A calculation method for the stress condition of ballastless track fastener system

Abstract

The present invention provides a method for calculating the stress condition of a ballastless track fastener system, comprising the following steps: establishing a beam-rail integrated calculation model; inputting rotation angle parameters θ1 and θ2 occurring at both ends of a beam body; calculating the vertical displacement Δy of each fastener on the rail according to the beam-rail integrated calculation model and the rotation angle parameters; simulating and solving the state of each fastener according to the vertical displacement Δy of each fastener and the stiffness coefficient K of each fastener; and calculating the additional force F exerted on each fastener on the rail according to the state of each fastener. f By considering the joint effects of the bridge, rails and fastener system as a whole, a beam-rail integrated calculation model is established. This model is basically consistent with the actual situation, which improves the consistency between the model and the actual situation and can accurately check the stress conditions of the fasteners and rails; further, it also improves the calculation accuracy and simplifies the calculation process.

Description

Technical Field

[0001] The present application relates to the field of railway transportation technology, and in particular to a method for calculating the stress condition of a ballastless track fastener system. Background Art

[0002] According to the "Railway Bridge and Culvert Design Code" and "High-speed Railway Design Code", under the action of vertical static and live loads of trains, the vertical rotation angle of the bridge beam end needs to meet the limit requirements. The vertical rotation angle is as follows: Figure 1 For ballastless track bridges, when the rotation angle limit at the beam end does not meet the requirements in the regulations, the forces on the beam end track structure and fastener system should be checked and calculated.

[0003] Generally, bridge sections are arranged above every two adjacent bridge piers through the support under the beam, and the ends of every two adjacent bridge sections are butted on a common bridge pier to form the entire bridge. In addition, structures such as ballastless track and rails are arranged above the bridge, and the rails are fixed on the bridge through a fastener system (the fastener system includes multiple fasteners distributed along the rails). Due to the large angular deformation at the end of a large-span steel bridge, the angular deformation of the beam end will cause the rails to deflect or move downward as a whole, and the vertical deformation of the rails will be transmitted and distributed through each fastener node. Therefore, within a certain range on both sides of the beam seam at the joint of two adjacent bridge sections on a bridge pier, additional pull-out force or downward force will be generated at the fastener node of the rail, and at the same time, the fastener system buckled on the rail will be subjected to additional forces with different distributions, and the pull-out force will damage the fastener system, thereby affecting the stability, safety and smoothness of the train.

[0004] In the prior art, Germany has studied the relationship between bridge deformation and track interaction, proposed a corresponding calculation method, and put forward corresponding limit requirements for beam end deformation. In order to meet the comfort of passengers, Japan controls the vertical rotation angle of the beam end support section and the vertical relative displacement of the beam end support section of the bridge. In general, the above research is carried out by establishing a finite element analysis model of the influence of the beam end rotation angle on the force of the fastener system. However, the modeling of this model is relatively complex, and the bridge and the track are not studied in association, making it difficult to control the pull-out force and rotation limit of the beam end fastener. In addition, although some displacement calculation models have been proposed in China, in the actual stress condition of the beam end track structure, the influence of the stiffness of the rail at the support point on the magnitude and direction distribution of the support additional force is often very different from the assumptions in the model, and the conformity of the model with the actual situation is low. In addition, some scholars have proposed a calculation model for continuous rails with elastic support points, but this method ignores the deformation of the fastener system along the vertical line caused by the vertical rotation angle of the beam end.

[0005] In summary, since the calculation model for the ballastless track beam end angle in the prior art has the shortcomings as mentioned above, a better calculation method for the stress condition of the ballastless track fastener system is proposed, which can improve the consistency of the calculation model with the actual situation, improve the calculation accuracy, and simplify the calculation process. This is a problem that needs to be urgently solved in this field. Summary of the invention

[0006] In view of this, the present invention provides a method for calculating the stress conditions of a ballastless track fastener system, thereby improving the consistency between the calculation model of the beam end rotation angle and the actual situation; it can also calculate the additional forces and distributions of the rails at each fastener and fastener node, and further, it can also calculate the additional bending moment and distribution of the rails, thereby improving the calculation accuracy and simplifying the calculation process.

[0007] The technical solution of the present invention is specifically achieved as follows:

[0008] A method for calculating the stress condition of a ballastless track fastener system comprises the following steps:

[0009] Step A: Establishing beam-rail integrated calculation model;

[0010] Step B: Input the rotation angle parameters θ1 and θ2 at both ends of the beam;

[0011] Step C: Calculate the vertical displacement Δy of each fastener on the rail according to the beam-rail integrated calculation model and the rotation angle parameter;

[0012] Step D: simulating and solving the state of each fastener according to the vertical displacement Δy of each fastener and the stiffness coefficient K of each fastener;

[0013] Step E: Calculate the additional force F on each fastener on the rail according to the status of each fastener f .

[0014] Preferably, the beam-rail integrated calculation model includes: a first beam model, a plurality of first upper rigid walls, a first lower rigid wall, a second beam model, a plurality of second upper rigid walls, a second lower rigid wall, a first nonlinear spring, a second nonlinear spring and a rail model; the first beam model is arranged at the neutral axis position of the first beam to simulate the first beam; the plurality of first upper rigid walls are evenly distributed at the upper end of the first beam model to simulate the rigid structure between the first beam and the rail; the first lower rigid wall is fixed to the lower end of the first beam model on one side close to the second beam model to simulate the first support on the pier below the first beam; the second beam model is arranged at the neutral axis position of the second beam, Used to simulate the second beam; multiple second upper rigid walls are evenly distributed at the upper end of the second beam model, used to simulate the rigid structure between the second beam and the rail; the second lower rigid wall is fixed to the lower end of the second beam model on the side close to the first beam model, used to simulate the second support on the pier under the second beam; the first nonlinear spring is fixed to the top of the first upper rigid wall and the second upper rigid wall on both sides of the beam joint to simulate ordinary fasteners; the second nonlinear spring 3 is fixed to the top of the first upper rigid wall and the second upper rigid wall away from the beam joint to simulate special fasteners; the rail model is fixed to the top of the first nonlinear spring and the second nonlinear spring to simulate the rail.

[0015] Preferably, a transition plate model is provided on the first upper rigid wall and the second upper rigid wall on both sides of the beam joint to simulate the transition plate at the beam joint.

[0016] Preferably, in step C, the vertical displacement Δy of each fastener can be approximately calculated according to the following formula:

[0017] Δy≈(θ1+θ2)·Δx

[0018] Among them, θ1 and θ2 are the rotation angles at the two ends of the beam respectively; Δx is the distance Δx1 from the fastener to the first support or the distance Δx2 from the fastener to the second support.

[0019] Preferably, the stiffness coefficient K of each fastener includes: spring buckling stiffness coefficient K s and pad stiffness coefficient K p .

[0020] Preferably, the states of the fastener include: a compressed state, a failed state and a stretched state.

[0021] Preferably, the buckle is in the compressed state, and the value of the vertical displacement of the buckle falls within the first value range. At this time, the spring buckle stiffness coefficient K s and pad stiffness coefficient K p It is in normal working state.

[0022] Preferably, the fastener is in the failure state, and the value of the vertical displacement of the fastener falls within the second value range, at which time only the pad stiffness coefficient K p , the spring buckling fails, the buckling pressure is zero, K s =0.

[0023] Preferably, the fastener is in a stretched state, the vertical displacement of the fastener falls within the third value range, the fastener system is subjected to an upward pull force, the spring buckle pressure increases, and there is a spring buckle stiffness coefficient K s , pad stiffness coefficient K p =0.

[0024] Preferably, in step E, the additional force F applied to the fastener is calculated according to the following formula: f :

[0025] {F f}={K ij}·{Δy}

[0026] Among them, K ij is the unit stiffness coefficient in the fastener system, and the spring compression stiffness coefficient K sij and pad stiffness coefficient K pij Two kinds of association, K ij =K sij +K pij , K ij Represents the unit displacement Δy of the jth degree of freedom j The additional force F generated in the i-th degree of freedom fi .

[0027] As can be seen from the above, in the calculation method of the stress condition of the ballastless track fastener system of the present invention, an integrated beam-rail calculation model is established by considering the combined effects of the bridge, rails and fastener system as a whole. This model is basically consistent with the actual situation, which improves the consistency between the model and the actual situation, and can accurately check and calculate the stress conditions of the fasteners and rails; further, the calculation accuracy is also improved and the calculation process is simplified. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 Schematic diagram of beam end rotation angle.

[0029] Figure 2 Flow chart of the calculation method in the embodiment of the present invention.

[0030] Figure 3 It is a schematic diagram of the turning angle generated by the beam-rail structure in an embodiment of the present invention.

[0031] Figure 4 Schematic diagram of the beam end track structure model in the embodiment of the present invention Figure 1 .

[0032] Figure 5 It is a schematic diagram of a beam-rail structure with a transition plate in an embodiment of the present invention.

[0033] Figure 6 It is a top view of the beam-rail structure with a transition plate in an embodiment of the present invention.

[0034] Figure 7 Schematic diagram of the beam end track structure model in the embodiment of the present invention Figure 2 .

[0035] Figure 8 The fastener state in the embodiment of the present invention Figure 1 .

[0036] Fig. 9 The fastener state in the embodiment of the present invention Figure 2 .

[0037] Fig.10 The fastener state in the embodiment of the present invention Figure 3 .

[0038] Fig.11 It is a distribution diagram of the additional force at each fastener node in an embodiment of the present invention. DETAILED DESCRIPTION

[0039] In order to make the technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and specific embodiments.

[0040] This application provides a method for calculating the stress of a ballastless track fastener system. Figure 2 As shown, the following steps are included:

[0041] Step 101: Establishing a beam-rail integrated calculation model;

[0042] Step 102: input the rotation angle parameters θ1 and θ2 occurring at both ends of the beam;

[0043] Step 103: Calculate the vertical displacement Δy of each fastener on the rail according to the beam-rail integrated calculation model and the rotation angle parameter;

[0044] Step 104: simulating and solving the state of each fastener according to the vertical displacement Δy of each fastener and the stiffness coefficient K of each fastener;

[0045] Step 105: Calculate the additional force F on each fastener on the rail according to the status of each fastener. f .

[0046] Since the ballastless track, rails, fastener system and other structures are firmly connected to the bridge, the ballastless track, rails, fastener system and other structures together with the bridge can be regarded as a rigid whole. The rails are fixed to the bridge through the fastener system. When the beam end undergoes rigid body displacement, the ballastless track, rails and other structures regarded as a whole with the bridge will also undergo corresponding rigid body displacement, and additional forces such as upward pull or downward pressure will be generated on the fastener system.

[0047] Therefore, in the technical solution of the present application, a beam-rail integrated calculation model can be established first, and then the displacement of the beam at the joint of two adjacent bridge sections on the same pier and the additional force on the fastener system within a certain range on both sides of the beam gap at the joint of the two bridge sections can be simulated and calculated based on the model. Furthermore, the distribution of the additional force on the fastener system on the rail can be obtained, so as to determine whether the additional force meets the standard.

[0048] In the technical solution of the present invention, a variety of implementation methods can be used to implement the above-mentioned calculation model. The technical solution of the present invention will be described in detail below by taking one of the implementation methods as an example.

[0049] For example, preferably, in a specific embodiment of the present invention, Figure 3 to Figure 4 As shown, the beam-rail integrated calculation model includes: a first beam body model 6, a plurality of first upper rigid walls 4, a first lower rigid wall 8, a second beam body model 7, a plurality of second upper rigid walls 5, a second lower rigid wall 9, a first nonlinear spring 2, a second nonlinear spring 3 and a rail model 1;

[0050] The first beam model 6 is arranged at the neutral axis position of the first beam to simulate the first beam;

[0051] A plurality of the first upper rigid walls 4 are evenly distributed at the upper end of the first beam model 6, and are used to simulate a rigid structure between the first beam and the rail (for example, a ballastless track and a sleeper rail);

[0052] The first lower rigid wall 8 is fixed to the lower end of the first beam model 6 on one side close to the second beam model 7, and is used to simulate the first support on the pier below the first beam;

[0053] The second beam model 7 is arranged at the neutral axis position of the second beam, and is used to simulate the second beam;

[0054] A plurality of the second upper rigid walls 5 are evenly distributed at the upper end of the second beam model 7, and are used to simulate a rigid structure between the second beam and the rail (for example, a ballastless track and a sleeper rail);

[0055] The second lower rigid wall 9 is fixed to the lower end of the second beam model 7 on one side close to the first beam model 6, and is used to simulate the second support on the pier below the second beam;

[0056] The first nonlinear spring 2 is fixed to the top of the first upper rigid wall 4 and the second upper rigid wall 5 on both sides of the beam gap to simulate ordinary fasteners; the second nonlinear spring 3 is fixed to the top of the first upper rigid wall 4 and the second upper rigid wall 5 away from the beam gap to simulate special fasteners;

[0057] The rail model 1 is fixed to the top of the first nonlinear spring 2 and the second nonlinear spring 3 and is used to simulate the rail.

[0058] In the above beam-rail integrated calculation model, the rigidly connected beam, ballastless track and rail are simulated and calculated as a whole, nonlinear springs are used to simulate fasteners, and the vertical displacement of the beam and rail is simulated by the deformation of the nonlinear springs. The spacing between each nonlinear spring is the actual spacing of the fastener nodes. Since the nonlinearity of the fastener stiffness is taken into account in the above beam-rail integrated calculation model, accurate calculation results can be obtained for the additional force on the fastener system under large rotation angle and large displacement conditions.

[0059] For another example, preferably, in a specific embodiment of the present invention, Figures 5 to 7 As shown, in the above beam-rail integrated calculation model, a transition plate model 10 can also be set on the first upper rigid wall 4 and the second upper rigid wall 5 on both sides of the beam gap to simulate the transition plate at the beam gap.

[0060] In order to reduce the influence of the beam end rotation angle, a transition plate can be set across the beam joint. The transition plate is a concrete structure (micro bridge). The support center of the transition plate structure is on the same vertical plane as the support center of the bridge superstructure. Setting up the transition plate can transfer the actual beam end rotation angle displacement on the transition plate and offset part of the additional force.

[0061] In addition, preferably, in a specific embodiment of the present invention, in step 103, the vertical displacement Δy of each fastener can be approximately calculated according to the following formula:

[0062] Δy≈(θ1+θ2)·Δx(1)

[0063] Among them, θ1 and θ2 are the rotation angles at the two ends of the beam respectively; Δx is the distance Δx1 from the fastener to the first support or the distance Δx2 from the fastener to the second support.

[0064] Since the rail is a continuous whole, the vertical displacement Δy of each fastener is affected by the rotation angle of the first beam and the rotation angle of the second beam. Therefore, when calculating the vertical displacement of each fastener, it is necessary to consider the joint influence of θ1 and θ2 at the same time, and obtain the vertical displacement of each fastener Δy = Δx·sin(θ1+θ2). Since the rotation angle of the beam is very small, the value of the vertical displacement Δy is also very small, and the formula Δy≈(θ1+θ2)·Δx can be used to approximate the solution.

[0065] Preferably, when Δx1<Δx2, the fastener is closer to the first support, it can be considered that θ1 has a major impact on the fastener, and Δx is Δx1; when Δx1>Δx2, θ2 has a major impact on the fastener, and Δx is Δx2 (for example, Figure 3 As shown, the distance between fastener 1 and the first support is Δx1, and the distance between fastener 1 and the second support is Δx2, Δx1<Δx2, so the vertical displacement of fastener 1 at this time is Δy≈(θ1+θ2)·Δx1).

[0066] In addition, preferably, in a specific embodiment of the present invention, the stiffness coefficient K of each fastener includes: the spring buckle stiffness coefficient K s (Simulated by the first nonlinear spring 2 and the second nonlinear spring 3) and the pad stiffness coefficient K p (Simulated by the first upper rigid wall 4 and the second upper rigid wall 5 or the transition plate model 10).

[0067] In addition, preferably, in a specific embodiment of the present invention, in step 104, the state of the fastener includes: a compressed state, a failed state, and a stretched state; the state of the corresponding fastener can be simulated and solved according to the vertical displacement Δy0, Δy1, or Δy2 of each fastener and its stiffness coefficient K:

[0068] When the fastener is in compression, such as Figure 8 As shown, the value of the vertical displacement of the fastener (for example, Δy0) falls within the first value range, at which time the spring buckle stiffness coefficient K s and pad stiffness coefficient K p It is in normal working state;

[0069] When the fastener is in a failed state, such as Fig. 9 As shown, the value of the vertical displacement of the fastener (for example, Δy1) falls within the second value range, at which time only the pad stiffness coefficient K p , and the spring buckling fails, the buckling pressure is zero, K s =0;

[0070] When the fastener is in tension, such as Fig.10As shown, the value of the vertical displacement of the fastener (for example, Δy2) falls within the third value range, the fastener system is subjected to the upward pull force, and the spring buckle pressure increases. At this time, there is a spring buckle stiffness coefficient K s , and the pad stiffness coefficient K p =0.

[0071] When the beam rail deflects and there is a turning angle, the middle part of the beam rail sinks downward and the end of the suspended support tilts up. There will be no obvious vertical displacement at the support, and the fastener system on the rail will be in different states. For example, the fastener at the support will not produce obvious vertical displacement, and the fastener is in a normal compression state (i.e., spring compression), and the rail is normally fastened to the ballastless track; the fastener at the tilted beam rail will be subjected to the upward force of the rail, that is, there is a K p At this time, under the action of the upward force, the compressed fastener will return to its original length (that is, the spring is the original length), and k s = 0, the clamping pressure of the fastener on the rail fails, and the fastener is in a failed state; in the place where the middle part of the beam and rail sinks, the sinking of the beam and rail causes the rigid structure to have no upward force on the rail, at this time k p =0, and the clamping pressure of the fastener on the rail increases (the spring is stretched). At this time, the fastener is subjected to an upward pull force (the upward pull force is the tensile force). The fastener is in a tensile state, and at the same time, components such as anchor bolts and T-bolts are also subjected to additional upward pull force.

[0072] In addition, preferably, in a specific embodiment of the present invention, in step 105, according to finite element analysis, the additional force F exerted on the fastener can be calculated according to the following formula: f :

[0073] {F f}={K ij}·{Δy} (2)

[0074] Among them, K ij is the unit stiffness coefficient in the fastener system, and the spring compression stiffness coefficient K sij and pad stiffness coefficient K pij Two kinds of association, K ij =K sij +K pij , K ij Represents the unit displacement Δy of the jth degree of freedom j The additional force F generated in the i-th degree of freedom fi .

[0075] Since the fastener is a nonlinear structure, when the fastener has a vertical displacement Δy, different vertical displacements Δy correspond to different stiffness coefficients K and also to different additional forces. Therefore, using the basic finite element theory, the formula {F f}={Kij}·{Δy}Calculate the additional force.

[0076] The above calculation method can be used to calculate the additional force on each fastener when the beam body rotates. Since the vertical displacement of the fastener at the end of the beam is the largest, the additional force at the beam end rotation can be calculated to check and judge whether the fastener system meets the safety requirements under this rotation. For example, for a simply supported steel truss beam, the beam end rotation parameter of 1.319‰ is input under the most unfavorable conditions (the angle is simplified to a proportional value due to the small beam body rotation value and the corresponding calculation algorithm). Through the calculation method of this application, it can be calculated that when the transition plate is not set, the maximum additional force on the beam end fastener is 9.94kN; when the transition plate is set, the maximum additional force on the beam end fastener is 6.62kN. According to the relevant regulations of 1.5 times the safety factor, it is checked and judged that under this rotation parameter, the fastener system is within the safety range (according to relevant regulations, the additional force is ≤15KN).

[0077] Preferably, through the calculation method provided by the present invention, each fastener can be subjected to different additional forces according to its different vertical displacements, and a relationship image between the additional force exerted on the fastener and its vertical displacement can be obtained.

[0078] In addition, preferably, in a specific embodiment of the present invention, the calculation method provided by the present invention is used to solve the additional force on each fastener on the rail through simulation calculation, so that the additional force on the rail at each fastener node can be obtained according to the principle of interaction force, and then the distribution of the additional force on the fastener system and / or the rail can be obtained, such as Fig.11 As shown; further, it can be checked whether the force on the fastener system and / or the rail meets the safety standards.

[0079] Preferably, the displacement function can be further determined according to the additional force on the rail, and the additional bending moment and stress value of the rail can be solved by using the equilibrium equation, the relationship between force and displacement and the node force equilibrium equation, so that the force condition of the rail can be checked more comprehensively and accurately.

[0080] Preferably, the distribution of the additional bending moment on the rail at each fastener node can also be obtained.

[0081] In summary, in the technical solution of the present invention, since the joint effects of the bridge-ballastless track-fastener system-rail are considered as a whole, the established beam-rail integrated calculation model is basically consistent with the actual state, has high calculation accuracy, and a relatively simple calculation process, so that the additional force on the fastener system can be calculated, and then the additional force and additional bending moment on the rail at the fastener node can be calculated, and the distribution of the additional force and additional bending moment on the rail at each rail support can be obtained. With the increase of the vertical rotation angle of the cross-section of the beam end support of the high-speed railway under the action of static and live loads, the force influence on the beam end structure also increases accordingly. The force on the track structure at the beam end of the ballastless track bridge increases with the increase of the overhang length of the beam end support, and increases with the increase of the spacing between the rail fasteners and the bridge span beam gap. The use of the beam-rail integrated calculation model to analyze the force calculation accuracy of the beam end structure of the ballastless track bridge is high, which can meet the design needs and improve the design efficiency.

[0082] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for calculating the stress condition of a ballastless track fastener system, characterized in that: The steps include: Step A: Establishing beam-rail integrated calculation model; Step B: Input the rotation angle parameters θ1 and θ2 at both ends of the beam; Step C: Calculate the vertical displacement Δy of each fastener on the rail according to the beam-rail integrated calculation model and the rotation angle parameter; Step D: simulating and solving the state of each fastener according to the vertical displacement Δy of each fastener and the stiffness coefficient K of each fastener; Step E: Calculate the additional force F on each fastener on the rail according to the status of each fastener f ; Wherein: the beam-rail integrated calculation model includes: a first beam model, a plurality of first upper rigid walls, a first lower rigid wall, a second beam model, a plurality of second upper rigid walls, a second lower rigid wall, a first nonlinear spring, a second nonlinear spring and a rail model; The first beam model is arranged at the neutral axis position of the first beam, and is used to simulate the first beam; A plurality of the first upper rigid walls are evenly distributed at the upper end of the first beam model, and are used to simulate the rigid structure between the first beam and the rail; The first lower rigid wall is fixed to the lower end of the first beam model on one side close to the second beam model, and is used to simulate the first support on the pier below the first beam; The second beam model is arranged at the neutral axis position of the second beam, and is used to simulate the second beam; A plurality of the second upper rigid walls are evenly distributed at the upper end of the second beam model, and are used to simulate the rigid structure between the second beam and the rail; The second lower rigid wall is fixed to the lower end of the second beam model on one side close to the first beam model, and is used to simulate the second support on the pier below the second beam; The first nonlinear spring is fixed to the top of the first upper rigid wall and the second upper rigid wall on both sides of the beam gap to simulate ordinary fasteners; the second nonlinear spring is fixed to the top of the first upper rigid wall and the second upper rigid wall away from the beam gap to simulate special fasteners; The rail model is fixed to the top of the first nonlinear spring and the second nonlinear spring, and is used to simulate the rail.

2. The method according to claim 1, characterized in that: A transition plate model is arranged on the first upper rigid wall and the second upper rigid wall at both sides of the beam gap, so as to simulate the transition plate at the beam gap.

3. The method according to claim 1, characterized in that: In step C, the vertical displacement Δy of each fastener is approximately calculated according to the following formula: Δy≈(θ1+θ2)·Δx Among them, θ1 and θ2 are the rotation angles at the two ends of the beam respectively; Δx is the distance Δx1 from the fastener to the first support or the distance Δx2 from the fastener to the second support.

4. The method according to claim 1, characterized in that: The stiffness coefficient K of each fastener includes: spring buckle stiffness coefficient K s and pad stiffness coefficient K p .

5. The method according to claim 4, characterized in that: The states of the fastener include: a compressed state, a failed state and a stretched state.

6. The method according to claim 5, characterized in that: The buckle is in the compressed state, and the value of the vertical displacement of the buckle falls within the first value range. At this time, the spring buckle stiffness coefficient K s and pad stiffness coefficient K p It is in normal working state.

7. The method according to claim 5, characterized in that: The fastener is in the failure state, and the value of the vertical displacement of the fastener falls within the second value range. At this time, only the pad stiffness coefficient K p , the spring buckling fails, the buckling pressure is zero, K s =0.

8. The method according to claim 5, characterized in that: The fastener is in a stretched state, the vertical displacement of the fastener falls within the third value range, the fastener system is subjected to upward pull force, the spring buckle pressure increases, and there is a spring buckle stiffness coefficient K s , pad stiffness coefficient K p =0.

9. The method according to claim 1, characterized in that: In step E, the additional force F applied to the fastener is calculated according to the following formula: f : {F f }={K ij }·{Δy} Among them, K ij is the unit stiffness coefficient in the fastener system, and the spring compression stiffness coefficient K sij and pad stiffness coefficient K pij Two kinds of association, K ij =K sij +K pij , K ij Represents the unit displacement Δy of the jth degree of freedom j The additional force F generated in the i-th degree of freedom fi .

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