Tenon joint node fatigue damage evolution finite element simulation method and system

Abstract

The invention discloses a finite element simulation method and system for fatigue damage evolution of a tenon joint node, and the method comprises the steps: pulling a tenon out of a tenon hole under the condition of high-cycle fatigue due to the change of a friction coefficient and a matching relation; the process that the friction coefficient and the matching amount between the tenon and the mortise change along with fatigue damage evolution is considered in the simulation model; the fatigue performance (friction coefficient, matching amount and service life) in the simulation model is influenced by the load amplitude; establishing a finite element simulation model by using implicit dynamics analysis steps; modifying a friction coefficient in the contact attribute into a function numerical value which changes along with the change of the loading time; modifying the matching quantity amplitude in the contact attribute into a function numerical value which changes along with the change of the loading time; carrying out numerical simulation on the fatigue working condition of the mortise and tenon joint in an implicit dynamic analysis step mode, wherein the simulation comprises a complete fatigue working condition process; therefore, the state of the mortise and tenon joint under any loading times is obtained. According to the method, the operation efficiency is improved, and fatigue damage evolution and life prediction of the tenon joint node are simulated from the perspective of dynamics.

Description

Technical Field

[0001] The present invention relates to the field of fatigue simulation analysis of wooden furniture and wooden building structures, and in particular to a finite element simulation method and system for fatigue damage evolution and life prediction of mortise and tenon joints. Background Art

[0002] Low-load, high-cycle fatigue conditions are the main reason for the reduction in furniture structural strength. The durability of furniture is even more important in the design and evaluation of furniture. However, testing the fatigue mechanical properties of furniture structures is an expensive and time-consuming experiment. The furniture structure test cycle is long and requires repeated testing, and material loss increases costs. Therefore, the traditional test methods for the fatigue mechanical properties of furniture structures require high costs and time.

[0003] However, most of the existing fatigue performance prediction methods calculate the fatigue mechanical properties of components based on the fatigue life of the material. Although the fatigue mechanical properties experimental method for materials has a stronger universal applicability, in actual situations, the same material will show different fatigue mechanical properties under different structural conditions; in addition, there are many factors that affect the fatigue mechanical properties of materials, and conventional simulations are difficult to meet the actual application conditions; for furniture structures, its fatigue phenomenon is mainly manifested in the loosening of furniture structure nodes and the reduction of the bonding strength of furniture structure nodes due to long-term use. Summary of the invention

[0004] Purpose of the invention: In order to overcome the deficiencies in the prior art, the present invention provides a finite element simulation method for fatigue damage evolution of mortise and tenon joints, which can improve computational efficiency while simulating the fatigue damage evolution and life prediction of mortise and tenon joints from a dynamics perspective.

[0005] Technical solution: To achieve the above purpose, the technical solution adopted by the present invention is:

[0006] A finite element simulation method for fatigue damage evolution of mortise and tenon joints is provided. Under high cycle fatigue conditions, the tenon is pulled out of the mortise hole due to changes in the friction coefficient and the matching relationship. The simulation model considers the process in which the friction coefficient and the matching amount between the tenon and the tenon hole change with the evolution of fatigue damage. The finite element simulation model is established using an implicit dynamic analysis step. By modifying the edit keywords (Edit Keywords), the friction coefficient in the contact properties is modified to a function value that changes with the loading time (number of times). By setting the amplitude (Amplitude), the matching amount amplitude in the contact properties is modified to a function value that changes with the loading time (number of times). The fatigue condition of the mortise and tenon joint is numerically simulated in the form of a dynamic analysis step, and the simulation includes a complete fatigue condition process. Thus, the state of the mortise and tenon joint under any number of loading times is obtained, which specifically includes the following steps:

[0007] Step S1, using implicit dynamics analysis step to establish a finite element simulation model.

[0008] Step S2, establishing a time friction coefficient model of the elliptical tenon of wooden furniture according to the time and friction coefficient of the elliptical tenon of wooden furniture.

[0009] Step S3, establishing a time interference fit model of the elliptical tenon of wooden furniture according to the time and interference fit of the elliptical tenon of wooden furniture.

[0010] Step S4, creating a tenon component and a mortise component in the finite element simulation model and assembling them. Creating two implicit dynamics analysis steps, which are respectively recorded as the first implicit dynamics analysis step and the second implicit dynamics analysis step.

[0011] Step S5, setting two contact properties including normal behavior and tangential behavior, the normal behavior is set to hard contact, and the tangential behavior is set to "penalty" attribute. The two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component, the tenon shoulder surface of the tenon component and the corresponding surface of the mortise component are set as "surface contact" contact surfaces, a total of 3 pairs of contact surfaces.

[0012] Step S6, changing the contact properties of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component in the second implicit dynamics analysis step. Create a first equally spaced amplitude, and input the time friction coefficient model of the elliptical tenon of wooden furniture into the first equally spaced amplitude.

[0013] Step S7, set the matching relationship of the two pairs of arc contact surfaces in the width direction of the tenon part and the length direction of the mortise part in the first implicit dynamics analysis step to interference fit. Create a second equally spaced amplitude, and input the time interference fit model of the elliptical tenon of wooden furniture into the second equally spaced amplitude.

[0014] Step S8, set a reference point at the outer position of the other end of the tenon component, and establish a coupling constraint between the reference point and the tenon end face. Create boundary conditions and set the lower end of the mortise component to a completely fixed constraint. Apply displacement constraint boundary conditions to the reference point of the tenon component. Set the mesh type of the tenon component and the mortise component to C3D8R, set the mesh control to the frontier advancement method of hexagonal sweep, and complete the creation of the finite element simulation model.

[0015] Step S9, simulating the fatigue performance, friction coefficient and matching relationship of the mortise and tenon joint at any time according to the created finite element simulation model, and completing the fatigue damage evolution of the mortise and tenon joint.

[0016] Preferred: The fatigue failure model during damage evolution is as follows:

[0017]

[0018] Where t represents the loading time, f represents the loading frequency, β1 represents the time friction coefficient constant, β2 represents the time interference fit constant, α1 represents the time friction coefficient index, α2 represents the time interference fit index, E represents the material elastic modulus, and F y represents the load amplitude, and θ represents the rotation angle of the component after the force is applied.

[0019] Optimum: Time friction coefficient model is:

[0020]

[0021] Among them, μ represents the friction coefficient, t represents the loading time, f represents the loading frequency, β1 represents the time friction coefficient constant, and α1 represents the time friction coefficient exponent.

[0022] Optimum: Time interference fit model is:

[0023]

[0024] Among them, d represents the interference fit, t represents the loading time, f represents the loading frequency, β2 represents the time interference fit constant, and α2 represents the time interference fit index.

[0025] Preferably: the tenon component and the mortise component created in step S4 are both 3D deformable bodies. The tenon component and the mortise component are assembled, and the tenon of the tenon component is assembled into the mortise of the mortise component.

[0026] Preferably, in step S4, a material including density and mechanical elasticity is created, and the type of mechanical elasticity is orthogonal anisotropy. The material is assigned to the tenon component and the mortise component, and the material directions are assigned to them respectively.

[0027] Preferably, the tenon size of the tenon component is consistent with the mortise size of the mortise component.

[0028] Another object of the present invention is to provide a finite element simulation system for fatigue damage evolution of mortise and tenon joints, which is used to implement the finite element simulation method for fatigue damage evolution of mortise and tenon joints, including a time friction coefficient model unit, a time interference fit model unit, and a finite element simulation model unit, wherein:

[0029] The time friction coefficient model unit is used to store the time friction coefficient model of the elliptical tenon of wooden furniture.

[0030] The time interference fit quantity model unit is used to store the time interference fit quantity model of the elliptical tenon of wooden furniture.

[0031] The finite element simulation model unit is used to establish a finite element simulation model using an implicit dynamics analysis step. A tenon component and a mortise component are created in the finite element simulation model and assembled. Two implicit dynamics analysis steps are created, which are recorded as the first implicit dynamics analysis step and the second implicit dynamics analysis step respectively. Two contact properties including normal behavior and tangential behavior are set, the normal behavior is set to hard contact, and the tangential behavior is set to a "penalty" property. The two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component, and the tenon shoulder surface of the tenon component and the corresponding surface of the mortise component are set to "face-to-face contact" contact surfaces, for a total of 3 pairs of contact surfaces. The contact properties of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component are changed in the second implicit dynamics analysis step. The first equally spaced amplitude is created, and the time friction coefficient model of the elliptical tenon of wooden furniture is input into the first equally spaced amplitude. The matching relationship of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component in the first implicit dynamics analysis step is set to interference fit. Create a second equally spaced amplitude and input the time interference fit model of the elliptical tenon of wooden furniture into the second equally spaced amplitude. Set a reference point at the outer position of the other end of the tenon component and establish a coupling constraint between the reference point and the tenon end face. Create boundary conditions and set the lower end of the mortise component as a completely fixed constraint. Apply displacement constraint boundary conditions to the reference point of the tenon component. Set the mesh type of the tenon component and the mortise component to C3D8R, set the mesh control to the frontier advancement method of hexagonal sweep, and complete the creation of the finite element simulation model. According to the created finite element simulation model, simulate the fatigue performance, friction coefficient and fit relationship of the tenon joint node at any time, and complete the fatigue damage evolution of the tenon joint node.

[0032] Another object of the present invention is to provide a computer system, characterized in that it comprises a memory and a processor, wherein the memory is used to store computer programs / instructions, and the processor is used to execute the computer programs / instructions to implement the finite element simulation method for fatigue damage evolution of joints.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. According to the actual fatigue mechanical properties of wooden elliptical tenon furniture, the fatigue performance evolution and failure process of the tenon joint node are described and simulated from the perspectives of friction coefficient, interference fit and fatigue life, rather than just fatigue life, which is more in line with actual working conditions.

[0035] 2. The fatigue condition of the elliptical tenon of wooden furniture is numerically simulated in the form of dynamic analysis steps. The simulation includes the complete fatigue condition process, and the analysis process is efficient and accurate.

[0036] 3. The model can be established using the graphical user interface of general finite element software (such as ABAQUS), without the need to use other functions such as subroutines or secondary development, making it easier to master. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a finite element numerical simulation embodiment model of an embodiment of the present invention;

[0038] Figure 2 The loading times-friction coefficient function curve of the embodiment of the present invention;

[0039] Figure 3 The loading times-matching amount function curve of the embodiment of the present invention;

[0040] Figure 4 It is a structural force analysis diagram of an embodiment of the present invention;

[0041] Figure 5 This is a model failure simulation result of an embodiment of the present invention;

[0042] Figure 6 The present invention is a flowchart of a finite element numerical simulation method for fatigue performance evolution of an elliptical tenon of wooden furniture according to an embodiment of the present invention. DETAILED DESCRIPTION

[0043] The present invention is further explained below in conjunction with the accompanying drawings and specific embodiments. It should be understood that these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. After reading the present invention, various equivalent forms of modifications to the present invention by those skilled in the art all fall within the scope defined by the claims attached to this application.

[0044] A finite element simulation method for fatigue damage evolution of mortise and tenon joints, (1) Under high cycle fatigue conditions, the tenon is pulled out of the mortise due to changes in the friction coefficient and fit relationship; the simulation model considers the process of changes in the friction coefficient and fit between the tenon and the mortise as fatigue damage evolves; the finite element simulation model is established using an implicit dynamics analysis step; (2) The finite element model should contain at least one pair of tenon and mortise components; (3) The type of the tenon and mortise components is 3D deformable; (4) The material properties of the tenon and mortise components in the finite element model of the elliptical tenon of wooden furniture are elastic-plastic materials, and the type of elasticity is orthotropic; (5) The finite element model of the elliptical tenon of wooden furniture has two pairs of contact surfaces in the width direction of the tenon component and the length direction of the mortise component; (6) By modifying the edit keyword (Edit Keywords) module, modify the friction coefficient in the contact properties to a function value that changes with the loading time (number of times); (7) By setting the amplitude (Amplitude), modify the fit amount in the contact properties to a function value that changes with the loading time (number of times); (8) Apply completely fixed constraints to both ends of the mortise and tenon component, and apply fatigue load to the mortise and tenon component. The load direction should be parallel to the normal of the contact surface between the tenon and the mortise component, and the stress ratio of the fatigue load amplitude R = -1; (9) Through the time friction coefficient model of the elliptical tenon of wooden furniture and the time interference fit model of the elliptical tenon of wooden furniture, simulate the node fatigue performance, friction coefficient and fit relationship at any time, such as Figure 5 As shown in the figure, it is implemented based on ABAQUS finite element software, specifically simulating the complete process of fatigue performance evolution and failure of a wooden furniture elliptical tenon with an applied load amplitude of 200N and a fatigue life of 100,000 times, which specifically includes the following steps:

[0045] Step S1, using implicit dynamics analysis step to establish a finite element simulation model.

[0046] Step S2, establishing a time friction coefficient model of the elliptical tenon of wooden furniture according to the time and friction coefficient of the elliptical tenon of wooden furniture.

[0047] like Figure 2 As shown in the figure, the loading times-friction coefficient model of the elliptical tenon of wooden furniture is:

[0048]

[0049] in:

[0050] N = t × f;

[0051] Then the time friction coefficient model is:

[0052]

[0053] Wherein, μ represents the friction coefficient, N represents the number of loadings, t represents the loading time, f represents the loading frequency, β1 represents the time friction coefficient constant, α1 represents the time friction coefficient index, α1<0, β1>0.

[0054] Step S3, establishing a time interference fit model of the elliptical tenon of wooden furniture according to the time and interference fit of the elliptical tenon of wooden furniture.

[0055] like Figure 3 As shown in the figure, the loading times-interference fit model of the elliptical tenon of wooden furniture is:

[0056]

[0057] in:

[0058] N = t × f;

[0059] Then the time interference fit model is:

[0060]

[0061] Wherein, d represents the interference fit, N represents the number of loadings, t represents the loading time, f represents the loading frequency, β2 represents the time interference fit constant, α2 represents the time interference fit index, α2<0, β2>0.

[0062] Step S4, creating a tenon component and a mortise component in the finite element simulation model and assembling them. Creating two implicit dynamics analysis steps, which are respectively recorded as the first implicit dynamics analysis step and the second implicit dynamics analysis step.

[0063] Specifically, Figure 1 As shown, a tenon component and a mortise component are created, and both the tenon and mortise components are 3D deformable bodies (Deformable); the tenon size of the tenon component is consistent with the mortise size of the mortise component.

[0064] The tenon component and the mortise component are assembled, and the tenon of the tenon component is assembled into the mortise of the mortise component.

[0065] In step S4, a material including density and mechanical elasticity is created, and the type of mechanical elasticity is orthogonal anisotropy. The material is assigned to the tenon component and the mortise component, and the material directions are assigned to them respectively.

[0066] Create a material that contains density and mechanical elasticity. The type of mechanical elasticity is orthogonal anisotropic. Assign the material to the tenon part and the mortise part, and assign material directions to them respectively.

[0067] Create two implicit dynamics analysis steps, recorded as the first implicit dynamics analysis step and the second implicit dynamics analysis step. The time of the first implicit dynamics analysis step is set to 1S, and the time of the second implicit dynamics analysis step is set to greater than 100000S. The geometric nonlinearity (Nlgeom) of both analysis steps is set to on; the frequency of the field output and history output of the first implicit dynamics analysis step is set to every increment step (Every n increments), n is set to 1, and the frequency of the field output and history output of the second implicit dynamics analysis step is set to evenly spaced time intervals, and the interval value is set to twice the analysis step time.

[0068] Step S5, setting two contact properties including normal behavior and tangential behavior, the normal behavior is set to hard contact, and the tangential behavior is set to "penalty" attribute. The two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component, the tenon shoulder surface of the tenon component and the corresponding surface of the mortise component are set as "surface contact" contact surfaces, a total of 3 pairs of contact surfaces.

[0069] Set two contact properties including normal behavior and tangential behavior. The normal behavior is set to hard contact, and the tangential behavior is set to the "Penalty" attribute. Among them, set the friction coefficient in the "Penalty" attribute of one contact attribute to 0.3, and the other to 1.

[0070] Two pairs of arc contact surfaces in the width direction of the tenon part and the length direction of the mortise part, and the shoulder surface of the tenon part and the corresponding surface of the mortise part are set as "surface to surface contact" contact surfaces, for a total of three pairs of contact surfaces; a contact attribute with a friction coefficient of 0.3 is assigned to the three pairs of contact surfaces.

[0071] Step S6, changing the contact properties of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component in the second implicit dynamics analysis step. Create a first equally spaced amplitude, and input the time friction coefficient model of the elliptical tenon of wooden furniture into the first equally spaced amplitude.

[0072] Specifically, the contact properties of the two pairs of arc contact surfaces in the width direction of the tenon and the length direction of the mortise in the second implicit dynamics analysis step are changed to the contact properties with a friction coefficient of 1; the first equal-spaced amplitude is created, and the time friction coefficient model of the elliptical tenon of wooden furniture (such as Figure 2As shown in the figure, input it into the first equally spaced amplitude, and name the time friction coefficient model of the elliptical tenon of wooden furniture "Change of friction coefficient"; modify the keywords of the model, and add "AMPLITUDE=Change of friction coefficient" after the "*Change Friction,interaction=XXX(contact surface name)" keyword of the two pairs of arc contact surfaces in the width direction of the tenon part and the length direction of the mortise part in the second implicit dynamics analysis step.

[0073] Step S7, set the matching relationship of the two pairs of arc contact surfaces in the width direction of the tenon part and the length direction of the mortise part in the first implicit dynamics analysis step to interference fit. Create a second equally spaced amplitude, and input the time interference fit model of the elliptical tenon of wooden furniture into the second equally spaced amplitude.

[0074] Specifically, the fitting relationship of the two pairs of arc contact surfaces in the width direction of the tenon part and the length direction of the mortise part in the first implicit dynamics analysis step is set to interference fit, the fitting amount (Magnitude at start of step) is set to -0.06, and the amplitude is set to increase uniformly from 0 to 1; create a second equally spaced amplitude, input the time interference fit model of the elliptical tenon of wooden furniture into the second equally spaced amplitude, and name the time interference fit model of the elliptical tenon of wooden furniture as "Change of interference fit"; modify the amplitude of the fitting relationship of the second implicit dynamics analysis step to the amplitude of "Change of interference fit".

[0075] Step S8, set a reference point at the outer position of the other end of the tenon component, and establish a coupling constraint between the reference point and the tenon end face. Create boundary conditions and set the lower end of the mortise component to a completely fixed constraint. Apply displacement constraint boundary conditions to the reference point of the tenon component. Set the mesh type of the tenon component and the mortise component to C3D8R, set the mesh control to the frontier advancement method of hexagonal sweep, and complete the creation of the finite element simulation model.

[0076] Specifically, a reference point is set at the outer side of the other end of the tenon component, and a coupling constraint is established between the reference point and the tenon end face. A boundary condition is created to set the lower end of the mortise component as a completely fixed constraint.

[0077] Create a tabular amplitude, set a fatigue load amplitude of 20 loads every 60 seconds, each load lasting 1 second, and a stress ratio of R = -1, and name it "Fatigue load"; apply a displacement constraint boundary condition to the reference point of the tenon component, set its 3 displacement and 3 rotation degrees of freedom to 0 in analysis step 1, set its displacement in the loading direction to 1.5 in analysis step 2, and set the degrees of freedom in the other 5 directions to 0, and set the amplitude of this analysis step to the "Fatigue load" amplitude.

[0078] Set the mesh type of the tenon and mortise parts to C3D8R, set the mesh control to Hex sweep advancing front, set the mesh size to 5, and change the mesh size to 3 at the tenon and mortise positions.

[0079] Through the above steps, a finite element simulation model can be established to reflect the fatigue performance evolution and failure effects of the elliptical tenon of wooden furniture from a dynamic level.

[0080] Step S9, simulating the fatigue performance, friction coefficient and matching relationship of the mortise and tenon joint at any time according to the created finite element simulation model, and completing the fatigue damage evolution of the mortise and tenon joint.

[0081] The method for establishing the fatigue failure model during the damage evolution process is as follows:

[0082] Step S91, the formula for the pull-out force on the wooden furniture elliptical tenon in the horizontal direction is:

[0083]

[0084] In the formula, F x Indicates the horizontal pull-out force, F y represents the load amplitude, and θ represents the rotation angle of the component after the force is applied.

[0085] Step S92, the pull-out resistance model of the elliptical tenon of wooden furniture is;

[0086] F b =μ×d×E;

[0087] In the formula, F b represents the pull-out resistance of the node, μ represents the friction coefficient, d represents the interference fit amount, and E represents the elastic modulus of the material.

[0088] Step S93, during the damage evolution process, when the pull-out resistance of the wooden furniture elliptical tenon is less than or equal to the pull-out force it receives in the horizontal direction, the tenon is pulled out from the mortise, that is:

[0089] F b≤F x ;

[0090] The fatigue failure model is as follows:

[0091]

[0092] Where t represents the loading time, f represents the loading frequency, β1 represents the time friction coefficient constant, β2 represents the time interference fit constant, α1 represents the time friction coefficient index, α2 represents the time interference fit index, E represents the material elastic modulus, and F y represents the load amplitude, and θ represents the rotation angle of the component after the force is applied.

[0093] Another object of the present invention is to provide a finite element simulation system for fatigue damage evolution of mortise and tenon joints, which is used to implement the finite element simulation method for fatigue damage evolution of mortise and tenon joints, including a time friction coefficient model unit, a time interference fit model unit, and a finite element simulation model unit, wherein:

[0094] The time friction coefficient model unit is used to store the time friction coefficient model of the elliptical tenon of wooden furniture.

[0095] The time interference fit quantity model unit is used to store the time interference fit quantity model of the elliptical tenon of wooden furniture.

[0096] The finite element simulation model unit is used to establish a finite element simulation model using an implicit dynamics analysis step. A tenon component and a mortise component are created in the finite element simulation model and assembled. Two implicit dynamics analysis steps are created, which are recorded as the first implicit dynamics analysis step and the second implicit dynamics analysis step respectively. Two contact properties including normal behavior and tangential behavior are set, the normal behavior is set to hard contact, and the tangential behavior is set to a "penalty" property. The two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component, and the tenon shoulder surface of the tenon component and the corresponding surface of the mortise component are set to "face-to-face contact" contact surfaces, for a total of 3 pairs of contact surfaces. The contact properties of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component are changed in the second implicit dynamics analysis step. The first equally spaced amplitude is created, and the time friction coefficient model of the elliptical tenon of wooden furniture is input into the first equally spaced amplitude. The matching relationship of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component in the first implicit dynamics analysis step is set to interference fit. Create a second equally spaced amplitude and input the time interference fit model of the elliptical tenon of wooden furniture into the second equally spaced amplitude. Set a reference point at the outer position of the other end of the tenon component and establish a coupling constraint between the reference point and the tenon end face. Create boundary conditions and set the lower end of the mortise component as a completely fixed constraint. Apply displacement constraint boundary conditions to the reference point of the tenon component. Set the mesh type of the tenon component and the mortise component to C3D8R, set the mesh control to the frontier advancement method of hexagonal sweep, and complete the creation of the finite element simulation model. According to the created finite element simulation model, simulate the fatigue performance, friction coefficient and fit relationship of the tenon joint node at any time, and complete the fatigue damage evolution of the tenon joint node.

[0097] Another object of the present invention is to provide a computer system, characterized in that it comprises a memory and a processor, wherein the memory is used to store computer programs / instructions, and the processor is used to execute the computer programs / instructions to implement the finite element simulation method for fatigue damage evolution of joints.

[0098] When the model of this embodiment reaches 100,000 loadings, due to the reduction of the friction coefficient and the interference fit, the tenon part gradually separates from the mortise part under the action of the load. The numerical simulation effect of the model is as follows: Figure 4 shown.

[0099] The implicit dynamics analysis step is used to establish the finite element simulation model. Different from the traditional table-based analysis method for fatigue life analysis based on the SN curve (such as the Fatigue module of Ansys workbench and the Fe-safe module of ABAQUS), it is based on the general static and dynamic simulation modules. Therefore, the simulation can include the entire development process of the model fatigue damage evolution. In addition, all the settings and adjustments of the static and dynamic analysis modules are retained. Users can adjust, modify and redevelop the model as needed. The model can be established using the graphical user interface of general finite element software (such as ABAQUS), without the need to use subroutines or other functions such as secondary development, which is easier to master.

[0100] The present invention can intuitively reflect the fatigue performance evolution process of the tenon joint at the dynamic level according to the fatigue mechanical performance characteristics of the tenon joint structure, including the attenuation of the friction coefficient and the interference and the failure of the structural mechanical performance. While improving the computational efficiency, the fatigue damage evolution and life prediction of the tenon joint are simulated from the perspective of dynamics.

[0101] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A finite element simulation method for fatigue damage evolution of mortise and tenon joints, characterized in that: The following steps are involved: Step S1, using implicit dynamics analysis step to establish a finite element simulation model; Step S2, establishing a time friction coefficient model of the wooden furniture elliptical tenon according to the time and friction coefficient of the wooden furniture elliptical tenon; Step S3, establishing a time interference fit model of the elliptical tenon of wooden furniture according to the time and interference fit of the elliptical tenon of wooden furniture; Step S4, creating a tenon component and a mortise component in the finite element simulation model and assembling them; creating two implicit dynamics analysis steps, which are respectively recorded as the first implicit dynamics analysis step and the second implicit dynamics analysis step; Step S5, setting two contact properties including normal behavior and tangential behavior, the normal behavior is set to hard contact, and the tangential behavior is set to "penalty" attribute; setting two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component, and the tenon shoulder surface of the tenon component and the corresponding surface of the mortise component as "surface contact" contact surfaces, a total of 3 pairs of contact surfaces; Step S6, changing the contact properties of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component in the second implicit dynamics analysis step; creating a first equally spaced amplitude, and inputting the time friction coefficient model of the elliptical tenon of wooden furniture into the first equally spaced amplitude; Step S7, setting the matching relationship of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component in the first implicit dynamics analysis step to interference fit; creating a second equally spaced amplitude, and inputting the time interference fit model of the elliptical tenon of wooden furniture into the second equally spaced amplitude; Step S8, set a reference point at the outer position of the other end of the tenon component, establish a coupling constraint between the reference point and the tenon end face; create boundary conditions, set the lower end of the mortise component as a completely fixed constraint; apply a displacement constraint boundary condition load of a fatigue condition to the reference point of the tenon component; set the mesh type of the tenon component and the mortise component to C3D8R, set the mesh control to the front advancing method of hexagonal sweeping, and complete the creation of the finite element simulation model; Step S9, simulating the fatigue performance, friction coefficient and matching relationship of the mortise and tenon joint at any time according to the created finite element simulation model, and completing the fatigue damage evolution of the mortise and tenon joint.

2. The finite element simulation method for fatigue damage evolution of mortise and tenon joints according to claim 1 is characterized in that: The fatigue failure model during the damage evolution process is as follows: Among them, t represents the loading time, f represents the loading frequency, β1 represents the time friction coefficient constant, β2 represents the time interference fit constant, α1 represents the time friction coefficient index, α2 represents the time interference fit index, E represents the material elastic modulus, Fy represents the load amplitude, and θ represents the rotation angle generated after the component is subjected to force.

3. The finite element simulation method for fatigue damage evolution of mortise and tenon joints according to claim 2 is characterized in that: The time friction coefficient model is: Among them, μ represents the friction coefficient, t represents the loading time, f represents the loading frequency, β1 represents the time friction coefficient constant, and α1 represents the time friction coefficient exponent.

4. The finite element simulation method for fatigue damage evolution of mortise and tenon joints according to claim 3 is characterized by: The time interference fit model is: Among them, d represents the interference fit, t represents the loading time, f represents the loading frequency, β2 represents the time interference fit constant, and α2 represents the time interference fit index.

5. The finite element simulation method for fatigue damage evolution of mortise and tenon joints according to claim 4 is characterized in that: The tenon component and the mortise component created in step S4 are both 3D deformable bodies; the tenon component and the mortise component are assembled, and the tenon of the tenon component is assembled into the mortise of the mortise component.

6. The finite element simulation method for fatigue damage evolution of mortise and tenon joints according to claim 5 is characterized in that: In step S4, a material including density and mechanical elasticity is created, and the type of mechanical elasticity is orthogonal anisotropy; the material is assigned to the tenon component and the mortise component, and material directions are assigned to them respectively.

7. The finite element simulation method for fatigue damage evolution of mortise and tenon joints according to claim 6 is characterized in that: The tenon size of the tenon component and the mortise size of the mortise component are consistent.

8. A finite element simulation system for fatigue damage evolution of mortise and tenon joints, characterized by: A finite element simulation method for fatigue damage evolution of a mortise and tenon joint node according to any one of claims 1 to 6, comprising a time friction coefficient model unit, a time interference fit model unit, and a finite element simulation model unit, wherein: The time friction coefficient model unit is used to store the time friction coefficient model of the elliptical tenon of wooden furniture; The time interference fit model unit is used to store the time interference fit model of the elliptical tenon of wooden furniture; The finite element simulation model unit is used to establish a finite element simulation model using an implicit dynamics analysis step; create a tenon component and a mortise component in the finite element simulation model and assemble them; create two implicit dynamics analysis steps, which are respectively recorded as the first implicit dynamics analysis step and the second implicit dynamics analysis step; set two contact properties including normal behavior and tangential behavior, the normal behavior is set to hard contact, and the tangential behavior is set to a "penalty" property; set two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component, and the tenon shoulder surface of the tenon component and the corresponding surface of the mortise component as "face-to-face contact" contact surfaces, for a total of three pairs of contact surfaces; change the contact properties of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component in the second implicit dynamics analysis step; create a first equally spaced amplitude, and input the time friction coefficient model of the elliptical tenon of wooden furniture into the first equally spaced amplitude. In the spacing amplitude; the matching relationship of the two pairs of arc contact surfaces in the width direction of the tenon component and the length direction of the mortise component in the first implicit dynamics analysis step is set to interference fit; create a second equally spaced amplitude, and input the time interference fit model of the elliptical tenon of wooden furniture into the second equally spaced amplitude; set a reference point at the outer position of the other end of the tenon component, and establish a coupling constraint between the reference point and the tenon end face; create boundary conditions, and set the lower end of the mortise component to a completely fixed constraint; apply displacement constraint boundary conditions to the reference point of the tenon component; set the mesh type of the tenon component and the mortise component to C3D8R, and set the mesh control to the frontier advancement method of hexagonal sweeping to complete the creation of the finite element simulation model; simulate the fatigue performance, friction coefficient and matching relationship of the mortise joint node at any time according to the created finite element simulation model, and complete the fatigue damage evolution of the mortise joint node.

9. A computer system, characterized in that: It comprises a memory and a processor, wherein the memory is used to store computer programs / instructions; and the processor is used to execute the computer programs / instructions to implement the finite element simulation method for fatigue damage evolution of a joint node as described in any one of claims 1-7.

Images