ABSTRACT
Objective To compare the method based on computational fluid dynamics (CFD) and fluid structure interaction (FSI) with the traditional Reynolds equation method in the study of an artificial hip joint lubrication system. Methods Using business software Adina as a computing platform, the metal-on-metal total hip replacement (MOM THR) model was developed as the subject to establish the rigid and elastic CFD model, respectively. Results The film- thickness curve obtained by the CFD&FSI method had a significant depression in the center, which was more reasonable than that obtained by the traditional Reynolds equation method. The model with elastic surface under the given load showed a significant deformation at the FSI surface of the acetabular cup femoral head, and the deformation was consistent with the pressure and film thickness distribution in fluid field. Conclusions The CFD&FSI method used here was more reasonable than the traditional method when computing the elasto-hydrodynamic lubrication of an artificial hip joint system.
ABSTRACT
The human mandible is always under the condition of loading by the various forces exterted by the attached muscles. The loading is an important condition of the stomatognathic system. This condition is composed of the direction and amount of forces of the masticatory muscles, which are controlled by the neuromuscular system, and always influenced by the movement of both opening and closing. Mandible is a strong foundation for the teeth or various prostheses, nevetheless it is a elastic body which accompanies deformation by the external forces on it. The elastic properties of the mandible is influenced by the various procedures such as conventional restorative treatments, osseointegrated implant treatments, reconstructive surgical procedures and so forth. Among the treatments the osseointegrated implant has no periodontal ligaments, which exist around the natural teeth to allow physiologic mobility in the alveolar socket. And so around the osseointegrated implant, there is almost no damping effect during the transmission of occlusal stree and displacements. If the osseointegrated implants are connceted by the superstructure for the stabilization and effective distribution of occlusal stresses, the elastic properties of mandible is restricted accordding to the extent of 'splinting'by the superstructure and implants. To investigate the change of elastic behaviour of the mandible which has osseointegrated impalnt prosthesis of various numbers of implant installment and span of superstructure, a three dimensional finite element model was developed and analyzed with conditions mentioned above. The conclusions are as follows : 1. The displacements are primarily developed at the area of muscle attachment and distributed all around the mandible according to the various properties of bone. 2. The segmentation in the superstructure has few influence on the distribution of stress and displacement. 3. In the load case of ICP, the concetration of tensional stress was observed at the anterior portion of the ramus(9.22E+6Nmm2) and at the lingual portion of the symphysis menti(8.36E+6Nmm2). 4. In the load case of INC, the concentration of tensional stress was observed at the anterior portion of the ramus(9.90E+6Nmm2) and the concentration of tensional stress was observed at the lingual portion of the symphysis menti(2.38E+6Nmm2). 5. In the load case of UTCP, the relatively high concentration of tensional stress(3.66E+7N/mm2) was observed at the internal surface of the condylar neck.