Study On Material Parameters Identification Of Periodontal Ligament Based On Inverse Analysis Method

With socio-economic development,attention is focused on appearance and oral health.The periodontal ligament(PDL)is the adhesive tissue,which plays a big role in transplantation and correction.Obtaining the material property parameters of the PDL is the key to exploring its mechanical properties.Parameter inversion based on finite element(FE)inverse analysis and biological experiments has become an important subject for researchers at home and abroad.For efficient parametric calculation,the material parameters of the PDL were predetermined in combination with the experiment,FE analysis,and response surface(RS)method.By combining genetic algorithm(GA)with particle swarm optimization(PSO),the parameters of PDL were further studied compared with other methods.The main contents of the study are as follows.Based on the relaxation experiment of the PDL,a linear viscoelastic FE model based on the Prony series was established.The range of parameters to be identified was determined by FE analysis based on the median fixation method.The influence of each parameter during the relaxation process was analyzed.The results show that the elastic modulus and temperature are the most influential,followed by Poisson’s ratio.The density had virtually no effect.The Box-Behnken method obtained the parametric combination and took the mean square error of the parametric combination experiment and simulation results as the objective function to build,detect,analyze,and simplify the RS model.The influence of various parameters on the stress during relaxation was further investigated and the optimal parameters were preliminarily identified.The results showed that dispersion analysis,residue analysis,and interaction analysis can determine the influence of each of the following parameters: temperature > elastic modulus > Poisson’s ratio > density.The simulation results of optimal parameters based on the RS method were not completely consistent with the experimental results.The RS function was further optimized by GA and PSO,respectively,and the value range of material parameters to be identified was taken as the binding condition to obtain the optimal parameters that fit the actual conditions,and which method was better in the identification of the PDL material parameters was decided.The results show that the PSO or GA simulated results were similar to the experimental results,the curve trend was steady and the fitting degree was good.The error of parameter identification was reduced by introducing an optimization algorithm to the RS function.In terms of computation and iteration times,the iteration times of PSO of 50 generations were far less than that of GA of 200 generations,so the optimization time was shorter and the optimization efficiency was higher.This paper combined experiments,FE method,RS method,GA,and PSO to put forward different methods for searching parameters that were most consistent with the actual conditions and then compared them to realize the identification of parameters of the PDL materials.The results showed that the model parameters of the test results are more matched with the test results,which proved that the parameter measurement is reliable.It provided important scientific implications and practical research results for theory-based diseases such as oral hygiene and opened up new ways to determine other biological parameters.