Wall Stress Estimation of Human Heart Under the Effect of High Accelerations

2013 ◽  
Author(s):  
Masood Jamshidi ◽  
Mohammad Taghi Ahmadian
Keyword(s):  
Finite Element ◽  
Human Heart ◽  
Heart Function ◽  
Wall Stress ◽  
Least Square ◽  
Three Dimension ◽  
Stress Distributions ◽  
Compression Tests ◽  
Element Analysis ◽  
Hyperelastic Model

Human body is constantly under the influence of acceleration loads in environments such as combat flying. This study investigates the effect of body acceleration on human heart function by using finite element analysis. The nonlinear mechanical behavior of myocardium is modeled by Yeoh hyperelastic model. Stress-strain curves of myocardium are determined based on uniaxial compression tests on bovine heart samples. Nonlinear least square curve fitting is conducted in order to obtain material parameters. Heart geometrical modeling in three-dimension is done by segmentation of cardiac MRI images. Obtained material coefficients are assigned to the constructed heart model and appropriate pressure and acceleration loads are considered. By application of finite element method, stress distributions are calculated. Results indicate average stress in the internal wall of left ventricle is increased by 9.4% from 15.9 to 17.4kPa as the acceleration increases from +1G to +6G.

Finite Element Analysis of Stress Distributions on the Diamond Pick

2011 ◽  
Vol 487 ◽  
pp. 184-188
Author(s):  
Shu Tao Huang ◽  
Li Zhou ◽  
J. Li
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Finite Element Modeling ◽  
Lateral Pressure ◽  
Normal Pressure ◽  
Three Dimension ◽  
Stress Distributions ◽  
Element Analysis ◽  
Modeling Software ◽  
And Performance

Commercial finite element modeling software ANSYS was used to calculate the stress distributions of diamond pick at different loads. The three-dimension model of the pick was built and the direction and magnitude of load were varied to determine their effect on the stress distributions of diamond pick. The results show that the stresses located on the pick increase with the increasing of the normal and lateral pressure, and if the maximum normal pressure and lateral pressure are not higher than 480 kN and 150 kN, respectively, the diamond pick will not be damaged. The results obtained can provide available data for pick selection, design and performance.

Finite Element Analysis of Tire/Rim Interface Forces Under Braking and Cornering Loads

1992 ◽  
Vol 20 (2) ◽  
pp. 83-105 ◽  
Author(s):  
J. P. Jeusette ◽  
M. Theves
Keyword(s):  
Finite Element ◽  
Shear Stress ◽  
Contact Pressure ◽  
Element Model ◽  
Shear Stresses ◽  
Detailed Knowledge ◽  
Stress Distributions ◽  
Element Analysis ◽  
Plane Shear ◽  
Normal Contact

Abstract During vehicle braking and cornering, the tire's footprint region may see high normal contact pressures and in-plane shear stresses. The corresponding resultant forces and moments are transferred to the wheel. The optimal design of the tire bead area and the wheel requires a detailed knowledge of the contact pressure and shear stress distributions at the tire/rim interface. In this study, the forces and moments obtained from the simulation of a vehicle in stationary braking/cornering conditions are applied to a quasi-static braking/cornering tire finite element model. Detailed contact pressure and shear stress distributions at the tire/rim interface are computed for heavy braking and cornering maneuvers.

scholarly journals Comparison of Tooth- and Bone-Borne Appliances on the Stress Distributions and Displacement Patterns in the Facial Skeleton in Surgically Assisted Rapid Maxillary Expansion—A Finite Element Analysis (FEA) Study

Materials ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1152
Author(s):  
Rafał Nowak ◽  
Anna Olejnik ◽  
Hanna Gerber ◽  
Roman Frątczak ◽  
Ewa Zawiślak
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Three Dimensional ◽  
Element Model ◽  
Rapid Maxillary Expansion ◽  
Stress Distributions ◽  
Maxillary Expansion ◽  
Facial Skeleton ◽  
Element Analysis ◽  
Maxillary Constriction

The aim of this study was to compare the reduced stresses according to Huber’s hypothesis and the displacement pattern in the region of the facial skeleton using a tooth- or bone-borne appliance in surgically assisted rapid maxillary expansion (SARME). In the current literature, the lack of updated reports about biomechanical effects in bone-borne appliances used in SARME is noticeable. Finite element analysis (FEA) was used for this study. Six facial skeleton models were created, five with various variants of osteotomy and one without osteotomy. Two different appliances for maxillary expansion were used for each model. The three-dimensional (3D) model of the facial skeleton was created on the basis of spiral computed tomography (CT) scans of a 32-year-old patient with maxillary constriction. The finite element model was built using ANSYS 15.0 software, in which the computations were carried out. Stress distributions and displacement values along the 3D axes were found for each osteotomy variant with the expansion of the tooth- and the bone-borne devices at a level of 0.5 mm. The investigation showed that in the case of a full osteotomy of the maxilla, as described by Bell and Epker in 1976, the method of fixing the appliance for maxillary expansion had no impact on the distribution of the reduced stresses according to Huber’s hypothesis in the facial skeleton. In the case of the bone-borne appliance, the load on the teeth, which may lead to periodontal and orthodontic complications, was eliminated. In the case of a full osteotomy of the maxilla, displacements in the buccolingual direction for all the variables of the bone-borne appliance were slightly bigger than for the tooth-borne appliance.

Finite Element Analysis of Poor Distal Contact of the Femoral Component of a Cementless Hip Endoprosthesis

1993 ◽  
Vol 207 (4) ◽  
pp. 255-261 ◽  
Author(s):  
M Taylor ◽  
E W Abel
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Influencing Factor ◽  
Three Dimensional ◽  
Stress Distributions ◽  
Element Analysis ◽  
Hip Endoprosthesis ◽  
Applied Loading ◽  
Femoral Geometry ◽  
Contact Models

The difficulty of achieving good distal contact between a cementless hip endoprosthesis and the femur is well established. This finite element study investigates the effect on the stress distribution within the femur due to varying lengths of distal gap. Three-dimensional anatomical models of two different sized femurs were generated, based upon computer tomograph scans of two cadaveric specimens. A further six models were derived from each original model, with distal gaps varying from 10 to 60 mm in length. The resulting stress distributions within these were compared to the uniform contact models. The extent to which femoral geometry was an influencing factor on the stress distribution within the bone was also studied. Lack of distal contact with the prosthesis was found not to affect the proximal stress distribution within the femur, for distal gap lengths of up to 60 mm. In the region of no distal contact, the stress within the femur was at normal physiological levels associated with the applied loading and boundary conditions. The femoral geometry was found to have little influence on the stress distribution within the cortical bone. Although localized variations were noted, both femurs exhibited the same general stress distribution pattern.

Finite Element Analysis of Temperature and Stress Distributions on Touching Area of Freight Train Wheel

2011 ◽  
Vol 120 ◽  
pp. 56-60
Author(s):  
Han Wu Liu ◽  
Zhi Qiang Li ◽  
Yun Hui Du ◽  
Peng Zhang
Keyword(s):  
Finite Element ◽  
Development Trend ◽  
Stress Distributions ◽  
Railway Transportation ◽  
Element Analysis ◽  
Work Condition ◽  
Freight Train ◽  
The Development Trend ◽  
The Relationship ◽  
Wheel Track

With the development trend of constant speeding and heavy loading of the railway transportation, the freight train wheels which take the way of touching area breaking are in the bad conditions of strong friction, fever load and big wheel track forces. After many times’ repeated breaking, the wheels will come to be thermal fatigue, then, result in expired puncture. In this article, according to the actual work condition of the freight train wheel, its temperature and stress fields in the process of an urgently breaking when the wheel speed is 120 km/h with the 21 tons shaft weight were analyzed and simulated by Finite Element Method. The relationship between the injury occurring on the touching area of freight wheel and the fields of the temperature and stress was also studied. The research results showed that the maximum values of the temperature and thermal stress lied in the breaking process all locate in the touching friction area between the breaking and the wheel, and the temperature rises continuously with the breaking process going on. When the value of the temperature gets to the crest value, it slowly descends. The wheel temperature reduces from the touching area to the wheel shaft, and the nearer of the distance to wheel shaft, the lower of the temperature and stress values. After the end of the breaking process, the temperature into the wheel is higher than that on the touching area, and the maximum stress exists under the wheel touching area.

scholarly journals A Methodology for the Derivation of Unloaded Abdominal Aortic Aneurysm Geometry With Experimental Validation

2016 ◽  
Vol 138 (10) ◽  
Author(s):  
Santanu Chandra ◽  
Vimalatharmaiyah Gnanaruban ◽  
Fabian Riveros ◽  
Jose F. Rodriguez ◽  
Ender A. Finol
Keyword(s):  
Finite Element ◽  
Abdominal Aortic Aneurysm ◽  
Aortic Aneurysm ◽  
Stress Component ◽  
Wall Stress ◽  
Patient Specific ◽  
Element Analysis ◽  
Nodal Surface ◽  
Abdominal Aortic ◽  
Peak Wall Stress

In this work, we present a novel method for the derivation of the unloaded geometry of an abdominal aortic aneurysm (AAA) from a pressurized geometry in turn obtained by 3D reconstruction of computed tomography (CT) images. The approach was experimentally validated with an aneurysm phantom loaded with gauge pressures of 80, 120, and 140 mm Hg. The unloaded phantom geometries estimated from these pressurized states were compared to the actual unloaded phantom geometry, resulting in mean nodal surface distances of up to 3.9% of the maximum aneurysm diameter. An in-silico verification was also performed using a patient-specific AAA mesh, resulting in maximum nodal surface distances of 8 μm after running the algorithm for eight iterations. The methodology was then applied to 12 patient-specific AAA for which their corresponding unloaded geometries were generated in 5–8 iterations. The wall mechanics resulting from finite element analysis of the pressurized (CT image-based) and unloaded geometries were compared to quantify the relative importance of using an unloaded geometry for AAA biomechanics. The pressurized AAA models underestimate peak wall stress (quantified by the first principal stress component) on average by 15% compared to the unloaded AAA models. The validation and application of the method, readily compatible with any finite element solver, underscores the importance of generating the unloaded AAA volume mesh prior to using wall stress as a biomechanical marker for rupture risk assessment.

Through-Thickness Residual Stress Distribution After the Cold Expansion of Fastener Holes and Its Effect on Fracturing

2004 ◽  
Vol 126 (1) ◽  
pp. 129-135 ◽  
Author(s):  
A. Tamer O¨zdemir ◽  
Lyndon Edwards
Keyword(s):  
Thickness Effect ◽  
Fourier Series Expansion ◽  
Hole Drilling ◽  
Three Dimension ◽  
Stress Distributions ◽  
Element Analysis ◽  
Cold Expansion ◽  
Residual Strains ◽  
Hoop Stresses ◽  
Stress Patterns

Many analytical and experimental techniques utilize two-dimensional analysis approach to determine residual strains and stresses at cold expanded holes. In the present work, a recently developed technique of hole drilling was used to sketch stress patterns in three-dimension at a particular orientation of split-sleeve cold expanded holes. At this orientation, similarities were obtained in between the present results and the stress distributions measured by Fourier series expansion, neutron diffraction methods and prediction of a recent finite element analysis. It is clear that after cold expansion there are significant variations in residual hoop stresses at different sections through the thickness of the plate. However, finish reaming and de-burring around the hole redistributes residual stresses such that hoop stresses adjacent to the hole along its entire length becomes more compressive and almost uniform. Finally a correlation between stress pattern and crack profile, displaying the through-thickness effect was shown.

Finite Element Analysis for Shock Resistance Evaluation of Cushion-Packaged Multifunction Printer Considering Internal Modules

2013 ◽  
Vol 135 (4) ◽  
Author(s):  
Se-Chang Kim ◽  
Dae-Geun Cho ◽  
Tae-Gyu Kim ◽  
Se-Hun Jung ◽  
Ja-Choon Koo ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Shock Acceleration ◽  
External Shocks ◽  
Compression Tests ◽  
Element Analysis ◽  
Dynamic Behaviors ◽  
Shock Resistance ◽  
The Impact ◽  
Multifunction Printer

Failures in IT electronics are often caused by falling or external shocks during transportation. These failures cause customers to mistrust the reliability of the products. Many manufacturers of IT electronics have not only used cushioning materials but also increased the shock resistance of their products for failure prevention. Especially in case of printer products, the design of the packaging and the product robustness are extremely important because of their substantial weight and the fragility of the internal modules. For product design, it is essential to understand the impact failure mechanism of the products. In this study, a compression test, a drop impact test, and a finite element analysis (FEA) were performed to analyze the dynamic behaviors of a packaged multifunction printer (MFP). The mechanical properties of a cushioning material were measured by compression tests. The FE models of the cushion packaging and the MFP included the physical characteristics of the internal modules, and their dynamic behaviors were obtained using the commercial software ls-dyna3d. Simulation results were also compared with drop test results to verify the proposed FE models. The shock resistance of the MFP was assessed by stress analysis and strength evaluation. We also expect our FE models will be useful for evaluating the fragility of the internal modules because the models can numerically estimate the shock acceleration profiles of the internal modules, which are difficult to measure experimentally.

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