Research On 3D Finite Element Head Mold Based On Large Sample CT Data

Head anthropometric measurements is of great significance for the comfort research of headwear products.Headwear products such as masks and goggles need to have ergonomic design forms to well suit the faces of target user groups.For the design of headwear products for Chinese users,special consideration should be given to the head data of Chinese people.The purpose of this study is to develop a finite element head model based on a large sample of Chinese head data,so as to provide support for the design of headwear products.Based on the reference headform established by Wang Haining et al.,a threedimensional finite element head model was established by using facial soft tissue thickness(FSTT)data obtained from the high-precision CT images of 1174 Chinese subjects.The reference headform developed by Wang Haining et al.is based on the data of 33 facial measurements from 3400 3D head scans in Chinese Headbase survey,which is representative of the population.The head model in this study is based on the 50th percentile headform.Due to the different structure and layer thickness of facial soft tissue in different parts of the head,referring to anatomy books,the head is divided into 17 regions,and each region is divided into four layers from outside to inside:skin layer,fat layer,muscle layer and bone layer.Using the statistics of facial soft tissue thickness(FSTT)data obtained from the high-precision CT images of 1174 Chinese subjects,the soft tissue thickness of each layer in each region was obtained.Thus,a multi-level and multi-region headform is established.In order to verify the necessity of detailed regional division and hierarchical division of the headform,a multi-level and non regional headform and a single level and non regional headform are established as a comparison.In order to verify the finite element simulation effect of using multi-level and multi-region head model,the contact between headform and N95 mask is simulated by ANSYS finite element software.For comparison,the three head models are simulated with the mask respectively.Except that the headforms are different,other simulation conditions are the same.The contact pressure of three headforms and the deformation of facial soft tissue were calculated.In order to verify the accuracy of finite element simulation and evaluate the simulation effect of three headforms,offline experiments is carried out using force sensing resistors(FSR)sensors.The obj ective pressure sensing experiment tested the contact pressure between the headform and the N95 mask,and also tested the facial pressure of the real person after wearing the N95 mask.The results show that the finite element simulation results of the multi-level and multi-region headform is closer to the experimental results of pressure sensing worn by the real person.Therefore,it can be concluded that the multi-level and multi-region model considers the hierarchy and thickness of different regions of the face,so its simulation results are more real than other models.