Finite element modeling method for parafoil structure based on cable-membrane structure

Abstract

The application provides a wing parachute structure finite element modeling method based on a cable membrane structure, establishes a wing parachute structure single air chamber geometric model; establishes a wing parachute structure primary chord direction folding model and a secondary chord direction folding model; attributes are given to the grid elements, wherein, a film element is selected for a canopy part in the wing parachute structure single air chamber geometric model, a string element is selected for a canopy rope part, and a penalty function method is used to process a contact collision problem between the film element and the string element; a fluid-solid coupling model is established, and wing parachute inflation and deployment simulation calculation is performed. The simulation efficiency is obviously improved, the wing parachute structure model is established and simulation calculation is performed, stress, strain and other parameters of the canopy and the canopy rope structure of the wing parachute can be obtained, and reliable reference is provided for engineering practice.

Description

Technical Field

[0001] This invention belongs to the field of airborne equipment technology, specifically relating to a finite element modeling method for a parachute structure based on a cable membrane structure. Background Technology

[0002] Ram-air parachutes are made of flexible fabric and have advantages such as small storage space, high glide ratio, and good maneuverability, playing an important role in space reentry.

[0003] Ram-pressed parachutes have rectangular wings, with the upper and lower surfaces of the wing separated and fixed by internal ribs, forming a box-shaped airfoil chamber. When the parachute opens, ram air enters through the leading edge notch, creating stagnant pressure to maintain the parachute's shape. They possess high lift-to-drag ratio aerodynamic performance, excellent gliding ability, good stability and maneuverability, enabling safe and accurate landings. Furthermore, ram-pressed parachutes can be easily folded and packaged like traditional parachutes, featuring small size, light weight, and ease of carrying and transport, making them widely used in aerospace, civilian, and military fields.

[0004] Based on the experience and lessons learned from the development of precision airdrop technology models at home and abroad, 70% of system failures occur during the parachute opening and parachute disturbance stages. Therefore, to improve the reliability of precision airdrop, it is necessary to have a full understanding of the nonlinear large deformation characteristics and fluid-structure interaction characteristics of the parachute and the multibody dynamics of the airdrop system.

[0005] Among the various operational stages of a parachute, the inflation and deployment phase is generally considered the most physically complex. The complexity of the inflation stage is mainly reflected in the following aspects: First, the parachute canopy is composed of flexible fabric, which undergoes rapid shape changes during inflation. Therefore, this is a complex large-deformation structural dynamics problem involving both geometric and material nonlinearities. Mathematical modeling, analysis, and solutions for such problems are quite difficult, and related theories are not yet mature. Second, in addition to the complex structural deformation, the internal and external flow fields near the canopy area also undergo rapid and complex changes. Inside the canopy, the flow is in a significantly turbulent state; outside the canopy, there is flow field separation and the interaction of complex vortex systems. These are challenging problems in fluid mechanics that have not yet been well resolved. Finally, considering that the flow field changes and structural deformation during inflation are not independent but rather mutually influential and interactive, the entire inflation process is essentially a complex fluid-structure interaction problem with a high degree of coupling between structural dynamics and fluid dynamics. Summary of the Invention

[0006] To address the shortcomings of the existing technology, this invention provides a finite element modeling method for parachute structures that can improve the simulation calculation efficiency during the inflation and deployment process of a parachute after folding.

[0007] The technical solution proposed in this invention is as follows:

[0008] This invention discloses a finite element modeling method for wing umbrella structures based on cable-membrane structures, comprising the following steps:

[0009] Establish a geometric model of a single air chamber in a parachute structure;

[0010] The single-chamber geometric model of the parachute structure is meshed to obtain a parachute structure mesh model; based on the parachute structure mesh model, a freeform surface modeling method is used to obtain a parachute structure spanwise folding model; based on the parachute structure spanwise folding model, a first-order chord folding model and a second-order chord folding model are obtained using an inverse dynamics modeling method.

[0011] The mesh elements are assigned properties, wherein the canopy part of the single-cell geometric model of the parachute structure is selected as a thin film element and the parachute rope part is selected as a cable element, and the penalty function method is used to handle the contact and collision problem between the thin film element and the cable element.

[0012] A fluid-structure interaction model was established, and simulation calculations were performed on the inflatable deployment of the parachute.

[0013] Furthermore, the dynamic governing equations of the parachute structure are as follows:

[0014]

[0015] Where, ρ s σ is the material density of the parachute structure. s Let f be the Cocteau stress tensor. s The external force acting on the parachute structure is μ, the velocity vector of the parachute structure particles is t, and the calculation time is t. This is the partial differential operator.

[0016] Furthermore, the constitutive equation of the thin film unit is:

[0017]

[0018]

[0019]

[0020] Wherein, ε1 is the longitudinal strain of the wing canopy membrane element, σ1 is the longitudinal stress of the wing canopy membrane element, θ1 is the longitudinal Poisson's ratio of the wing canopy membrane element, E1 is the longitudinal elastic modulus of the wing canopy membrane element, ε2 is the transverse strain of the wing canopy membrane element, σ2 is the transverse stress of the wing canopy membrane element, θ2 is the transverse Poisson's ratio of the wing canopy membrane element, and E2 is the transverse elastic modulus of the wing canopy membrane element.12 τ represents the tangential strain of the thin-film unit of the parachute canopy structure. 12 G represents the shear stress of the membrane unit of the parachute canopy structure. 12 Let α be the shear modulus of the wing canopy structure film unit, and α be the nonlinear coefficient of the wing canopy structure film unit.

[0021] Furthermore, the constitutive equation of the cable element is:

[0022]

[0023] Where ε is the longitudinal strain of the parachute rope element, σ is the longitudinal stress of the parachute rope element, and σ is the longitudinal elastic modulus of the parachute rope element.

[0024] Furthermore, the penalty function method is specifically as follows:

[0025] At the beginning of each time step, check each slave node. If the slave node does not penetrate the master surface, no action is taken. If the slave node penetrates the master surface, a contact force is added between the slave node and the master surface.

[0026] Furthermore, the magnitude of the contact force is proportional to the distance penetrated from the node and the stiffness of the main surface.

[0027] Furthermore, the degree of oscillation of the contact force is reduced by decreasing the time step.

[0028] Furthermore, a fluid-structure interaction model was established using the ALE method and radial basis function interpolation.

[0029] Furthermore, the fluid motion control equations during the parachute inflation and deployment process are as follows:

[0030]

[0031]

[0032] Where, ρ f Let u be the density of the fluid domain unit in the gas of the first fluid domain. f f is the velocity vector of the fluid domain element in the first fluid domain. f σ is the external force acting on the fluid domain element in the first fluid domain. f Let be the stress tensor of the fluid domain element in the first fluid domain. For Hamiltonian operators, To find the divergence of the velocity tensor corresponding to the fluid domain element in the first fluid domain, t represents the partial differential operator, and t represents the computation time.

[0033] Existing technologies often lack a full understanding of the nonlinear large deformation characteristics, fluid-structure interaction properties, and multibody dynamics of airdrop systems for parachutes. This invention proposes a finite element modeling method for parachutes based on cable-membrane structures. This method uses cable elements and thin membrane elements to model the parachute structure using finite element methods. At the same time, it uses the penalty function method to handle the contact and collision problems between thin membrane elements and cable elements. It performs fluid-structure interaction simulation calculations on the parachute's secondary folding model during the inflation and deployment process, which significantly improves simulation efficiency. The establishment and simulation calculation of this parachute structure model can obtain parameters such as stress and strain of the parachute canopy and parachute rope structure, providing a reliable reference for engineering practice. Attached Figure Description

[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in describing the technical solutions will be briefly introduced below. Obviously, the illustrative embodiments of the present invention and their descriptions are only for explaining the present invention and do not constitute an improper limitation of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort. In the drawings:

[0035] Figure 1 This is a schematic diagram of the geometric model of a single air chamber of the parachute structure in an embodiment of the present invention;

[0036] Figure 2 This is a schematic diagram of the longitudinal symmetry plane of the parachute structure in an embodiment of the present invention;

[0037] Figure 3 This is a schematic diagram of the wing parachute structure mesh model in an embodiment of the present invention;

[0038] Figure 4 A schematic diagram of the spanwise folding model of the parachute structure in an embodiment of the present invention;

[0039] Figure 5 A schematic diagram of a single chordal folding model of a parachute structure in an embodiment of the present invention;

[0040] Figure 6 A schematic diagram of the secondary chordal folding model of the parachute structure in this embodiment of the invention;

[0041] Figure 7 A schematic diagram of the contact coupling between the flow field and the structural interface in an embodiment of the present invention;

[0042] Figure 8 A schematic diagram of the surface stress on the upper wing surface of the parachute canopy in this embodiment of the invention;

[0043] Figure 9 A schematic diagram of the surface stress on the lower wing surface of the parachute canopy in an embodiment of the present invention;

[0044] Figure 10A schematic diagram of the stress on the parachute ropes in an embodiment of the present invention. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0046] This embodiment provides a finite element modeling method for a parachute structure based on a cable-membrane structure, which includes the following steps:

[0047] S1: Establish a geometric model of a single-chamber parachute;

[0048] Specifically, this embodiment uses CATIA software to establish a geometric model of a single-cell parachute, referring to... Figure 1 and Figure 2 , Figure 1 The image shows a single-chamber geometric model of a parachute structure. Figure 2 The diagram shows the longitudinal symmetry plane of the parachute structure. The relevant parameters of the model are shown in Table 1.

[0049] Table 1 Geometric parameters of the parachute model

[0050]

[0051]

[0052] S2: Establish the first-order chord folding model and the second-order chord folding model of the geometric model of the single air chamber of the parachute structure;

[0053] Specifically, the geometric model of the single-chamber wing parachute structure is meshed to obtain the mesh model of the wing parachute structure. Figure 3 The model is shown as a mesh model of the parachute structure. Using freeform surface modeling, the mesh model is processed through translation and stretching to create a spanwise folded model. Then, using inverse dynamics modeling, the spanwise folded model is folded in the chord direction to obtain a first-order chord-folded model and a second-order chord-folded model. Figure 4 The image shows a spanwise folding model of the parachute structure. Figure 5 The image shows a single-chord folding model of a parachute structure. Figure 6 The image shows a model of a parachute structure with a secondary chordal fold.

[0054] S3: Assign properties to grid cells;

[0055] Specifically, among the various working stages of a parachute, the inflation and deployment stage is generally considered to be the most physically complex, involving a complex large-deformation fluid-structure interaction problem with both geometric and material nonlinearities. Numerical calculations using fluid-structure interaction have become a feasible method for studying the inflation and deployment process of parachutes. Preliminary stress analysis of the parachute canopy and lines reveals that the stress characteristics of the canopy are similar to those of a membrane structure, while the stress characteristics of the lines are similar to those of a cable structure. Since the stress forms of cable and membrane elements are simpler, this embodiment uses membrane elements for the canopy and cable elements for the lines in the single-chamber geometric model of the parachute, while ensuring computational accuracy and saving computational resources and costs. Using membrane elements, which cannot withstand bending moments, to simulate the canopy is more consistent with the structural characteristics of the canopy; similarly, using cable elements, which cannot withstand bending moments and can only be subjected to unidirectional tension, to simulate the function of the lines is also more reasonable.

[0056] Furthermore, the dynamic control equations of the parachute structure in this embodiment are:

[0057] Where, ρ s σ is the material density of the parachute structure. s Let f be the Cocteau stress tensor. s The external force acting on the parachute structure is μ, the velocity vector of the mass point of the parachute structure is t, and the calculation time is t. This is the partial differential operator;

[0058] Furthermore, in this embodiment, thin film elements are used to mesh the three-dimensional geometry of the parachute canopy. The constitutive equation of the thin film element is:

[0059]

[0060]

[0061]

[0062] Wherein, ε1 is the longitudinal strain of the wing canopy membrane element, σ1 is the longitudinal stress of the wing canopy membrane element, θ1 is the longitudinal Poisson's ratio of the wing canopy membrane element, E1 is the longitudinal elastic modulus of the wing canopy membrane element, ε2 is the transverse strain of the wing canopy membrane element, σ2 is the transverse stress of the wing canopy membrane element, θ2 is the transverse Poisson's ratio of the wing canopy membrane element, and E2 is the transverse elastic modulus of the wing canopy membrane element. 12 τ represents the tangential strain of the thin-film unit of the parachute canopy structure. 12 G represents the shear stress of the membrane unit of the parachute canopy structure. 12 Let α be the shear modulus of the wing canopy structure film unit, and α be the nonlinear coefficient of the wing canopy structure film unit.

[0063] Furthermore, in this embodiment, cable elements are used to mesh the parachute rope structure, and the constitutive equation of the cable element is:

[0064]

[0065] Where ε is the longitudinal strain of the parachute rope element, σ is the longitudinal stress of the parachute rope element, and σ is the longitudinal elastic modulus of the parachute rope element.

[0066] Furthermore, a contact collision algorithm is employed for the cable and membrane elements of the parachute lines and canopy to prevent interpenetration of the finite element model meshes of the parachute cable-membrane structure, enabling simulation calculations during the parachute inflation and deployment process. In the numerical simulation analysis of the parachute opening process, the contact problem is both a key focus and a challenge. There are self-contact processes involving the canopy and lines, as well as the canopy itself. Due to its high nonlinearity, the contact interface and contact state change unpredictably during motion and deformation. Previous methods for handling contact problems typically couple the structure with the load, assuming a spatiotemporal load distribution based on theory or experiments. This method is feasible for preliminary estimation analysis and for structures with low flexibility, but it introduces significant analytical errors in collision processes involving large deformations.

[0067] In this embodiment, the penalty function method is used to handle the contact collision problem between the parachute cable and the membrane unit. The basic principle of the penalty function method is as follows: At the beginning of each time step t, each slave node is checked. If a slave node does not penetrate the master surface, no action is taken. If a slave node penetrates the master surface, a force (i.e., a contact force) is added between the slave node and the master surface. The magnitude of this force is proportional to the penetration distance and the stiffness of the master surface; this contact force is called the penalty function value. This approach is equivalent to placing a spring between the slave node and the master surface to limit the penetration. Based on the actual operation steps of this method, the contact force, impact velocity, and acceleration between the structures are oscillating. The degree of oscillation is related to the penalty factor value, and the oscillation can be reduced by decreasing the time step.

[0068] The interfacial coupling force between the canopy element and the flow field element is calculated using the penalty function method in the contact algorithm. Within a unit time step Δt, the contact algorithm illustrating the coupling between the flow field node and the structural node is shown below. Figure 7 As shown, the contact force F acting on the flow field node f Contact force F on structural nodes s They are equal in size but opposite in direction, and have the following properties: Where k is the contact stiffness determined by material properties, C is the damping coefficient (relevant literature uses 5% of the critical damping for calculation), and d is the contact displacement. The contact displacement d is calculated from the relative velocity between the structural node and the flow field node, i.e., d t0+Δt=d t0 +(v s -v f )·Δt, where v s With v f These are the velocity vectors of the structural nodes and the flow field nodes, respectively.

[0069] S4: Establish a fluid-structure interaction model and perform simulation calculations for parachute inflation and deployment;

[0070] Specifically, in this embodiment, the ALE method and radial basis function interpolation method are used to establish a complete fluid-structure interaction model and carry out simulation calculations for parachute inflation and deployment;

[0071] Furthermore, since the incoming flow velocity is relatively low during the gas unfolding process, the compressibility of the fluid motion is not considered, and the governing equations for fluid motion are as follows:

[0072]

[0073]

[0074] Where, ρ f u is the density of the fluid domain unit in the gas of the first fluid domain. f f is the velocity vector of the fluid domain element in the first fluid domain. f σ is the external force acting on the fluid domain element in the first fluid domain. f Let be the stress tensor of the fluid domain element in the first fluid domain. For Hamiltonian operators, To find the divergence of the velocity tensor corresponding to the fluid domain element in the first fluid domain, is the partial differential operator, and t is the computation time;

[0075] Furthermore, in continuum mechanics, there are two classical methods for describing motion: the Lagrangian and Eulerian descriptions. The former is not suitable for solving problems involving large mesh deformations, while the latter cannot accurately determine the location of moving boundaries. The ALE description, however, integrates these two perspectives, deconsolidating the computational mesh and removing its dependence on fluid particles, thus enabling its application to free surface problems while overcoming mesh distortion. Essentially, it introduces an independent reference domain into the material domain of the Lagrangian description and the spatial domain of the Eulerian description. This reference domain always coincides with the mesh during flow field calculations. The mapping relationship between the material and spatial domains can be expressed as:

[0076] x=φ(X,t) (1)

[0077] X represents the spatial domain coordinates at time t, and x represents the corresponding material domain coordinates at time t, thus reflecting the motion of the material. Similarly, the mapping relationship between the reference domain and the spatial domain is as follows:

[0078]

[0079] Let χ be the coordinates of the reference domain at time t. Since the reference domain always coincides with the mesh, equation (1) can be used to express the motion of the mesh, and this motion is independent of the material. Observing equations (1) and (2), it can be found that the mapping relationship between the material domain and the reference domain can be obtained through inverse transformation. Thus, the relationship between the Lagrange description, the Eulerian description, and the ALE description is finally obtained. Finally, the fluid control equations (continuity equation, momentum conservation equation, and energy conservation equation) under the ALE description can be obtained.

[0080] In the Euler description, the continuity equation for fluids is:

[0081]

[0082] Assuming the fluid is steady, then according to the transformation relationship of equations (1) and (2), equation (3) can be transformed into the ALE form:

[0083]

[0084] Similarly, the momentum and energy equations in the ALE form become:

[0085]

[0086]

[0087] Furthermore, radial basis function (RBF) interpolation is employed to achieve data transfer at the coupling interface. After constructing the reduced-dimensional plane, a suitable interpolation method is selected to accurately transfer the flow field node data to the parachute surface nodes. RBF interpolation offers advantages such as high numerical accuracy and independence from mesh topology, making it a universal interpolation method suitable for achieving bidirectional load / displacement transfer on arbitrary mesh topologies. Taking displacement interpolation as an example, RBF interpolation is explained. The basic form of RBF interpolation is:

[0088]

[0089] In the formula, F(r) is the interpolation function, and N is the total number of radial basis functions used in the interpolation problem. It uses the general form of the radial basis functions, ||rr i || is the Euclidean distance between two position vectors, r i The position of the support point of the i-th radial basis function, w iThese are the weighting coefficients corresponding to the i-th radial basis function. There are many types of radial basis functions; for mesh deformation, Wendland's C2 function is commonly used, and its specific form is...

[0090]

[0091] In the formula, d is the radius of action of the radial basis function. When η > 1, this is forcibly set. The value is zero. When the mesh deforms, the approximation provided by radial basis function interpolation does not describe the actual position of the mesh nodes on the object surface, but rather the deformation displacement of the mesh. Utilizing the property that the function takes zero at locations outside its radius of action d, the support points can be taken as mesh nodes on the object surface, thus limiting mesh deformation to a finite range d from the object surface.

[0092] The interpolation conditions for the radial basis functions are described in matrix form, namely:

[0093] ΔX S =ΦW X ③

[0094] ΔY S =ΦW Y ④

[0095] ΔZ S =ΦW Z ⑤

[0096] In the formula, the subscript S represents the surface attribute of the object. and Let be the displacement components of N boundary nodes on the object surface in the x, y, and z directions, respectively. It is a sequence of weight coefficients to be determined. The specific form of matrix Φ is:

[0097]

[0098] The weighting coefficients Wx, Wy, and Wz can be solved using equations ③ to ⑥. After solving for the weighting coefficients, the displacement of any grid node j within the computational domain can be obtained, as shown in the following formula:

[0099]

[0100]

[0101]

[0102] Since the memory consumption for solving formulas ③, ④, and ⑤ after constructing formula ⑥ is N, the memory consumption is N. 2 The order of magnitude, the computational complexity is N. 3Because of the scale, directly using the above formula for interpolation can only solve small-scale problems (with fewer than 1000 basis functions). For large-scale interpolation, additional algorithms are needed to select support points to reduce the amount of computation.

[0103] Reference Figures 8-10 The results are the simulation calculation results of this embodiment. Based on the calculation results, it can be seen that:

[0104] The maximum stress on the upper wing surface mainly occurs at the leading edge air intake of the canopy; while the maximum stress on the lower wing surface is mainly concentrated around the load-bearing ribs. The stress on the parachute lines connecting the middle of the canopy is relatively small, while the stress on other parachute lines is not significantly different.

[0105] Analysis: In the initial stage, the bottom of the canopy on the lower wing surface is subjected to high-pressure airflow and bears a large aerodynamic force. At the same time, it is pulled down by the parachute lines. The stress of the canopy is mainly concentrated around the bearing ribs on the lower surface. As the drag area increases during the opening process, the aerodynamic force decreases and the load on the lower wing surface canopy decreases. The stress of the canopy on the upper wing surface is mainly concentrated at the leading edge air inlet, because it is less constrained and always bears the airflow.

[0106] The parachute lines are generally subjected to relatively even stress, but the shape of the parachute changes continuously due to aerodynamic forces during the opening process, and some of the parachute lines in the middle of the canopy will experience moments of lower stress.

[0107] In addition, embodiments of the present invention also provide a computer-readable storage medium, wherein the computer-readable storage medium may store a program, which, when executed, includes some or all of the steps of any of the finite element modeling methods for wing umbrella structures based on cable membrane structures described in the above method embodiments.

[0108] Furthermore, the functional units in the various embodiments of the present invention can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit. The integrated unit can be implemented in hardware or as a software functional unit.

[0109] If the integrated unit is implemented as a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage device (CMD). Based on this understanding, the technical solution of this invention, in essence, or the part that contributes to the prior art, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a memory and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned memory includes various media capable of storing program code, such as USB flash drives, read-only memory (ROM), random access memory (RAM), portable hard drives, magnetic disks, or optical disks.

[0110] Those skilled in the art will understand that all or part of the steps in the various methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage device, which may include: a flash drive, a read-only memory, a random access memory, a magnetic disk, or an optical disk, etc.

[0111] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of this application. It should be understood that the above description is only a specific embodiment of this application and is not intended to limit the scope of protection of this application. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solution of this application should be included within the scope of protection of this application.

Claims

1. A finite element modeling method for a wing umbrella structure based on a cable-membrane structure, characterized in that, The method includes the following steps: Establish a geometric model of a single air chamber in a parachute structure; The single-chamber geometric model of the parachute structure is meshed to obtain a parachute structure mesh model; based on the parachute structure mesh model, a freeform surface modeling method is used to obtain a parachute structure spanwise folding model; based on the parachute structure spanwise folding model, a first-order chord folding model and a second-order chord folding model are obtained using an inverse dynamics modeling method. The mesh elements are assigned properties, wherein the canopy part of the single-cell geometric model of the parachute structure is selected as a thin film element and the parachute rope part is selected as a cable element, and the penalty function method is used to handle the contact and collision problem between the thin film element and the cable element. The penalty function method is specifically as follows: At the beginning of each time step, check each slave node. If the slave node does not penetrate the master surface, no action is taken. If the slave node penetrates the master surface, a contact force is added between the slave node and the master surface. A fluid-structure interaction model was established to perform simulation calculations for the inflation and deployment of the parachute; The dynamic governing equations of the parachute structure are: ； in, The material density of the parachute structure, For the Cocteau stress tensor, The external force acting on the parachute structure, Let t be the velocity vector of the particle in the parachute structure, and t be the calculation time. This is the partial differential operator; The constitutive equation of the thin film unit is: ； ； ； in, The longitudinal strain is the thin film unit of the canopy structure of the parachute. For the longitudinal stress of the membrane unit of the parachute canopy structure, For the longitudinal Poisson's ratio of the thin film unit of the parachute canopy structure, The longitudinal elastic modulus of the thin film unit of the parachute canopy structure. The transverse strain is the thin film unit of the canopy structure of the parachute. For the lateral stress of the membrane unit of the parachute canopy structure, The lateral Poisson's ratio of the thin film unit in the canopy structure of the parachute is given. The transverse elastic modulus of the thin film unit of the wing canopy structure. The tangential strain represents the thin-film unit of the canopy structure of the parachute. For the shear stress of the membrane unit of the parachute canopy structure, The shear modulus of the thin film unit of the wing canopy structure. For the nonlinear coefficients of the thin film unit of the canopy structure; The constitutive equation of the cable element is: ； in, For the longitudinal strain of the parachute rope element, For the longitudinal stress of the parachute rope element, The longitudinal elastic modulus of the parachute cord unit.

2. The finite element modeling method for a wing umbrella structure based on a cable-membrane structure according to claim 1, characterized in that, The magnitude of the contact force is proportional to the distance penetrated from the node and the stiffness of the main surface.

3. The finite element modeling method for a wing umbrella structure based on a cable-membrane structure according to claim 1, characterized in that, The degree of oscillation of the contact force is reduced by decreasing the time step.

4. The finite element modeling method for a wing umbrella structure based on a cable-membrane structure according to claim 1, characterized in that, A fluid-structure interaction model was established using the ALE method and radial basis function interpolation.

5. The finite element modeling method for a wing umbrella structure based on a cable-membrane structure according to claim 1, characterized in that, The fluid motion control equations during the parachute inflation and deployment process are as follows: ； =0； in, Let be the density of the fluid domain unit in the gas of the first fluid domain. Let be the velocity vector of the fluid domain element in the first fluid domain. The external force acting on the fluid domain element in the first fluid domain. Let be the stress tensor of the fluid domain element in the first fluid domain. For Hamiltonian operators, To find the divergence of the velocity tensor corresponding to the fluid domain element in the first fluid domain, t represents the partial differential operator, and t represents the computation time.

6. A computer-readable storage medium, characterized in that, The storage medium stores computer execution instructions, which, when executed, implement the finite element modeling method for a parachute structure based on a cable membrane structure as described in any one of claims 1 to 5.

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