Possible Role of Stresses in Inducing Spinal Stenosis—A Long Term Complication Following Disk Excision

1990 ◽  
Vol 112 (4) ◽  
pp. 478-481 ◽  
Author(s):  
Vijay K. Goel ◽  
Young E. Kim ◽  
Tae-H. Lim

A three-dimensional finite element model of an intact ligamentous lumbar motion segment (L3-4) was used to predict stresses in the pars interarticularis regions of the modeled vertebral bodies. The changes in stresses following disk excision, as compared to the intact model, also were computed. The predicted results show an increase in stresses in the posterior bony elements following disk excision. In some patients over a long period of time this increase in stresses, in association with other clinical factors, may lead to bony hypertrophy of the structures that surround the nerve roots. Ultimately, over a long period of time the increase in pressure on the entrapped nerve root may induce recurrent pain and other complications reported in the literature.

2013 ◽  
Vol 336-338 ◽  
pp. 760-763
Author(s):  
Hui Yue

A short explanation of the finite element method as a powerful tool for mathematical modeling is provided, and an application using constitutive modeling of the behavior of ligaments is introduced. Few possible explanations of the role of water in ligament function are extracted from two dimensional finite element models of a classical ligament. The modeling is extended to a three dimensional finite element model for the human anterior cruciate ligament. Simulation of ligament force in pitching motion of basketball player is studied in this paper.


2007 ◽  
Vol 35 (3) ◽  
pp. 226-238 ◽  
Author(s):  
K. M. Jeong ◽  
K. W. Kim ◽  
H. G. Beom ◽  
J. U. Park

Abstract The effects of variations in stiffness and geometry on the nonuniformity of tires are investigated by using the finite element analysis. In order to evaluate tire uniformity, a three-dimensional finite element model of the tire with imperfections is developed. This paper considers how imperfections, such as variations in stiffness or geometry and run-out, contribute to detrimental effects on tire nonuniformity. It is found that the radial force variation of a tire with imperfections depends strongly on the geometrical variations of the tire.


2021 ◽  
Vol 11 (5) ◽  
pp. 2225
Author(s):  
Fu Wang ◽  
Guijun Shi ◽  
Wenbo Zhai ◽  
Bin Li ◽  
Chao Zhang ◽  
...  

The steel assembled support structure of a foundation pit can be assembled easily with high strength and recycling value. Steel’s performance is significantly affected by the surrounding temperature due to its temperature sensitivity. Here, a full-scale experiment was conducted to study the influence of temperature on the internal force and deformation of supporting structures, and a three-dimensional finite element model was established for comparative analysis. The test results showed that under the temperature effect, the deformation of the central retaining pile was composed of rigid rotation and flexural deformation, while the adjacent pile of central retaining pile only experienced flexural deformation. The stress on the retaining pile crown changed little, while more stress accumulated at the bottom. Compared with the crown beam and waist beam 2, the stress on waist beam 1 was significantly affected by the temperature and increased by about 0.70 MPa/°C. Meanwhile, the stress of the rigid panel was greatly affected by the temperature, increasing 78% and 82% when the temperature increased by 15 °C on rigid panel 1 and rigid panel 2, respectively. The comparative simulation results indicated that the bending moment and shear strength of pile 1 were markedly affected by the temperature, but pile 2 and pile 3 were basically stable. Lastly, as the temperature varied, waist beam 2 had the largest change in the deflection, followed by waist beam 1; the crown beam experienced the smallest change in the deflection.


2007 ◽  
Vol 129 (6) ◽  
pp. 1028-1034 ◽  
Author(s):  
Liang Wang ◽  
Sergio Felicelli

A three-dimensional finite element model was developed to predict the temperature distribution and phase transformation in deposited stainless steel 410 (SS410) during the Laser Engineered Net Shaping (LENS™) rapid fabrication process. The development of the model was carried out using the SYSWELD software package. The model calculates the evolution of temperature in the part during the fabrication of a SS410 plate. The metallurgical transformations are taken into account using the temperature-dependent material properties and the continuous cooling transformation diagram. The ferritic and martensitic transformation as well as austenitization and tempering of martensite are considered. The influence of processing parameters such as laser power and traverse speed on the phase transformation and the consequent hardness are analyzed. The potential presence of porosity due to lack of fusion is also discussed. The results show that the temperature distribution, the microstructure, and hardness in the final part depend significantly on the processing parameters.


2012 ◽  
Vol 178-181 ◽  
pp. 2373-2377 ◽  
Author(s):  
Wen Tsung Liu ◽  
Yi Yi Li

From the 921 earthquake to the major typhoons, including the Morakot typhoon, they damaged original landscape of rivers in Taiwan. In recent years, it alleged that abutment bridge exposed to the most serious security problems. Because of bridge piers in addition to the face of long-term river erosion, the flood on the pier will produce localized erosion near the bridge. The pier will be due to inadequate bearing capacity, resulting in subsidence, displacement, bridge version accompanied by tilting and even caving. The river erosion of soil around the piers deposits and production of contraction will often reduce the bearing capacity. Therefore, how to accurately estimate the scour depth, calculate piers to withstand water impact and analyses its stability for preventing injuries in the first place is the current pressing issues. In this study, three-dimensional finite element method (FEM) analysis program Plaxis 3D foundation is used. Polaris second bridge is selected for analysis. Based on local scouring of the model and various numerical variable conditions, the parameter of bridge pier is studied.


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