Finite element analysis of stress around a sternum screw used to prevent sternal dehiscence after heart surgery

2002 ◽  
Vol 216 (5) ◽  
pp. 315-321 ◽  
Author(s):  
R S Jutley ◽  
M A Watson ◽  
D E T Shepherd ◽  
D W L Hukins
Keyword(s):  
Finite Element ◽  
Contact Stress ◽  
Heart Surgery ◽  
High Stress ◽  
Median Sternotomy ◽  
Element Model ◽  
Element Analysis ◽  
Sternal Dehiscence ◽  
Cortical Shell ◽  
The Wire

The sternum screw has been proposed as a means of preventing sternal dehiscence, following heart surgery, by increasing the contact area between the wire used to close the median sternotomy and the surrounding bone; as a result, the contact stress is reduced. A finite element model was constructed of a cylindrical wire or screw passing through a block of sternum which consisted of cancellous bone sandwiched within a cortical shell. The thickness of the cortical shell and the material properties of bone were varied between reasonable values. The stress distribution in the sternum was calculated for each model when the wire was subjected to a tension (250 N) which would be required for six wires to withstand a strong cough (40kPa). Results were validated by comparison with a simple analytical model in which the bone and wire were considered incompressible. They show that the screw reduces the contact stress to almost one-seventh of its value when wire is used alone. Contact stresses are especially high if the cortical shell is thin. The high stress in the bone around a screw falls off within a few millimetres. As a result, no problems are anticipated in placing six screws in each half-sternum so that the sternotomy may be closed with the usual six wires.

Finite Element Analysis for Gear Contact Based on UG and ABAQUS

2013 ◽  
Vol 442 ◽  
pp. 229-232 ◽  
Author(s):  
Li Mei Wu ◽  
Fei Yang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Stress ◽  
Three Dimensional ◽  
Element Model ◽  
Tooth Surface ◽  
Element Analysis ◽  
Tooth Width ◽  
Gear Contact ◽  
Maximum Contact

According to the cutting theory of involute tooth profile, established an exact three-dimensional parametric model by UG. Used ABAQUS to crate finite element model for gear meshing. After simulated the meshing process, discussed the periodicity of the tooth surface contact stress. Based on the result of finite element analysis, made a comparison of the maximum contact stress between finite element solution and Hertz theoretical solution, analyzed the contact stress distribution on tooth width, and researched the effect of friction factor on contact stress. All that provided some theoretical basis for gear contact strength design.

The Role of Fluid Dynamics in Distributing Ankle Stresses in Anatomic and Injured States

2016 ◽  
Vol 37 (12) ◽  
pp. 1343-1349 ◽  
Author(s):  
Kamran S. Hamid ◽  
Aaron T. Scott ◽  
Benedict U. Nwachukwu ◽  
Kerry A. Danelson
Keyword(s):  
Finite Element ◽  
Synovial Fluid ◽  
Principal Stress ◽  
Maximum Stress ◽  
High Stress ◽  
Distal Tibia ◽  
Element Model ◽  
Maximum Principal Stress ◽  
Ankle Injuries ◽  
Element Analysis

Background: In 1976, Ramsey and Hamilton published a landmark cadaveric study demonstrating a dramatic 42% decrease in tibiotalar contact area with only 1 mm of lateral talar shift. An increase in maximum principal stress of at least 72% is predicted based on these findings though the delayed development of arthritis in minimally misaligned ankles does not appear to be commensurate with the results found in dry cadaveric models. We hypothesized that synovial fluid could be a previously unrecognized factor that contributes significantly to stress distribution in the tibiotalar joint in anatomic and injured states. Methods: As it is not possible to directly measure contact stresses with and without fluid in a cadaveric model, finite element analysis (FEA) was employed for this study. FEA is a modeling technique used to calculate stresses in complex geometric structures by dividing them into small, simple components called elements. Four test configurations were investigated using a finite element model (FEM): baseline ankle alignment, 1 mm laterally translated talus and fibula, and the previous 2 bone orientations with fluid added. The FEM selected for this study was the Global Human Body Models Consortium–owned GHBMC model, M50 version 4.2, a model of an average-sized male (distributed by Elemance, LLC, Winston-Salem, NC). The ankle was loaded at the proximal tibia with a distributed load equal to the GHBMC body weight, and the maximum principal stress was computed. Results: All numerical simulations were stable and completed with no errors. In the baseline anatomic configuration, the addition of fluid between the tibia, fibula, and talus reduced the maximum principal stress computed in the distal tibia at maximum load from 31.3 N/mm2 to 11.5 N/mm2. Following 1 mm lateral translation of the talus and fibula, there was a modest 30% increase in the maximum stress in fluid cases. Qualitatively, translation created less high stress locations on the tibial plafond when fluid was incorporated into the model. Conclusions: The findings in this study demonstrate a meaningful role for synovial fluid in distributing stresses within the ankle that has not been considered in historical dry cadaveric studies. The increase in maximum stress predicted by simulation of an ankle with fluid was less than half that projected by cadaveric data, indicating a protective effect of fluid in the injured state. The trends demonstrated by these simulations suggest that bony alignment and fluid in the ankle joint change loading patterns on the tibia and should be accounted for in future experiments. Clinical Relevance: Synovial fluid may play a protective role in ankle injuries, thus delaying the onset of arthritis. Reactive joint effusions may also function to additionally redistribute stresses with higher volumes of viscous fluid.

Crane Wheel-Rail Contact Stresses Research Based on Experimental Test and Finite Element Analysis

2014 ◽  
Vol 496-500 ◽  
pp. 662-665 ◽  
Author(s):  
Feng Qi Wu ◽  
Jin Zhang ◽  
Wen Qing Yao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Theoretical Calculation ◽  
Contact Stress ◽  
Element Model ◽  
Complex Problem ◽  
Element Analysis ◽  
Highly Nonlinear ◽  
Before And After ◽  
Calculation Results

The wheel-rail contact is a boundary condition highly nonlinear complex problem, which need to accurately track the wheel-rail movement and the interaction contact stress between wheel-rail before and after the occurrence of wheel-rail contact, nonlinear contact stress of wheel-rail is analyzed through the contrast of finite element analysis and the actual detection, the experimental and theoretical calculation results show the compliance of the finite element model of wheel-rail, at the same time also point out some differences of theoretical calculation and actual manufacturing, which establish the theoretical and experimental foundation for the advanced research movement friction etc..

Strength Evaluation of Polymer Composite Spur Gear by Finite Element Analysis

2008 ◽  
Author(s):  
Mohammad Robiul Hossan ◽  
Zhong Hu
Keyword(s):  
Finite Element ◽  
Polymer Composite ◽  
Volume Fraction ◽  
Gear Tooth ◽  
Axial Stress ◽  
High Stress ◽  
Element Model ◽  
Simulation Method ◽  
Spur Gear ◽  
Element Analysis

Modern advanced polymer composite materials have opened a new level of noiseless, lubricant free, high resilience and precision gearing in power and motion transmission. The proper understanding and evaluation of gear strength and performance is an important prerequisite for any reliable application. In this paper, a 20% short glass fiber reinforced nylon66 spur gear fabricated by injection molding has been carefully investigated. A three-dimensional finite element model was used to simulate the multi-axial stress-strain behaviors of a gear tooth under the dynamic load for a complete working cycle with a special geometry, operating condition, fiber orientation and volume fraction. The strength of composite gears has been compared with isotropic un-reinforced nylon66 and steel gears. The tooth root region of a gear which usually experiences high stress and potential to failure has been carefully investigated. This computer simulation method can be used as a useful tool for evaluating strength and predicting failure of the polymer composite gears.

scholarly journals Study of Stress Distribution in Maxillary Anterior Region during True Intrusion of Maxillary Incisors using Finite Element Methodology

2012 ◽  
Vol 1 (2) ◽  
pp. 89-92 ◽  
Author(s):  
Vinay Vadvadgi ◽  
Amit Bhardwaj ◽  
Sagar S Padmawar ◽  
Anup Belludi
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
High Stress ◽  
Element Model ◽  
Anterior Region ◽  
Element Analysis ◽  
Posterior Teeth ◽  
Mini Implants ◽  
Maxillary Incisors ◽  
Finite Element Methodology

ABSTRACT Introduction One of the major challenges of fixed clinical orthodontics is the correction of deep overbite. Miniscrew implants are ideally suited for absolute intrusion because they make it possible to apply light continuous forces of known magnitudes without producing any reciprocal reactionary effect on posterior teeth. The purpose of this finite element method (FEM) study was to evaluate and compare the stresses generated in maxillary anterior region during absolute en masse intrusion of six maxillary teeth using mini-implants at strategic locations. Materials and methods Finite element model was generated using FEM software and on the same model finite element analysis was carried out to study the stress distribution in maxillary anterior region during true incisor intrusion. Results Soft bone and hard bone showed significantly high stress distribution in maxillary anterior region. Conclusion Stresses on the teeth, soft bone and hard bone, were concentrated more on and near the central incisors as compared to lateral incisors. This was probably because the point of force application was between the central incisors and away from the lateral incisors. How to cite this article Padmawar SS, Belludi A, Bhardwaj A, Vadvadgi V, Saini R. Study of Stress Distribution in Maxillary Anterior Region during True Intrusion of Maxillary Incisors using Finite Element Methodology. Int J Experiment Dent Sci 2012;1(2):89-92.

Using Finite Element Analysis to Evaluate Countermeasures to Bone Demineralization During Long Duration Space Flight

1999 ◽  
Author(s):  
Benjamin M. Murphy ◽  
Linda C. Shackelford ◽  
Beth A. Todd ◽  
James F. Cuttino
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Space Flight ◽  
Weight Bearing ◽  
High Stress ◽  
Element Model ◽  
Magnetic Resonance Images ◽  
Element Analysis ◽  
Bone Demineralization ◽  
Long Duration

Abstract During long duration space flight, astronauts must exercise to prevent bone demineralization. Exercises are used as countermeasures to the bone mineral loss. The effectiveness of the countermeasures is closely related to the mechanical stress developed during the exercises. A finite element model of the human femur was developed to determine the stress distribution during weight bearing. The model was developed using serial, transverse magnetic resonance images. The finite element analysis performed on the femur model showed an area of high stress in the femoral neck of approximately 1,200 psi. The highest stress seen in the model was approximately 2,000 psi. This information will then be used to evaluate the proposed exercises to be used as countermeasures.

Contact stress and transmission errors under load of a modified curvilinear gear set based on finite element analysis

2014 ◽  
Vol 229 (2) ◽  
pp. 191-204 ◽  
Author(s):  
Yi-Cheng Chen ◽  
Chien-Cheng Lo
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Contact Stress ◽  
Element Model ◽  
Contact Analysis ◽  
Tooth Contact Analysis ◽  
Element Analysis ◽  
Transmission Errors ◽  
Mesh Density

This study conducted a loaded tooth contact analysis of a modified curvilinear gear set with localized bearing contact based on finite element analysis. The contact stress and transmission errors under load were examined. First, a mesh generation program was developed according to the mathematical model of a curvilinear gear generated using a male fly cutter. A finite element model containing one contacting tooth pair was built, and the mesh density at the contact-sensitive area was adjusted to attain a reasonable finite element model for estimating the contact pressure. Adequate mesh density at the possible contact region predicted by tooth contact analysis was defined based on the theoretical Hertzian contact stress and the calculated contact ellipse. A finite element model containing five tooth pairs was developed and applied to examine the contact stress and transmission errors under load of the modified curvilinear gear set. Finally, numerical examples were provided to demonstrate the contact stress and transmission errors under load for various design parameters and loads.

FEA of Large-Scale Cross-Roller Slewing Bearing Used in Special Propeller

2012 ◽  
Vol 150 ◽  
pp. 165-169 ◽  
Author(s):  
Gang Zhang ◽  
Xue Zhang ◽  
De De Jiang ◽  
Ming Yan Li ◽  
Jian Zhang
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Stress ◽  
Large Scale ◽  
Element Model ◽  
Element Analysis ◽  
Slewing Bearing ◽  
Design And Optimization ◽  
The Finite Element Analysis ◽  
The Finite Element Model

According to the property of contact problem, the calculation formula of contact stress of cross-roller slewing bearing is derived under the action of eccentric axial load. The finite element model of slewing bearing is analyzed in ANSYS, and then the finite element analysis software is used to analyze the contact stress. In this way, the distribution condition of contact stress between roller and rings is obtained. By comparing the finite element analysis results with theoretical analysis results, the correctness of finite element analysis is certified, which provides a guide for the design and optimization of slewing bearing.

Finite Element Analysis of Ring-Plate Indexing Cam Mechanism Contact Stress Based on MATLAB and ANSYS

2011 ◽  
Vol 383-390 ◽  
pp. 2862-2867
Author(s):  
Yan Qi Li ◽  
Ming Tao Liu ◽  
Guang Cai Tian
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Contact Stress ◽  
Maximum Stress ◽  
Element Model ◽  
Element Analysis ◽  
Cam Mechanism ◽  
Ring Plate ◽  
The Finite Element Analysis ◽  
New Type

This paper is aimed to analyse contact stress of ring-plate indexing cam mechanism which is a new type of indexing cam mechanism. A contact finite element model of the cam and the pin gear is established with the commercial software of MATLAB and ANSYS. With the finite element analysis, the contact stress of the cam and the pin gear is predicted in one motion cycle. On the basis of the finite element analysis, the force and the position of maximum stress are obtained. The conclusion proposed here is reliable to instruct the design of ring-plate indexing cam mechanism.

Dynamic Finite Element Analysis for Tapered Roller Bearings

2014 ◽  
Vol 533 ◽  
pp. 21-26 ◽  
Author(s):  
Hong Bin Liu ◽  
Lei Zhang ◽  
Yong Sheng Shi
Keyword(s):  
Finite Element ◽  
Contact Stress ◽  
Roller Bearing ◽  
Three Dimensional ◽  
Element Model ◽  
Contact Dynamics ◽  
Element Analysis ◽  
Tapered Roller Bearing ◽  
Tapered Roller ◽  
Tapered Roller Bearings

Based on the finite element method of explicit dynamics and contact dynamics mechanics, a three dimensional solid finite element model was developed introducing physical elements for tapered roller bearing. The dynamic process numerical simulation of tapered roller bearing was carried out in ABAQUS. The vibration curves of the nodes on roller were drew. The changes of contact stress and contact stress distribution of rings, rollers and the cage in the process were analyzed. The results show it is basically consistent with the actual movement of rolling bearings.

Sign in / Sign up

Export Citation Format

Share Document