Prediction method for critical internal pressure causing fruit crack propagation

Abstract

The invention discloses a method for predicting critical internal pressure causing fruit crack propagation, and belongs to the field of agricultural engineering, and the method comprises the steps: obtaining fruit peel physical parameters which comprise fruit peel thickness and fruit peel biomechanical parameters; constructing a geometric model according to the peel physical parameters; the geometric model is verified; simulating the fruits with different peel thicknesses and biomechanical parameters through the verified geometric model to obtain a simulated cracking result; according to the simulated cracking result, constructing a multiple linear regression model; the method comprises the following steps: acquiring to-be-measured data which are peel thickness and biomechanical parameter data of a to-be-measured fruit, and calculating the to-be-measured data through a multiple linear regression model to obtain a predicted cracking result of the fruit. A direction is provided for gardening management and biological breeding, so that the risk of fruit cracking is reduced.

Description

Technical Field

[0001] The invention belongs to the technical fields of agricultural engineering and computational biology, and in particular relates to a method for predicting a critical internal pressure causing crack expansion in a fruit. Background Art

[0002] Fruit cracking during maturity is one of the important factors affecting fruit yield and quality. Horticultural management has a direct impact on the moisture status of the fruit, the biomechanical properties of the fruit, etc., which in turn affects the risk of fruit cracking. At present, the research on the mechanism of fruit cracking is mainly focused on biological level analysis, and there is a lack of in-depth simulation research on the expansion of cracks. It is impossible to effectively predict the risk of fruit cracking, that is, the critical internal pressure for the expansion of peel cracks, and thus it is impossible to effectively manage the fruit according to the fruit cracking mechanism to ensure that the fruit does not crack as much as possible. Summary of the invention

[0003] In order to solve the above technical problems, the present invention proposes a method for predicting the critical internal pressure that causes fruit crack propagation. By establishing the relationship between the physical parameters of the fruit and the critical pressure value of the crack propagation of the fruit, the horticultural management strategy is optimized and breeding direction is provided, the risk of fruit cracking is reduced, and the problems existing in the above-mentioned prior art are solved.

[0004] To achieve the above object, the present invention provides a method for predicting the critical internal pressure that causes crack propagation in fruits, comprising:

[0005] Acquiring physical parameters of the peel, wherein the physical parameters of the peel include peel thickness and biomechanical parameters;

[0006] constructing and defining a geometric model according to the physical parameters of the peel, and verifying the geometric model;

[0007] Setting different numerical combinations of peel thickness and peel biomechanical parameters, and using the verified geometric model to simulate the peel under different numerical combinations of peel thickness and peel biomechanical parameters for several times, to obtain simulated cracking results;

[0008] A sensitivity analysis was performed based on the simulated cracking results, and the main physical parameters affecting the crack propagation of the peel were screened out. A multivariate linear regression model was constructed based on the main physical parameters, in which the independent variables of the multivariate linear regression model were the main physical parameters screened out, and the dependent variable was the critical pressure result of crack propagation.

[0009] The data to be tested are obtained, wherein the data to be tested are data of physical parameters of the peel of the fruit to be tested, and the data to be tested are calculated by a multivariate linear regression model to obtain a predicted cracking result of the fruit.

[0010] Optionally, the biomechanical parameters are obtained by performing a tensile test on the peel of the fruit using a texture analyzer, wherein the biomechanical parameters include peel failure stress, peel failure strain, peel elastic modulus, and peel fracture energy.

[0011] Optionally, the geometric model construction process includes:

[0012] constructing an initial geometric model in finite element software, wherein components in the initial geometric model include a peel, a loading probe, a prefabricated crack, and a fixing bracket;

[0013] The material properties of the initial geometric model are defined according to the biomechanical parameters, and other model parameters are defined and meshes are divided for the initial geometric model to obtain a geometric model.

[0014] Optionally, the process of verifying the geometric model includes:

[0015] A three-point bending test is performed on the fruit peel using a texture analyzer to obtain video data of the three-point bending test, and photos in the video data are extracted to obtain measured data based on the photos and data derived from the texture analyzer, wherein the measured data includes the relationship between the loading force and the deflection and the crack length obtained from the photos and the deflection data and the loading force data derived from the texture analyzer;

[0016] A tensile test is performed on the peel of the fruit to obtain mechanical data of the peel under the tensile test, material properties of the geometric model are adjusted according to the mechanical data of the peel under the tensile test, and the adjusted geometric model is simulated to obtain simulation results, the simulation results are compared with the measured data, and a verified geometric model is obtained based on the comparison results.

[0017] Optionally, the simulation cracking results include the relationship between the loading force and the crack extension area of ​​the fruit, and the critical pressure value for the crack area extension is found.

[0018] Optionally, a sensitivity analysis is performed on the physical parameters of the peel to screen out the main physical parameters that significantly affect the critical pressure value, and to establish the relationship between the main physical parameters and the critical pressure value.

[0019] Among them, the relationship between the main physical parameters and the critical pressure value is represented by a multivariate linear regression model, and the critical pressure value in the multivariate linear regression model is equal to the sum of the weighted sum of different main physical parameters and the influence constant, wherein the weight coefficient and influence constant in the weighted sum are obtained by fitting.

[0020] Compared with the prior art, the present invention has the following advantages and technical effects:

[0021] The method of the present invention can effectively predict the critical internal pressure of crack propagation of fruits under different physical parameters, and by adjusting the horticultural management method and optimizing breeding, the critical internal pressure of crack propagation can be increased, thereby significantly reducing the risk of fruit cracking and improving the quality and yield of fruits. The experimental results show that the cracking phenomenon can be alleviated by optimizing management and breeding to change the thickness of the peel and the biomechanical properties of the peel. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting a part of the present application are used to provide a further understanding of the present application. The illustrative embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0023] Figure 1 The finite element model verification result of the embodiment of the present invention;

[0024] Figure 2 A schematic diagram of the expansion of the crack area of ​​a fruit and the definition of the critical pressure of crack expansion according to an embodiment of the present invention;

[0025] Figure 3 Schematic diagram of sensitivity analysis of different parameters on the critical pressure of crack growth;

[0026] Figure 4 Schematic diagram of the critical pressure value of crack growth under different levels of peel failure stress and peel thickness;

[0027] Figure 5 This is a schematic diagram of measuring the biomechanics of the fruit peel according to an embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of a three-point bending test actually measured in an embodiment of the present invention;

[0029] Figure 7 A schematic diagram of a three-point bending simulation according to an embodiment of the present invention;

[0030] Figure 8 The figure is a schematic diagram of a method flow of an embodiment of the present invention. DETAILED DESCRIPTION

[0031] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0032] It should be noted that the steps shown in the flowcharts of the accompanying drawings can be executed in a computer system such as a set of computer executable instructions, and that, although a logical order is shown in the flowcharts, in some cases, the steps shown or described can be executed in an order different from that shown here.

[0033] like Figure 8 As shown, this embodiment provides a method for predicting the critical internal pressure that causes fruit crack expansion, comprising:

[0034] Through the texture analyzer tensile test, the biomechanical parameters of the fruit peel after the test are obtained, and a finite element model is constructed based on the biomechanical parameters of the fruit peel; wherein, the fruits targeted by the present invention include but are not limited to edible, ornamental or economic crop fruits, such as mature melons, tomatoes or apples.

[0035] The geometric model of the fruit peel is constructed using finite element software; the material properties of the geometric model are defined according to the biomechanical parameters of the peel, and the geometric model is simulated to obtain the corresponding relationship between the loading force and the deflection, and the crack extension length;

[0036] A three-point bending test is carried out on the peel using a texture analyzer, and the process of the three-point bending test is video captured to obtain test video data, key frames are extracted from the test video data, and measured data are extracted from the key frames. The measured data include the relationship between the measured deflection and crack extension length. At the same time, the data is exported from the texture analyzer to determine its deflection and loading force data. The peel mechanical data of the peel in the three-point bending test is collected through a tensile test and defined in the geometric model, and the geometric model is simulated. The simulation results are compared with the measured data to evaluate and verify the prediction accuracy of the geometric model. It should be noted that the peel mechanical data is the corresponding specific numerical data of the peel biomechanical parameters.

[0037] After the geometric model is verified, a sensitivity analysis is performed on all material property parameters (peel thickness, peel fracture stress, peel elastic modulus, peel fracture energy), and the main physical parameters that have a significant impact on the critical pressure value, namely the key parameters (i.e., peel thickness and peel fracture stress), are screened out, and the screened key parameters are used as independent variables, and the critical pressure that causes the expansion of the fruit crack area is used as the dependent variable. A multivariate linear regression model is constructed, and the multivariate linear regression model is used as an evaluation model to predict the critical pressure, so as to provide guidance for horticultural management and biological breeding, and to ensure that the risk of cracking is reduced under guidance as much as possible. As some embodiments, the biomechanical parameters of the peel are collected and obtained through a texture analyzer tensile test. The biomechanical parameters of the peel include peel thickness, peel fracture stress, peel elastic modulus, and peel fracture energy. The above-mentioned peel biomechanical parameters are mainly used for the material property definition of the geometric model.

[0038] like Figure 5 As shown in the figure, in the tensile test, a customized dual-toughness cutter was used to prepare a melon peel sample (length × width × thickness: 60mm × 10mm × 2.5mm) for tensile testing. Then, an A / TG probe was used to stretch the sample along the length direction at a speed of 0.5mm / s. The fracture stress was then calculated using the subsequent formula ( )、Failure strain( ), elastic modulus (E) and failure energy (G).

[0039]

[0040]

[0041]

[0042]

[0043] Among them, F max represents the breaking strength, A represents the cross-sectional area, and L represents the length before deformation. represents the elongation after deformation, w represents the width of the specimen cross section, b represents the thickness of the specimen cross section, and F(x) represents the force value when the displacement is x.

[0044] As some embodiments, in constructing a geometric model of the fruit peel, a finite element software, such as Abaqus / CAE software, is used to establish a three-dimensional geometric model that can simulate the three-point bending of the peel. In the three-dimensional geometric model, its components mainly include the peel, the loading probe, the prefabricated crack and the fixed bracket, wherein the prefabricated crack is a microscopic crack on the fruit, indicating the starting position of the crack extension on the fruit;

[0045] The material properties of the peel geometric model are defined according to the peel biomechanical parameters, wherein the material properties include peel thickness, peel fracture stress, peel elastic modulus, and peel fracture energy;

[0046] Define the analysis steps and field output of the geometric model in the finite element software;

[0047] The analysis step is set to static, general analysis step, time length is 1, geometric nonlinearity is set to on, and the maximum number of incremental steps is set to 10000000; the incremental step size is initially set to 0.01, the minimum is set to 1E-09, and the maximum is set to 1.

[0048] The scope of field output is the entire model, and the output variables are CDISP (contact displacement), CF (concentrated force and moment), CSTRESS (contact stress), ENRRTXFEM (strain energy release rate based on XFEM), LE (logarithmic strain component), PE (plastic strain component), PEEQ (equivalent plastic strain), PEMAG (plastic strain), PHILSM (hierarchical set value phi), PSILSM (pound level), RF (reaction force and moment), S (stress component and unequal quantity), STATUSXFEM (status of xfem unit), U (translation and rotation). The scope of historical output is set: the midpoint on the probe is the characteristic point, and the output variables are RF2 (reaction force and moment), U2 (translation and rotation). Among them, the field variable output is used to describe the change of a certain quantity with spatial position, and the historical output variable is used to describe the change of a certain quantity with time.

[0049] Define the interaction between the components in the geometric model, set the contact between the loading probe and the fixed support and the peel, and the contact between the prefabricated crack and the peel to be surface-to-surface contact, so as to realize the constraint between the components and the crack extension;

[0050] Define the boundary conditions of the geometric model, including that the fixed bracket is completely fixed and the loading probe has freedom only in the y direction to achieve the simulation of three-point bending;

[0051] Meshing the geometric model, including meshing of the peel, probe, and fixed bracket;

[0052] Submit the assignment in the finite element software to perform analytical calculation simulation on the above-mentioned geometric model, and extract the relationship between the loading force and the deflection and crack extension length from the analytical calculation simulation results.

[0053] As some embodiments, Figure 6-7 As shown, a three-point bending test was carried out on the peel using a texture analyzer, and real-time video was recorded through a fixed camera during the three-point bending test to collect test video data. Then, photos corresponding to key frames were extracted from the video using Pr software, where the key frames were video frames collected at fixed intervals. Image J was used to extract the relationship between the measured deflection and crack length from the photos, and the deflection and loading force data were obtained in the exported data of the texture analyzer.

[0054] In the three-point bending test, the geometric dimensions (length × width × thickness) of the peel were 60 × 10 × 2.5 mm. A rectangular corner crack (length × width: 2 × 0.5 mm) was prefabricated outside the center of the peel sample. The test sample was placed on the support beam of the three-point bending fixture of the texture analyzer, and its span was set to 20 mm. The loading probe was at the center of the span of the two support beams, and the loading speed was set to 0.5 mm / s.

[0055] A tensile test is performed on the peel, and the mechanical data of the peel obtained from the tensile test is set into the material properties of the geometric model. The geometric model is analyzed and calculated and simulated according to the above method to obtain the final simulation results, wherein the three-point bending test and the geometric model simulation are for the same peel or the peels at adjacent positions under the same fruit.

[0056] The results of the geometric model simulation and the three-point bending test were compared, such as Figure 1 As shown, the relationship between the measured and simulated load and deflection, and the relationship between deflection and crack length are compared to see if they are within the preset error. At the same time, the deflection and loading force data in the data derived from the texture analyzer are substituted into the simulated relationship, and the errors between the calculated data and the deflection and loading force data after the substitution into the simulated relationship are compared to see if they are within the preset error. Figure 2 As shown in the figure, when all the above conditions are met, it means that the geometric model can be used for subsequent use. After the geometric model is verified, the critical force value that causes the crack area to expand is defined as the critical crack expansion pressure, and then sensitivity analysis is performed on all material property parameters (peel thickness, peel fracture stress, peel elastic modulus, peel fracture energy), and parameters that have a significant impact on the critical pressure value are screened out, such as Figure 3 It is concluded that the peel thickness and peel rupture stress have a significant effect on the critical pressure of crack propagation. Then multiple simulations are performed for different peel thicknesses and peel rupture stresses, and the critical pressure values ​​of fruit crack propagation after multiple simulations are obtained from the simulation results of the geometric model, such as Figure 4 .

[0057] Based on the critical pressure value of fruit crack propagation, the correlation between the biomechanical parameters of the peel and the critical pressure value of the crack was analyzed. For example, taking melon fruit as an example, if the key parameters are peel thickness and peel fracture stress, peel thickness and peel fracture stress are used as independent variables, and the critical internal pressure that causes peel crack propagation is used as the dependent variable, a multivariate linear regression model is constructed to predict the critical internal pressure that causes peel crack propagation:

[0058] Crack extension critical internal pressure = A*peel thickness + B*peel fracture stress + C

[0059] Among them, A and B are the corresponding coefficient terms of different independent variables, and C is a constant.

[0060] The present invention provides a method and idea for establishing the relationship between fruit biological traits and critical internal pressure of crack extension. Its multivariate linear regression model can also select other forms of multivariate regression models or select a simple deep learning model to fit the relationship.

[0061] Based on the above multivariate linear regression model, the critical pressure value that causes fruit crack expansion is calculated, which can guide relevant personnel to prevent fruit cracking as much as possible. It can help researchers to have a deeper understanding of the physical process and biomechanical mechanism of fruit cracking, and provide a theoretical basis for further research. The prediction model can be used as a risk assessment tool to help growers predict the risk of fruit cracking. In the method of predicting the critical pressure value, the predicted critical pressure value under different breeding or horticultural management conditions is used as a reference value. Through the selection or optimization of breeding methods or horticultural management conditions by relevant personnel, the physical properties or mechanical properties of the fruit are regulated, and the critical internal pressure of fruit cracking, that is, the cracking threshold, is increased to reduce the probability of fruit cracking. By predicting the critical internal pressure of crack expansion, ideas are provided for horticultural management and biological breeding, thereby improving the overall quality and yield of the fruit.

[0062] At the same time, within the planting area, a uniform sampling method can be used to collect the fruits in the planting area, and the fruit peel mechanical data can be obtained to calculate the corresponding critical internal pressure of the peel, predict the possibility of cracking, and reduce the risk of cracking.

[0063] For ease of understanding, the present invention is described by the following contents:

[0064] The present invention provides a method for predicting the critical internal pressure that causes crack propagation in a fruit, which is described by taking a ripe melon fruit as an example, and comprises:

[0065] 1. Material property determination: Through the texture analyzer tensile test, the biomechanical parameters of the melon peel, such as failure stress, failure strain, elastic modulus, fracture energy, etc., are obtained, which are used in "Defining the material properties of melon peel" in "2. Establishment of finite element model".

[0066] 2. Establishment of finite element model:

[0067] Abaqus / CAE software was used to establish a three-dimensional geometric model that can simulate the three-point bending of the peel. The components included the peel, loading probe, prefabricated cracks and fixed brackets.

[0068] Define the material properties of melon peel, including peel elastic modulus, Poisson's ratio, fracture stress, fracture strain, fracture energy, etc.

[0069] Define the analysis steps and field output.

[0070] The interactions between the geometric models were defined, and the contacts between the probe and the bracket and the peel, as well as the contacts between the crack and the peel were set to be surface-to-surface contacts, so as to realize the constraints between the components and the crack extension.

[0071] The boundary conditions of the model are defined, including that the fixed bracket is completely fixed and the loading probe has freedom only in the y direction to achieve the simulation of three-point bending.

[0072] Divide the mesh, including the peel and probe, and the mesh of the fixed bracket.

[0073] Submit the assignment and extract the relationship between the loading force and the deflection and crack extension length from the results.

[0074] 3. Verification of finite element model:

[0075] A three-point bending test was carried out using a texture analyzer, and the entire process was recorded in real time with a fixed camera. Then, photos were extracted from the video using Pr, and the measured load-deflection-crack length relationship was extracted from the photos. At the same time, the deflection and loading force data were obtained from the data exported from the texture analyzer.

[0076] The peel mechanical data of the tensile test required for verification is set into the geometric model, and simulation calculation is performed according to step 2 to obtain the simulation results. The peel mechanical data is the specific value assignment data corresponding to the peel biomechanical parameters.

[0077] Compare the simulated and experimental data to evaluate the predictive accuracy of the model.

[0078] 4. Model implementation:

[0079] The model was validated and used to simulate the peel cracking process of melon fruit under different breeding or horticultural management conditions, including:

[0080] Based on the step 2 method, the influence of different levels of peel biological characteristics on the critical pressure of crack propagation is considered, and the material properties are defined based on this. Multiple simulations are performed to obtain the corresponding data of fruit crack propagation area and extract the critical pressure value of fruit crack propagation.

[0081] 5. Sensitivity analysis

[0082] A sensitivity analysis was performed on the effects of all material property parameters on the critical pressure (peel thickness, peel fracture stress, peel elastic modulus, peel fracture energy), and the parameters that have a significant impact on the critical pressure value were screened out, such as peel thickness and peel fracture stress.

[0083] 6. Prediction of critical internal pressure for fruit crack growth

[0084] By analyzing the simulation results, a multivariate linear regression mathematical model was established for melon fruits, with peel thickness and peel fracture stress as independent variables and the critical pressure of peel crack propagation as the dependent variable (for example, critical internal pressure of crack propagation = A*peel thickness+B*peel fracture stress+C), providing a theoretical basis for the correlation with fruit crack propagation.

[0085] The above are only preferred specific implementations of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A method for predicting the critical internal pressure causing crack propagation in fruit, characterized in that: include: Acquiring physical parameters of the peel, wherein the physical parameters of the peel include peel thickness and biomechanical parameters; constructing and defining a geometric model according to the physical parameters of the peel, and verifying the geometric model; Setting different numerical combinations of peel thickness and peel biomechanical parameters, and using the verified geometric model to simulate the peel under different numerical combinations of peel thickness and peel biomechanical parameters for several times, to obtain simulated cracking results; A sensitivity analysis was conducted based on the simulated cracking results to screen out the main physical parameters that affect the crack extension of the peel. A multiple linear regression model was constructed based on the main physical parameters, in which the independent variables of the multiple linear regression model were the main physical parameters screened out, and the dependent variable was the critical pressure result of crack extension. The data to be tested are obtained, wherein the data to be tested are data of physical parameters of the peel of the fruit to be tested, and the data to be tested are calculated by a multivariate linear regression model to obtain a predicted cracking result of the fruit.

2. The method according to claim 1, characterized in that The biomechanical parameters are obtained by performing a tensile test on the peel of the fruit using a texture analyzer, wherein the biomechanical parameters include peel failure stress, peel failure strain, peel elastic modulus, and peel fracture energy.

3. The method according to claim 1, characterized in that The construction process of the geometric model includes: constructing an initial geometric model in finite element software, wherein components in the initial geometric model include a peel, a loading probe, a prefabricated crack, and a fixing bracket; The material properties of the initial geometric model are defined according to the biomechanical parameters, and other model parameters are defined and meshes are divided for the initial geometric model to obtain a geometric model.

4. The method according to claim 1, characterized in that: The process of validating the geometric model includes: A three-point bending test is performed on the fruit peel using a texture analyzer to obtain video data of the three-point bending test, and photos in the video data are extracted to obtain measured data based on the photos and data derived from the texture analyzer, wherein the measured data includes the relationship between the loading force and the deflection and the crack length obtained from the photos and the deflection data and the loading force data derived from the texture analyzer; A tensile test is performed on the peel of the fruit to obtain mechanical data of the peel under the tensile test, material properties of the geometric model are adjusted according to the mechanical data of the peel under the tensile test, and the adjusted geometric model is simulated to obtain simulation results, the simulation results are compared with the measured data, and a verified geometric model is obtained based on the comparison results.

5. The method according to claim 1, characterized in that The simulated cracking results include the relationship between the simulated loading force and the crack extension area of ​​the fruit and the critical pressure value for the crack area extension.

6. The method according to claim 5, characterized in that Conduct sensitivity analysis on the physical parameters of the peel, screen out the main physical parameters that significantly affect the critical pressure value, and establish the relationship between the main physical parameters and the critical pressure value; The relationship between the main physical parameters and the critical pressure value is represented by a multiple linear regression model, in which the critical pressure value is equal to the sum of the weighted sum of different main physical parameters and the influence constant, wherein the weight coefficient and the influence constant in the weighted sum are obtained by fitting; When the internal pressure of the fruit is greater than the critical internal pressure of crack propagation of the measured data, the predicted cracking result of the fruit is that the fruit cracks rapidly.

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