JPH04343042A - Method for testing interlayer release breakdown toughness - Google Patents

Abstract

PURPOSE:To enable a simple and highly accurate interlayer release breakdown toughness to be evaluated and tested by excluding complexity and poor accuracy caused by using a sample support hinge. CONSTITUTION:A sample 1 where an artificial release defect 2 is formed at one edge and at the same time a lower portion of the artificial release defect 2 is reduced is used. While an upper portion of the artificial release defect 2 of the sample 1 and the other edge are supported by a sample-supporting tool 3, a load 5 is loaded at a central portion of the sample 1 by a load-loading tool 4. A load 5 when the artificial release defect 2 grows is measured and an interlayer release breakdown toughness under breakdown mode where an open type and shear type are mixed is evaluated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a delamination fracture toughness test method suitable for evaluating the fracture toughness of composite laminates, honeycomb sandwich panels, etc. due to delamination defects.

0002

2. Description of the Related Art Conventionally, in a test method for evaluating the fracture toughness of plate materials due to delamination defects, as shown in the perspective view of FIG. A specimen support hinge 8 that can freely rotate around a fulcrum and always exerts an upward force is attached to the upper part of the peeled part at one end that has a peeling defect 2, fixing only the upper part of the peeled part, and fixing the other end to the specimen supporting hinge 8. It is simply supported by a tool 3, a load 5 is applied via a load-loading jig 4, and the load 5 when the artificial peeling defect 2 grows is measured to evaluate the delamination fracture toughness.

However, in such a test method, a part of the specimen 1 above the artificial peeling defect 2 is suspended and fixed, so a specimen support hinge 8, which is a special jig for this purpose, is used.
is necessary. In addition, when the specimen 1 is deformed by the applied load 5, it must have a structure that rotates around a fulcrum so that the condition of simple support equivalent to that of the specimen support jig 3 is satisfied. Even if the structure is
Because the center of rotation when supporting the specimen 1 is far from the specimen 1, and the joint between the specimen 1 and the specimen support hinge 8 has a certain width, the conditions for simple support cannot be completely satisfied. Furthermore, much time is required to attach the specimen 1 to the specimen support hinge 8 and to determine the relative positions of the specimen support hinge 8 and the specimen support jig 3.

0004

[Problems to be Solved by the Invention] The present invention was proposed in view of the above circumstances, and it is an object of the present invention to eliminate the complexity and poor precision caused by using a specimen support hinge, and to provide a simpler and more accurate solution. It is an object of the present invention to provide a delamination fracture toughness test method that enables a high delamination fracture toughness evaluation test and reduces test time and costs.

[0005]

[Means for Solving the Problems] In order to solve the problems, the present invention uses a specimen having an artificial peeling defect formed at one end and a shortened lower part of the artificial peeling defect. While supporting the other end with a specimen supporting jig, a load was applied to the center of the specimen using a loading jig, and the applied load when the artificial peeling defect grew was measured. It is characterized by evaluating delamination fracture toughness under mixed shear-type failure modes.

[0006]

[Operation] In the delamination fracture toughness test method of the present invention,
By changing the shape of the specimen so that the lower part of the artificial peeling defect is short, the upper part of the artificial peeling defect can be easily moved using a simple jig such as a specimen support jig without being obstructed by the specimen. It becomes possible to support. In addition, by simply supporting both ends of the specimen using a specimen support jig, it becomes possible to conduct tests under conditions that completely satisfy the conditions for simple support, and the test is performed under conditions that completely satisfy the conditions for simple support. Since the test is similar to the point bending test, the time required for relative positioning of the specimen support jig and installation of the specimen can be reduced. Furthermore, since the specimen support jig used in conventional three-point bending tests is used instead of the specimen support hinge, the cost required for manufacturing the specimen support hinge, which is a dedicated jig, can be reduced, and the The time and cost required for joining the specimen and specimen support hinge can be reduced.

[0007]

[Example] Examples of the delamination fracture toughness testing method of the present invention will be explained with reference to the drawings. FIG. 1 is a perspective view of a test situation according to the first example, and FIG. 2 is a perspective view of a test situation according to the second example. 3 is a perspective view of a test situation according to the third embodiment, and FIG. 4 is a perspective view of a test situation according to the fourth embodiment.

First, in FIG. 1 of the first embodiment, a specimen 1 having an artificial exfoliation defect 2 formed at one end and a shortened lower part of the artificial exfoliation defect 2 is prepared. The upper part and the other end of the artificial peeling defect 2 of the specimen 1 are simply supported by the specimen support jig 3 that has been used in the three-point bending test, and the specimen 1 is then An applied load 5 is applied to the artificial peeling defect 2, and the applied load 5 during growth of the artificial peeling defect 2 is measured to evaluate the delamination fracture toughness. At this time, the force that tries to open the tip of the artificial peeling defect 2 and the force that tries to displace it laterally act simultaneously, so the fracture mode is a mixture of opening type and shearing type. It is possible to evaluate fracture toughness, and using a composite laminate as specimen 1, it is suitable for evaluating the growth of delamination between the layers of the laminate.

Next, a second example shown in FIG. 2 is a case where the bonding strength of the bonding portion between the honeycomb core 1a and the outer panel 1b in the honeycomb sandwich panel specimen 1 is evaluated. In this case, the bonding strength between the outer plate 1b and the honeycomb core 1a can be evaluated by conducting a similar test on the specimen 1 in which the honeycomb core 1a and outer plate 1b below the artificial peeling defect 2 are cut and shortened. , it can be evaluated from the applied load 5 during the growth of the artificial peeling defect 2.

The third example shown in FIG. 3 is a case where the adhesive strength of an adhesive is evaluated using this test method. in this case,
Two flat plates 1 with one end unbonded and artificial peeling defect 2
By conducting this test using the specimen 1 to which c is adhered, it is possible to peel the adhesive joint 1d and evaluate the bonding strength of the adhesive joint 1d from the applied load 5 when the artificial peeling defect 2 grows. can.

Furthermore, a fourth example shown in FIG. 4 is a case where the delamination fracture toughness is evaluated by changing the ratio of the open type and shear type failure modes. In this case, by attaching the fracture mode adjustment jig 6 to the lower part of the artificial peeling defect 2 and applying the fracture mode adjustment load 7 to adjust its size,
It is possible to evaluate delamination fracture toughness under various conditions with different ratios of open-type and shear-type fracture modes. Here, the destruction mode adjustment jig 6 is a hinge, and it is possible to always apply a load in a fixed direction.

[0012] Thus, the test method of the present invention
The shape was made shorter than the artificial peeling defect 2, and instead of using the specimen support hinge used in the conventional test method, only the specimen support jig 3, which is a jig for three-point bending tests, was used. Simply support the specimen 1 and apply load 5 to the specimen 1.
It is possible to evaluate delamination fracture toughness with the same ease as a simple three-point bending test. In addition, in this test method, the specimen 1 is supported by the specimen support jig 3 and the test is conducted under conditions that completely satisfy the conditions of simple support. It is possible to improve test accuracy. Furthermore, since the specimen 1 is supported by the specimen support jig 3 instead of using the specimen support hinge, it is possible to reduce the time and cost for joining the specimen 1 and the specimen support hinge. In addition, conventionally, it took time to determine the relative position of the specimen support hinge and the specimen support jig, but since only the specimen support jig 3 is used, the time required to determine the relative position between the specimen support hinge and the specimen support jig 3 is reduced. Positioning is possible simply by setting the distance, reducing the time required for test preparation.

[0013]

In short, according to the present invention, a specimen having a shape in which an artificial peeling defect is formed at one end and the lower part of the artificial peeling defect is shortened is used, and the upper part of the artificial peeling defect and the other end of the specimen are While supporting the specimen with a support jig, a load was applied to the center of the specimen using a load-loading jig, and the load when the artificial peeling defect grew was measured. By evaluating the delamination fracture toughness under mixed failure modes, we can eliminate the complexity and inaccuracy caused by the use of specimen support hinges, and perform a simpler and more accurate evaluation test for delamination fracture toughness. This provides a delamination fracture toughness test method that can reduce test time and costs.
The present invention is extremely useful industrially.

[Brief explanation of drawings]

FIG. 1 is a perspective view of a test situation according to a first embodiment of the delamination fracture toughness test method of the present invention.

FIG. 2 is a perspective view of a test situation according to a second embodiment.

FIG. 3 is a perspective view of a test situation according to a third embodiment.

FIG. 4 is a perspective view of a test situation according to a fourth embodiment.

FIG. 5 is a perspective view showing a conventional test situation.

[Explanation of symbols]

1 Specimen 1a Honeycomb core 1b Outer panel 1c flat plate 1d Adhesive joint 2 Artificial peeling defect 3 Specimen support jig 4 Load loading jig 5 Load load 6. Destruction mode adjustment jig 7 Load for fracture mode adjustment 8 Specimen support hinge

Claims (1)

[Claims] Claim 1: Using a specimen in which an artificial peeling defect is formed at one end and the lower part of the artificial peeling defect is shortened, the upper part of the artificial peeling defect and the other end of the specimen are connected using a specimen support jig. While supporting the specimen, a load was applied to the central part of the specimen using a load-bearing jig, and the applied load was measured when the artificial peeling defect grew. A delamination fracture toughness test method characterized by evaluating delamination fracture toughness.