Method and device for determining prying-off strength of composite laminated plate

Abstract

The invention belongs to the field of composite material structural strength design, and particularly relates to a method and device for determining prying-off strength of a composite material laminated plate. The method comprises the following steps: S1, determining a prying damage load for prying a cantilever beam manufactured by a composite material laminated plate at a specified position until the cantilever beam is damaged; s2, calculating a prying failure bending moment according to the prying failure load; s3, determining a shearing force caused by the prying damage bending moment at the fixed end of the cantilever beam; and S4, determining the prying strength according to the prying failure load and the shearing force. According to the method, the prying-off strength of the composite laminated plate can be rapidly calculated.

Description

Technical Field

[0001] This application belongs to the field of composite material structural strength design, and specifically relates to a method and apparatus for determining the pry-off strength of composite laminates. Background Technology

[0002] Composite laminate structures are widely used in the aerospace field due to their significant high specific stiffness and specific strength. With the continuous expansion of the application of composite laminate structures, a pry-out failure mode is prone to occur at bolted connections. When subjected to shear or bending loads, composite laminate structures may experience pry-out failure. In order to improve the strength design of composite laminate structures, it is necessary to determine the pry-out strength of composite laminate structures. Summary of the Invention

[0003] To address the aforementioned issues, this application provides a method and apparatus for determining the pry-off strength of composite laminates, which can be used to guide the design of connection strength in composite material structures.

[0004] The first aspect of this application provides a method for determining the pry-off strength of composite laminates, mainly including:

[0005] Step S1: Determine the pry-off failure load at which the cantilever beam made of composite laminate is pried off at a specified location until failure occurs;

[0006] Step S2: Calculate the pry-out failure moment based on the pry-out failure load;

[0007] Step S3: Determine the shear force at the fixed end of the cantilever beam caused by the pry-off failure moment;

[0008] Step S4: Determine the pry-off strength based on the pry-off failure load and the shear force.

[0009] Preferably, in step S2, the pry-off failure moment is determined using the following formula. :

[0010] ;

[0011] in, In order to pry off the destructive load, The distance between the location where the load is applied to pry off the cantilever beam and the fixed point of the cantilever beam.

[0012] Preferably, in step S3, the shear force is determined using the following formula. :

[0013] ;

[0014] in, To pry off the failure bending moment, The length of the cantilever beam on the shorter side at the fixed point, where "end side" refers to the side of the cantilever beam that is fully attached to the connected structure and located opposite the pry-off end. Let R be the side length of the inscribed square within the radius R of the bolt head.

[0015] Preferably, in step S4, the pry strength is determined using the following formula. :

[0016] ;

[0017] Wherein, is the sum of the pry-off failure load and the shear force. The thickness is the thickness of the cantilever beam.

[0018] The second aspect of this application provides a device for determining the pry-off strength of composite laminates, mainly comprising:

[0019] The pry-off failure load determination module is used to determine the pry-off failure load required to pry off a cantilever beam made of composite laminate at a specified location until failure occurs.

[0020] The pry-out failure bending moment determination module is used to calculate the pry-out failure bending moment based on the pry-out failure load;

[0021] The shear force determination module is used to determine the shear force at the fixed end of the cantilever beam caused by the pry-off failure moment;

[0022] The pry-off strength determination module is used to determine the pry-off strength based on the pry-off failure load and the shear force.

[0023] Preferably, in the pry-out failure bending moment determination module, the pry-out failure bending moment is determined by the following formula. :

[0024] ;

[0025] in, In order to pry off the destructive load, The distance between the location where the load is applied to pry off the cantilever beam and the fixed point of the cantilever beam.

[0026] Preferably, in the shear force determination module, the shear force is determined using the following formula. :

[0027] ;

[0028] in, To pry off the failure bending moment, The length of the cantilever beam on the shorter side at the fixed point, where "end side" refers to the side of the cantilever beam that is fully attached to the connected structure and located opposite the pry-off end. Let R be the side length of the inscribed square within the radius R of the bolt head.

[0029] Preferably, in the pry-out strength determination module, the pry-out strength is determined by the following formula. :

[0030] ;

[0031] Wherein, is the sum of the pry-off failure load and the shear force. The thickness is the thickness of the cantilever beam.

[0032] This application can quickly calculate the pry-off strength of composite laminates, providing a reference for the design of structural parameters and selection of connectors for composite laminates. Attached Figure Description

[0033] Figure 1 This is a flowchart of a preferred embodiment of the method for determining the pry-off strength of composite laminates in this application.

[0034] Figure 2 yes Figure 1 A schematic diagram of the pry-off strength calculation model for the composite laminate in the embodiment shown.

[0035] Figure 3 This is a schematic diagram of the pry-off failure mode of composite laminates. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this application clearer, the technical solutions in the embodiments of this application will be described in more detail below with reference to the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The described embodiments are only some, not all, of the embodiments of this application. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain this application, and should not be construed as limiting this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. The embodiments of this application will be described in detail below with reference to the accompanying drawings.

[0037] The first aspect of this application provides a method for determining the pry-off strength of composite laminates, such as... Figure 1 As shown, it mainly includes:

[0038] Step S1: Determine the pry-off failure load at which the cantilever beam made of composite laminate is pried off at a specified location until failure occurs;

[0039] Step S2: Calculate the pry-out failure moment based on the pry-out failure load;

[0040] Step S3: Determine the shear force at the fixed end of the cantilever beam caused by the pry-off failure moment;

[0041] Step S4: Determine the pry-off strength based on the pry-off failure load and the shear force.

[0042] In step S1 of this application, a pry-off strength analysis model for the composite laminate structure is first constructed. Typically, the composite laminate structure can be simplified as a cantilever beam fixed at one end, such as... Figure 2 As shown, the composite laminate is connected to the structure by a single bolt, with the bolt axis at a distance of [distance missing] from the end of the connection point. The connected structure remains fixed. The distance from the bolt axis to the composite laminate is... A shear force perpendicular to the plane of the composite laminate is applied at the point. .

[0043] Subsequently, the pry-off failure load of the composite laminate structure was obtained.

[0044] shear force Keeping the direction unchanged, continuously increasing its load, when the shear force Increase to At that time, the composite laminate structure experienced a pry-out failure mode, such as... Figure 3 As shown, it is called This refers to the pry-out failure load of a composite laminate structure. A typical pry-out failure mode for a composite laminate structure is that the composite laminate is damaged or destroyed near the load side at the bolt connection, and the bolt head is embedded in or detached from the composite laminate.

[0045] Therefore, the pry-off failure moment can be calculated in step S2.

[0046] In some alternative implementations, in step S2, the pry-off failure moment is determined using the following formula. :

[0047] ;

[0048] in, In order to pry off the destructive load, The distance between the location where the load is applied to pry off the cantilever beam and the fixed point of the cantilever beam.

[0049] Next, in step S3, the shear force is calculated.

[0050] In some alternative implementations, in step S3, the shear force is determined using the following formula. :

[0051] ;

[0052] in, To pry off the failure bending moment, The length of the cantilever beam on the shorter side at the fixed point, where "end side" refers to the side of the cantilever beam that is fully attached to the connected structure and located opposite the pry-off end. Let R be the side length of the inscribed square within the radius R of the bolt head.

[0053] In this embodiment, the bolt head radius is measured. The drawing radius is Draw an inscribed square within the circle, with a side length of . ,but This application considers the bending moment at the bolted connection to be determined by the bending length of the bolt. The distance bears the shear force caused by the pry-off moment of the composite laminate. for:

[0054] .

[0055] Finally, in step S4, the pry-off strength is calculated.

[0056] In some alternative implementations, in step S4, the pry-off strength is determined using the following formula. :

[0057] ;

[0058] Wherein, is the sum of the pry-off failure load and the shear force. The thickness is the thickness of the cantilever beam.

[0059] Total shear force of composite laminate pry-out failure External shear force and shear force caused by pry-off failure moment It consists of two parts:

[0060] .

[0061] This application argues that when a composite laminate is subjected to external shear force, the prying stress at the bolted connection exceeds the prying strength. The composite laminate experienced pry-out failure. The pry-out strength of the composite laminate is:

[0062] .

[0063] This application presents a method for calculating the pry-out strength of composite laminate structures under external shear force. This method can quickly calculate the pry-out strength of composite laminates, providing a design approach for composite laminate structure parameter design, connector selection, and pry-out failure load calculation. Compared to the commonly used finite element method, it is faster and requires less technical expertise from designers.

[0064] In a specific calculation example, the thickness of a certain composite laminate is obtained. =4.08mm, the root of the bolt head radius A bolt connection with a diameter of 3.855mm is used, with the bolt axis 18mm from the end of the connection. The distance from the bolt axis is... Shear force is applied at a point of 152 mm.

[0065] Obtaining the pry-out failure load of composite laminate structure =590N;

[0066] Calculate the pry-out failure moment of composite laminates =590×152=89680N·mm;

[0067] Calculate the shear force caused by the pry-out failure moment. =4327.04N;

[0068] Calculate the total shear force of the pry-out failure. =590+4=4917.04N;

[0069] Calculate the pry-off strength of composite laminates =221.09MPa.

[0070] The second aspect of this application provides a device for determining the pry-off strength of composite laminates corresponding to the above method, mainly comprising:

[0071] The pry-off failure load determination module is used to determine the pry-off failure load required to pry off a cantilever beam made of composite laminate at a specified location until failure occurs.

[0072] The pry-out failure bending moment determination module is used to calculate the pry-out failure bending moment based on the pry-out failure load;

[0073] The shear force determination module is used to determine the shear force at the fixed end of the cantilever beam caused by the pry-off failure moment;

[0074] The pry-off strength determination module is used to determine the pry-off strength based on the pry-off failure load and the shear force.

[0075] In some optional embodiments, the pry-out failure bending moment determination module determines the pry-out failure bending moment using the following formula. :

[0076] ;

[0077] in, In order to pry off the destructive load, The distance between the location where the load is applied to pry off the cantilever beam and the fixed point of the cantilever beam.

[0078] In some alternative implementations, the shear force is determined in the shear force determination module using the following formula. :

[0079] ;

[0080] in, To pry off the failure bending moment, The length of the cantilever beam on the shorter side at the fixed point, where "end side" refers to the side of the cantilever beam that is fully attached to the connected structure and located opposite the pry-off end. Let R be the side length of the inscribed square within the radius R of the bolt head.

[0081] In some alternative implementations, the pry-out strength determination module determines the pry-out strength using the following formula. :

[0082] ;

[0083] Wherein, is the sum of the pry-off failure load and the shear force. The thickness is the thickness of the cantilever beam.

[0084] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A method for determining the pry-off strength of a composite laminate, characterized in that, include: Step S1: Determine the pry-off failure load at which the cantilever beam made of composite laminate is pried off at a specified location until failure occurs; Step S2: Calculate the pry-out failure moment based on the pry-out failure load; Step S3: Determine the shear force at the fixed end of the cantilever beam caused by the pry-off failure moment; Step S4: Determine the pry-off strength based on the pry-off failure load and the shear force.

2. The method for determining the pry-off strength of composite laminates as described in claim 1, characterized in that, In step S2, the pry-off failure moment is determined using the following formula. : ； in, In order to pry off the destructive load, The distance between the location where the load is applied to pry off the cantilever beam and the fixed point of the cantilever beam.

3. The method for determining the pry-off strength of composite laminates as described in claim 1, characterized in that, In step S3, the shear force is determined using the following formula. : ； in, To pry off the failure bending moment, The length of the cantilever beam on the shorter side at the fixed point, where "end side" refers to the side of the cantilever beam that is fully attached to the connected structure and located opposite the pry-off end. Let R be the side length of the inscribed square within the radius R of the bolt head.

4. The method for determining the pry-off strength of composite laminates as described in claim 1, characterized in that, In step S4, the pry-off strength is determined using the following formula. : ； Wherein, is the sum of the pry-off failure load and the shear force. The thickness is the thickness of the cantilever beam.

5. A device for determining the pry-off strength of composite laminates, characterized in that, include: The pry-off failure load determination module is used to determine the pry-off failure load required to pry off a cantilever beam made of composite laminate at a specified location until failure occurs. The pry-out failure bending moment determination module is used to calculate the pry-out failure bending moment based on the pry-out failure load; The shear force determination module is used to determine the shear force at the fixed end of the cantilever beam caused by the pry-off failure moment; The pry-off strength determination module is used to determine the pry-off strength based on the pry-off failure load and the shear force.

6. The apparatus for determining the pry-off strength of composite laminates as described in claim 5, characterized in that, In the pry-out failure bending moment determination module, the pry-out failure bending moment is determined by the following formula. : ； in, In order to pry off the destructive load, The distance between the location where the load is applied to pry off the cantilever beam and the fixed point of the cantilever beam.

7. The composite laminate pry-off strength determining device as described in claim 5, characterized in that, In the shear force determination module, the shear force is determined using the following formula. : ； in, To pry off the failure bending moment, The length of the cantilever beam on the shorter side at the fixed point, where "end side" refers to the side of the cantilever beam that is fully attached to the connected structure and located opposite the pry-off end. Let R be the side length of the inscribed square within the radius R of the bolt head.

8. The apparatus for determining the pry-off strength of composite laminates as described in claim 5, characterized in that, In the pry-out strength determination module, the pry-out strength is determined by the following formula. : ； Wherein, is the sum of the pry-off failure load and the shear force. The thickness is the thickness of the cantilever beam.

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