In-situ determination method for time-varying performance parameters of 3D printing concrete material

Abstract

According to the in-situ determination method for the time-varying performance parameters of the 3D printing concrete material, the time-varying performance parameters of the concrete can be deduced without traditional material tests by utilizing an inversion strategy combining numerical simulation and machine vision technologies. The method comprises the following steps: firstly, setting to-be-tested parameters based on a constitutive model of the early-age 3D printing concrete; then, different values of the parameters are set for numerical simulation, and each group of simulation generates a corresponding structural deformation result. Secondly, deformation data in the actual 3D printing process is obtained through a machine vision technology and serves as a reference standard; and by comparing the deformation result of each group of numerical simulation with the actual measurement data, reversely deducing the time-varying performance parameter which most accords with the actual condition. According to the method, the concrete time-varying material parameters are measured on the premise that the printing process is not interfered, monitoring of the printing process can be enhanced, and a foundation is laid for verification of an early-age mechanical model and proposing of a new constitutive model driven by data.

Description

Technical Field

[0001] The invention relates to the field of civil engineering and construction, and in particular to a real-time determination technology of printing material parameters. Background Art

[0002] With the continuous development of construction engineering technology, research on additive manufacturing technology (i.e. 3D printing technology) in the field of civil engineering has made significant progress, especially in the application of concrete materials. 3D printing concrete technology achieves the rapid construction of complex geometric structures by stacking materials layer by layer, and shows great potential in reducing construction time, cost and material consumption. However, since 3D printed concrete materials solidify in a very short time due to the action of admixtures, have significant time-varying characteristics, and are affected by complex environmental conditions, the accurate prediction and characterization of their mechanical properties still face huge challenges.

[0003] The constitutive model of 3D printed concrete is a basic tool for describing its mechanical behavior. The continuity and time-varying characteristics of the material make it particularly important to obtain and update these model parameters in real time during the printing process. However, existing technologies mainly rely on material testing under laboratory conditions, which usually takes a long time. During the testing time, the performance of 3D printed concrete has changed significantly, making it difficult to accurately capture the time-varying parameters that describe the changes in material properties. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and propose a method for determining the parameters of the constitutive model of the time-varying performance of 3D printed concrete materials, which solves the problem that the material performance parameters cannot be accurately obtained and updated in real time during the printing process in the prior art. The present invention realizes the real-time inference and update of material parameters, thereby providing reliable data support for subsequent model research and structural design.

[0005] Technical solution of the present invention

[0006] A method for in-situ determination of time-varying performance parameters of 3D printed concrete materials, comprising the following steps:

[0007] (S100) determining the parameters to be measured according to the selected time-varying constitutive model, wherein these parameters are used to describe the key mechanical properties of the concrete material in the time-varying process; and proceeding to steps S200 and S300 respectively;

[0008] (S200) setting multiple groups of different values ​​for the parameters to be measured, performing numerical simulation, and generating corresponding structural deformation results;

[0009] (S300) using a binocular vision monitoring system to obtain three-dimensional geometric data of the concrete structure in the 3D printing process in real time through stereo matching and parallax calculation, generating and transmitting three-dimensional point cloud data, and obtaining actual measured deformation data;

[0010] (S400) comparing the structural deformation results obtained by numerical simulation in S200 with the deformation data actually measured in S300, and deriving the time-varying performance parameters through inverse analysis;

[0011] (S500) The time-varying performance parameters obtained by inversion are stored, and a new time-varying constitutive model is gradually proposed and improved in a data-driven manner.

[0012] The technical equipment and methods involved are:

[0013] (1) Binocular vision monitoring system:

[0014] The binocular vision monitoring system used in the present invention uses binocular camera equipment to capture and record the three-dimensional geometric shape of each layer of concrete in real time during the 3D printing process. The system uses stereo matching and parallax calculation technology to generate high-precision three-dimensional point cloud data to ensure that the geometric shape during the printing process can be accurately recorded. These point cloud data are used for subsequent parameter inversion analysis to monitor and evaluate changes in material properties in real time.

[0015] (2) Numerical simulation tools:

[0016] Numerical simulation tools use advanced software platforms to calculate the deformation response of the structure based on the set values ​​of the parameters to be measured. The tool can include analysis methods such as finite element or discrete element to accurately evaluate the impact of different parameter values ​​on the performance of the structure. Through numerical simulation, the deformation behavior of concrete structures can be predicted under different assumptions.

[0017] (3) Parameter inversion analysis method:

[0018] The parameter inversion analysis method compares the actual measured three-dimensional point cloud data with the numerical simulation results to determine the time-varying performance parameters that best meet the actual conditions. The method includes the following steps:

[0019] a. Data matching and error analysis: First, the actual measurement data is matched with the numerical simulation results, and the error between the two is analyzed.

[0020] b. Iterative optimization: According to the error analysis results, the parameters to be tested are continuously adjusted, and the parameter settings are gradually optimized through multiple simulation calculations until the simulation results are highly consistent with the actual data.

[0021] c. Result verification: The parameters obtained from the final inversion are verified and serve as a reliable basis for subsequent structural design and analysis.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The present invention combines real-time monitoring with numerical simulation to accurately measure the time-varying performance parameters of concrete materials in situ during the printing process, breaking through the limitations of laboratory conditions and reflecting the dynamic changes in the performance of concrete materials under actual construction environments.

[0024] The present invention is applicable to 3D printing concrete technology in various complex construction environments, especially in extreme conditions such as high temperature and high humidity, and can provide accurate material parameter determination to meet the diverse needs in engineering practice. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 The figure is a flow chart of the method of the present invention. DETAILED DESCRIPTION

[0026] The technical solution provided by the present application will be further described below in conjunction with specific embodiments and accompanying drawings. The advantages and features of the present application will become more apparent with the following description.

[0027] The present invention provides an in-situ determination method for time-varying performance parameters of 3D printed concrete materials. By using an inversion strategy combining numerical simulation and machine vision technology, the time-varying performance parameters of concrete can be inferred without traditional material testing. The method first sets the parameters to be measured based on the constitutive model of 3D printed concrete at an early age. Subsequently, different values ​​of the parameters are set for numerical simulation, and each group of simulations produces corresponding structural deformation results. Then, the deformation data in the actual 3D printing process is obtained by machine vision technology and used as a reference standard. By comparing the deformation results of each group of numerical simulations with the actual measurement data, the time-varying performance parameters that best meet the actual conditions are inferred. The method realizes the determination of time-varying material parameters of concrete without interfering with the printing process, which can not only enhance the monitoring of the printing process, but also lays the foundation for the verification of early-age mechanical models and the proposal of new data-driven constitutive models.

[0028] In this embodiment, the Burgers model based on viscoelastic creep behavior is selected, combined with a binocular vision monitoring system and numerical simulation tools to determine the time-varying performance parameters of 3D printed concrete and optimize the printing process. The detailed operations of each step are as follows:

[0029] S100: Determine the parameters to be measured based on the constitutive model

[0030] First, the Burgers model of viscoelastic creep behavior is selected as the basis for analyzing the mechanical behavior of 3D printed concrete. This model can describe the time-varying mechanical properties of concrete during the printing process, especially under the conditions of material creep and relaxation. Its specific expression is as follows:

[0031]

[0032] in:

[0033] ∈(t) is the strain at time t;

[0034] ·σ 0 is the applied constant stress, here the stress due to the deadweight load;

[0035] ·E 1 is the instantaneous elastic modulus, which describes the instantaneous stress response of the material upon initial loading;

[0036] ·η 1 is the instantaneous viscosity coefficient, which describes the instantaneous viscous resistance of the material at the time of initial loading;

[0037] ·E 2 is the delayed elastic modulus, which describes the stress relaxation characteristics of the material under long-term loading;

[0038] ·η 2 is the delayed viscosity coefficient, which describes the viscous resistance of the material in the delayed creep stage.

[0039] The parameters to be measured include the instantaneous elastic modulus E 1 , delayed elastic modulus E 2 , and the viscosity coefficient η 1 and η 2 , these parameters represent the key mechanical properties of concrete in time-varying processes.

[0040] S200: Set multiple sets of material parameters and perform numerical simulation

[0041] In this step, multiple possible material parameter combinations are set, and the corresponding structural deformation results are generated through numerical simulation tools. Through numerical simulation, the deformation patterns under different parameter combinations are obtained, laying the foundation for subsequent inversion analysis.

[0042] S300: Binocular measurement to monitor the printing process

[0043] A binocular vision monitoring system is used to obtain the 3D geometric data of the concrete structure in real time during the 3D printing process. The system generates high-precision 3D point cloud data through stereo matching and parallax calculation. These data reflect the actual deformation of the concrete during the printing process and are transmitted to the analysis system as a reference standard for inversion analysis.

[0044] S400: Compare deformation results and infer the time-varying performance parameters that are closest to actual conditions

[0045] The structural deformation results obtained by numerical simulation in step S200 are compared with the deformation data actually measured in step S300, and the time-varying performance parameters closest to the actual conditions are inferred through error analysis and parameter optimization. In this step, the system will continuously adjust the parameters in the Burgers model until the simulation results and the actual data reach the best fit.

[0046] S500: Accumulate data and propose new time-varying constitutive models driven by data

[0047] The final determined time-varying performance parameters will be stored and used in the system database. As more data is accumulated, new time-varying constitutive models will be gradually proposed and improved. This data-driven process can continuously optimize the accuracy of the model and provide a scientific basis for parameter setting in future 3D printing tasks.

[0048] The present invention provides a new in-situ determination method for time-varying parameters of a time-varying performance constitutive model, which can infer and update the time-varying performance parameters of concrete materials in real time during the printing process. This method can not only improve the prediction accuracy of existing constitutive models, but also propose new optimized constitutive models through data-driven methods, which will help promote the development of 3D printing concrete technology in complex and changeable practical application environments.

[0049] The above description of the embodiments is to facilitate the understanding and application of the present invention by those skilled in the art. Those familiar with the art can easily make various modifications to the embodiments and apply the general principles described to other embodiments without creative work. Therefore, the present invention is not limited to the embodiments herein, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A method for in-situ determination of time-varying performance parameters of 3D printed concrete materials, characterized in that: The following steps are included: (S100) determining the parameters to be measured according to the selected time-varying constitutive model, wherein these parameters are used to describe the key mechanical properties of the concrete material in the time-varying process; and proceeding to steps S200 and S300 respectively; (S200) setting multiple groups of different values ​​for the parameters to be measured, performing numerical simulation, and generating corresponding structural deformation results; (S300) using a binocular vision monitoring system to obtain three-dimensional geometric data of the concrete structure in the 3D printing process in real time through stereo matching and parallax calculation, generating and transmitting three-dimensional point cloud data, and obtaining actual measured deformation data; (S400) comparing the structural deformation results obtained by numerical simulation in S200 with the deformation data actually measured in S300, and deriving the time-varying performance parameters through inverse analysis; (S500) The time-varying performance parameters obtained by inversion are stored, and a new time-varying constitutive model is gradually proposed and improved in a data-driven manner.

2. The method according to claim 1, characterized in that In step (S100), different parameters to be measured are selected according to different constitutive models, and the parameters to be measured include elastic modulus, viscosity coefficient, and strength parameter.

3. The method according to claim 1, characterized in that In step (S200), a plurality of different values ​​of the parameters to be measured are set, a numerical simulation tool is used to generate corresponding structural deformation modes, and the results are used for inversion analysis.

4. The method according to claim 1, characterized in that Step (S300) uses the three-dimensional geometric data acquired by the binocular vision monitoring system to generate high-precision three-dimensional point cloud data through stereo matching and parallax calculation, and updates the material deformation information during the printing process in real time.

5. The method according to claim 1, characterized in that In step (S400), by comparing the numerical simulation results with the actual measurement data, an iterative optimization method is used to infer the time-varying performance parameters that are closest to the actual conditions.

6. The method according to claim 1, characterized in that In step (S500), the time-varying performance parameters obtained by inversion are accumulated and stored in a system database, and through data analysis and model optimization, a new time-varying constitutive model is gradually proposed and improved.

7. The method according to claim 3, characterized in that The inverse analysis is achieved through large-scale data accumulation and analysis to support the optimization and material design of future 3D printing tasks.

8. The method according to claim 6, characterized in that The model optimization is achieved through large-scale data accumulation and analysis to support the optimization and material design of future 3D printing tasks.

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