A theoretical model-based dlp printing hydrogel structure control method

Abstract

The application discloses a DLP printing hydrogel structure control method based on a theoretical model and belongs to the field of intelligent additive manufacturing. The application applies a hydrogel swelling theory to DLP printing technology, and proposes a 3D printing hydrogel uneven swelling behavior prediction model based on DLP. Based on the prediction model, a post-swelling predicted shape of a hydrogel printing piece can be obtained through existing printing parameters, material attribute parameters and an original computer digital model, and the post-swelling predicted shape is compared and analyzed with the original computer digital model, the original computer digital model is reversely deformed and compensated, and a compensated digital model is obtained. Based on the compensated digital model, only printing according to a conventional process can obtain a target structure preset by the original computer digital model, so that the problem that an actual forming structure deviates from a design structure due to a swelling effect is solved.

Claims

1. A method for controlling the structure of DLP-printed hydrogels based on a theoretical model, characterized in that, include: S1. Based on the single-layer printing thickness set for hydrogel printed parts in the current printing process, call the working curve to determine the single-layer exposure time; According to the DLP printing sequence, calculate the cumulative soaking time of each hydrogel curing layer in the precursor solution at the time of printing completion. S2. Combining the hydrogel non-uniform swelling behavior prediction model, the swelling behavior of each hydrogel solidified layer under the corresponding cumulative immersion time is quantitatively predicted, and the predicted shape of the hydrogel printed part after swelling is determined based on the structural size of each hydrogel solidified layer after swelling. S3. Using the original computer digital model of the hydrogel print as the target shape, compare the predicted shape of the hydrogel print after swelling with the target shape, calculate the deformation deviation of each hydrogel curing layer, and perform reverse deformation compensation design on the original computer digital model so that the hydrogel print based on the compensated digital model is close to the target shape.

2. The method for controlling the structure of DLP-printed hydrogels based on a theoretical model as described in claim 1, characterized in that, The working curve is obtained by fitting the measured data of DLP printing of the same hydrogel precursor liquid system. It is in the form of a logarithmic equation with the single-layer printing thickness as the dependent variable and the single-layer exposure time as the independent variable, and the dependent variable is proportional to the logarithm of the independent variable.

3. The method for controlling the structure of DLP-printed hydrogels based on a theoretical model as described in claim 1, characterized in that, The cumulative soaking time of any hydrogel curing layer is the sum of the single-layer exposure times of all subsequent printed layers of that hydrogel curing layer.

4. The method for controlling the structure of DLP-printed hydrogels based on a theoretical model as described in claim 1, characterized in that, The hydrogel non-uniform swelling behavior prediction model. spatiotemporal distribution The corresponding nonlinear diffusion partial differential equation is used in the calculation of quantitative prediction of swelling behavior. The equation is as follows: ； In the formula: and For hydrogels in two orthogonal directions on the layer plane and The elongation ratio as a function of time t. denoted as εt, where εt is the elongation ratio of the hydrogel in the normal direction along the layer plane as a function of time t; N is the crosslinking density; and k is the Boltzmann constant. The volume of a single small molecule; It is a dimensionless parameter; denoted as the diffusion coefficient of small molecules.

5. The method for controlling the structure of DLP-printed hydrogels based on a theoretical model as described in claim 4, characterized in that, To quantitatively predict the swelling behavior of each hydrogel cured layer under corresponding cumulative immersion time, firstly... and Equivalent to and used as the parameter to be solved, while The elongation ratio is kept constant at 1, and the hydrogel is used to balance the swelling under constrained conditions in the plane direction where swelling needs to be controlled. As boundary conditions, and with the initial condition set to 1, the nonlinear diffusion partial differential equation is numerically solved to obtain... ; Then, for each hydrogel solidification layer, based on the solution obtained... And the cumulative immersion time corresponding to this hydrogel curing layer. In the direction of the layer plane where swelling needs to be controlled Moment Spatial distribution By integrating, the structural dimensions of this hydrogel solidified layer after swelling along the plane of the layer are obtained.

6. The method for controlling the structure of DLP-printed hydrogels based on a theoretical model as described in claim 1, characterized in that, Steps S2 and S3 require multiple iterations. After obtaining the compensated digital model each time, the quantitative prediction needs to be re-executed to obtain the predicted shape of the hydrogel print after swelling, and then the reverse deformation compensation design is re-executed. When the deviation between the predicted shape of the hydrogel print after swelling and the target shape is within the tolerance range, the iteration terminates and the final digital model is used for actual DLP printing to obtain a hydrogel print that conforms to the target shape.

7. The method for controlling the structure of DLP-printed hydrogels based on a theoretical model as described in claim 1, characterized in that, In the DLP printing process, the light source is below the moving platform, and the printing proceeds layer by layer from bottom to top. The moving platform moves upward layer by layer, leaving space for the next layer to cure below the already printed hydrogel curing layer.

8. A computer program product comprising a computer program / instructions, characterized in that, When the computer program / instruction is executed by the processor, it can realize the DLP printing hydrogel structure control method based on the theoretical model as described in any one of claims 1 to 7.

9. A computer-readable storage medium, characterized in that, The storage medium stores a computer program, which, when executed by a processor, implements the DLP printing hydrogel structure control method based on a theoretical model as described in any one of claims 1 to 7.

10. A computer electronic device, characterized in that, Including memory and processor; The memory is used to store computer programs; The processor is configured to, when executing the computer program, implement the DLP printing hydrogel structure control method based on the theoretical model as described in any one of claims 1 to 7.

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