₁ , t ₂ , E ₁ , E ₂ , W, L, a of the specimen used for the measurement of (1 ′) and the obtained tensile load value are used. The fracture mechanics parameters are then calculated. The calculated fracture mechanics parameters are the mode I and mode II fracture mechanics parameters G _Id and G _IId when the fracture starts from the defect.

In the step (3), the mixing ratio G _Id / G _IId when the destruction starts from the defect is calculated from the acquired G _Id and G _IId .

  By the above process, the delamination strength of the specimen 1 and the mixing ratio are correlated. Therefore, if a mixing ratio of specimens having arbitrary specimen parameters is obtained, the delamination strength of the defect portion introduced into the specimen can be acquired.

  The mixing ratio obtained by the fracture mechanics parameter measurement method of the present embodiment can be used for designing a structural member in which a plurality of members are laminated.

For example, as illustrated in FIG. 5 and FIG. 6, a relationship diagram between the taper ratio t ₂ / L, the elastic modulus ratio E ₁ / E ₂ , the defect ratio a / W, and the mixing ratio G _I / G _II is acquired in advance. Keep it. Moreover, the delamination strength at each mixing ratio is acquired in advance. The required delamination strength is determined from the magnitude of the tensile load applied to the structural member. Delamination strength so associated with the mixing ratio can be determined and G _I and G _II when a load is imparted. That is, the fracture toughness value at a certain mixing ratio can be acquired.
Note that G _{I for} mode I only and G _{II for} mode II only are acquired in accordance with JIS K7086.

As the use of other than the above, for example, a case of bonding the separate member (second member) to a substrate having a thickness t ₁ (first member). The plate thickness t ₂ , length W, and taper ratio t ₂ / L of the second member are fixed. In this case, referring to the relationship diagram between the taper ratio and the mixing ratio when the defect ratio is changed as shown in FIG. 5, when the predetermined taper ratio t ₂ / L and the length W of the second member are provided. It is also possible to obtain the allowable defect length a.

Alternatively, the plate thickness _{t 1,} the base material having a modulus of elasticity _{E 1} (first member), a plate thickness _{t 2,} it is assumed that bonding the member (second member) having a modulus of elasticity _{E 2.} The length W of the second member and the width a of the introduced defect are fixed. In this case, referring to the relationship diagram between the taper ratio and the mixing ratio when the elastic modulus ratio is changed as shown in FIG. 6, the taper ratio at which no fracture occurs can be determined by the mixing ratio of the structural members. .

Second Embodiment
FIG. 7 is a schematic diagram illustrating a fracture mechanics parameter measurement method according to the second embodiment. FIG. 7A is a side view, and FIG. 7B is a plan view. The specimen 1 in FIG. 7 has the same shape as that in FIG. 1, but may be the same specimen as in FIG.

  In this embodiment, the part where the second member 3 of the specimen 1 is installed is sandwiched between the first pressing jig 6 and the second pressing jig 7. A first pressing jig 6 is installed on the side of the specimen 1 where the second member 3 is provided. The surface of the first pressing jig 6 that contacts the second member 3 is processed into a shape that follows the shape of the second member 3. A second presser jig 7 is installed on the surface of the specimen 1 opposite to the surface on which the first presser jig 6 is provided. The surface of the second pressing jig 7 that contacts the first member 2 follows the shape of the first member 2.

  The first presser jig 6 and the second presser jig 7 are fixed with bolts 8. The bolt 8 is installed outside the specimen 1 as shown in FIG.

  The gripping jig 5 is fixed so as to sandwich both ends of the first member 2, but the first pressing jig 6 and the second pressing jig 7 are not sandwiched.

  The method for measuring fracture mechanics parameters in the second embodiment is the same as in the first embodiment. Also in this embodiment, the central axis of the specimen 1 and the axis C in the tensile direction are deviated. For this reason, a bending force and a tensile force are applied to the specimen 1, and a mixed mode deformation is applied to the defect 4 portion. In the first embodiment, the specimen is deformed by the bending force. On the other hand, in the second embodiment, since the portion where the second member 3 is installed is fixed by the first pressing jig 6 and the second pressing jig 7, the specimen 1 is deformed while a load is applied. Does not occur. For this reason, the relative position between the central axis of the specimen and the axis C in the tensile direction is fixed. Moreover, if it is this embodiment, a compressive load can also be given to a specimen.

  FIG. 8 is a relationship diagram between the taper ratio and the mixing ratio when there is no holding jig (first embodiment) and when there is a holding jig (second embodiment). In the figure, the horizontal axis is the taper ratio, and the vertical axis is the mixing ratio.

  In the measurement method of the second embodiment, the specimen is not deformed while a tensile load is applied, so that the fracture mechanics parameters can be acquired more accurately. Therefore, the accuracy of the obtained mixing ratio is improved.

<Third Embodiment>
FIG. 9 is a schematic diagram illustrating a fracture mechanics parameter measurement method according to the third embodiment. FIG. 9 is a side view of the specimen 10. The specimen 10 of the third embodiment has a shape in which the first members 12a and 12b of two molded bodies having the same shape as in FIG. In the present embodiment, the first members 12a and 12b may be bonded to each other or may not be bonded. Defects 14a and 14b are introduced between the first members 12a and 12b and the second members 13a and 13b, respectively. Defects 14a and 14b are introduced on the same side.
In the third embodiment, a molded body having the same shape as that of FIG. 3 can be applied.

  In a state where the first members 12 a and 12 b are in contact with each other, both ends of the specimen 10 are sandwiched and fixed by the jig 15. The specimen 10 is subjected to a tensile load in the length direction of the first members 12 a and 12 b via the gripping jig 15.

  In the present embodiment, two molded bodies are combined so as to be symmetric about the contact surface. In addition, defects are introduced on the same side. For this reason, the contact surface of the molded body becomes the central axis of the specimen 10 and the axis in the tensile direction. Since the central axis and the axis in the tensile direction coincide with each other, deformation of the specimen 10 while applying a tensile load can be suppressed without using a holding jig. Since the central axis of the specimen does not fluctuate while the tensile load is applied, the fracture mechanics parameter can be acquired more accurately, and the accuracy of the obtained mixing ratio is improved.

<Fourth embodiment>
FIG. 10 is a schematic diagram for explaining a fracture mechanics parameter measurement method according to the fourth embodiment. FIG. 10 is a side view of the specimen 20. In the specimen 20 of the fourth embodiment, two second members 23 a and 23 b having the same shape are bonded to both surfaces of the first member 22. The defect 24a introduced between the first member 22 and the second member 23a and the defect 24b introduced between the first member 22 and the second member 23b are formed on the same side.
In FIG. 10, the pair of sides of the second member are machined into an inclined shape, but may be machined so as to be vertical as shown in FIG.

  Both ends of the first member 22 of the specimen 20 are sandwiched and fixed by a gripping jig 25. The specimen 20 is loaded with a tensile load in the length direction of the first member 22 via the gripping jig 25.

  In the present embodiment, the second members 23a and 23b and the defects 24a and 24b are arranged so as to be symmetric with respect to the first member 22. For this reason, since the center axis | shaft of the test body 20 and the axis | shaft of a tension | pulling direction correspond, even if it does not use a holding jig, the deformation | transformation of the test body 20 is suppressed during providing the tensile load. As a result, the fracture mechanics parameter can be acquired more accurately, and the accuracy of the obtained mixing ratio is improved.

1, 10, 20 Specimen 2, 12a, 12b, 22 First member 3, 13a, 13b, 23a, 23b Second member 4, 14a, 14b, 24a, 24b Defect 5, 15, 25 Grab jig 6 First Presser jig 7 Second presser jig 8 Bolt

Claims (5)

A plate-like first member extending in a first direction; and a plate-like second member having a pair of opposing sides that are smaller than the first member and processed into a vertical or inclined shape; The one planar portion of the second member is placed on the one planar portion of the first member so that a defect of a predetermined size is introduced into the contact surface between the first member and the second member. Is a molded body that is disposed and bonded in a direction intersecting the first direction,
As specimen parameters of the specimen, the thickness of the first member, the thickness of the second member, the elastic modulus of the first member, the elastic modulus of the second member, and the first member are bonded. A length of a pair of sides extending in the first direction of the planar portion of the second member, a width of the defect in the first direction, and a first shape of the inclined shape in the first direction. Specimen parameter setting process in which the width is set to an arbitrary value,
When both end portions in the first direction of the first member in the specimen having the set specimen parameters are fixed and a predetermined tensile load is applied to the specimen in the first direction , the fracture mechanics parameters G _II of fracture mechanics parameters G _I and mode II mode I in the defect, and fracture mechanics parameter calculation step is calculated using the FEM analysis,
From the fracture mechanics parameters calculated in the first fracture mechanics parameter calculation step, the mixture ratio G _I / G _{II of the} set specimen parameters and the fracture mechanics parameters of the mode I and the mode II at the load A fracture mechanics parameter measurement method comprising: a mixing ratio calculation step in which is calculated. When both ends of the first direction of the first member in the specimen having the set specimen parameters are fixed and a tensile load is applied to the specimen in the first direction. And a delamination strength measurement step in which the value of the tensile load when the fracture starts from the defect is acquired,
In the fracture mechanics parameter calculation step, using the value of the tensile load acquired in the strength measurement step, the mode I fracture mechanics parameter _GId when the fracture starts from the defect and the mode II fracture mechanics. Parameter G _IId is calculated,
2. The fracture mechanics parameter measurement method according to claim 1, wherein, in the mixing ratio calculation step, the mixing ratio G _Id / G _IId when the fracture starts from the defect is calculated from the calculated fracture mechanics parameter. A first holding jig having a shape following the shape of the second member is installed on the surface of the specimen on the side where the second member is provided,
The second presser jig following the shape of the first member is installed on the surface of the specimen opposite to the surface on which the first presser jig is installed. The fracture mechanics parameter measurement method described.   The fracture mechanics parameter measurement method according to claim 1 or 2, wherein two specimens having the same shape in which the other planar portions of the first member are in contact with each other are used as the specimen.   3. The fracture mechanics parameter measurement method according to claim 1, wherein a molded body in which the second member is brought into contact with the other planar portion of the first member of the molded body is used as the specimen.

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