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Finite element modeling

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https://www.readbyqxmd.com/read/28922733/assessing-the-ground-vibrations-produced-by-a-heavy-vehicle-traversing-a-traffic-obstacle
#1
Loïc Ducarne, Daniel Ainalis, Georges Kouroussis
Despite advancements in alternative transport networks, road transport remains the dominant mode in many modern and developing countries. The ground-borne motions produced by the passage of a heavy vehicle over a geometric obstacle (e.g. speed hump, train tracks) pose a fundamental problem in transport annoyance in urban areas. In order to predict the ground vibrations generated by the passage of a heavy vehicle over a geometric obstacle, a two-step numerical model is developed. The first step involves simulating the dynamic loads generated by the heavy vehicle using a multibody approach, which includes the tyre-obstacle-ground interaction...
September 14, 2017: Science of the Total Environment
https://www.readbyqxmd.com/read/28922650/constitutive-modeling-of-the-passive-inflation-extension-behavior-of-the-swine-colon
#2
Bhavesh Patel, Huan Chen, Aashish Ahuja, Joshua F Krieger, Jillian Noblet, Sean Chambers, Ghassan S Kassab
In the present work, we propose the first structural constitutive model of the passive mechanical behavior of the swine colon that is validated against physiological inflation-extension tests, and accounts for residual strains. Sections from the spiral colon and the descending colon were considered to investigate potential regional variability. We found that the proposed constitutive model accurately captures the passive inflation-extension behavior of both regions of the swine colon (coefficient of determination R(2)=0...
August 31, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28922141/towards-an-in-plane-methodology-to-track-breast-lesions-by-using-mammograms-and-patient-specific-finite-element-simulations
#3
Andres Lapuebla-Ferri, Jose Cegoñino-Banzo, Antonio-Jose Jimenez-Mocholi, Amaya Perez Del Palomar
In breast cancer screening or diagnosis, it is usual to combine different images in order to locate a lesion as accurately as possible. These images are generated by using a single or several imaging techniques. As X-ray based mammography is used widespread, a breast lesion is located in the same plane of the image (mammogram), but tracking of a breast lesion across mammograms corresponding to different views is a daring task for medical physicians. According to this, simulation tools and methodologies that use patient-specific numerical models can facilitate the task of fusing information from different images...
September 18, 2017: Physics in Medicine and Biology
https://www.readbyqxmd.com/read/28921655/fast-dynamic-ventilation-mri-of-hyperpolarized-129-xe-using-spiral-imaging
#4
Ozkan Doganay, Tahreema N Matin, Anthony Mcintyre, Brian Burns, Rolf F Schulte, Fergus V Gleeson, Daniel Bulte
PURPOSE: To develop and optimize a rapid dynamic hyperpolarized (129) Xe ventilation (DXeV) MRI protocol and investigate the feasibility of capturing pulmonary signal-time curves in human lungs. THEORY AND METHODS: Spiral k-space trajectories were designed with the number of interleaves Nint  = 1, 2, 4, and 8 corresponding to voxel sizes of 8 mm, 5 mm, 4 mm, and 2.5 mm, respectively, for field of view = 15 cm. DXeV images were acquired from a gas-flow phantom to investigate the ability of Nint  = 1, 2, 4, and 8 to capture signal-time curves...
September 16, 2017: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
https://www.readbyqxmd.com/read/28920894/electro-thermal-equivalent-3d-finite-element-model-of-a-single-neuron
#5
I Cinelli, M Destrade, M Duffy, P McHugh
OBJECTIVE: We propose a novel approach for modelling the inter-dependence of electrical and mechanical phenomena in nervous cells, by using electro-thermal equivalences in finite element (FE) analysis so that existing thermo-mechanical tools can be applied. METHODS: First, the equivalence between electrical and thermal properties of the nerve materials is established, and results of a pure heat conduction analysis performed in Abaqus CAE Software 6.13-3 are validated with analytical solutions for a range of steady and transient conditions...
September 14, 2017: IEEE Transactions on Bio-medical Engineering
https://www.readbyqxmd.com/read/28918008/a-finite-element-study-on-the-mechanical-response-of-the-head-neck-interface-of-hip-implants-under-realistic-forces-and-moments-of-daily-activities-part-2
#6
Khosro Fallahnezhad, Hamidreza Farhoudi, Reza H Oskouei, Mark Taylor
A finite element model was developed to investigate the effect of loading regimes caused by various daily activities on the mechanical behaviour of the head-neck taper junction in modular hip replacements. The activities included stair up, stair down, sit to stand, stand to sit, one leg standing and knee bending. To present the real mechanical environment of the junction, in addition to the force components, the frictional moments produced by the frictional sliding of the head and cup were applied to a CoCr/CoCr junction having a 12/14 taper with a proximal mismatch angle of 0...
September 7, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28917580/the-influence-of-ligament-modelling-strategies-on-the-predictive-capability-of-finite-element-models-of-the-human-knee-joint
#7
Hamid Naghibi Beidokhti, Dennis Janssen, Sebastiaan van de Groes, Javad Hazrati, Ton Van den Boogaard, Nico Verdonschot
In finite element (FE) models knee ligaments can represented either by a group of one-dimensional springs, or by three-dimensional continuum elements based on segmentations. Continuum models closer approximate the anatomy, and facilitate ligament wrapping, while spring models are computationally less expensive. The mechanical properties of ligaments can be based on literature, or adjusted specifically for the subject. In the current study we investigated the effect of ligament modelling strategy on the predictive capability of FE models of the human knee joint...
September 5, 2017: Journal of Biomechanics
https://www.readbyqxmd.com/read/28917130/bending-behaviors-of-fully-covered-biodegradable-polydioxanone-biliary-stent-for-human-body-by-finite-element-method
#8
Yanhui Liu, Guoqing Zhu, Huazhe Yang, Conger Wang, Peihua Zhang, Guangting Han
This paper presents a study of the bending flexibility of fully covered biodegradable polydioxanone biliary stents (FCBPBs) developed for human body. To investigate the relationship between the bending load and structure parameter (monofilament diameter and braid-pin number), biodegradable polydioxanone biliary stents derived from braiding method were covered with membrane prepared via electrospinning method, and nine FCBPBSs were then obtained for bending test to evaluate the bending flexibility. In addition, by the finite element method, nine numerical models based on actual biliary stent were established and the bending load was calculated through the finite element method...
August 24, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28916110/a-fast-and-accurate-langmuir-type-polymer-microtensiometer
#9
REVIEW
Pieter Gijsenbergh, Robert Puers
A semi-flexible polymer microtensiometer for local surface pressure measurements of Langmuir monolayers is presented. The current device geometry and read-out method via image analysis result in a theoretical accuracy of ±0.02mN⋅m(-1) for a dynamic range between 0 and 75mN⋅m(-1). The tensiometer sensitivity and dynamic range are easily tunable as they are solely based on the tensiometer spring dimensions. Finite element simulations are used to determine the response time of 20ms for a subphase viscosity of 1mPa⋅s...
September 5, 2017: Advances in Colloid and Interface Science
https://www.readbyqxmd.com/read/28915471/characterization-of-mechanical-properties-of-pericardium-tissue-using-planar-biaxial-tension-and-flexural-deformation
#10
Kyle Murdock, Caitlin Martin, Wei Sun
Flexure is an important mode of deformation for native and bioprosthetic heart valves. However, mechanical characterization of bioprosthetic leaflet materials has been done primarily through planar tensile testing. In this study, an integrated experimental and computational cantilever beam bending test was performed to characterize the flexural properties of glutaraldehyde-treated bovine and porcine pericardium of different thicknesses. A strain-invariant based structural constitutive model was used to model the pericardial mechanical behavior quantified through the bending tests of this study and the planar biaxial tests previously performed...
September 12, 2017: Journal of the Mechanical Behavior of Biomedical Materials
https://www.readbyqxmd.com/read/28915352/all-atom-simulations-reveal-protein-charge-decoration-in-the-folded-and-unfolded-ensemble-is-key-in-thermophilic-adaptation
#11
Lucas Sawle, Jonathan Huihui, Kingshuk Ghosh
Thermophilic proteins denature at much higher temperature compared to their mesophilic homologues, in spite of high structural and sequential similarity. Computational approaches to understand this puzzle faces three major challenges: i) unfolded ensembles are usually neglected, ii) simulation studies of the folded states are often too short and iii) majority of investigations focus on a few protein pairs, obscuring the prevalence of different strategies across multiple protein systems. We address these concerns by carrying out all-atom simulations to characterize physicochemical properties of both the folded and disordered ensemble in multiple (12) thermophilic-mesophilic homologous protein pairs...
September 15, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28914615/apoptosis-generates-mechanical-forces-that-close-the-lens-vesicle-in-the-chick-embryo
#12
Alina Oltean, Larry A Taber
During the initial stages of eye development, optic vesicles grow laterally outward from both sides of the forebrain and come into contact with the surrounding surface ectoderm (SE). Within the region of contact, these layers then thicken locally to create placodes and invaginate to form the optic cup (primitive retina) and lens vesicle (LV), respectively. This paper examines the biophysical mechanisms involved in LV formation, which consists of three phases: (1) lens placode formation; (2) invagination to create the lens pit (LP); and (3) closure to form a complete ellipsoidally shaped LV...
September 15, 2017: Physical Biology
https://www.readbyqxmd.com/read/28913763/a-patient-specific-three-dimensional-hemodynamic-model-of-the-circle-of-willis
#13
Hamed Rezaie, Ali Ashrafizadeh, Afsaneh Mojra
Circle of Willis (CoW) is one of the most important cerebral arteries in the human body and various attempts have been made to study the hemodynamic of blood flow in this vital part of the brain. In the present study, blood flow in a patient specific CoW is numerically modeled to predict disease-prone regions of the CoW. Medical images and computer aided design software are used to construct a realistic three-dimensional model of the CoW for this particular case. The arteries are considered as elastic conduits and the interactions between arterial walls and the blood flow are taken into account...
September 14, 2017: Cardiovascular Engineering and Technology
https://www.readbyqxmd.com/read/28910701/biomechanical-analysis-of-lumbar-decompression-surgery-in-relation-to-degenerative-changes-in-the-lumbar-spine-validated-finite-element-analysis
#14
Quan You Li, Ho-Joong Kim, Juhyun Son, Kyoung-Tak Kang, Bong-Soon Chang, Choon-Ki Lee, Hyun Sik Seok, Jin S Yeom
BACKGROUND: There are no studies about the biomechanical analysis of lumbar decompression surgery in relation to degenerative changes of the lumbar spine. Therefore, the purpose of this study was to compare, by using finite element (FE) analysis, the biomechanical changes of the lumbar spine in terms of annulus stress and nucleus pressure after two different kinds of lumbar decompression surgery in relation to disc degenerative changes. METHODS: The validated intact and degenerated FE models (L2-5) were used in this study...
September 6, 2017: Computers in Biology and Medicine
https://www.readbyqxmd.com/read/28910537/analysis-of-mechanics-of-side-impact-test-defined-in-un-ece-regulation-129
#15
Pawel Baranowski, Krzysztof Damaziak, Lukasz Mazurkiewicz, Jerzy Malachowski, Artur Muszynski, Dario Vangi
OBJECTIVE: This article discusses differences between a side impact procedure described in UN/ECE Regulation 129 and scenarios observed in real world cases. METHODS: Numerical simulations of side impact tests utilizing different boundary conditions are used to compare the severity of the Regulation 129 test and the other tests with different kinematics of child resistant systems (CRS). In the simulations, the authors use a validated finite element (FE) model of real world CRS together with a fully deformable numerical model of the Q3 anthropomorphic test device (ATD) by Humanetics Innovative Solution, Inc...
September 14, 2017: Traffic Injury Prevention
https://www.readbyqxmd.com/read/28910530/an-efficient-implicit-solvation-method-for-full-potential-dft
#16
Markus Sinstein, Christoph Scheurer, Sebastian Matera, Volker Blum, Karsten Reuter, Harald Oberhofer
With the advent of efficient electronic structure methods, effective continuum solvation methods have emerged as a way to, at least partially, include solvent effects into simulations without the need for expensive sampling over solvent degrees of freedom. The multipole moment expansion (MPE) model, while based on ideas initially put forward almost 100 years ago, has recently been updated for the needs of modern electronic structure calculations. Indeed, for an all-electron code relying on localized basis sets and---more importantly---a multipole moment expansion of the electrostatic potential, the MPE method presents a particularly cheap way of solving the macroscopic Poisson equation to determine the electrostatic response of a medium surrounding a solute...
September 14, 2017: Journal of Chemical Theory and Computation
https://www.readbyqxmd.com/read/28906447/material-viscoelasticity-induced-drift-of-micro-accelerometers
#17
Wu Zhou, Peng Peng, Huijun Yu, Bei Peng, Xiaoping He
Polymer-based materials are commonly used as an adhesion layer for bonding die chip and substrate in micro-system packaging. Their properties exhibit significant impact on the stability and reliability of micro-devices. The viscoelasticity, one of most important attributes of adhesive materials, is investigated for the first time in this paper to evaluate the long-term drift of micro-accelerometers. The accelerometer was modeled by a finite element (FE) method to emulate the structure deformation and stress development induced by change of adhesive property...
September 14, 2017: Materials
https://www.readbyqxmd.com/read/28905122/static-and-free-vibration-analyses-of-dental-prosthesis-and-atherosclerotic-human-artery-by-refined-finite-element-models
#18
E Carrera, D Guarnera, A Pagani
Static and modal responses of representative biomechanical structures are investigated in this paper by employing higher-order theories of structures and finite element approximations. Refined models are implemented in the domain of the Carrera unified formulation (CUF), according to which low- to high-order kinematics can be postulated as arbitrary and, eventually, hierarchical expansions of the generalized displacement unknowns. By using CUF along with the principle of virtual work, the governing equations are expressed in terms of fundamental nuclei of finite element arrays...
September 13, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/28902148/a-fatigue-crack-size-evaluation-method-based-on-lamb-wave-simulation-and-limited-experimental-data
#19
Jingjing He, Yunmeng Ran, Bin Liu, Jinsong Yang, Xuefei Guan
This paper presents a systematic and general method for Lamb wave-based crack size quantification using finite element simulations and Bayesian updating. The method consists of construction of a baseline quantification model using finite element simulation data and Bayesian updating with limited Lamb wave data from target structure. The baseline model correlates two proposed damage sensitive features, namely the normalized amplitude and phase change, with the crack length through a response surface model. The two damage sensitive features are extracted from the first received S₀ mode wave package...
September 13, 2017: Sensors
https://www.readbyqxmd.com/read/28895760/application-of-a-semi-automatic-cartilage-segmentation-method-for-biomechanical-modeling-of-the-knee-joint
#20
Mimmi K Liukkonen, Mika E Mononen, Petri Tanska, Simo Saarakkala, Miika T Nieminen, Rami K Korhonen
Manual segmentation of articular cartilage from knee joint 3D magnetic resonance images (MRI) is a time consuming and laborious task. Thus, automatic methods are needed for faster and reproducible segmentations. In the present study, we developed a semi-automatic segmentation method based on radial intensity profiles to generate 3D geometries of knee joint cartilage which were then used in computational biomechanical models of the knee joint. Six healthy volunteers were imaged with a 3T MRI device and their knee cartilages were segmented both manually and semi-automatically...
September 12, 2017: Computer Methods in Biomechanics and Biomedical Engineering
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