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Finite elements analysis

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https://www.readbyqxmd.com/read/28110182/a-large-taper-mismatch-is-one-of-the-key-factors-behind-high-wear-rates-and-failure-at-the-taper-junction-of-total-hip-replacements-a-finite-element-wear-analysis
#1
Ariyan Ashkanfar, David J Langton, Thomas J Joyce
Total hip replacement (THR) is one of the most successful orthopaedic surgeries; however, failures can occur due to adverse reactions to wear debris. Recently, a large number of failures linked to the release of metal particles from the taper junction between femoral head and femoral stem have been reported. One possible reason for this may be design variations such as taper mismatches associated with the taper and trunnion angles. Could a large taper mismatch lead to inappropriate contact mechanics and increase relative micromotion and thus wear? In this study, 3D finite element (FE) models of a commercial THR from a perfectly matched interface to large taper mismatches and a wear algorithm were used to investigate the extent of wear that could occur at this junction and identify the optimum tolerances in order to reduce the wear...
January 12, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28110179/analysis-the-effect-of-different-geometries-of-afm-s-cantilever-on-the-dynamic-behavior-and-the-critical-forces-of-three-dimensional-manipulation
#2
Moharam Habibnejad Korayem, Maniya B Saraie, Mahdieh B Saraee
An important challenge when using an atomic force microscope (AFM) is to be able to control the force exerted by the AFM for performing various tasks. Nevertheless, the exerted force is proportional to the deflection of the AFM cantilever, which itself is affected by a cantilever's stiffness coefficient. Many papers have been published so far on the methods of obtaining the stiffness coefficients of AFM cantilevers in 2D; however, a comprehensive model is yet to be presented on 3D cantilever motion. The discrepancies between the equations of the 2D and 3D analysis are due to the number and direction of forces and moments that are applied to a cantilever...
January 13, 2017: Ultramicroscopy
https://www.readbyqxmd.com/read/28109796/minimization-of-dental-implant-diameter-and-length-according-to-bone-quality-determined-by-finite-element-analysis-and-optimized-calculation
#3
Nana Ueda, Yoshiyuki Takayama, Atsuro Yokoyama
PURPOSE: The purpose of this study was to investigate the influences of bone quality and implant size on the maximum equivalent elastic strain (MES) in peri-implant bone using finite element (FE) analysis, and to minimize implant size via optimized calculation based on MES. METHODS: Three-dimensional FE models consisting of a mandible and a titanium implant with a superstructure were constructed and applied a vertical load or an oblique load of 60N. We investigated the effects of four variables: the thickness of the cortical bone (C), Young's modulus of the trabecular bone (T), and the diameter (D) and length (L) of the implant...
January 18, 2017: Journal of Prosthodontic Research
https://www.readbyqxmd.com/read/28109795/bone-morphological-effects-on-post-implantation-remodeling-of-maxillary-anterior-buccal-bone-a-clinical-and-biomechanical-study
#4
Nobuhiro Yoda, Keke Zheng, Junning Chen, Wei Li, Michael Swain, Keiichi Sasaki, Qing Li
PURPOSE: This study combines clinical investigation with finite element (FE) analysis to explore the effects of buccal bone thickness (BBT) on the morphological changes of buccal bone induced by the loaded implant. METHODS: One specific patient who had undergone an implant treatment in the anterior maxilla and experienced the buccal bone resorption on the implant was studied. Morphological changes of the bone were measured through a series of cone-beam computed tomography (CT) scans...
January 18, 2017: Journal of Prosthodontic Research
https://www.readbyqxmd.com/read/28109098/-impact-of-anterior-cervical-fusion-surgeries-on-adjacent-segments-a-finite-element-analysis
#5
Teng Lu, Ting Zhang, Jun Dong, Quan-Jin Zang, Bao-Hui Yang, Dong Wang, Hao-Peng Li, Xi-Jng He
OBJECTIVE: To investigate the changes in the range of motion (ROM) and stress of the intervertebral disc and facet joint of the adjacent segments following anterior cervical corpectomy and fusion (ACCF) and anterior cervical discectomy and fusion (ACDF) using finite element analysis. METHODS: A three-dimensional finite element model of the lower cervical vertebrae was constructed and validated by comparing the ROM of the finite element model against the published data...
January 20, 2017: Nan Fang Yi Ke da Xue Xue Bao, Journal of Southern Medical University
https://www.readbyqxmd.com/read/28108173/broach-handle-design-changes-force-distribution-in-the-femur-during-total-hip-arthroplasty
#6
Dustin A Greenhill, Pooyan Abbasi, Kurosh Darvish, Andrew M Star
BACKGROUND: Curved broach handles were developed to overcome limited surgical exposures during total hip arthroplasty. Some authors report increased intraoperative fracture rates during limited exposures. This study evaluates mechanical force ratios transmitted to the bone while broaching with curved vs straight handles. METHODS: An experimental model utilized a 6-axis load cell to measure force distributions produced by 4 different broach handles, each with increasing offset and curvature...
December 29, 2016: Journal of Arthroplasty
https://www.readbyqxmd.com/read/28107694/evaluation-in-the-field-of-social-services-for-minors-measuring-the-efficacy-of-interventions-in-the-italian-service-for-health-protection-and-promotion
#7
Antonio Iudici, Agnese Gagliardo Corsi
This article presents the availment of a new Methodology for the efficacy evaluation of interventions in the field of social science: the Method of Computerized Textual Data Analysis (M.A.D.I.T.). In the beginning, we present some elements of the international and Italian legislation referred to the efficacy evaluation and about the child protection. Subsequently this work describes the process of efficacy evaluation of an intervention of minor protection delivered by a public Italian Service, the Minor and Family Service, MiFa...
November 30, 2016: Evaluation and Program Planning
https://www.readbyqxmd.com/read/28107637/survival-predictions-of-ceramic-crowns-using-statistical-fracture-mechanics
#8
S Nasrin, N Katsube, R R Seghi, S I Rokhlin
This work establishes a survival probability methodology for interface-initiated fatigue failures of monolithic ceramic crowns under simulated masticatory loading. A complete 3-dimensional (3D) finite element analysis model of a minimally reduced molar crown was developed using commercially available hardware and software. Estimates of material surface flaw distributions and fatigue parameters for 3 reinforced glass-ceramics (fluormica [FM], leucite [LR], and lithium disilicate [LD]) and a dense sintered yttrium-stabilized zirconia (YZ) were obtained from the literature and incorporated into the model...
January 1, 2017: Journal of Dental Research
https://www.readbyqxmd.com/read/28107385/evaluating-the-significance-of-viscoelasticity-in-diagnosing-early-stage-liver-fibrosis-with-transient-elastography
#9
Jingxin Zhao, Fei Zhai, Jun Cheng, Qiong He, Jianwen Luo, Xueping Yang, Jinhua Shao, Huichun Xing
Transient elastography quantifies the propagation of a mechanically generated shear wave within a soft tissue, which can be used to characterize the elasticity and viscosity parameters of the tissue. The aim of our study was to combine numerical simulation and clinical assessment to define a viscoelastic index of liver tissue to improve the quality of early diagnosis of liver fibrosis. This is clinically relevant, as early fibrosis is reversible. We developed an idealized two-dimensional axisymmetric finite element model of the liver to evaluate the effects of different viscoelastic values on the propagation characteristics of the shear wave...
2017: PloS One
https://www.readbyqxmd.com/read/28106226/applied-taguchi-method-for-fatigue-testing-of-customized-hip-implant
#10
Mangesh R Dharme, Abhaykumar M Kuthe, Tushar R Deshmukh
PURPOSE: Human activities generate stresses, which vary with time and may result in fatigue failure of the customized hip implant. This study aims to investigate fatigue testing of customized hip implants using the minimum number of experiments by the Taguchi method, for 147 patients. This study was also useful to determine the influential geometrical parameters on the fatigue safety factor of customized hip implants. METHODS: Horizontal offset (HO), vertical offset (VO) and neck shaft angle (NSA) of the hip joint of 147 patients were measured on computed tomography (CT) scanned images...
January 20, 2017: International Journal of Artificial Organs
https://www.readbyqxmd.com/read/28105122/analysis-of-3-dimensional-finite-element-after-reconstruction-of-impaired-ankle-deltoid-ligament
#11
Yunhan Ji, Xianzhong Tang, Yifan Li, Wei Xu, Wenjun Qiu
We compared four repair techniques for impaired ankle ligament deltoideum, namely Wiltberger, Deland, Kitaoka and Hintermann using a 3-dimensional finite element. We built an ankle ligament deltoideum model, including six pieces of bone structures, gristles and main ligaments around the ankle. After testing the model, we built an impaired ligament deltoideum model plus four reconstruction models. Subsequently, different levels of force on ankles with different flexion were imposed and ankle biomechanics were compared...
December 2016: Experimental and Therapeutic Medicine
https://www.readbyqxmd.com/read/28104926/the-bending-stress-distribution-in-bilayered-and-graded-zirconia-based-dental-ceramics
#12
Douglas Fabris, Júlio C M Souza, Filipe S Silva, Márcio Fredel, Joana Mesquita-Guimarães, Yu Zhang, Bruno Henriques
The purpose of this study was to evaluate the biaxial flexural stresses in classic bilayered and in graded zirconia-feldspathic porcelain composites. A finite element method and an analytical model were used to simulate the piston-on-ring test and to predict the biaxial stress distributions across the thickness of the bilayer and graded zirconia-feldspathic porcelain discs. An axisymmetric model and a flexure formula of Hsueh et al. were used in the FEM and analytical analysis, respectively. Four porcelain thicknesses were tested in the bilayered discs...
July 2016: Ceramics International
https://www.readbyqxmd.com/read/28102869/design-considerations-to-minimize-the-impact-of-drug-absorption-in-polymer-based-organ-on-a-chip-platforms
#13
V S Shirure, S C George
Biocompatible polymers, such as polydimethylsiloxane (PDMS), are the materials of choice for creating organ-on-a-chip microfluidic platforms. Desirable qualities include ease of fabrication, optical clarity, and hydrophobicity, the latter of which facilitates oxygen transport to encased cells. An emerging and important application of organ-on-a-chip technology is drug discovery; however, a potential issue for polymer-based microfluidic devices has been highlighted by recent studies with PDMS, which have demonstrated absorption (and thus loss) of hydrophobic drugs into PDMS under certain experimental conditions...
January 19, 2017: Lab on a Chip
https://www.readbyqxmd.com/read/28102170/complication-of-a-femoral-fracture-treated-by-intramedullary-nailing-numerical-analysis-of-a-clinical-case
#14
Jakub J Słowiński, Konrad Kudłacik
The aim of this paper is to conduct a numerical analysis of a case of femoral fracture treated by intramedullary nailing and confirm the conditions which led to the formation of a pseudarthrosis at the fracture site. A low-energy femoral fracture was treated by placing a ChFN System intramedullary nail with a derotation pin. Using the finite element method, a bone-implant system was generated which made it possible to observe the displacement area and strains in the region of the fracture gap. The calculations were conducted for 3 variants of the model, using a titanium nail (10 mm and 12 mm) and a steel one (10 mm)...
August 30, 2016: Ortopedia, Traumatologia, Rehabilitacja
https://www.readbyqxmd.com/read/28097687/requirements-for-accurate-estimation-of-anisotropic-material-parameters-by-magnetic-resonance-elastography-a-computational-study
#15
D J Tweten, R J Okamoto, P V Bayly
PURPOSE: To establish the essential requirements for characterization of a transversely isotropic material by magnetic resonance elastography (MRE). THEORY AND METHODS: Three methods for characterizing nearly incompressible, transversely isotropic (ITI) materials were used to analyze data from closed-form expressions for traveling waves, finite-element (FE) simulations of waves in homogeneous ITI material, and FE simulations of waves in heterogeneous material. Key properties are the complex shear modulus μ2 , shear anisotropy ϕ=μ1/μ2-1, and tensile anisotropy ζ=E1/E2-1...
January 17, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28097526/improved-measurement-of-elastic-properties-of-cells-by-micropipette-aspiration-and-its-application-to-lymphocytes
#16
Gustavo Esteban-Manzanares, Blanca González-Bermúdez, Julia Cruces, Mónica De la Fuente, Qingxuan Li, Gustavo V Guinea, José Pérez-Rigueiro, Manuel Elices, Gustavo R Plaza
Mechanical deformability of cells is an important property for their function and development, as well as a useful marker of cell state. The classical technique of micropipette aspiration allows single-cell studies and we provide here a method to measure the two basic mechanical parameters, elastic modulus and Poisson's ratio. The proposed method, developed from finite-element analysis of micropipette aspiration experiments, may be implemented in future technologies for the automated measurement of mechanical properties of cells, based on the micropipette aspiration technique or on the cell transit through flow constrictions...
January 17, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/28097524/pubovisceralis-muscle-fiber-architecture-determination-comparison-between-biomechanical-modeling-and-diffusion-tensor-imaging
#17
Sofia Brandão, Marco Parente, Elisabete Silva, Thuane Da Roza, Teresa Mascarenhas, João Leitão, João Cunha, Renato Natal Jorge, Rita Gouveia Nunes
Biomechanical analysis of pelvic floor dysfunction requires knowledge of certain biomechanical parameters, such as muscle fiber direction, in order to adequately model function. Magnetic resonance (MR) diffusion tensor imaging (DTI) provides an estimate of overall muscle fiber directionality based on the mathematical description of water diffusivity. This work aimed at evaluating the concurrence between pubovisceralis muscle fiber representations obtained from DTI, and the maximum principal stress lines obtained through the finite element method...
January 17, 2017: Annals of Biomedical Engineering
https://www.readbyqxmd.com/read/28097386/biomechanical-analysis-of-clavicle-hook-plate-implantation-with-different-hook-angles-in-the-acromioclavicular-joint
#18
Li-Kun Hung, Kuo-Chih Su, Wen-Hsien Lu, Cheng-Hung Lee
PURPOSE: A clavicle hook plate is a simple and effective method for treating acromioclavicular dislocation and distal clavicle fractures. However, subacromial osteolysis and peri-implant fractures are complicated for surgeons to manage. This study uses finite element analysis (FEA) to investigate the post-implantation biomechanics of clavicle hook plates with different hook angles. METHODS: This FEA study constructed a model with a clavicle, acromion, clavicle hook plate, and screws to simulate the implantation of clavicle hook plates at different hook angles (90°, 95°, 100°, 105°, and 110°) for treating acromioclavicular joint dislocations...
January 18, 2017: International Orthopaedics
https://www.readbyqxmd.com/read/28093648/predicting-cell-viability-within-tissue-scaffolds-under-equiaxial-strain-multi-scale-finite-element-model-of-collagen-cardiomyocytes-constructs
#19
Mostafa Elsaadany, Karen Chang Yan, Eda Yildirim-Ayan
Successful tissue engineering and regenerative therapy necessitate having extensive knowledge about mechanical milieu in engineered tissues and the resident cells. In this study, we have merged two powerful analysis tools, namely finite element analysis and stochastic analysis, to understand the mechanical strain within the tissue scaffold and residing cells and to predict the cell viability upon applying mechanical strains. A continuum-based multi-length scale finite element model (FEM) was created to simulate the physiologically relevant equiaxial strain exposure on cell-embedded tissue scaffold and to calculate strain transferred to the tissue scaffold (macro-scale) and residing cells (micro-scale) upon various equiaxial strains...
January 16, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28092094/comparison-and-evaluation-of-stresses-generated-by-rapid-maxillary-expansion-and-the-implant-supported-rapid-maxillary-expansion-on-the-craniofacial-structures-using-finite-element-method-of-stress-analysis
#20
Varun Jain, Tarulatha R Shyagali, Prabhuraj Kambalyal, Yagnesh Rajpara, Jigar Doshi
BACKGROUND: The study aimed to evaluate and compare the stress distribution and 3-dimensional displacements along the craniofacial sutures in between the Rapid maxillary Expansion (RME) and Implant supported RME (I-RME). METHODS: Finite element model of the skull and the implants were created using ANSYS software. The finite element model thus built composed of 537692 elements and 115694 nodes in RME model & 543078 elements and 117948 nodes with implants model. The forces were applied on the palatal surface of the posterior teeth to cause 5mm of transverse displacement on either side of the palatal halves, making it a total of 10mm...
December 2017: Progress in Orthodontics
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