Four-point bending test piece connected by composite material
By designing a composite four-point bending test piece with a frame, long string, skin and reinforcing ring structure, the problems of easy debonding and loading difficulty in the connection between the long string and the skin were solved, the stability of the loading point and the constraint point was achieved, and the load-bearing capacity was accurately obtained.
Patent Information
- Application Number
- CN202422688920.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-05
- Publication Date
- 2025-09-30
- Estimated Expiration
- 2034-11-05
AI Technical Summary
When existing aircraft composite panels are subjected to out-of-plane loads, the connections between the long stringers and the skin are prone to debonding, the four-point bending test pieces are difficult to load, and the damage location is difficult to control.
A four-point bending test specimen for composite material connection is designed. The frame, stringer, skin and reinforcement ring structure are connected by co-curing and co-bonding. Reinforcement rings are placed on the stringer and skin components and filled with adhesive. A test fixture is used to provide simple support constraints.
The stability of the loading points and constraint points is achieved, the authenticity of the loading is ensured, and the bearing capacity of the composite material connection joint under bending load is accurately obtained.
Smart Images
Figure CN223396375U_ABST
Abstract
Description
Technical Field
[0001] The present application belongs to the technical field of aviation structure design, and in particular relates to a four-point bending test piece connected with composite materials. Background Art
[0002] In the design of aircraft composite panels, the skin and frame, as well as the skin and stringers, are generally co-cured or co-glued. When the panel is subjected to out-of-plane loads such as airtightness, the connection area between the stringers and the skin is subjected to bending loads, and the bonding surface between the stringers and the skin is prone to debonding under the bending load. Generally, the risk of model development is reduced by conducting tests and assessments on test pieces under the same load-transfer form after the structural form is simplified in the model design. For panel structures that bear out-of-plane loads, four-point bending test pieces are usually used to simulate their loading form. Since the test piece is asymmetrical up and down, loading the test piece is more difficult. It is necessary to design the loading area adaptively and ensure that the damaged part of the test piece is within the assessment area. This is an important part of the test piece design.
[0003] Therefore, it is desired to have a technical solution to overcome or at least alleviate at least one of the above-mentioned deficiencies of the prior art. Utility Model Content
[0004] The purpose of the present application is to provide a four-point bending test piece connected with composite materials to solve at least one problem existing in the prior art.
[0005] The technical solution of this application is:
[0006] A four-point bending test piece for composite material connection, comprising:
[0007] a frame having a first frame connecting portion and a second frame connecting portion perpendicular to each other;
[0008] The long stringers include two long stringers, each having a first long stringer connecting portion and a second long stringer connecting portion perpendicular to each other, and the two long stringers are respectively arranged on both sides of the frame, wherein the end of the first long stringer connecting portion is overlapped on the first frame connecting portion, and the second long stringer connecting portion is connected to the second frame connecting portion through a T-shaped joint;
[0009] a skin, the skin being connected to the first frame connection portion of the frame and the first long stringer connection portions of the two long stringers respectively;
[0010] The reinforcement ring has a closed annular cross-section and is sleeved on an assembly consisting of the stringer and the skin, with a gap between the reinforcement ring and the assembly being filled with adhesive.
[0011] In one embodiment of the present application, the stringer and the skin are both made of composite materials.
[0012] In one embodiment of the present application, the skin and the first frame connection portion are connected by co-curing.
[0013] In one embodiment of the present application, the skin and the first stringer connection portion are connected by co-bonding.
[0014] In one embodiment of the present application, the first long string connection part and the second long string connection part of the long string are locally thickened at locations corresponding to the reinforcement ring.
[0015] In one embodiment of the present application, the two long stringers and the skin constitute a first component and a second component respectively, wherein the first component is provided with two reinforcement rings, and the second component is provided with two reinforcement rings, and the reinforcement rings on the first component and the second component are symmetrically arranged.
[0016] In one embodiment of the present application, the reinforcement ring is a rectangular ring structure.
[0017] In one embodiment of the present application, a test fixture is further included. The test fixture is respectively arranged at the top and bottom of the reinforcement ring, and is used to provide a simply supported constraint for the test piece when a test load acts on the test piece.
[0018] The utility model shall have at least the following beneficial technical effects:
[0019] The four-point bending test piece of the composite material connection of the present application does not slip at the loading point and the constraint point under constraint and loading, ensuring the authenticity of constraint and loading, and can accurately obtain the bearing capacity of the composite material connection joint under bending load. BRIEF DESCRIPTION OF THE DRAWINGS
[0020] Figure 1 This is an overall schematic diagram of a four-point bending test piece connected with composite materials according to one embodiment of the present application;
[0021] Figure 2 is a schematic diagram of a T-shaped connector according to one embodiment of the present application;
[0022] Figure 3 is a schematic diagram of a reinforcement ring according to one embodiment of the present application;
[0023] Figure 4 It is a schematic diagram of constrained loading of a four-point bending test piece of composite material connection according to one embodiment of the present application.
[0024] in:
[0025] 1-long stringer; 2-skin; 3-frame; 4-T-joint; 5-reinforcement ring; 6-test fixture; 7-test load. DETAILED DESCRIPTION
[0026] In order to make the purpose, technical solutions and advantages of the implementation of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below in conjunction with the drawings in the embodiments of this application. In the drawings, the same or similar reference numerals throughout represent the same or similar elements or elements with the same or similar functions. The described embodiments are part of the embodiments of this application, not all of the embodiments. The embodiments described below with reference to the drawings are exemplary and are intended to be used to explain this application, and should not be understood as limitations on this application. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application. The embodiments of this application are described in detail below in conjunction with the drawings.
[0027] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation. Therefore, it should not be understood as limiting the scope of protection of this application.
[0028] The following is combined with Figures 1 to 4 This application is described in further detail.
[0029] The present application provides a four-point bending test piece of composite material connection, comprising: a frame 3 , a long stringer 1 , a skin 2 and a reinforcement ring 5 .
[0030] Specifically, such as Figure 1 As shown, the four-point bending test piece of the composite material connection is designed to be bilaterally symmetrical. The cross section of the frame 3 is T-shaped, and it has a first frame connection part and a second frame connection part that are perpendicular to each other; the cross section of the long stringer 1 is T-shaped, and it has a first long stringer connection part and a second long stringer connection part that are perpendicular to each other. The long stringer 1 includes two, and the two long stringers 1 are symmetrically arranged on both sides of the frame 3, wherein the end of the first long stringer connection part of the long stringer 1 overlaps the first frame connection part of the frame 3, and the second long stringer connection part of the long stringer 1 is connected to the second frame connection part of the frame 3 through a T-shaped joint 4. The T-shaped joint 4 has a first joint connection part and a second joint connection part that are perpendicular to each other. The first joint connection part is connected to the second frame connection part of the frame 3 by bolts, and the second joint connection part is connected to the second long stringer connection part of the long stringer 1 by bolts.
[0031] The skin 2 is an integral structure, which is arranged at the bottom of the integral structure composed of the frame 3 and the two long girders 1. The skin 2 is respectively connected to the first frame connection part of the frame 3 and the first long girders connection part of the two long girders 1. The reinforcement ring 5 has a closed annular cross-section. The reinforcement ring 5 is mounted on the assembly composed of the long girders 1 and the skin 2, and the gap between the reinforcement ring 5 and the assembly is filled with adhesive. The specific filling method is that after the reinforcement ring 5 is mounted on the assembly composed of the long girders 1 and the skin 2, the openings at both ends of the reinforcement ring 5 are sealed by baffles, and an adhesive filling port is left on the baffle. The adhesive is passed through the filling port to fill the gap between the entire structure composed of the reinforcement ring 5, the long girders 1 and the skin 2. After the adhesive is cured, the baffle is removed. The reinforcement ring 5 is mainly used to apply the load when the four-point bending test piece connected by the composite material is subjected to a four-point bending test.
[0032] In a preferred embodiment of the present application, the stringer 1 and the skin 2 are both made of composite materials. The skin 2 is connected to the first frame connection portion by co-curing, and the skin 2 is connected to the first stringer connection portion by co-bonding.
[0033] In a preferred embodiment of the present application, the first stringer connecting portion and the second stringer connecting portion of the stringer 1 are locally ply-thickened at locations corresponding to the reinforcement rings 5 .
[0034] It is understood that multiple reinforcement rings 5 can be provided, and the specific number of reinforcement rings 5 can be adaptively selected based on the length of the stringer 1. In a preferred embodiment of the present application, two stringers 1 and the skin 2 constitute a first assembly and a second assembly, respectively. Two reinforcement rings 5 are sleeved on the first assembly, and two reinforcement rings 5 are sleeved on the second assembly. The reinforcement rings 5 on the first and second assemblies are arranged symmetrically, with a predetermined spacing between two reinforcement rings 5 on the same assembly. Advantageously, in this embodiment, the reinforcement rings 5 are rectangular ring structures, with multiple flat surfaces facilitating connection and loading.
[0035] The four-point bending test piece of the composite material connection of this application, such as Figure 4 As shown, the test fixture 6 is also included. The test fixture 6 is respectively installed at the top and bottom of the reinforcement ring 5 to provide a simply supported constraint for the test piece when the test load 7 acts on the test piece. It can be understood that during the four-point bending test, the test fixture 6 is installed on two symmetrically arranged reinforcement rings 5, and the test load 7 is applied simultaneously to the other two symmetrically arranged reinforcement rings 5.
[0036] The four-point bending test piece of the composite material connection of the present application does not slip at the loading point and the constraint point under constraint and loading, ensuring the authenticity of constraint and loading, and can accurately obtain the bearing capacity of the composite material connection joint under bending load.
[0037] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of the present application. Therefore, the scope of protection of the present application should be based on the scope of protection of the claims.
Claims
1. A four-point bending test piece for composite material connection, characterized in that: include: A frame (3), wherein the frame (3) has a first frame connecting portion and a second frame connecting portion that are perpendicular to each other; The long girder (1) comprises two long girders (1), each of which has a first long girder connection portion and a second long girder connection portion perpendicular to each other, and the two long girders (1) are respectively arranged on both sides of the frame (3), wherein the end of the first long girder connection portion is overlapped on the first frame connection portion, and the second long girder connection portion is connected to the second frame connection portion via a T-shaped joint (4); A skin (2), the skin (2) being connected to the first frame connection portion of the frame (3) and the first long stringer connection portions of the two long strings (1); A reinforcement ring (5) having a closed annular cross-section is provided. The reinforcement ring (5) is sleeved on an assembly consisting of the long stringer (1) and the skin (2), and a gap between the reinforcement ring (5) and the assembly is filled with an adhesive.
2. The four-point bending test piece for composite material connection according to claim 1, characterized in that: The long stringer (1) and the skin (2) are both made of composite materials.
3. The four-point bending test piece for composite material connection according to claim 1, characterized in that: The skin (2) and the first frame connection portion are connected by co-curing.
4. The four-point bending test piece for composite material connection according to claim 1, characterized in that: The skin (2) is connected to the first long stringer connection portion by means of co-bonding.
5. The four-point bending test piece for composite material connection according to claim 1, characterized in that: The first long stringer connection part and the second long stringer connection part of the long stringer (1) are locally ply-thickened at locations corresponding to the reinforcement ring (5).
6. The four-point bending test piece for composite material connection according to claim 1, characterized in that: The two long stringers (1) and the skin (2) respectively constitute a first component and a second component, wherein the first component is provided with two reinforcement rings (5), and the second component is provided with two reinforcement rings (5), and the reinforcement rings (5) on the first component and the second component are symmetrically arranged.
7. The four-point bending test piece for composite material connection according to claim 1, characterized in that: The reinforcement ring (5) is a rectangular ring structure.
8. The four-point bending test piece for composite material connection according to claim 1, characterized in that: The invention also comprises a test fixture (6), which is respectively arranged at the top and bottom of the reinforcement ring (5) and is used to provide a simple support constraint for the test piece when a test load (7) acts on the test piece.