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Finite element analysis

Wenguang Zhang, Jiaqi Tang, Zhengwei Li, Yakun Ma
In order to solve the problem of the short lifespan of the neural electrode caused by micro motion, this study designed a novel neural electrode based on lumped compliance compliant mechanism to control different modes of micro-motion in a more effective way. According to the mathematical modeling of the novel neural electrode, the equivalent bending stiffness and equivalent tensile (compression) stiffness were calculated. The results of the finite element analysis based on the mathematical modeling revealed that the novel neural electrode showed excellent micro-motion-attenuation capability...
April 18, 2018: Medical & Biological Engineering & Computing
Annette L Adams, Heidi Fischer, David L Kopperdahl, David C Lee, Dennis M Black, Mary L Bouxsein, Shireen Fatemi, Sundeep Khosla, Eric S Orwoll, Ethel S Siris, Tony M Keaveny
Methods now exist for analyzing previously taken clinical computed tomography (CT) scans to measure a dual-energy X-ray absorptiometry (DXA)-equivalent bone mineral density (BMD) at the hip and a finite element analysis-derived femoral strength. We assessed the efficacy of this "biomechanical CT" (BCT) approach for identifying patients at high risk of incident hip fracture in a large clinical setting. Using a case-cohort design sampled from 111,694 women and men aged 65 or older who had a prior hip CT scan, a DXA within 3 years of the CT, and no prior hip fracture, we compared those with subsequent hip fracture (n = 1959) with randomly selected sex-stratified controls (n = 1979) and analyzed their CT scans blinded to all other data...
April 17, 2018: Journal of Bone and Mineral Research: the Official Journal of the American Society for Bone and Mineral Research
Elyas Goli, Ian D Robertson, Philippe H Geubelle, Jeffrey S Moore
As frontal polymerization is being considered as a faster and more energy efficient manufacturing technique for polymer-matrix fiber-reinforced composites, we perform a finite-element-based numerical study of the initiation and propagation of a polymerization front in dicyclopentadiene (DCPD). The transient thermochemical simulations are complemented by an analytical study of the steady-state propagation of the polymerization front, allowing to draw a direct link between the cure kinetics model and the key characteristics of the front, i...
April 17, 2018: Journal of Physical Chemistry. B
Thomas A Püschel, Jordi Marcé-Nogué, Thomas M Kaiser, Robert J Brocklehurst, William I Sellers
Primates are interpreted to be ancestrally adapted to frugivory, although some modern groups show clear adaptations to other diets. Among them, pitheciids stand out for specifically predating seeds. This dietary specialization is known as sclerocarpy and refers to the extraction of seeds from surrounding hard tissues using the anterior dentition followed by the mastication of seeds by the molars. It has been proposed that Callicebus-Pithecia-Chiropotes-Cacajao represent a morphocline of increasingly specialized anatomical traits for sclerocarpic foraging...
April 17, 2018: American Journal of Primatology
Fanwei Kong, Thuy Pham, Caitlin Martin, Raymond McKay, Charles Primiano, Sabet Hashim, Susheel Kodali, Wei Sun
Despite the growing clinical interest in the tricuspid valve (TV), there is an incomplete understanding of TV biomechanics which is important in normal TV function and successful TV repair techniques. Computational models with patient-specific human TV geometries can provide a quantitative understanding of TV biomechanic. Therefore, this study aimed to develop finite element (FE) models of human TVs from multi-slice computed tomography (MSCT) images to investigate chordal forces and leaflet stresses and strains...
April 16, 2018: Annals of Biomedical Engineering
Yan Wang, Zengyong Li, Duo Wai-Chi Wong, Cheng-Kung Cheng, Ming Zhang
Background: Total ankle arthroplasty is gaining popularity as an alternation to ankle arthrodesis for end-stage ankle arthritis. Owing to the complex anatomical characteristics of the ankle joint, total ankle arthroplasty has higher failure rates. Biomechanical exploration of the effects of total ankle arthroplasty on the foot and ankle is imperative for the precaution of postoperative complications. The objectives of this study are (1) to investigate the biomechanical differences of the foot and ankle between the foot with total ankle arthroplasty and the intact foot and (2) to investigate the performance of the three-component ankle prosthesis...
January 2018: Journal of Orthopaedic Translation
Leilei Chen, GuoJu Hong, Bin Fang, Guangquan Zhou, Xiaorui Han, Tianan Guan, Wei He
Collapse of the femoral head is the most significant pathogenic complication arising from osteonecrosis of the femoral head. It is related to the disruption of the maintenance of cartilage and bone, and results in an impaired function of the vascular component. A method for predicting the collapse of the femoral head can be treated as a type of clinical index. Efforts in recent years to predict the collapse of the femoral head due to osteonecrosis include multiple methods of radiographic analysis, stress distribution analysis, finite element analysis, and other innovative methods...
October 2017: Journal of Orthopaedic Translation
Wenqiang Fang, Joyce Mok, Haneesh Kesari
Design against adhesion in microelectromechanical devices is predicated on the ability to quantify this phenomenon in microsystems. Previous research related the work of adhesion for an adhered microbeam to the beam's unadhered length, and as such, interferometric techniques were developed to measure that length. We propose a new vibration-based technique that can be easily implemented with existing atomic force microscopy tools or similar metrology systems. To make such a technique feasible, we analysed a model of the adhered microbeam using the nonlinear beam theory put forth by Woinowsky-Krieger...
March 2018: Proceedings. Mathematical, Physical, and Engineering Sciences
K E N'souglo, A Srivastava, S Osovski, J A Rodríguez-Martínez
At high strain rates, the fragmentation of expanding structures of ductile materials, in general, starts by the localization of plastic deformation in multiple necks. Two distinct mechanisms have been proposed to explain multiple necking and fragmentation process in ductile materials. One view is that the necking pattern is related to the distribution of material properties and defects. The second view is that it is due to the activation of specific instability modes of the structure. Following this, we investigate the emergence of necking patterns in porous ductile bars subjected to dynamic stretching at strain rates varying from 103   s -1 to 0...
March 2018: Proceedings. Mathematical, Physical, and Engineering Sciences
Yifeng Xiong, Wenhu Wang, Ruisong Jiang, Kunyang Lin, Mingwei Shao
The in-situ TiB₂/7050Al composite is a new kind of Al-based metal matrix composite (MMC) with super properties, such as low density, improved strength, and wear resistance. This paper, for a deep insight into its cutting performance, involves a study of the chip formation process and finite element simulation during orthogonal cutting in-situ TiB₂/7050Al MMC. With chips, material properties, cutting forces, and tool geometry parameters, the Johnson-Cook (J-C) constitutive equation of in-situ TiB₂/7050Al composite was established...
April 15, 2018: Materials
Shaun N Robertson, Paul Campsie, Peter G Childs, Fiona Madsen, Hannah Donnelly, Fiona L Henriquez, William G Mackay, Manuel Salmerón-Sánchez, Monica P Tsimbouri, Craig Williams, Matthew J Dalby, Stuart Reid
Mechanical signals are ubiquitous in our everyday life and the process of converting these mechanical signals into a biological signalling response is known as mechanotransduction. Our understanding of mechanotransduction, and its contribution to vital cellular responses, is a rapidly expanding field of research involving complex processes that are still not clearly understood. The use of mechanical vibration as a stimulus of mechanotransduction, including variation of frequency and amplitude, allows an alternative method to control specific cell behaviour without chemical stimulation (e...
May 28, 2018: Philosophical Transactions. Series A, Mathematical, Physical, and Engineering Sciences
Sean G Smith, Boyce E Griffith, David A Zaharoff
Ailments of the bladder are often treated via intravesical delivery-direct application of therapeutic into the bladder through a catheter. This technique is employed hundreds of thousands of times every year, but protocol development has largely been limited to empirical determination. Furthermore, the numerical analyses of intravesical delivery performed to date have been restricted to static geometries and have not accounted for bladder deformation. This study uses a finite element analysis approach with biphasic solute transport to investigate several parameters pertinent to intravesical delivery including solute concentration, solute transport properties and instillation volume...
April 5, 2018: Mathematical Medicine and Biology: a Journal of the IMA
Katarzyna Arkusz, Tomasz Klekiel, Niezgoda Niezgoda, Romuald Będziński
PURPOSE: The aim of this study was to determine the effect of bone mineral density (BMD) on the stress distribution in pelvic-hip complex (PHC) model which included bone structures and soft tissues. Bone mass changes in osteoporosis and osteopenia were considered in this analysis. In addition, the relations between force direction and stress distribution causing PHC fractures were determined. METHODS: This paper presents the development and validation of a detailed 3D finite element model with high anatomical fidelity of the PHC and BMD changes in trabecular and cortical bones, modelled based on CT scans...
2018: Acta of Bioengineering and Biomechanics
Yue Xuan, Zhongjie Wang, Raymond Liu, Henrik Haraldsson, Michael D Hope, David A Saloner, Julius M Guccione, Liang Ge, Elaine Tseng
OBJECTIVE: Guidelines for repair of bicuspid aortic valve-associated ascending thoracic aortic aneurysms have been changing, most recently to the same criteria as tricuspid aortic valve-ascending thoracic aortic aneurysms. Rupture/dissection occurs when wall stress exceeds wall strength. Recent studies suggest similar strength of bicuspid aortic valve versus tricuspid aortic valve-ascending thoracic aortic aneurysms; thus, comparative wall stress may better predict dissection in bicuspid aortic valve versus tricuspid aortic valve-ascending thoracic aortic aneurysms...
March 8, 2018: Journal of Thoracic and Cardiovascular Surgery
Tuğrul Aslan, Yakup Üstün, Emir Esim
The aim of this study was to evaluate the stresses within simulated roots with internal resorption cavities at the apical, middle and coronal root levels, after obturation with gutta-percha and/or MTA utilising finite element analysis (FEA). Mandibular premolar teeth with internal resorption cavities at different root levels were modelled. Models were restored with gutta-percha and/or MTA. An oblique force of 300 N was applied and stress evaluations were carried out. In the MTA-filled resorption models, the stresses were distributed more homogeneously than the gutta-percha filled models, and the stress concentrations were lower in the remaining dentinal tissues...
April 15, 2018: Australian Endodontic Journal: the Journal of the Australian Society of Endodontology Inc
Pierre Guillemé, Julie Stervinou, Tony Rohel, Charles Cornet, David Gachet, Stéphane Balac, Fabrice Mahé, Yannick Dumeige, Yoan Léger
Whispering gallery mode resonators are key devices for integrated photonics. Despite their generalization in fundamental and applied science, information on spatial confinement of light in these structures is mostly retrieved from purely spectral analysis. In this work, we present a detailed spectral and spatial characterization of whispering gallery modes in active semiconductor microdisk resonators by use of hyperspectral cathodoluminescence. By comparing our experimental findings to finite element simulations, we demonstrate that the combination of spectral and spatial measurements enables unique identification of the modes and even reveals specific features of the microresonator geometry, such as a wedge profile...
April 15, 2018: Optics Letters
Oscar Araque, Nelson Arzola, Edgar Hernández
This research deals with the fatigue behavior of butt-welded joints, by considering the geometry and post-welding cooling cycles, as a result of cooling in quiet air and immersed in water. ASTM A-36 HR structural steel was used as the base metal for the shielded metal arc welding (SMAW) process with welding electrode E6013. The welding reinforcement was 1 mm and 3 mm, respectively; axial fatigue tests were carried out to determine the life and behavior in cracks propagation of the tested welded joints, mechanical characterization tests of properties in welded joints such as microhardness, Charpy impact test and metallographic analysis were carried out...
April 12, 2018: Materials
Kotaro Mori, Tadashi Horibe, Shigekazu Ishikawa
This study deals with the numerical and experimental study of the effect of weight on the resonant tuning and energy harvesting characteristics of energy harvesting devices using giant magnetostrictive materials. The energy harvesting device is made in a cantilever shape using a thin Terfenol-D layer, stainless steel (SUS) layer and a movable proof mass, among other things. In this study, two types of movable proof mass were prepared, and the device was designed to adjust its own resonant frequency automatically to match external vibration frequency in real time...
April 10, 2018: Materials
Alessandro Ruggiero, Massimiliano Merola, Saverio Affatato
The hip joint replacement is one of the most successful orthopedic surgical procedures although it involves challenges to overcome. The patient group undergoing total hip arthroplasty now includes younger and more active patients who require a broad range of motion and a longer service lifetime for the replacement joint. It is well known that wear tests have a long duration and they are very expensive, thus studying the effects of geometry, loading, or alignment perturbations may be performed by Finite Element Analysis...
April 9, 2018: Materials
Tyler Scogin, Sumith Yesudasan, Mitchell L R Walker, Rodney D Averett
Blood clots occur in the human body when they are required to prevent bleeding. In pathological states such as diabetes and sickle cell disease, blood clots can also form undesirably due to hypercoagulable plasma conditions. With the continued effort in developing fibrin therapies for potential life-saving solutions, more mechanical modeling is needed to understand the properties of fibrin structures with inclusions. In this study, a fibrin matrix embedded with magnetic micro particles (MMPs) was subjected to a magnetic field to determine the magnitude of the required force to create plastic deformation within the fibrin clot...
2018: Journal of Mechanics in Medicine and Biology
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