Path evolution method for energy absorption performance prediction and structural response simulation of aramid fabric

Abstract

The invention provides a path evolution method for energy absorption performance prediction and structural response simulation of an aramid fiber fabric, and relates to the technical field of performance simulation, and the method comprises the steps: obtaining three-dimensional weaving structure data and material characteristic parameters of the aramid fiber fabric, discretizing the data into a node unit set, and establishing a connection topology; and identifying the direct bearing unit group according to the high-speed impact load, and generating an evolution path sequence of energy propagation according to the topological coupling strength. And calculating the stress state of each unit along the path, marking a failure unit according to a composite failure criterion and blocking energy transfer, and meanwhile, accumulating the elastic strain energy release amount and the interface friction dissipation energy, and taking the sum of the elastic strain energy release amount and the interface friction dissipation energy as an energy absorption performance prediction value. According to the method, efficient and high-precision simulation of energy absorption and damage evolution of the aramid fabric under impact is realized.

Description

Technical Field

[0001] This invention relates to the field of performance simulation technology, and in particular to a path evolution method for predicting the energy absorption performance and simulating the structural response of aramid fabrics. Background Technology

[0002] In the field of impact resistance research on aramid fabrics, existing techniques typically rely on global numerical simulations based on the finite element method. This type of method establishes a refined three-dimensional model of the fabric structure, assigning it constitutive relations such as elastoplasticity and damage evolution. Under given boundary conditions and impact loads, it solves for the dynamic response of the entire model over continuous time steps. The simulation process calculates the stress, strain, and damage state of all elements at every moment, and finally evaluates its energy absorption performance by integrating the energy dissipation history of the entire model. This method attempts to capture the complex mechanical behavior in impact events through detailed calculations.

[0003] However, these conventional holistic simulation methods have significant drawbacks. Due to the highly complex multi-scale weave structure of aramid fabrics, their refined finite element models often contain a massive number of elements and nodes, resulting in extremely large computational scales. When simulating transient nonlinear processes such as high-speed impacts, extremely small time steps are required to ensure numerical stability, leading to lengthy overall computations and enormous computational resource consumption, making it difficult to meet the needs of rapid evaluation and iterative optimization in engineering design. Furthermore, holistic simulations distribute computational resources evenly across the entire model, while the energy transfer and dissipation of impact loads typically exhibit strong localization and path dependence. Unnecessary detailed calculations are performed on many regions that do not participate in the main energy transfer processes, resulting in significant computational redundancy and inefficiency. Summary of the Invention

[0004] The present invention provides a path evolution method for predicting the energy absorption performance and simulating the structural response of aramid fabrics, which can solve the problems in the prior art.

[0005] A first aspect of the present invention provides a path evolution method for predicting the energy absorption performance and simulating the structural response of aramid fabrics, comprising: The three-dimensional braiding structure data and material property parameters of aramid fabric are obtained. The three-dimensional braiding structure data includes the yarn centerline coordinate sequence, and the material property parameters include tensile modulus, shear modulus, and fracture toughness. The three-dimensional braided structure data is discretized into a set of node units, and the connection topology between node units is established based on the continuity of the yarn centerline coordinate sequence. The connection topology characterizes the mechanical coupling strength through the angle between the normal vectors of adjacent node units and the distance parameter. Based on the momentum component and contact area range of the high-speed impact load, a direct bearing unit group is identified in the set of node units. Using the direct bearing unit group as the source point, a breadth-first traversal is performed according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in the propagation time sequence. The termination criterion of the evolution path sequence is a preset proportion in which the energy density transmitted between node units decays to the initial value. For each node unit in the evolution path sequence, the tensile stress component and shear stress component are calculated based on the material property parameters. When the equivalent combined stress of the tensile stress component and shear stress component exceeds the composite failure criterion, the node unit is marked as a failure state and its subsequent energy transfer is blocked. At the same time, the elastic strain energy release and interface friction dissipation energy of the node unit are recorded. The sum of the elastic strain energy released by all node units in the evolution path sequence and the interface friction dissipation energy is used as the predicted value of energy absorption performance.

[0006] The three-dimensional braided structure data is discretized into a set of node units, and the connection topology between node units is established based on the continuity of the yarn centerline coordinate sequence, including: Spatial sampling points are extracted along the coordinate sequence of the center line of each yarn at preset intervals, and each spatial sampling point is used as the geometric center of the node unit to form a set of node units; For each node unit in the node unit set, candidate associated node units within a spatial neighborhood are searched based on its geometric center coordinates. The spatial neighborhood is determined by the characteristic dimensions of the yarn cross-section. For each node unit and its candidate associated node units, calculate the angle between the normal vectors of the tangent vectors of the geometric centers of the node unit and the tangent vectors of the geometric centers of the candidate associated node units. The tangent vectors are obtained by the local differentiation of the yarn centerline coordinate sequence. When the included angle of the normal vectors is less than the angle threshold and the Euclidean distance between the geometric center of the node element and the geometric center of the candidate associated node element is less than the distance threshold, a connection relationship is established between the node element and the candidate associated node element. For each established connection, the mechanical coupling strength coefficient is calculated. All node units in the node unit set and their connection relationships, along with the mechanical coupling strength coefficients, are organized into a data structure representation of the connection topology. This data structure representation uses an adjacency matrix to store the connection relationships between node units and their corresponding mechanical coupling strength coefficients.

[0007] Calculate the mechanical coupling strength coefficient, including: Obtain the material property parameters of the two node units corresponding to the connection relationship, wherein the material property parameters include the yarn cross-sectional area and the yarn linear density; The angle attenuation factor, which characterizes the angle effect between yarns, is determined by a power function of the cosine of the angle between the normal vectors; the distance attenuation factor, which characterizes the stress transfer efficiency, is determined by a negative exponential function of the Euclidean distance. A cross-sectional correction factor characterizing the bearing capacity of the contact interface is calculated based on the yarn cross-sectional area, and the cross-sectional correction factor is proportional to the geometric mean of the yarn cross-sectional areas of the two node units; a mass correction factor characterizing the inertial transmission characteristics is calculated based on the yarn linear density, and the mass correction factor is inversely proportional to the harmonic mean of the yarn linear densities of the two node units. The mechanical coupling strength coefficient is obtained by performing a weighted product of the angle attenuation factor, distance attenuation factor, cross section correction factor, and mass correction factor.

[0008] Based on the momentum component and contact area range of the high-speed impact load, the directly bearing unit group is identified in the nodal unit set. Using the directly bearing unit group as the source point, a breadth-first traversal is performed according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in propagation time order, including: Based on the contact area range of the high-speed impact load, select node elements whose geometric center is located within the contact area from the node element set to form an initial candidate element set; for each node element in the initial candidate element set, calculate the normal impact intensity and tangential impact intensity borne by the node element based on the momentum component of the high-speed impact load. The normal impact strength and the tangential impact strength are combined into a comprehensive impact strength, and node elements whose comprehensive impact strength exceeds the excitation threshold are selected to form a direct load-bearing unit group; The evolution path sequence is initialized to an empty set. The queue to be traversed is initialized and all node units in the directly carrying unit group are added to the queue to be traversed. The propagation time of each node unit is set to the initial time. The head node unit is taken out from the queue to be traversed as the current node unit. The connection topology is queried to obtain all adjacent node units of the current node unit and their corresponding mechanical coupling strength coefficients. Calculate the energy density propagating from the current node unit to the adjacent node unit, determine whether the energy density of the adjacent node unit satisfies the termination criterion of the evolution path sequence, if the termination criterion is not satisfied and the adjacent node unit has not been visited, then add the adjacent node unit to the queue to be traversed, and record the path segment from the current node unit to the adjacent node unit and the propagation time. Repeat the above operation of retrieving node units from the queue to be traversed and traversing them until the queue to be traversed is empty. Sort all recorded path segments according to their propagation time to form an evolution path sequence.

[0009] Calculating the energy density propagated from the current node cell to the adjacent node cell includes: Obtain the displacement vector of the current node element at the current time step, calculate the velocity vector based on the difference between the displacement vectors of adjacent time steps and the time step length, and calculate the acceleration vector based on the difference between the velocity vectors of adjacent time steps and the time step length. The kinetic energy density of the current node unit is calculated based on the equivalent mass parameter of the current node unit and the sum of squares of each component of the velocity vector. The equivalent mass parameter is determined by the product of the yarn linear density and the representative length of the node unit. Obtain the connection vector between the current node element and each of its adjacent node elements, calculate the ratio of the length change of the connection vector to the initial length as the axial strain, and calculate the change of the angle between the connection vectors as the shear strain. The axial strain energy density component is calculated based on the axial strain and tensile modulus, and the shear strain energy density component is calculated based on the shear strain and shear modulus. The two components are then added together to obtain the total strain energy density of the current node element. The energy density of the current node element is obtained by adding the kinetic energy density to the total strain energy density.

[0010] For each node element in the evolution path sequence, the tensile stress components and shear stress components are calculated based on material property parameters. When the equivalent combined stress of the tensile stress components and shear stress components exceeds the composite failure criterion, the node element is marked as in a failure state and its subsequent energy transfer is blocked. Simultaneously, the elastic strain energy release and interfacial friction dissipation energy of the node element are recorded, including: For each node unit in the evolution path sequence, the strain tensor is calculated based on the relative displacement between the node unit and its neighboring node units. The strain tensor includes normal strain components and shear strain components. The tensile stress components borne by the node element are calculated based on the normal strain components and tensile modulus, and the shear stress components borne by the node element are calculated based on the shear strain components and shear modulus. The equivalent combined stress is determined by the square root of the weighted sum of the squares of the tensile stress components and the squares of the shear stress components. The critical stress value of the composite failure criterion is determined based on the fracture toughness in the material property parameters and the geometric characteristics of the node element. The critical stress value is directly proportional to the fracture toughness and inversely proportional to the square root of the characteristic length of the node element. Determine whether the equivalent combined stress exceeds the critical stress value. If it does, mark the node element as a failure state and remove all connections of the node element from the connection topology to block subsequent energy transfer. For node elements marked as in failure state, the elastic strain energy release is calculated based on the strain tensor and material property parameters before failure. The elastic strain energy release is determined by the product of strain energy density and node element volume. The interface friction dissipation energy is calculated based on the relative slip between the failed node element and its adjacent node elements and the interface contact pressure. The interface friction dissipation energy is determined by the product of the relative slip, the contact pressure and the friction coefficient.

[0011] A second aspect of the present invention provides a path evolution system for predicting the energy absorption performance and simulating the structural response of aramid fabrics, comprising: The data acquisition unit is used to acquire three-dimensional braiding structure data and material property parameters of aramid fabric. The three-dimensional braiding structure data includes a yarn centerline coordinate sequence, and the material property parameters include tensile modulus, shear modulus, and fracture toughness. Discretization unit is used to discretize the three-dimensional braided structure data into a set of node units, and to establish the connection topology between node units based on the continuity of the yarn centerline coordinate sequence. The connection topology characterizes the mechanical coupling strength through the angle between the normal vectors of adjacent node units and the distance parameter. The path generation unit is used to identify the direct bearing unit group in the set of node units based on the momentum component and contact area range of the high-speed impact load, and to perform a breadth-first traversal of the direct bearing unit group as the source point according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in the propagation time sequence. The termination criterion of the evolution path sequence is a preset ratio of the energy density transmitted between node units decaying to the initial value. The stress calculation unit is used to calculate the tensile stress component and shear stress component of each node unit in the evolution path sequence in combination with the material property parameters. When the equivalent combined stress of the tensile stress component and shear stress component exceeds the composite failure criterion, the node unit is marked as a failure state and its subsequent energy transfer is blocked. At the same time, the elastic strain energy release and interface friction dissipation energy of the node unit are recorded. The performance prediction unit is used to calculate the sum of the elastic strain energy release and the interface friction dissipation energy of all node units in the evolution path sequence as the predicted value of energy absorption performance.

[0012] A third aspect of the present invention provides an electronic device, comprising: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the aforementioned method.

[0013] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the aforementioned method.

[0014] This method enables accurate prediction of the energy absorption performance of aramid fabrics under high-speed impact and precise simulation of the structural response process, based on the three-dimensional braided structure data and material property parameters. By discretizing the three-dimensional braided structure into a set of node units and establishing a connection topology based on geometric continuity, this method can accurately characterize the mechanical coupling relationship between yarns, laying a geometric and mechanical foundation for subsequent energy transfer path analysis. Based on the momentum component and contact area of ​​the high-speed impact load, the method identifies the directly bearing unit group and performs a breadth-first traversal with coupling strength as the weight, generating a temporal evolution path sequence that conforms to the laws of physical propagation, thereby dynamically characterizing the diffusion process of impact energy within the fabric.

[0015] This method effectively defines the main impact area of ​​impact events by introducing an energy density decay to a preset ratio as the termination criterion for path evolution, avoiding unnecessary full-structure calculations and significantly improving simulation efficiency. During path evolution, real-time stress state calculations and composite failure assessments are performed on each node element, enabling accurate simulation of the tensile and shear failure behavior of aramid yarn and its blocking effect on energy transfer paths. The method simultaneously records the release of elastic strain energy and interfacial frictional dissipation of the failed elements, achieving the tracking and quantification of the microscopic mechanism of energy dissipation.

[0016] Finally, by statistically analyzing the cumulative energy dissipation of all units in the evolutionary path sequence, this method can directly output a predicted value for the energy absorption performance of aramid fabrics. This predicted value is derived from the physical simulation of the structural dynamic response and failure evolution during impact, thus possessing higher reliability and mechanism revelation capability than traditional empirical formulas or static tests. Attached Figure Description

[0017] Figure 1 This is a flowchart illustrating the path evolution method for predicting the energy absorption performance and simulating the structural response of aramid fabrics. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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.

[0019] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0020] Figure 1This is a schematic flowchart illustrating the path evolution method for predicting the energy absorption performance and simulating the structural response of aramid fabrics according to an embodiment of the present invention. Figure 1 As shown, the method includes: The three-dimensional braiding structure data and material property parameters of aramid fabric are obtained. The three-dimensional braiding structure data includes the yarn centerline coordinate sequence, and the material property parameters include tensile modulus, shear modulus, and fracture toughness. The three-dimensional braided structure data is discretized into a set of node units, and the connection topology between node units is established based on the continuity of the yarn centerline coordinate sequence. The connection topology characterizes the mechanical coupling strength through the angle between the normal vectors of adjacent node units and the distance parameter. Based on the momentum component and contact area range of the high-speed impact load, a direct bearing unit group is identified in the set of node units. Using the direct bearing unit group as the source point, a breadth-first traversal is performed according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in the propagation time sequence. The termination criterion of the evolution path sequence is a preset proportion in which the energy density transmitted between node units decays to the initial value. For each node unit in the evolution path sequence, the tensile stress component and shear stress component are calculated based on the material property parameters. When the equivalent combined stress of the tensile stress component and shear stress component exceeds the composite failure criterion, the node unit is marked as a failure state and its subsequent energy transfer is blocked. At the same time, the elastic strain energy release and interface friction dissipation energy of the node unit are recorded. The sum of the elastic strain energy released by all node units in the evolution path sequence and the interface friction dissipation energy is used as the predicted value of energy absorption performance.

[0021] For example, the structure of an aramid fabric sample is reconstructed using a high-precision 3D scanning device to extract the spatial coordinate sequence of the yarn centerlines. Taking a plain-weave aramid fabric as an example, the coordinate sequence of the warp and weft centerlines includes a set of three-dimensional spatial points along the length and width of the fabric. The centerline of each yarn consists of several discrete coordinate points, with the spacing between adjacent coordinate points being approximately 0.2 mm to 0.5 mm. Material property parameters are obtained through standard mechanical tests. The tensile modulus of aramid fibers is typically between 120 GPa and 130 GPa, the shear modulus is approximately 4 GPa to 6 GPa, and the fracture toughness is determined based on the fracture energy density, with typical values ​​ranging from 80 kJ / m² to 120 kJ / m².

[0022] For example, the three-dimensional braided structure data is discretized into a set of node units, and the connection topology between node units is established based on the continuity of the yarn centerline coordinate sequence, including: Spatial sampling points are extracted along the coordinate sequence of the center line of each yarn at preset intervals, and each spatial sampling point is used as the geometric center of the node unit to form a set of node units; For each node unit in the node unit set, candidate associated node units within a spatial neighborhood are searched based on its geometric center coordinates. The spatial neighborhood is determined by the characteristic dimensions of the yarn cross-section. For each node unit and its candidate associated node units, calculate the angle between the normal vectors of the tangent vectors of the geometric centers of the node unit and the tangent vectors of the geometric centers of the candidate associated node units. The tangent vectors are obtained by the local differentiation of the yarn centerline coordinate sequence. When the included angle of the normal vectors is less than the angle threshold and the Euclidean distance between the geometric center of the node element and the geometric center of the candidate associated node element is less than the distance threshold, a connection relationship is established between the node element and the candidate associated node element. For each established connection, the mechanical coupling strength coefficient is calculated. All node units in the node unit set and their connection relationships, along with the mechanical coupling strength coefficients, are organized into a data structure representation of the connection topology. This data structure representation uses an adjacency matrix to store the connection relationships between node units and their corresponding mechanical coupling strength coefficients.

[0023] When numerically modeling aramid fabrics, the continuous three-dimensional braided structure first needs to be converted into a computable discrete form. Using the spatial coordinate data of the aramid yarn centerline, a spatial sampling point is extracted at intervals of 0.5 mm to 2 mm. The specific value of this interval is determined based on the yarn diameter and braiding density. When the yarn diameter is 0.8 mm and the braiding density is 40 yarns per square centimeter, the sampling interval is set to 1.2 mm. Each extracted spatial sampling point is assigned a unique number, and its three-dimensional coordinates (x_i, y_i, z_i) serve as the geometric center of that node unit. It also inherits the cross-sectional shape parameters of the yarn at that location, including the major and minor axes of the elliptical cross-section.

[0024] After generating the node elements, it is necessary to establish the mechanical relationships between the nodes. For the node element numbered i, with its geometric center as the center of a sphere, and a search radius of 3 to 5 times the major axis dimension of the yarn cross-section, other node elements are searched within this spherical space. When the major axis of the yarn cross-section is 1.2 mm, the search radius is set to 4.5 mm. Node elements located within this range are listed as candidate association objects.

[0025] For each pair of candidate associated nodes, the tangent vector is calculated using the two sampling points before and after the centerline coordinate sequence. Specifically, the tangent vector of node i is obtained by the coordinate difference of the three sampling points before and after that node, using a five-point difference scheme to ensure calculation accuracy. The tangent vector of candidate node j is obtained in the same way. The normal vectors of the two tangent vectors are obtained by cross product operation, and their included angle is calculated using the inverse cosine function. When the included angle is less than 25 degrees and the Euclidean distance between the nodes is less than 3 mm, it is determined that there is a significant mechanical coupling between the two nodes, and a connection relationship is established between them.

[0026] The calculation of the mechanical coupling strength coefficient takes into account both geometric distance and orientation factors. The closer the distance and the more parallel the tangent vectors, the stronger the coupling. The specific formula is as follows: , Where d ij d0 is the distance between nodes, θ is the characteristic distance parameter, which is taken as 1.5 times the yarn diameter. ij This is the angle between the normal vectors. The value of this coefficient ranges from 0 to 1, with a value closer to 1 indicating a stronger coupling.

[0027] Arrange all node cells in numerical order and construct an adjacency matrix, where the row and column indices of the matrix correspond to the node numbers, and matrix element A... ij The mechanical coupling strength coefficient between storage node i and node j. When the two nodes are not connected, A... ij The value is zero. This matrix typically exhibits sparse characteristics, with non-zero elements accounting for approximately 5% to 15%. Therefore, a compressed sparse row format is used for storage to save memory space. This data structure allows for querying the connection status and coupling strength of any pair of nodes in constant time complexity, providing efficient topology lookup capabilities for subsequent energy propagation path calculations.

[0028] For example, calculating the mechanical coupling strength coefficient includes: Obtain the material property parameters of the two node units corresponding to the connection relationship, wherein the material property parameters include the yarn cross-sectional area and the yarn linear density; The angle attenuation factor, which characterizes the angle effect between yarns, is determined by a power function of the cosine of the angle between the normal vectors. The distance attenuation factor, which characterizes stress transfer efficiency, is determined by expressing it as a negative exponential function of Euclidean distance. A cross-sectional correction factor characterizing the load-bearing capacity of the contact interface is calculated based on the cross-sectional area of ​​the yarn, and the cross-sectional correction factor is proportional to the geometric mean of the cross-sectional areas of the yarns of the two node units. The mass correction factor characterizing the inertial transmission characteristics is calculated based on the yarn linear density, and the mass correction factor is inversely proportional to the harmonic average of the yarn linear densities of the two node units. The mechanical coupling strength coefficient is obtained by performing a weighted product of the angle attenuation factor, distance attenuation factor, cross section correction factor, and mass correction factor.

[0029] In establishing the connection topology between node units, the calculation of the mechanical coupling strength coefficient directly affects the accuracy of the stress wave propagation path. For each pair of connections formed by adjacent yarn segments in aramid fabric, the material property parameters of the corresponding node unit are first extracted from the three-dimensional braided structure data. The yarn cross-sectional area is usually determined according to the specifications of the aramid filament bundle; for example, the cross-sectional area of ​​a 1500 denier aramid filament bundle is approximately 0.12 square millimeters. The yarn linear density corresponds to the mass of yarn per unit length, with a common range of 0.2 to 0.5 grams per meter.

[0030] The angle attenuation factor is calculated based on the spatial angle between the normal vectors of adjacent node elements, and the cosine value is obtained through dot product. When the yarn segments are nearly parallel, the cosine value approaches 1, at which point the stress transfer efficiency is highest; efficiency decreases as the angle increases. The angle attenuation factor is expressed as follows: , The index α is set between 1.5 and 2.5 based on experimental calibration of aramid materials. The larger the index value, the more significant the inhibitory effect of the included angle on the transmission efficiency.

[0031] The distance attenuation factor reflects the spatial attenuation characteristics of stress waves propagating between adjacent elements. The Euclidean distance between the center points of two nodal elements is calculated; for typical aramid fabrics, this distance is usually in the range of 0.1 to 5 mm. The weakening effect of distance on coupling strength is characterized using a negative exponential function, where the attenuation coefficient needs to be determined based on the wave velocity and damping characteristics of the aramid fiber, and is typically taken in the range of 0.5 to 1.2 per millimeter.

[0032] The cross-sectional correction factor is used to characterize the difference in load-bearing capacity at the contact interface. The geometric mean is calculated for the yarn cross-sectional areas A1 and A2 of the two nodal elements: , The cross-section correction factor is expressed as: , Where the proportionality coefficient k A By normalizing the dimensions, a correction factor of 1 is determined for the standard cross-sectional area. This factor ensures that yarn connections with larger cross-sectional areas have a higher force transmission capacity.

[0033] The quality correction factor reflects the effect of yarn inertia on dynamic response. The harmonic mean of the yarn linear density at two node units is calculated, and the quality correction factor is defined as follows: , Where, ρ h The proportionality coefficient k represents the harmonic mean. mIt is also normalized. Using the harmonic mean allows the lightweight yarn to play a dominant role in the connection pair, which conforms to the physical laws of inertial transmission. Yarns with lower linear density have a faster acceleration response.

[0034] The four correction factors are weighted and multiplied to obtain the mechanical coupling strength coefficient. The weight coefficients satisfy the normalization condition and are inverted and calibrated based on impact experimental data of aramid fabrics. For high-speed impact scenarios, the weights for distance attenuation and angle attenuation are typically set relatively high, at 0.35 and 0.30 respectively, while the weights for section correction and mass correction are set at 0.20 and 0.15 respectively. This coupling strength coefficient is used as an edge weight value in the subsequent breadth-first traversal to generate the evolution path, participating in the calculation of propagation priority.

[0035] For example, based on the momentum component and contact area range of the high-speed impact load, a direct-bearing unit group is identified in the set of node elements. Then, using the direct-bearing unit group as the source point, a breadth-first traversal is performed according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in propagation time order, including: Based on the contact area range of the high-speed impact load, select node elements whose geometric center is located within the contact area from the node element set to form an initial candidate element set; For each node element in the initial candidate element set, the normal impact strength and tangential impact strength borne by the node element are calculated based on the momentum component of the high-speed impact load. The normal impact strength and the tangential impact strength are combined into a comprehensive impact strength, and node elements whose comprehensive impact strength exceeds the excitation threshold are selected to form a direct load-bearing unit group; The evolution path sequence is initialized to an empty set. The queue to be traversed is initialized and all node units in the directly carrying unit group are added to the queue to be traversed. The propagation time of each node unit is set to the initial time. Take the head node unit from the queue to be traversed as the current node unit, and query the connection topology to obtain all adjacent node units of the current node unit and their corresponding mechanical coupling strength coefficients; Calculate the energy density propagating from the current node unit to the adjacent node unit, determine whether the energy density of the adjacent node unit satisfies the termination criterion of the evolution path sequence, if the termination criterion is not satisfied and the adjacent node unit has not been visited, then add the adjacent node unit to the queue to be traversed, and record the path segment from the current node unit to the adjacent node unit and the propagation time. Repeat the above operation of retrieving node units from the queue to be traversed and traversing them until the queue to be traversed is empty. Sort all recorded path segments according to their propagation time to form an evolution path sequence.

[0036] After obtaining the set of node elements and connection topology of the aramid fabric, it is necessary to determine the direct load-bearing elements under high-speed impact load and track the propagation process of stress waves within the fabric. First, the contact area is determined based on the geometric characteristic parameters of the high-speed impact load. This contact area is typically represented as an elliptical or circular projection in three-dimensional space, with its boundary determined by the geometric dimensions of the impactor. All elements in the node element set are traversed, and the geometric center coordinates of each node element are extracted. It is then determined whether these coordinates fall within the boundary of the contact area. Specifically, the distance between the geometric center point and the center of the contact area is calculated. If this distance is less than the characteristic radius of the contact area, the node element is included in the initial candidate element set.

[0037] Mechanical screening is performed on the node elements in the initial candidate element set. The momentum p along the normal direction of the fabric is decomposed based on the momentum component of the impact load. n With tangential momentum p along the fabric plane t The normal impact strength is calculated by combining the mass parameters of the node element with the contact area. With tangential impact strength Where m is the equivalent mass of the node element and Δt is the impact duration. The composite impact intensity is synthesized by taking the square root of the sum of squares. The composite impact intensity is compared with a preset excitation threshold, which is determined based on the yield stress of the aramid material and the yarn diameter, typically ranging from 15% to 25% of the material's yield stress. Only node elements with a composite impact intensity exceeding the excitation threshold are retained; these elements constitute the direct load-bearing element group, representing the input source of the impact energy.

[0038] A breadth-first traversal mechanism is established to track stress wave propagation. A first-in-first-out queue is created to enqueue all node elements in the directly bearing unit group. The propagation time of each element is marked as time zero, and the energy density is initialized to the initial energy density value of the impact load transmission. The first element in the queue is taken as the current diffusion source. The connection topology data structure is queried to obtain all its adjacent elements and the mechanical coupling strength coefficient. This coefficient is characterized by the product of the cosine of the angle between the normal vectors of adjacent node elements and the reciprocal of the distance, reflecting the transmission efficiency of the stress wave when crossing the yarn interlacing point.

[0039] When calculating energy propagation, the energy density of the current node cell The energy density transferred to adjacent cells is: , in, The mechanical coupling strength coefficient, This is the material's inherent damping coefficient, typically ranging from 0.9 to 0.95. It checks whether the transmitted energy density is lower than a preset attenuation ratio for the initial energy density, usually set to 5%. If the termination condition is not met and the adjacent cell has not been visited, the adjacent cell is enqueued, and its propagation time is updated to the current time plus the propagation delay time. The propagation delay is determined by dividing the node spacing by the stress wave velocity in the material; for aramid materials, this wave velocity is approximately 1200 to 1500 meters per second. Simultaneously, it records the path segment information from the current cell to the adjacent cell, including the starting cell number, ending cell number, propagation time, and transmitted energy density value.

[0040] For example, dequeueing and adjacency diffusion operations are continuously performed until the queue to be traversed is empty, at which point all reachable units have been traversed. All recorded path segments are collected and sorted in ascending order of propagation time to form a complete evolution path sequence, which truly reflects the spatiotemporal diffusion process of impact energy within the three-dimensional structure of the fabric.

[0041] Calculating the energy density propagated from the current node cell to the adjacent node cell includes: Obtain the displacement vector of the current node element at the current time step, calculate the velocity vector based on the difference between the displacement vectors of adjacent time steps and the time step length, and calculate the acceleration vector based on the difference between the velocity vectors of adjacent time steps and the time step length. The kinetic energy density of the current node unit is calculated based on the equivalent mass parameter of the current node unit and the sum of squares of each component of the velocity vector. The equivalent mass parameter is determined by the product of the yarn linear density and the representative length of the node unit. Obtain the connection vector between the current node element and each of its adjacent node elements, calculate the ratio of the length change of the connection vector to the initial length as the axial strain, and calculate the change of the angle between the connection vectors as the shear strain. The axial strain energy density component is calculated based on the axial strain and tensile modulus, and the shear strain energy density component is calculated based on the shear strain and shear modulus. The two components are then added together to obtain the total strain energy density of the current node element. The energy density of the current node element is obtained by adding the kinetic energy density to the total strain energy density.

[0042] In the impact response of aramid fabrics, the propagation of energy between nodal elements is the core physical mechanism. To achieve accurate energy density calculation, a dynamic solution framework based on time-step iteration needs to be established.

[0043] Obtain the displacement vector u of the current node element at time step n. n This vector contains displacement components in a three-dimensional spatial coordinate system. The displacement difference between adjacent time steps... The ratio of the velocity vector to the time step is the velocity vector. The velocity vector is processed using the same difference method, and the acceleration vector is calculated from the ratio of the velocity vector to the time step. The time step must satisfy the Courant-Friedrich-Levy stability condition, and is usually taken as the value of the smallest unit characteristic length in the yarn divided by the longitudinal wave velocity.

[0044] The calculation of kinetic energy density depends on the equivalent mass parameter of the node element. This parameter is obtained by multiplying the linear density of the aramid yarn by the representative length of the node element, where the representative length is defined as the arithmetic mean of the distances between the node element and all adjacent node elements. The kinetic energy density per unit volume is obtained by multiplying the sum of the squares of the velocity vector components by the equivalent mass parameter and then dividing by the representative volume.

[0045] For the calculation of strain energy density, both axial and shear deformation modes need to be handled separately. The connection vectors from the current node element to each adjacent node element are obtained. The change in the magnitude of this vector relative to the initial configuration, divided by the initial length, yields the axial strain. The extraction of shear strain depends on the change in the angle between the connection vectors. The difference in angle between adjacent connection vectors in the current configuration and the initial configuration is determined through dot product operations; this difference is the engineering shear strain.

[0046] Axial strain energy density component through The calculation is performed, where E is the tensile modulus of the aramid fiber along the yarn direction, typically 120-130 GPa. Represents axial strain. The shear strain energy density component is expressed through... The calculation is performed, where G is the shear modulus, typically 1 / 30 to 1 / 40 of the tensile modulus, and γ represents the engineering shear strain. The sum of these two values ​​yields the total strain energy density of the nodal element, which reflects the elastic potential energy accumulated during local deformation.

[0047] Finally, the kinetic energy density is summed with the total strain energy density to obtain the comprehensive energy density of the current node element. The decay rate of this energy density in the evolution path determines the effective range of damage propagation. When it decreases to 5%-10% of the initial contact area energy density, the mechanical response of this path branch can be considered to contribute negligibly to the overall energy absorption, thus terminating the evolution calculation in this direction.

[0048] For example, for each node element in the evolution path sequence, the tensile stress component and shear stress component are calculated based on material property parameters. When the equivalent combined stress of the tensile stress component and shear stress component exceeds the composite failure criterion, the node element is marked as a failure state and its subsequent energy transfer is blocked. Simultaneously, the elastic strain energy release and interfacial friction dissipation energy of the node element are recorded, including: For each node unit in the evolution path sequence, the strain tensor is calculated based on the relative displacement between the node unit and its neighboring node units. The strain tensor includes normal strain components and shear strain components. The tensile stress components borne by the node element are calculated based on the normal strain components and tensile modulus, and the shear stress components borne by the node element are calculated based on the shear strain components and shear modulus. The equivalent combined stress is determined by the square root of the weighted sum of the squares of the tensile stress components and the squares of the shear stress components. The critical stress value of the composite failure criterion is determined based on the fracture toughness in the material property parameters and the geometric characteristics of the node element. The critical stress value is directly proportional to the fracture toughness and inversely proportional to the square root of the characteristic length of the node element. Determine whether the equivalent combined stress exceeds the critical stress value. If it does, mark the node element as a failure state and remove all connections of the node element from the connection topology to block subsequent energy transfer. For node elements marked as in failure state, the elastic strain energy release is calculated based on the strain tensor and material property parameters before failure. The elastic strain energy release is determined by the product of strain energy density and node element volume. The interface friction dissipation energy is calculated based on the relative slip between the failed node element and its adjacent node elements and the interface contact pressure. The interface friction dissipation energy is determined by the product of the relative slip, the contact pressure and the friction coefficient.

[0049] After obtaining the evolution path sequence, the mechanical response of each node element in the sequence is calculated sequentially. For the i-th node element, its spatial coordinates are extracted. The set of coordinates of its adjacent node elements Calculate the relative displacement vector. The coordinates with subscript 0 represent the initial configuration position. Based on the small deformation assumption, the normal strain components are extracted along the yarn axial direction. , where L ij Assuming the initial distance between nodes, extract the shear strain component along the direction perpendicular to the yarn. .

[0050] Using the tensile modulus E in the material property parameters 纵 and shear modulus G 12 The stress components are calculated according to Hooke's law. The tensile stress components are determined as follows: The shear stress components are determined as follows: Introducing anisotropic weighting coefficient α 拉 and α 剪 Equivalent combined stress is constructed by weighted quadratic form. The weighting coefficients are pre-calibrated based on the anisotropic characteristics of aramid fibers.

[0051] The failure criterion adopts the critical stress criterion based on fracture mechanics. The fracture toughness K is read from the material property parameters. IC Combined with the characteristic length l of the node element C (defined as the equivalent diameter of the control domain of this unit), according to Calculate the critical stress value. The scaling factor β is adjusted according to the weave structure type: 1.12 for plain weave and 0.95 for twill weave. Compare the equivalent combined stress of each node element with the corresponding critical stress value. When the equivalent combined stress is greater than the critical stress value, update the state identifier of the node element from 0 to 1, representing the failure state. Simultaneously update the connection topology matrix, resetting all connection weights related to the failed element to zero, cutting off the path for load and energy transfer from that element to adjacent elements.

[0052] For node elements deemed failed, calculate the amount of elastic strain energy released. The strain energy density is calculated according to: The density value is obtained by integration. Multiplying this density value by the volume of the nodal element (determined by the centerline coordinates and cross-sectional area parameters) yields the elastic strain energy release of that element. Calculating the interfacial frictional dissipation energy requires identifying the relative slip between the failed element and adjacent elements. The tangential slip component is extracted, and combined with the normal pressure in the contact area (determined by the distribution of the impact load in the local region) and the material friction coefficient (typically 0.15 to 0.25 for aramid-aramid contact interfaces), the frictional dissipation energy is calculated according to Coulomb's law of friction. The two energy components of a single nodal element are accumulated separately into a global register, and the total predicted energy absorption value is output after traversal.

[0053] A second aspect of the present invention provides a path evolution system for predicting the energy absorption performance and simulating the structural response of aramid fabrics, comprising: The data acquisition unit is used to acquire three-dimensional braiding structure data and material property parameters of aramid fabric. The three-dimensional braiding structure data includes a yarn centerline coordinate sequence, and the material property parameters include tensile modulus, shear modulus, and fracture toughness. Discretization unit is used to discretize the three-dimensional braided structure data into a set of node units, and to establish the connection topology between node units based on the continuity of the yarn centerline coordinate sequence. The connection topology characterizes the mechanical coupling strength through the angle between the normal vectors of adjacent node units and the distance parameter. The path generation unit is used to identify the direct bearing unit group in the set of node units based on the momentum component and contact area range of the high-speed impact load, and to perform a breadth-first traversal of the direct bearing unit group as the source point according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in the propagation time sequence. The termination criterion of the evolution path sequence is a preset ratio of the energy density transmitted between node units decaying to the initial value. The stress calculation unit is used to calculate the tensile stress component and shear stress component of each node unit in the evolution path sequence in combination with the material property parameters. When the equivalent combined stress of the tensile stress component and shear stress component exceeds the composite failure criterion, the node unit is marked as a failure state and its subsequent energy transfer is blocked. At the same time, the elastic strain energy release and interface friction dissipation energy of the node unit are recorded. The performance prediction unit is used to calculate the sum of the elastic strain energy release and the interface friction dissipation energy of all node units in the evolution path sequence as the predicted value of energy absorption performance.

[0054] A third aspect of the present invention provides an electronic device, comprising: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the aforementioned method.

[0055] A fourth aspect of the present invention provides a computer-readable storage medium having stored thereon computer program instructions that, when executed by a processor, implement the aforementioned method.

[0056] This invention can be a method, apparatus, system, and / or computer program product. The computer program product may include a computer-readable storage medium having computer-readable program instructions loaded thereon for performing various aspects of the invention.

[0057] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A path evolution method for predicting the energy absorption performance and simulating the structural response of aramid fabrics, characterized in that, include: The three-dimensional braiding structure data and material property parameters of aramid fabric are obtained. The three-dimensional braiding structure data includes the yarn centerline coordinate sequence, and the material property parameters include tensile modulus, shear modulus, and fracture toughness. The three-dimensional braided structure data is discretized into a set of node units, and the connection topology between node units is established based on the continuity of the yarn centerline coordinate sequence. The connection topology characterizes the mechanical coupling strength through the angle between the normal vectors of adjacent node units and the distance parameter. Based on the momentum component and contact area range of the high-speed impact load, a direct bearing unit group is identified in the set of node units. Using the direct bearing unit group as the source point, a breadth-first traversal is performed according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in the propagation time sequence. The termination criterion of the evolution path sequence is a preset proportion in which the energy density transmitted between node units decays to the initial value. For each node unit in the evolution path sequence, the tensile stress component and shear stress component are calculated based on the material property parameters. When the equivalent combined stress of the tensile stress component and shear stress component exceeds the composite failure criterion, the node unit is marked as a failure state and its subsequent energy transfer is blocked. At the same time, the elastic strain energy release and interface friction dissipation energy of the node unit are recorded. The sum of the elastic strain energy released by all node units in the evolution path sequence and the interface friction dissipation energy is used as the predicted value of energy absorption performance.

2. The method according to claim 1, characterized in that, The three-dimensional braided structure data is discretized into a set of node units, and the connection topology between node units is established based on the continuity of the yarn centerline coordinate sequence, including: Spatial sampling points are extracted along the coordinate sequence of the center line of each yarn at preset intervals, and each spatial sampling point is used as the geometric center of the node unit to form a set of node units; For each node unit in the node unit set, candidate associated node units within a spatial neighborhood are searched based on its geometric center coordinates. The spatial neighborhood is determined by the characteristic dimensions of the yarn cross-section. For each node unit and its candidate associated node units, calculate the angle between the normal vectors of the tangent vectors of the geometric centers of the node unit and the tangent vectors of the geometric centers of the candidate associated node units. The tangent vectors are obtained by the local differentiation of the yarn centerline coordinate sequence. When the included angle of the normal vectors is less than the angle threshold and the Euclidean distance between the geometric center of the node element and the geometric center of the candidate associated node element is less than the distance threshold, a connection relationship is established between the node element and the candidate associated node element. For each established connection, the mechanical coupling strength coefficient is calculated. All node units in the node unit set and their connection relationships, along with the mechanical coupling strength coefficients, are organized into a data structure representation of the connection topology. This data structure representation uses an adjacency matrix to store the connection relationships between node units and their corresponding mechanical coupling strength coefficients.

3. The method according to claim 2, characterized in that, Calculate the mechanical coupling strength coefficient, including: Obtain the material property parameters of the two node units corresponding to the connection relationship, wherein the material property parameters include the yarn cross-sectional area and the yarn linear density; The angle attenuation factor, which characterizes the angle effect between yarns, is determined by a power function of the cosine of the angle between the normal vectors; the distance attenuation factor, which characterizes the stress transfer efficiency, is determined by a negative exponential function of the Euclidean distance. A cross-sectional correction factor characterizing the bearing capacity of the contact interface is calculated based on the yarn cross-sectional area, and the cross-sectional correction factor is proportional to the geometric mean of the yarn cross-sectional areas of the two node units; a mass correction factor characterizing the inertial transmission characteristics is calculated based on the yarn linear density, and the mass correction factor is inversely proportional to the harmonic mean of the yarn linear densities of the two node units. The mechanical coupling strength coefficient is obtained by performing a weighted product of the angle attenuation factor, distance attenuation factor, cross section correction factor, and mass correction factor.

4. The method according to claim 1, characterized in that, Based on the momentum component and contact area range of the high-speed impact load, the directly bearing unit group is identified in the nodal unit set. Using the directly bearing unit group as the source point, a breadth-first traversal is performed according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in propagation time order, including: Based on the contact area range of the high-speed impact load, select node elements whose geometric center is located within the contact area from the node element set to form an initial candidate element set; for each node element in the initial candidate element set, calculate the normal impact intensity and tangential impact intensity borne by the node element based on the momentum component of the high-speed impact load. The normal impact strength and the tangential impact strength are combined into a comprehensive impact strength, and node elements whose comprehensive impact strength exceeds the excitation threshold are selected to form a direct load-bearing unit group; The evolution path sequence is initialized to an empty set. The queue to be traversed is initialized and all node units in the directly carrying unit group are added to the queue to be traversed. The propagation time of each node unit is set to the initial time. The head node unit is taken out from the queue to be traversed as the current node unit. The connection topology is queried to obtain all adjacent node units of the current node unit and their corresponding mechanical coupling strength coefficients. Calculate the energy density propagating from the current node unit to the adjacent node unit, determine whether the energy density of the adjacent node unit satisfies the termination criterion of the evolution path sequence, if the termination criterion is not satisfied and the adjacent node unit has not been visited, then add the adjacent node unit to the queue to be traversed, and record the path segment from the current node unit to the adjacent node unit and the propagation time. Repeat the above operation of retrieving node units from the queue to be traversed and traversing them until the queue to be traversed is empty. Sort all recorded path segments according to their propagation time to form an evolution path sequence.

5. The method according to claim 4, characterized in that, Calculating the energy density propagated from the current node cell to the adjacent node cell includes: Obtain the displacement vector of the current node element at the current time step, calculate the velocity vector based on the difference between the displacement vectors of adjacent time steps and the time step length, and calculate the acceleration vector based on the difference between the velocity vectors of adjacent time steps and the time step length. The kinetic energy density of the current node unit is calculated based on the equivalent mass parameter of the current node unit and the sum of squares of each component of the velocity vector. The equivalent mass parameter is determined by the product of the yarn linear density and the representative length of the node unit. Obtain the connection vector between the current node element and each of its adjacent node elements, calculate the ratio of the length change of the connection vector to the initial length as the axial strain, and calculate the change of the angle between the connection vectors as the shear strain. The axial strain energy density component is calculated based on the axial strain and tensile modulus, and the shear strain energy density component is calculated based on the shear strain and shear modulus. The two components are then added together to obtain the total strain energy density of the current node element. The energy density of the current node element is obtained by adding the kinetic energy density to the total strain energy density.

6. The method according to claim 1, characterized in that, For each node element in the evolution path sequence, the tensile stress components and shear stress components are calculated based on material property parameters. When the equivalent combined stress of the tensile stress components and shear stress components exceeds the composite failure criterion, the node element is marked as in a failure state and its subsequent energy transfer is blocked. Simultaneously, the elastic strain energy release and interfacial friction dissipation energy of the node element are recorded, including: For each node unit in the evolution path sequence, the strain tensor is calculated based on the relative displacement between the node unit and its neighboring node units. The strain tensor includes normal strain components and shear strain components. The tensile stress components borne by the node element are calculated based on the normal strain components and tensile modulus, and the shear stress components borne by the node element are calculated based on the shear strain components and shear modulus. The equivalent combined stress is determined by the square root of the weighted sum of the squares of the tensile stress components and the squares of the shear stress components. The critical stress value of the composite failure criterion is determined based on the fracture toughness in the material property parameters and the geometric characteristics of the node element. The critical stress value is directly proportional to the fracture toughness and inversely proportional to the square root of the characteristic length of the node element. Determine whether the equivalent combined stress exceeds the critical stress value. If it does, mark the node element as a failure state and remove all connections of the node element from the connection topology to block subsequent energy transfer. For node elements marked as in failure state, the elastic strain energy release is calculated based on the strain tensor and material property parameters before failure. The elastic strain energy release is determined by the product of strain energy density and node element volume. The interface friction dissipation energy is calculated based on the relative slip between the failed node element and its adjacent node elements and the interface contact pressure. The interface friction dissipation energy is determined by the product of the relative slip, the contact pressure and the friction coefficient.

7. A path evolution system for predicting the energy absorption performance and simulating the structural response of aramid fabrics, used to implement the method as described in any one of claims 1-6, characterized in that, include: The data acquisition unit is used to acquire three-dimensional braiding structure data and material property parameters of aramid fabric. The three-dimensional braiding structure data includes a yarn centerline coordinate sequence, and the material property parameters include tensile modulus, shear modulus, and fracture toughness. Discretization unit is used to discretize the three-dimensional braided structure data into a set of node units, and to establish the connection topology between node units based on the continuity of the yarn centerline coordinate sequence. The connection topology characterizes the mechanical coupling strength through the angle between the normal vectors of adjacent node units and the distance parameter. The path generation unit is used to identify the direct bearing unit group in the set of node units based on the momentum component and contact area range of the high-speed impact load, and to perform a breadth-first traversal of the direct bearing unit group as the source point according to the coupling strength weight of the connection topology to generate an evolution path sequence arranged in the propagation time sequence. The termination criterion of the evolution path sequence is a preset ratio of the energy density transmitted between node units decaying to the initial value. The stress calculation unit is used to calculate the tensile stress component and shear stress component of each node unit in the evolution path sequence in combination with the material property parameters. When the equivalent combined stress of the tensile stress component and shear stress component exceeds the composite failure criterion, the node unit is marked as a failure state and its subsequent energy transfer is blocked. At the same time, the elastic strain energy release and interface friction dissipation energy of the node unit are recorded. The performance prediction unit is used to calculate the sum of the elastic strain energy release and the interface friction dissipation energy of all node units in the evolution path sequence as the predicted value of energy absorption performance.

8. An electronic device, characterized in that, include: processor; Memory used to store processor-executable instructions; The processor is configured to invoke instructions stored in the memory to execute the method according to any one of claims 1 to 6.

9. A computer-readable storage medium having computer program instructions stored thereon, characterized in that, When the computer program instructions are executed by the processor, they implement the method described in any one of claims 1 to 6.

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