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Finite element

Nayeon Lee, M F Horstemeyer, R Prabhu, Jun Liao, Hongjoo Rhee, Youssef Hammi, Robert D Moser, Lakiesha N Williams
In this study a woodpecker's hyoid apparatus was characterized to determine its impact mitigation mechanism using finite element (FE) analysis. The woodpecker's hyoid apparatus, comprising bone and muscle, has a unique geometry compared to those of other birds. The hyoid starts at the beak tip, surrounds the woodpecker's skull, and ends at the upper beak/front head intersection while being surrounded by muscle along the whole length. A FE model of the hyoid apparatus was created based on the geometry, microstructure, and mechanical properties garnered from our experimental measurements...
October 25, 2016: Bioinspiration & Biomimetics
Matti Stenroos
Boundary element methods (BEM) are used for forward computation of bioelectromagnetic fields in multi-compartment volume conductor models. Most BEM approaches assume that each compartment is in contact with at most one external compartment. In this work, I present a general surface integral equation and BEM discretization that remove this limitation and allow BEM modeling of general piecewise-homogeneous medium. The new integral equation allows positioning of field points at junctioned boundary of more than two compartments, enabling the use of linear collocation BEM in such a complex geometry...
November 21, 2016: Physics in Medicine and Biology
Inge A E W van Loosdregt, Sylvia Dekker, Patrick W Alford, Cees W J Oomens, Sandra Loerakker, Carlijn V C Bouten
Understanding cell contractility is of fundamental importance for cardiovascular tissue engineering, due to its major impact on the tissue's mechanical properties as well as the development of permanent dimensional changes, e.g., by contraction or dilatation of the tissue. Previous attempts to quantify contractile cellular stresses mostly used strongly aligned monolayers of cells, which might not represent the actual organization in engineered cardiovascular tissues such as heart valves. In the present study, therefore, we investigated whether differences in organization affect the magnitude of intrinsic stress generated by individual myofibroblasts, a frequently used cell source for in vitro engineered heart valves...
October 24, 2016: Cardiovascular Engineering and Technology
Rakesh Khilwani, Peter J Gilgunn, Takashi D Y Kozai, Xiao Chuan Ong, Emrullah Korkmaz, Pallavi K Gunalan, X Tracy Cui, Gary K Fedder, O Burak Ozdoganlar
Stable chronic functionality of intracortical probes is of utmost importance toward realizing clinical application of brain-machine interfaces. Sustained immune response from the brain tissue to the neural probes is one of the major challenges that hinder stable chronic functionality. There is a growing body of evidence in the literature that highly compliant neural probes with sub-cellular dimensions may significantly reduce the foreign-body response, thereby enhancing long term stability of intracortical recordings...
December 2016: Biomedical Microdevices
Bor-Tsuen Lin, Cheng-Yu Yang
The developers of high aspect ratio components aim to minimize the processing stages in deep drawing processes. This study elucidates the application of microridge punches in multistage deep drawing processes. A microridge punch improves drawing performance, thereby reducing the number of stages required in deep forming processes. As an example, the original eight-stage deep forming process for a copper cylindrical cup with a high aspect ratio was analyzed by finite element simulation. Microridge punch designs were introduced in Stages 4 and 7 to replace the original punches...
2016: SpringerPlus
Hannah M Gustafson, Peter A Cripton, Stephen J Ferguson, Benedikt Helgason
The purpose of this study was to load cadaveric vertebral bodies (n=6) in compression and compare the response, measured with digital image correlation (DIC) on the cortex, with the predicted response from specimen-specific vertebral finite element (FE) models. Five modulus-density relationships were evaluated, and for the strongest modulus-density relationship, the correlation between the DIC and FE displacements had R(2) values from 0.75 to 0.93. The stiffnesses derived from the DIC measurements were strongly predicted by the FE stiffnesses (R(2)=0...
October 7, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Matteo Mazzotti, Marco Miniaci, Ivan Bartoli
A hybrid Finite Element-Plane Wave Expansion method is presented for the band structure analysis of phononic crystal plates with two dimensional lattice that are in contact with acoustic half-spaces. The method enables the computation of both real (propagative) and imaginary (attenuation) components of the Bloch wavenumber at any given frequency. Three numerical applications are presented: a benchmark dispersion analysis for an oil-loaded Titanium isotropic plate, the band structure analysis of a water-loaded Tungsten slab with square cylindrical cavities and a phononic crystal plate composed of Aurum cylinders embedded in an epoxy matrix...
October 14, 2016: Ultrasonics
Xiang Chen, Changxi Zheng, Kun Zhou
Stress analysis is a crucial tool for designing structurally sound shapes. However, the expensive computational cost has hampered its use in interactive shape editing tasks. We augment the existing example-based shape editing tools, and propose a fast subspace stress analysis method to enable stress-aware shape editing. In particular, we construct a reduced stress basis from a small set of shape exemplars and possible external forces. This stress basis is automatically adapted to the current user edited shape on the fly, and thereby offers reliable stress estimation...
October 19, 2016: IEEE Transactions on Visualization and Computer Graphics
Ren-Feng Ding, Chih-Wen Yang, Kuang-Yuh Huang, Ing-Shouh Hwang
In the operation of a dynamic mode atomic force microscope, a micro-fabricated rectangular cantilever is typically oscillated at or near its mechanical resonance frequency. Lateral bending resonances of cantilevers are rarely used because the resonances are not expected to be detected by the beam-deflection method. In this work, we found that micro-cantilevers with a large tip produced an out-of-plane displacement in lateral resonance (LR), which could be detected with the beam-deflection method. Finite-element analysis indicated that the presence of a large tip is the major source of the out-of-plane coupling for the LR...
October 24, 2016: Nanoscale
Markus Kauer, Valentina Belova-Magri, Carlos Cairós, Hans-Jürgen Schreier, Robert Mettin
Despite the increasing use of high frequency ultrasound in heterogeneous reactions, knowledge about the spatial distribution of cavitation bubbles at the irradiated solid surface is still lacking. This gap hinders controllable surface sonoreactions. Here we present an optimization study of the cavitation bubble distribution at a solid sample using sonoluminescence and sonochemiluminescence imaging. The experiments were performed at three ultrasound frequencies, namely 580, 860 and 1142kHz. We found that position and orientation of the sample to the transducer, as well as its material properties influence the distribution of active cavitation bubbles at the sample surface in the reactor...
January 2017: Ultrasonics Sonochemistry
S D Heintze, A Eser, D Monreal, V Rousson
OBJECTIVE: Dynamic loading is a more important predictor for the clinical longevity of ceramic crowns than static loading. However, dynamic loading machines are costly and mostly have only one test station. The SD Mechatronik Chewing Simulator (formerly Willytec) may be a cost-effective alternative to evaluate the fatigue resistance of metal ceramic crowns. METHOD: Four metal ceramic materials were tested on lower first molar crowns: GC InitiaI, Creation (Willy Geller), IPS InLine (Ivoclar Vivadent) and the new low-fusion IPS Style Ceram (Ivoclar Vivadent)...
September 14, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Srimanta Barui, Subhomoy Chatterjee, Sourav Mandal, Alok Kumar, Bikramjit Basu
The osseointegration of metallic implants depends on an effective balance among designed porosity to facilitate angiogenesis, tissue in-growth and bone-mimicking elastic modulus with good strength properties. While addressing such twin requirements, the present study demonstrates a low temperature additive manufacturing based processing strategy to fabricate Ti-6Al-4V scaffolds with designed porosity using inkjet-based 3D powder printing (3DPP). A novel starch-based aqueous binder was prepared and the physico-chemical parameters such as pH, viscosity, and surface tension were optimized for drop-on-demand (DOD) based thermal inkjet printing...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Zakieh Alihemmati, Bahman Vahidi, Nooshin Haghighipour, Mohammad Salehi
It has been found that cells react to mechanical stimuli, while the type and magnitude of these cells are different in various physiological and pathological conditions. These stimuli may affect cell behaviors via mechanotransduction mechanisms. The aim of this study is to evaluate mechanical responses of a mesenchymal stem cell (MSC) to a pressure loading using finite elements method (FEM) to clarify procedures of MSC mechanotransduction. The model is constructed based on an experimental set up in which statics and cyclic compressive loads are implemented on a model constructed from a confocal microscopy 3D image of a stem cell...
January 1, 2017: Materials Science & Engineering. C, Materials for Biological Applications
Yanfeng Shen, Carlos E S Cesnik
This article presents a parallel algorithm to model the nonlinear dynamic interactions between ultrasonic guided waves and fatigue cracks. The Local Interaction Simulation Approach (LISA) is further developed to capture the contact-impact clapping phenomena during the wave crack interactions based on the penalty method. Initial opening and closure distributions are considered to approximate the 3-D rough crack microscopic features. A Coulomb friction model is integrated to capture the stick-slip contact motions between the crack surfaces...
October 6, 2016: Ultrasonics
Jie Gao, John L Williams, Esra Roan
Growth plate chondrocytes are responsible for bone growth through proliferation and differentiation. However, the way they experience physiological loads and regulate bone formation, especially during the later developmental phase in the mature growth plate, is still under active investigation. In this study, a previously developed multiscale finite element model of the growth plate is utilized to study the stress and strain distributions within the cartilage at the cellular level when rapidly compressed to 20 %...
October 21, 2016: Biomechanics and Modeling in Mechanobiology
Cheng-Lin Yang, Sheng-Dong Zhao, Yue-Sheng Wang
In this paper, experimental evidence of large complete bandgaps in a kind of light-weighted zig-zag lattice structure (ZLS) is presented. Ultrasonic experiments are conducted on the stainless steel slab designed with ZLS to detect the complete bandgaps. Also, the numerical simulations of the experiments by the finite element method are carried out. For comparison, we conduct the same experiments and numerical simulations on the stainless steel slab with straight lattice structure (SLS). Good agreement is obtained between the experimental and numerical results...
October 8, 2016: Ultrasonics
Christian Voigt, Andreas Schaller, Carsten Klöhn, Roger Scholz
PURPOSE: In revision total hip arthroplasty, until today, orthopaedic surgeons are missing evidence-based guidelines on cementless acetabular cup fixation. METHODS: 5 finite element models were generated featuring the following anchorage strategies: 1 short peg, 1 long peg, 2 long screws, 3 short screws and zero anchoring components for reference. The micromotions at the implant-bone interface were analyzed for 3 different loadcases, "Seated leg-crossing" (joint force 940 N, impingement force 750 N), "Normal gait" (joint force 1820 N), and "Stumbling" (joint force 4520 N)...
October 15, 2016: Hip International: the Journal of Clinical and Experimental Research on Hip Pathology and Therapy
Mogeeb A El-Sheikh
PURPOSE: This work presents the mechanical design of 4 configurations of compliant fingers in order to address the need for commercially feasible prosthetic and robotic hands. METHODS: The fingers consist of a single part and utilize a compliant mechanism to reduce the cost and control complexity. The geometric parameters of the compliant finger designs follow the Fibonacci series. The first and second compliant fingers have 2 joints and 2 degrees of freedom. The others have 3 joints and 3 degrees of freedom...
October 18, 2016: International Journal of Artificial Organs
Takamasa Ogawa, Yuji Sato, Noboru Kitagawa, Momoe Nakatsu
STATEMENT OF PROBLEM: Although the retention force of maxillary complete dentures has been measured in numerous studies with different devices, the biomechanical mechanism associated with the generation of this retention force cannot be determined. PURPOSE: The purpose of this clinical study was to investigate whether 3-dimensional finite-element analysis can be used to estimate the retention force of maxillary complete dentures. MATERIAL AND METHODS: The study included 12 participants (6 men and 6 women, mean 77...
October 17, 2016: Journal of Prosthetic Dentistry
Ryo Suzuki, Kohta Ito, Taeyong Lee, Naomichi Ogihara
Accurate identification of the material properties of the plantar soft tissue is important for computer-aided analysis of foot pathologies and design of therapeutic footwear interventions based on subject-specific models of the foot. However, parameter identification of the hyperelastic material properties of plantar soft tissues usually requires an inverse finite element analysis due to the lack of a practical contact model of the indentation test. In the present study, we derive an analytical contact model of a spherical indentation test in order to directly estimate the material properties of the plantar soft tissue...
September 22, 2016: Journal of the Mechanical Behavior of Biomedical Materials
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