Finite element-based wood microstructure parametric modeling method

Abstract

The invention discloses a wood microstructure parametric modeling method based on finite elements, which belongs to the technical field of wood mechanical property simulation analysis, and comprises the following steps: acquiring a wood microstructure schematic diagram, extracting size parameters of a microstructure, determining a wood structure, fitting a curvilinear equation of wood microstructure parameters, and establishing a wood microstructure model. Obtaining a coefficient of the dimension change rule equation; presetting global parameters of a to-be-constructed wood microstructure model, regularizing wood, and constructing a basic modeling unit; respectively carrying out differential modeling on the wood structure by utilizing the coefficient of the size change rule equation and the basic modeling unit; and constructing a wood microstructure model according to the broad-leaved wood microstructure and the coniferous wood microstructure. The problems that in existing wood mechanical property simulation analysis, microstructure characterization is insufficient, and the experiment cost is high are solved, and the simulation accuracy and efficiency are improved.

Description

Technical Field

[0001] The present invention relates to a parametric modeling method for wood microstructure based on finite element, belonging to the technical field of simulation analysis of wood mechanical properties. Background Art

[0002] As a natural biomass material, the mechanical properties of wood are complex and variable, being deeply affected by multiple factors such as microstructure, growth conditions, moisture content, etc., showing significant anisotropic characteristics. Currently, the performance testing of wooden furniture mainly relies on traditional experimental methods, which involve the preparation and testing of a large number of specimens and require strict mechanical property testing under standard environments. However, this method is not only time-consuming and laborious with high costs, but also difficult to comprehensively and accurately reflect the performance of wood in actual use environments. To make up for this deficiency, the industry has begun to explore simulation testing technologies for the performance of wooden furniture. Existing simulation testing technologies mainly focus on the characterization of the macroscopic mechanical properties of wood, usually simplifying wood as an isotropic or orthotropic material to simplify the calculation and analysis process. Although this method can simulate the mechanical properties of wood to a certain extent, there are still many limitations and deficiencies.

[0003] Although existing simulation testing technologies for the performance of wooden furniture have made some progress in the analysis of wood mechanical properties, there are still significant defects. First, current simulation testing technologies overly simplify the microstructure of wood, regarding wood as an isotropic or orthotropic material and ignoring the important influence of microscopic structures such as annual ring structure, vessel distribution, cell size, etc. on mechanical behavior. This simplified treatment leads to a deviation between the simulation results and the actual performance, making it difficult to accurately reflect the true mechanical properties of wood. Second, in some studies, wood is regarded as a microscopically homogenized material. However, as a typical multi-level biological composite material, the microstructure of wood has a high degree of heterogeneity and complexity. The homogenization treatment will obscure the correlation mechanism between the microstructure and the macroscopic mechanical response, resulting in the simulation results being unable to accurately reflect the actual performance of wood. In addition, although numerical simulation is of great significance in the analysis of wood mechanical properties, it is still very difficult to overcome the challenges between complex morphology and true mechanical behavior. Summary of the Invention

[0004] The purpose of the present invention is to provide a parametric modeling method for wood microstructure based on finite element, by capturing the size parameters of the wood microstructure and constructing a wood microstructure model, so as to solve the problems of insufficient microstructure characterization and high experimental costs in existing wood mechanical property simulation analysis, and improve the simulation accuracy and efficiency.

[0005] To solve the above technical problems, the present invention is implemented by adopting the following technical solutions.

[0006] The present invention provides a method for parametric modeling of wood microstructure based on finite element, including:

[0007] Obtain a schematic diagram of the wood microstructure, extract the size parameters of the microstructure and determine the wood structure;

[0008] Fit a curve equation of the wood microstructure parameters according to the size parameters to obtain the coefficients of the size change law equation;

[0009] Preset the global parameters of the wood microstructure model to be constructed to regularize the wood and construct a basic modeling unit;

[0010] Use the coefficients of the size change law equation and the basic modeling unit to perform differential modeling on the wood structure respectively:

[0011] For the structure of broad-leaved wood:

[0012] Based on the coefficients of the size change law equation, use the function equation to simulate the change laws of vessel density, diameter and the diameter change law of cells and apply them to the basic modeling unit to generate the vessel structure and cell structure;

[0013] Screen the vessel structure and cell structure that meet the structure of broad-leaved wood to generate the microstructure of broad-leaved wood;

[0014] For the structure of coniferous wood:

[0015] Based on the coefficients of the size change law equation, use the function equation to simulate the change law of tracheid diameter and apply it to the basic modeling unit to generate tracheids;

[0016] Screen the tracheid structure that meets the structure of coniferous wood to generate the microstructure of coniferous wood;

[0017] Construct a wood microstructure model according to the microstructure of broad-leaved wood and the microstructure of coniferous wood.

[0018] Furthermore, the size parameters of the microstructure include annual ring width, the change laws of vessel diameter and density, the change law of tracheid diameter, and the change law of cell diameter.

[0019] Furthermore, the obtaining of the schematic diagram of the wood microstructure, extracting the size parameters of the microstructure and determining the wood structure includes:

[0020] Randomly select several positions with evenly distributed wood grains along the radial direction of the wood grain in the schematic diagram of the wood microstructure as the first measurement area;

[0021] Use a measuring tool to measure the annual ring width in each first measurement area to obtain the annual ring width;

[0022] Each first measurement area is evenly divided into a number of second measurement areas along the tangential direction of the wood grain. One vessel is randomly selected from each second measurement area, and a measuring tool is used to measure the diameter of the vessel. The diameter change law of the vessel is obtained by calculation;

[0023] The schematic diagram of the wood microstructure is divided into a number of grids according to the radial and tangential directions of the wood grain. Based on the radial direction of the wood grain, the number of vessels in each grid is counted, and the density change law of the vessels is obtained by calculation;

[0024] Based on the radial direction of the wood grain in the schematic diagram of the wood microstructure, a number of third measurement areas are selected according to the equidistant principle, and a measuring tool is used to measure the diameter of the tracheids in each third measurement area. The diameter change law of the tracheids is obtained by calculation;

[0025] Based on the vessel measurement method, a number of cells are randomly selected in the second measurement area, and a measuring tool is used to measure the diameter of the cells. The diameter change law of the cells is obtained by calculation.

[0026] Furthermore, it also includes calculating the porosity according to the wood microstructure model for testing the wood properties. The calculation formula of the porosity is expressed as:

[0027] ;

[0028] In the formula, represents the porosity, represents the total number of vessels and cells or the total number of tracheids, represents the monomer area of the vessels, tracheids and cells, represents the area of the wood microstructure model to be constructed.

[0029] Furthermore, according to the dimension parameters, the curve equation of the wood microstructure parameters is fitted, and the coefficients of the dimension change law equation are obtained, including:

[0030] Based on the dimension parameters, different curve equations are used for parameter fitting. By calculating the adjusted reduced chi-square value and the coefficient of determination value of each curve equation, the curve equation with the best fitting effect is determined;

[0031] The coefficients of the curve equation with the best fitting effect are extracted as the coefficients of the dimension change law equation.

[0032] Furthermore, the global parameters of the wood microstructure model to be constructed are preset to regularize the wood, and the basic modeling unit is constructed, including:

[0033] Preset the global parameters of the wood microstructure model to be constructed, including shape and size parameters and texture direction parameters;

[0034] Set the geometric shape of the wood and the side lengths of the geometric shape according to the preset shape and size parameters.

[0035] Set the wood grain angle parameter and the radial and tangential distribution parameters of the wood according to the preset texture direction parameters.

[0036] Construct a basic modeling unit based on the geometric shape of the wood, the side lengths of the geometric shape, the wood grain angle parameter, and the radial and tangential distribution parameters.

[0037] Further, based on the coefficients of the size change law equation, use the function equation to simulate the change laws of vessel density, vessel diameter, and cell diameter and apply them to the basic modeling unit to generate a vessel structure and a cell structure, including:

[0038] Based on the coefficients of the size change law equation, construct a vessel density change function, a vessel diameter change function, and a cell diameter change function according to the change laws of vessel density, vessel diameter, and cell diameter.

[0039] Within the annual ring width range, divide the annual ring width into several construction regions, and create a corresponding set of vessel diameters and a set of vessel numbers for each construction region.

[0040] Using a random algorithm, based on the set of vessel diameters and the set of vessel numbers, control the basic modeling unit to generate a vessel structure in each constructed region according to the vessel density change function and the vessel diameter change function.

[0041] Using nested loops, generate a closely arranged cell structure along the radial direction based on the basic modeling unit in each construction region according to the cell diameter change function.

[0042] Further, screen the vessel structure and cell structure that conform to the hardwood structure to generate a hardwood microstructure, including:

[0043] If the vessel structure and cell structure do not exceed the preset shape and size parameters, further determine whether there is interference between any two vessel structures.

[0044] If there is no interference between any two vessel structures, further determine whether there is interference between the cell structure and the vessel structure.

[0045] If there is no interference between the cell structure and the vessel structure, generate a hardwood microstructure according to the vessel structure and the cell structure.

[0046] Further, based on the coefficients of the size change law equation, use the function equation to simulate the change law of tracheid diameter and apply it to the basic modeling unit to generate tracheids, including:

[0047] Based on the coefficients of the size change law equation, according to the diameter change law of tracheids, a function for the diameter change of tracheids is constructed.

[0048] Within the annual ring width range, the annual ring width is divided into several construction regions, and a corresponding set of tracheid diameters is created for each construction region.

[0049] Using nested loops, the basic modeling unit is controlled according to the set of tracheid diameters to generate the tracheid structure within each construction region.

[0050] Furthermore, the tracheid structures that conform to the softwood structure are screened to generate the softwood microstructure, including:

[0051] If the tracheid structure does not exceed the preset shape and size parameters, the softwood microstructure is generated according to the tracheid structure.

[0052] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0053] 1. By extracting the size parameters of the wood microstructure and fitting the size change law equation based on the size parameters, the present invention realizes a highly accurate simulation of the wood microstructure. The present invention also constructs a basic modeling unit by presetting global parameters and differentiates the modeling of hardwoods and softwoods using the coefficients of the size change law equation, which can accurately reflect the differences in the microstructure of the two types of wood, such as the different morphologies and distribution laws of vessels and tracheids, significantly improving the fineness and authenticity of the wood microstructure model, and also providing a more reliable and accurate model basis for constructing the wood microstructure model using ABAQUS based on the hardwood and softwood microstructures, solving the problems of insufficient microstructure characterization and high experimental costs in the existing simulation analysis of wood mechanical properties, and improving the simulation accuracy and efficiency.

[0054] 2. By accurately extracting the annual ring width, the diameter change laws of vessels and tracheids, the density change law, and the diameter change law of cells in the wood microstructure, and using the fitted size change law equation for parametric modeling, the present invention accurately reflects the differences in the microstructure between hardwoods and softwoods. Through a differentiated modeling strategy, the present invention can generate highly realistic microstructure models for hardwoods and softwoods respectively, providing strong support for wood science research.

[0055] 3. The present invention also constructs functions for the change in the diameter of vessels, cells, and tracheids, i.e., the vessel diameter change function, the cell diameter change function, and the tracheid diameter change function, based on the rules of the annual ring width, the change rules of the diameters of vessels and tracheids, the change rules of density, and the change rules of the diameters of cells, thereby realizing the regular generation of vessels, cells, and tracheids. Within each range of annual ring widths, the annual ring characteristics are generated through cyclic iteration using the vessel diameter change function, the cell diameter change function, and the tracheid diameter change function, which not only improves the modeling efficiency but also makes the generated microscopic wood structure model more in line with the actual growth rules of wood.

[0056] 4. The microscopic wood structure model provided by the present invention can be directly applied to finite element analysis, providing a reliable model basis for the study of the mechanical properties and physical characteristics of wood, contributing to the in-depth development of wood science research, and helping to deeply study and understand the mechanical properties and physical characteristics of wood under different conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 is a schematic flowchart of a method for parametric modeling of microscopic wood structure based on finite element provided by an embodiment of the present invention;

[0058] Figure 2 is a schematic diagram of a visual interface for applying preset global parameters of microscopic wood structure provided by an embodiment of the present invention;

[0059] Figure 3 is a schematic diagram of a visual interface for obtaining the dimensional parameters of microscopic structure by applying microscopic wood structure provided by an embodiment of the present invention;

[0060] Figure 4 is a schematic diagram of a visual interface for determining the wood structure by applying microscopic wood structure provided by an embodiment of the present invention;

[0061] Figure 5 is a schematic diagram of microscopic wood structure provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0062] The technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific features in the embodiments of the present invention and the embodiments are detailed descriptions of the technical solutions of the present invention, rather than limitations on the technical solutions of the present invention. Without conflict, the technical features in the embodiments of the present invention and the embodiments can be combined with each other.

[0063] The term "and / or" merely describes the associated relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " generally represents an "or" relationship between the associated objects before and after.

[0064] Example 1

[0065] As Figure 1 shown, this example introduces a parametric modeling method for wood microstructure based on finite element, including:

[0066] Step 1: Obtain a schematic diagram of the wood microstructure, extract the size parameters of the microstructure, and determine the wood structure.

[0067] In the present invention, by obtaining a schematic diagram of the wood microstructure and extracting the size parameters of the microstructure, the microscopic characteristics of the wood are understood, the microscopic properties of the wood are quantified, so as to determine the wood structure such as hardwood or softwood, and specific modeling is carried out according to different types of wood.

[0068] Step 2: Fit a curve equation for the wood microstructure parameters according to the size parameters to obtain the coefficients of the size change law equation.

[0069] In the present invention, by fitting the curve equation, the change law of the wood microstructure parameters is described. The coefficients of the size change law equation are the key parameters for describing the change law of the wood microstructure parameters. In the present invention, a mathematical relationship between the wood microstructure parameters and the size change is established through the coefficients of the size change law equation, providing a basis for subsequent differential modeling of the wood structure.

[0070] Step 3: Preset the global parameters of the wood microstructure model to be constructed to regularize the wood and construct the basic modeling unit.

[0071] In the present invention, the overall characteristics of the wood microstructure model, including size and shape, are defined by presetting global parameters. At the same time, the present invention constructs the basic modeling unit by regularizing the wood structure, greatly simplifying the modeling process. In the subsequent steps, the present invention repeatedly uses these modeling units to construct a more complex wood microstructure and establish the basic framework of the wood microstructure model, not only improving the modeling efficiency but also enhancing the accuracy of the wood microstructure model.

[0072] Step 4: Use the coefficients of the size change law equation and the basic modeling unit to carry out differential modeling of the wood structure respectively:

[0073] For the hardwood structure:

[0074] Based on the coefficients of the size change law equation, use the function equation to simulate the change laws of vessel density, diameter and cell diameter and apply them to the basic modeling unit to generate the vessel structure and cell structure;

[0075] Screen the vessel structure and cell structure that meet the hardwood structure to generate the hardwood microstructure.

[0076] For the softwood structure:

[0077] Based on the coefficients of the size change law equation, use the function equation to simulate the change law of tracheid diameter and apply it to the basic modeling unit to generate tracheids.

[0078] Screen the tracheid structure that conforms to the softwood structure to generate the softwood microstructure.

[0079] For the hardwood structure of the present invention, the vessel structure and cell structure are generated by simulating the vessel density, diameter change and cell diameter change law. For the softwood of the present invention, the tracheid structure is generated by simulating the change law of tracheid diameter.

[0080] According to the wood structure of the present invention, such as hardwood structure or softwood structure, differential modeling is carried out by using the coefficients of the size change law equation and the basic modeling unit to generate a model that conforms to the microscopic characteristics of different types of wood, improving the accuracy and authenticity of the model.

[0081] Step Five: Use ABAQUS to construct a wood microstructure model according to the hardwood microstructure and softwood microstructure.

[0082] ABAQUS is a finite element analysis software used to simulate and analyze complex physical systems. The use of ABAQUS by the present invention to construct a wood microstructure model can perform more in-depth mechanical analysis and simulation, and finally obtain a wood microstructure model that can be used for finite element analysis, providing a powerful tool for the mechanical properties and structural analysis of wood.

[0083] Example 2

[0084] Based on the same inventive concept as in Example 1, this example introduces a parametric modeling method for wood microstructure based on finite elements. This example focuses on the practical application of the wood microstructure model, including:

[0085] Step 1: Obtain a schematic diagram of the wood microstructure, extract the size parameters of the microstructure and determine the wood structure.

[0086] In some embodiments, the size parameters of the microstructure include the annual ring width, the diameter change law and density change law of vessels, the diameter change law of tracheids, and the diameter change law of cells.

[0087] In some embodiments, the obtaining of the schematic diagram of the wood microstructure, extracting the size parameters of the microstructure and determining the wood structure includes:

[0088] Step 1.1: Randomly select several positions with evenly distributed wood grains along the radial direction of the wood grain of the schematic diagram of the wood microstructure as the first measurement area.

[0089] Step 1.2: Use a measuring tool to measure the width of the annual rings in each first measurement area to obtain the width of the annual rings.

[0090] Step 1.3: Divide each first measurement area into several second measurement areas along the tangential direction of the wood grain. Randomly select a conduit from each second measurement area, use a measuring tool to measure the diameter of the conduit, and calculate the variation law of the conduit diameter.

[0091] Step 1.4: Divide the schematic diagram of the wood microstructure into several grids according to the radial and tangential directions of the wood grain. Based on the radial direction of the wood grain, count the number of conduits in each grid, and calculate the variation law of the conduit density.

[0092] Step 1.5: Based on the radial direction of the wood grain in the schematic diagram of the wood microstructure, select several third measurement areas according to the equidistant principle. In each, use a measuring tool to measure the diameter of the tracheids in each third measurement area, and calculate the variation law of the tracheid diameter.

[0093] Step 1.6: Based on the conduit measurement method, randomly select several cells in the second measurement area, use a measuring tool to measure the diameter of the cells, and calculate the variation law of the cell diameter.

[0094] Step 2: Fit a curve equation for the wood microstructure parameters according to the size parameters to obtain the coefficients of the size variation law equation.

[0095] In some embodiments, fitting a curve equation for the wood microstructure parameters according to the size parameters to obtain the coefficients of the size variation law equation includes:

[0096] Step 2.1: Based on the size parameters, perform parameter fitting using different curve equations. By calculating the adjusted reduced chi-square value and the coefficient of determination value of each curve equation, determine the curve equation with the best fitting effect.

[0097] Step 2.2: Extract the coefficients of the curve equation with the best fitting effect as the coefficients of the size variation law equation.

[0098] Step 3: Preset the global parameters of the wood microstructure model to be constructed, regularize the wood, and construct the basic modeling unit.

[0099] In some embodiments, presetting the global parameters of the wood microstructure model to be constructed, regularizing the wood, and constructing the basic modeling unit includes:

[0100] Step 3.1: Preset the global parameters of the wood microstructure model to be constructed, including shape and size parameters and texture direction parameters.

[0101] Step 3.2: Set the geometric shape of the wood and the side lengths of the geometric shape according to the preset shape and size parameters.

[0102] Step 3.3: Set the grain angle parameter and the radial and tangential distribution parameters of the wood according to the preset texture direction parameter.

[0103] Step 3.4: Based on the geometric shape of the wood, the side lengths of the geometric shape, the grain angle parameter, and the radial and tangential distribution parameters, construct a basic modeling unit.

[0104] Step 4: Use the coefficients of the size change law equation and the basic modeling unit to perform differential modeling on the wood structure respectively:

[0105] For the hardwood structure:

[0106] Step 4.1: Based on the coefficients of the size change law equation, use the function equation to simulate the change laws of vessel density, diameter, and the diameter of cells, and apply them to the basic modeling unit to generate the vessel structure and the cell structure:

[0107] Step 4.1.1: Based on the coefficients of the size change law equation, construct a vessel density change function, a vessel diameter change function, and a cell diameter change function according to the change laws of vessel density, vessel diameter, and cell diameter.

[0108] Step 4.1.2: Within the annual ring width range, divide the annual ring width into several construction regions, and create corresponding vessel diameter sets and vessel number sets for each construction region.

[0109] Step 4.1.3: Use the random algorithm, based on the vessel diameter set and the vessel number set, and control the basic modeling unit to generate the vessel structure in each constructed region according to the vessel density change function and the vessel diameter change function.

[0110] Step 4.1.4: Use nested loops to generate a closely arranged cell structure along the radial direction based on the basic modeling unit in each construction region according to the cell diameter change function.

[0111] Step 4.1.5: Screen the vessel structure and the cell structure that meet the hardwood structure to generate the hardwood microstructure, including:

[0112] If the vessel structure and the cell structure do not exceed the preset shape and size parameters, further determine whether there is interference between any two vessel structures.

[0113] If there is no interference between any two vessel structures, further determine whether there is interference between the cell structure and the vessel structure.

[0114] If there is no mutual interference between the cell structure and the duct structure, generate the microstructure of hardwood based on the duct structure and the cell structure and export the porosity.

[0115] For the softwood structure:

[0116] Step 4.2: Based on the coefficients of the size change law equation, use the function equation to simulate the change law of the tracheid diameter and apply it to the basic modeling unit to generate tracheids:

[0117] Step 4.2.1: Based on the coefficients of the size change law equation, construct a tracheid diameter change function according to the change law of the tracheid diameter;

[0118] Step 4.2.2: Within the annual ring width range, divide the annual ring width into several construction regions and create a corresponding set of tracheid diameters for each construction region;

[0119] Step 4.2.3: Use nested loops to generate the tracheid structure within each construction region according to the tracheid diameter change function.

[0120] Step 4.2.4: Screen the tracheid structures that conform to the softwood structure to generate the softwood microstructure, including:

[0121] If the tracheid structure does not exceed the preset shape and size parameters, generate the softwood microstructure based on the tracheid structure and export the porosity.

[0122] Step 5: Use ABAQUS to construct a wood microstructure model based on the hardwood microstructure and the softwood microstructure.

[0123] Step 6: In this embodiment, it also includes calculating the porosity according to the wood microstructure model for testing the wood properties.

[0124] By traversing all the ducts, cells, and tracheids of the wood microstructure model, accumulating the diameters of each duct, cell, and tracheid to obtain the total diameter value, calculating the void area according to the total diameter value, comparing the void area with the total area of the wood microstructure model to be constructed, and calculating the porosity.

[0125] In this embodiment, the calculation formula of the porosity is expressed as:

[0126] ;

[0127] In the formula, represents the porosity, represents the total number of ducts and cells or the total number of tracheids, represents the monomer area of the ducts, tracheids, and cells, represents the area of the wood microstructure model to be constructed.

[0128] Step 7: Create a visual interactive dialogue interface according to the size parameters of the required microstructure, the wood structure, and the global parameters through the RSG constructor and the Abaqus GUI toolkit.

[0129] Figure 2 It is a schematic diagram of the visual interface for presetting global parameters of wood microstructure provided by an embodiment of the present invention; Figure 3 It is a schematic diagram of the visual interface for obtaining the annual ring width of wood microstructure provided by an embodiment of the present invention; Figure 4 It is a schematic diagram of the visual interface for determining the wood structure by applying the wood microstructure provided by an embodiment of the present invention; the size parameters of the microstructure include the annual ring width, the diameter change law and density change law of the vessels, the diameter change law of the tracheids, and the diameter change law of the cells.

[0130] In this embodiment, the visual interactive dialogue interface allows the user to input or select the size parameters of the wood microstructure and the wood type, so as to generate a customized wood microstructure model. This embodiment provides a user-friendly interface, enabling non-professional users to easily input parameters and generate a wood microstructure model, improving the flexibility of modeling and user participation.

[0131] Step 7: Obtain the size parameters of the microstructure and the wood structure in the dialog box of the visual interactive dialogue interface, and generate a wood microstructure model.

[0132] The wood microstructure generated in this embodiment is as Figure 5 shown. This embodiment can dynamically generate a wood microstructure model according to the size parameters of the wood microstructure input or selected by the user and the wood type, realizing the function of customizing the wood microstructure according to the user input, and providing a more flexible and personalized modeling experience.

[0133] Embodiment 3

[0134] Based on the same inventive concept as other embodiments, this embodiment introduces the application method of the wood microstructure model, including:

[0135] Step 1: Import and preprocess the wood microstructure model.

[0136] Step 1.1: Input the size parameters of the microstructure, including the annual ring width, the diameter change law and density change law of the vessels, and the diameter change law of the cells or the diameter change law of the tracheids, and use the wood microstructure model generated in Embodiment 1 or Embodiment 2 to generate a specified wood microstructure model.

[0137] Step 1.2: Load the model.

[0138] The wood microstructure model generated by directly importing through the ABAQUS interface.

[0139] Step 2: Multiphysics simulation analysis.

[0140] Step 2.1: Mechanical property analysis.

[0141] Compression / tension simulation: Apply a quasi-static load along the radial or tangential direction of the wood grain to obtain the stress-strain curve and failure mode, such as vessel collapse and cell wall buckling;

[0142] Dynamic response analysis: Apply an impact load (such as a drop hammer test) to evaluate the impact resistance of the wood microstructure model. Step 2.2: Thermal property analysis.

[0143] Define the temperature field boundary conditions, such as a linear temperature gradient, calculate the effective thermal conductivity and coefficient of thermal expansion, and analyze the influence of pore distribution on the heat insulation performance. Step 2.3: Moisture expansion property analysis.

[0144] Couple the humidity field and the mechanical field to simulate the moisture absorption and expansion behavior of wood and predict the dimensional stability under different porosities.

[0145] Step 3: Performance parameter extraction and evaluation.

[0146] Step 3.1: Porosity correlation analysis.

[0147] According to the porosity calculation formula, establish a quantitative relationship between porosity, elastic modulus, and strength. Step 3.2: Anisotropy index calculation.

[0148] Calculate the equivalent modulus in different directions (such as radial, tangential, and longitudinal) through coordinate transformation to generate an anisotropy factor map.

[0149] Step 4: Parametric optimization and inverse design.

[0150] Step 4.1: Goal-driven optimization.

[0151] Taking porosity, elastic modulus, or thermal conductivity as the optimization goal, adjust the size parameters of the microstructure, including the annual ring width, the variation law of vessel diameter, the density variation law, and the variation law of cell diameter or tracheid diameter:

[0152] Hardwood structure: Optimize the vessel arrangement to reduce the thermal conductivity;

[0153] Softwood structure: Adjust the tracheid diameter gradient to improve the compressive strength. Step 4.2: Topology optimization integration.

[0154] In this embodiment, by combining the topology optimization module of ABAQUS, an optimal vessel distribution scheme is automatically generated under a given load, and the optimized wood microstructure model is output.

[0155] Step 5: Experimental verification and model calibration.

[0156] Step 5.1: Micro-CT comparison.

[0157] Compare the micro-deformation field predicted by simulation with the results of micro-CT scanning to verify the model accuracy. Step 5.2: Macroscopic property benchmarking.

[0158] Compare the macroscopic mechanical properties of wood obtained from simulation, such as the three-point bending strength, with the experimental test data to calibrate the material constitutive model parameters.

[0159] Step 6: Engineering application expansion.

[0160] Step 6.1: Composite material design.

[0161] Embed the wood microstructure model into the simulation of polymer matrix composites to analyze the interfacial bonding strength and load transfer efficiency. Step 6.2: 3D printing preparation guidance.

[0162] Extract the optimized microstructure geometric data to generate printable STL files to guide the design of additive manufacturing process parameters.

[0163] In this embodiment, through the integration of parametric modeling, multi-physics field simulation, and optimization design, a closed-loop prediction from the micro-structure to the macro-properties is achieved, supporting the efficient development and customized design of wood materials. For example, by optimizing the vessel density gradient, the heat insulation performance of wood is improved by 12% while the compressive strength is only reduced by 5%, verifying the application value of the wood microstructure model provided by the present invention.

[0164] In summary, in the above embodiments, the present invention extracts the size parameters of the wood microstructure and fits the size change law equation based on the size parameters, achieving a highly accurate simulation of the wood microstructure. The present invention also constructs basic modeling units by presetting global parameters and differentiates the modeling of broad-leaved wood and coniferous wood using the coefficients of the size change law equation, which can accurately reflect the differences in the micro-structures of the two types of wood, such as the different morphologies and distribution laws of vessels and tracheids, significantly improving the fineness and authenticity of the wood microstructure model. It also provides a more reliable and accurate model basis for constructing the wood microstructure model using ABAQUS according to the micro-structures of broad-leaved wood and coniferous wood, solving the problems of insufficient micro-structure characterization and high experimental costs in the existing simulation analysis of wood mechanical properties, and improving the simulation accuracy and efficiency.

[0165] By precisely extracting the laws of annual ring width, the diameter changes of vessels and tracheids, the density change law, and the cell diameter change law in the wood microstructure, and using the parameterized modeling with the fitted size change law equations, the microstructure differences between hardwoods and softwoods are accurately reflected. Through the differentiated modeling strategy, the present invention can generate highly realistic microstructure models for hardwoods and softwoods respectively, providing strong support for wood science research.

[0166] The present invention also constructs functions for the change of vessel diameter, the change of cell diameter, and the change of tracheid diameter based on the laws of annual ring width, the diameter changes of vessels and tracheids, the density change law, and the cell diameter change law, realizing the regular generation of vessels, cells, and tracheids. Within each annual ring width range, the annual ring characteristics are generated by iteratively using the functions for the change of vessel diameter, the change of cell diameter, and the change of tracheid diameter, which not only improves the modeling efficiency but also makes the generated wood microstructure model more in line with the actual growth law of wood.

[0167] The wood microstructure model provided by the present invention can be directly applied to finite element analysis, providing a reliable model basis for the research on the mechanical properties and physical characteristics of wood, contributing to the in-depth development of wood science research and helping to deeply study and understand the mechanical properties and physical characteristics of wood under different conditions.

[0168] Those skilled in the art should understand that the embodiments of the present invention can be provided as a method, a system, or a computer program product. Therefore, the present invention can take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present invention can take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0169] The present invention is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present invention. It should be understood that each process and / or block in the flowchart and / or block diagram, and the combination of processes and / or blocks in the flowchart and / or block diagram can be realized by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for realizing the functions specified in Figure 1 one process or multiple processes and / or blocks Figure 1 one block or multiple blocks.

[0170] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing apparatus to work in a particular manner, such that the instructions stored in the computer-readable memory produce a manufacture including an instruction device that implements the functions specified in one or more of the processes and / or blocks Figure 1 in one or more of the processes and / or blocks Figure 1 specified in the block or blocks.

[0171] These computer program instructions can also be loaded onto a computer or other programmable data processing apparatus to cause a series of operational steps to be performed on the computer or other programmable apparatus to produce a computer-implemented process, whereby the instructions executed on the computer or other programmable apparatus provide steps for implementing the functions specified in one or more of the processes and / or blocks Figure 1 in one or more of the processes and / or blocks Figure 1 specified in the block or blocks.

[0172] The embodiments of the present invention have been described above in conjunction with the accompanying drawings. However, the present invention is not limited to the above specific embodiments. The above specific embodiments are merely illustrative and not restrictive. Under the inspiration of the present invention, those of ordinary skill in the art can also make many forms without departing from the spirit of the present invention and the scope protected by the claims. All of these are within the protection scope of the present invention.

Claims

1. A finite element-based parametric modeling method for wood microstructure, characterized in that, Including: Obtain a schematic diagram of the wood microstructure, extract the dimensional parameters of the microstructure, and determine the wood structure; Fit a curve equation of the wood microstructure parameters based on the dimensional parameters to obtain the coefficients of the dimensional change law equation; Preset the global parameters of the wood microstructure model to be constructed to regularize the wood and construct the basic modeling unit; Use the coefficients of the dimensional change law equation and the basic modeling unit to perform differential modeling on the wood structure respectively: For the hardwood structure: Based on the coefficients of the dimensional change law equation, use the function equation to simulate the change laws of vessel density, diameter, and the diameter change law of cells, and apply them to the basic modeling unit to generate the vessel structure and cell structure; Screen the vessel structure and cell structure that conform to the hardwood structure to generate the hardwood microstructure; For the softwood structure: Based on the coefficients of the dimensional change law equation, use the function equation to simulate the change law of tracheid diameter and apply it to the basic modeling unit to generate tracheids; Screen the tracheid structure that conforms to the softwood structure to generate the softwood microstructure; Use ABAQUS to construct a wood microstructure model based on the hardwood microstructure and the softwood microstructure.

2. The parametric modeling method of wood microstructure based on finite element according to claim 1, characterized in that The dimensional parameters of the microstructure include the annual ring width, the change laws of the diameter and density of vessels, the change law of the diameter of tracheids, and the change law of the diameter of cells.

3. The parametric modeling method for wood microstructure based on finite element according to claim 1, characterized in that, The obtaining of the schematic diagram of the wood microstructure, extracting the dimensional parameters of the microstructure, and determining the wood structure includes: Randomly select several positions with evenly distributed wood grains along the radial direction of the wood grain in the schematic diagram of the wood microstructure as the first measurement area; Use a measuring tool to measure the annual ring width in each first measurement area to obtain the annual ring width; Divide each first measurement area into several second measurement areas along the tangential direction of the wood grain, randomly select a vessel from each second measurement area, use a measuring tool to measure the diameter of the vessel, and calculate the change law of the vessel diameter; Divide the schematic diagram of the wood microstructure into several grids according to the radial and tangential directions of the wood grain. Based on the radial direction of the wood grain, count the number of vessels in each grid and calculate the change law of the vessel density; Based on the radial direction of the wood grain in the schematic diagram of the wood microstructure, select several third measurement areas according to the equal-distance principle, use a measuring tool to measure the diameter of tracheids in each third measurement area, and calculate the change law of the tracheid diameter; Based on the vessel measurement method, randomly select several cells in the second measurement area, use a measuring tool to measure the diameter of the cells, and calculate the change law of the cell diameter.

4. The parametric modeling method for wood microstructure based on finite element according to claim 3, wherein It also includes calculating the porosity according to the wood microstructure model for testing the wood performance. The calculation formula of the porosity is expressed as: ； In the formula, represents the porosity, represents the total number of vessels and cells or the total number of tracheids, represents the monomer area of vessels, tracheids and cells, represents the area of the wood microstructure model to be constructed.

5. The parametric modeling method of wood microstructure based on finite element according to claim 3, characterized in that Fitting a curve equation of the wood microstructure parameters based on the dimensional parameters to obtain the coefficients of the dimensional change law equation includes: Based on the dimensional parameters, perform parameter fitting using different curve equations, and determine the curve equation with the best fitting effect by calculating the adjusted reduced chi-square value and the coefficient of determination value of each curve equation; Extract the coefficients of each item of the curve equation with the best fitting effect as the coefficients of the dimensional change law equation.

6. The parametric modeling method for wood microstructure based on finite element according to claim 5, wherein Regularize the global parameters of the preset wood microstructure model to construct basic modeling units, including: Preset the global parameters of the wood microstructure model to be constructed, including shape and size parameters and texture direction parameters; According to the preset shape and size parameters, set the geometric shape of the wood and the side length of the geometric shape; According to the preset texture direction parameters, set the wood grain angle parameter and the radial and tangential distribution parameters of the wood; Based on the geometric shape of the wood, the side length of the geometric shape, the wood grain angle parameter, and the radial and tangential distribution parameters, construct basic modeling units.

7. The parametric modeling method of wood microstructure based on finite element according to claim 6, characterized in that Based on the coefficients of the size change law equation, use the function equation to simulate the density change law, diameter change law of the vessel, and diameter change law of the cells and apply them to the basic modeling unit to generate the vessel structure and cell structure, including: Based on the coefficients of the size change law equation, construct the vessel density change function, vessel diameter change function, and cell diameter change function according to the density change law of the vessel, the diameter change law of the vessel, and the diameter change law of the cells; Within the annual ring width range, divide the annual ring width into several construction regions, and create corresponding vessel diameter sets and vessel number sets for each construction region; Using a random algorithm, based on the vessel diameter set and vessel number set, control the basic modeling unit to generate the vessel structure in each constructed region according to the vessel density change function and vessel diameter change function; Using nested loops, generate a closely arranged cell structure along the radial direction based on the basic modeling unit in each construction region according to the cell diameter change function.

8. The parametric modeling method of wood microstructure based on finite element according to claim 7, characterized in that Screen the vessel structure and cell structure that meet the broad-leaved wood structure to generate the broad-leaved wood microstructure, including: If the vessel structure and cell structure do not exceed the preset shape and size parameters, further determine whether there is interference between any two vessel structures; If there is no interference between any two vessel structures, further determine whether there is interference between the cell structure and the vessel structure; If there is no interference between the cell structure and the vessel structure, generate the broad-leaved wood microstructure according to the vessel structure and cell structure.

9. The method for parametric modeling of the preset shape size parameters and structural parameters of wood based on finite element according to claim 6, wherein Based on the coefficients of the size change law equation, use the function equation to simulate the diameter change law of tracheids and apply it to the basic modeling unit to generate tracheids, including: Based on the coefficients of the size change law equation, construct the tracheid diameter change function according to the diameter change law of tracheids; Within the annual ring width range, divide the annual ring width into several construction regions, and create corresponding tracheid diameter sets for each construction region; Using nested loops, control the basic modeling unit to generate the tracheid structure in each construction region according to the tracheid diameter set.

10. The parametric modeling method of wood microstructure based on finite element according to claim 9, characterized in that Screen the tracheid structure that meets the coniferous wood structure to generate the coniferous wood microstructure, including: If the tracheid structure does not exceed the preset shape and size parameters, generate the coniferous wood microstructure according to the tracheid structure.

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