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Finite element

X Bai, B Tie, J-H Schmitt, D Aubry
The correlation between ultrasonic wave propagation and polycrystalline microstructures has significant implications in nondestructive evaluation. An original numerical approach using the finite element method to quantify in both time and frequency domains the ultrasonic noise scattering due to the elastic heterogeneity of polycrystalline microstructures is presented. Based on the reciprocity theorem, it allows the scattering evaluation using mechanical data recorded only on the boundary of polycrystal instead of within its volume and is applicable to any polycrystalline aggregate regardless of its crystallographic or morphological characteristics...
February 14, 2018: Ultrasonics
Harsha T Garimella, Reuben H Kraft, Andrzej J Przekwas
Subject-specific computer models (male and female) of the human head were used to investigate the possible axonal deformation resulting from the primary phase blast-induced skull flexures. The corresponding axonal tractography was explicitly incorporated into these finite element models using a recently developed technique based on the embedded finite element method. These models were subjected to extensive verification against experimental studies which examined their pressure and displacement response under a wide range of loading conditions...
2018: PloS One
Donghuan Liu, Jing Zhang
High-temperature thermal contact resistance (TCR) plays an important role in heat-pipe-cooled thermal protection structures due to the existence of contact interface between the embedded heat pipe and the heat resistive structure, and the reduction mechanism of thermal contact resistance is of special interests in the design of such structures. The present paper proposed a finite element model of the high-temperature thermal contact resistance based on the multi-point contact model with the consideration of temperature-dependent material properties, heat radiation through the cavities at the interface and the effect of thermal interface material (TIM), and the geometry parameters of the finite element model are determined by simple surface roughness test and experimental data fitting...
2018: PloS One
L J Cornelissen, J Liu, B J van Wees, R A Duine
Efficient manipulation of magnon spin transport is crucial for developing magnon-based spintronic devices. In this Letter, we provide proof of principle of a method for modulating the diffusive transport of thermal magnons in an yttrium iron garnet channel between injector and detector contacts. The magnon spin conductance of the channel is altered by increasing or decreasing the magnon chemical potential via spin Hall injection of magnons by a third modulator electrode. We obtain a modulation efficiency of 1...
March 2, 2018: Physical Review Letters
Young Woong Jang, DoHyung Lim, Hansol Seo, Myung Chul Lee, O-Sung Lee, Yong Seuk Lee
INTRODUCTION: Open-wedge high tibial osteotomy (OWHTO) is a well-established surgical option for medial compartment osteoarthritis of the varus knee. The initial strength of the fixation plate is critical for successful correction maintenance and healing of the osteotomy site. This study was conducted to verify if a newly designed anatomical plate (LCfit) improves the stability of both the medial implant and lateral hinge area, as well as to evaluate how the metal block contributes to both medial and lateral stability...
March 15, 2018: Archives of Orthopaedic and Trauma Surgery
Daisuke Nakashima, Tsukasa Kanchiku, Norihiro Nishida, Saki Ito, Junji Ohgi, Hidenori Suzuki, Yasuaki Imajo, Masahiro Funaba, Xian Chen, Toshihiko Taguchi
Vertebral fractures commonly occur at the thoracolumbar junction. These fractures can be treated with mild residual deformity in many cases, but are reportedly associated with increased risk of secondary vertebral fractures. In the present study, a three-dimensional (3D) whole spine model was constructed using the finite element method to explore the mechanism of development of compression fractures. The 3D model of the whole spine, from the cervical spine to the pelvis, was constructed from computed tomography (CT) images of an adult male...
April 2018: Experimental and Therapeutic Medicine
Alejandra Nieto, Holger Roehl
There has been a growing interest in recent years in the assessment of suitable vial/stopper combinations for storage and shipment of frozen drug products. Considering that the glass transition temperature (Tg) of butyl rubber stoppers used in Container Closure Systems (CCS) is between -55°C to -65°C, a storage or shipment temperature of a frozen product below the Tg of the rubber stopper, may require special attention, since below the Tg the rubber becomes more plastic-like and loses its elastic (sealing) characteristics...
March 15, 2018: PDA Journal of Pharmaceutical Science and Technology
Franz X Bauer, Veronika Heinrich, Florian D Grill, Felix Wölfle, Dennis M Hedderich, Andrea Rau, Klaus-Dietrich Wolff, Lucas M Ritschl, Denys J Loeffelbein
Nasoalveolar Molding (NAM) is associated with ambivalent acceptance regarding effectiveness and unknown long-term results. Our purpose was to analyze the stress distribution patterns within the viscero- and neurocranium of neonates during the first phase of NAM therapy. A finite element (FE) model of a healthy four-week-old neonate was generated, derived from a computed tomography scan allowing the implementation of a bone-density-dependent material model. The influence of dental germs with variable material properties, the cleft width and area of expected force application were analyzed in a worst-case scenario...
February 2, 2018: Journal of Cranio-maxillo-facial Surgery
Damith Mohotti, P L N Fernando, Amir Zaghloul
BACKGROUND AND OBJECTIVE: The aim of this research is to study the behaviour of a human head during the event of an impact of a cricket ball. While many recent incidents were reported in relation to head injuries caused by the impact of cricket balls, there is no clear information available in the published literature about the possible threat levels and the protection level of the current protective equipment. This research investigates the effects of an impact of a cricket ball on a human head and the level of protection offered by the existing standard cricket helmet...
May 2018: Computer Methods and Programs in Biomedicine
Aekaansh Verma, Mahdi Esmaily, Jessica Shang, Richard Figliola, Jeffrey A Feinstein, Tain-Yen Hsia, Alison L Marsden
BACKGROUND: First-stage single-ventricle palliation is challenging to manage, and significant interstage morbidity and mortality remain. Prior computational and in vitro studies of the assisted bidirectional Glenn (ABG), a novel first-stage procedure that has shown potential for early conversion to a more stable augmented Glenn physiology, demonstrated increased pulmonary flow and oxygen delivery while decreasing cardiac work, as compared to conventional stage-1 alternatives. This study aims to identify optimal shunt designs for the ABG to improve pulmonary flow while maintaining or decreasing superior vena caval (SVC) pressure...
March 2018: World Journal for Pediatric & Congenital Heart Surgery
Zhongkui Wang, Masamitsu Kido, Kan Imai, Kazuya Ikoma, Shinichi Hirai
Clinically in medializing calcaneal osteotomy (MCO), foot and ankle surgeons are facing difficulties in choosing appropriate surgical parameters due to the individual differences in deformities among flatfoot patients. Traditional cadaveric studies have provided important information regarding the biomechanical effects of tendons, ligaments, and plantar fascia, but limitations have been reached when dealing with individual differences and tailoring patient-specific surgeries. Therefore, this study aimed at implementing the finite element (FE) method to investigate the effect of different MCO parameters to help foot and ankle surgeons performing patient-specific surgeries...
March 15, 2018: Computer Methods in Biomechanics and Biomedical Engineering
Yasmine Mosleh, Martin Cajka, Bart Depreitere, Jos Vander Sloten, Jan Ivens
Oblique impact is the most common accident situation that occupants in traffic accidents or athletes in professional sports experience. During oblique impact, the human head is subjected to a combination of linear and rotational accelerations. Rotational movement is known to be responsible for traumatic brain injuries. In this article, composite foam with a column/matrix composite configuration is proposed for head protection applications to replace single-layer uniform foam, to better attenuate rotational movement of the head during oblique impacts...
March 1, 2018: Proceedings of the Institution of Mechanical Engineers. Part H, Journal of Engineering in Medicine
Zhikai Zhao, Ran Liu, Dirk Mayer, Maristella Coppola, Lu Sun, Youngsang Kim, Chuankui Wang, Lifa Ni, Xing Chen, Maoning Wang, Zongliang Li, Takhee Lee, Dong Xiang
A straightforward method to generate both atomic-scale sharp and atomic-scale planar electrodes is reported. The atomic-scale sharp electrodes are generated by precisely stretching a suspended nanowire, while the atomic-scale planar electrodes are obtained via mechanically controllable interelectrodes compression followed by a thermal-driven atom migration process. Notably, the gap size between the electrodes can be precisely controlled at subangstrom accuracy with this method. These two types of electrodes are subsequently employed to investigate the properties of single molecular junctions...
March 15, 2018: Small
Kyungjin Kim, Hao Luo, Ting Zhu, Olivier N Pierron, Samuel Graham
This work is concerned with the long-term behavior of environmentally-assisted subcritical cracking of PECVD SiNx barrier films on polyethylene terephthalate (PET) and polyimide (PI) substrates. While environmentally-assisted channel cracking in SiNx has been previously demonstrated, with constant crack growth rates over short periods of time (<1 hour) during which no substrate damage was observed, the present experiments over longer periods reveal a regime where cracking also develops in the polymer substrate...
March 14, 2018: Scientific Reports
Francesco Nappi, Antonio Nenna, Domenico Larobina, Angelo Rosario Carotenuto, Mohamed Jarraya, Cristiano Spadaccio, Massimiliano Fraldi, Massimo Chello, Christophe Acar, Thierry Carrel
OBJECTIVES: Reinforcements for the pulmonary autograft (PA) in the Ross operation have been introduced to avoid the drawback of conduit expansion and failure. With the aid of an in silico simulation, the biomechanical boundaries applied to a healthy PA during the operation were studied to tailor the best implant technique to prevent reoperation. METHODS: Follow-up echocardiograms of 66 Ross procedures were reviewed. Changes in the dimensions and geometry of reinforced and non-reinforced PAs were evaluated...
March 12, 2018: Interactive Cardiovascular and Thoracic Surgery
Royston K Y Tan, Xiaofei Wang, Shamira A Perera, Michaël J A Girard
PURPOSE: (1) To use finite element (FE) modelling to estimate local iris stresses (i.e. internal forces) as a result of mechanical pupil expansion; and to (2) compare such stresses as generated from several commercially available expanders (Iris hooks, APX dilator and Malyugin ring) to determine which design and deployment method are most likely to cause iris damage. METHODS: We used a biofidelic 3-part iris FE model that consisted of the stroma, sphincter and dilator muscles...
2018: PloS One
Huipeng Chen, David Poulard, Jason Forman, Jeff Crandall, Matthew B Panzer
STRUCTURED ABSTRACT Objective: Evaluating the biofidelity of pedestrian finite element models (PFEM) using post-mortem human subjects (PMHS) is a challenge as differences in anthropometry between PMHS and PFEM could limit a model's capability to accurately capture cadaveric responses. Geometrical personalization via morphing can modify the PFEM geometry to match the specific PMHS anthropometry which could alleviate this issue. In this study, the THUMS PFEM (v4.01) was compared to the cadaveric response in vehicle-pedestrian impacts using geometrically personalized models...
March 14, 2018: Traffic Injury Prevention
Jeremie Maire, Roman Anufriev, Takuma Hori, Junichiro Shiomi, Sebastian Volz, Masahiro Nomura
Semiconductor nanowires are potential building blocks for future thermoelectrics because of their low thermal conductivity. Recent theoretical works suggest that thermal conductivity of nanowires can be further reduced by additional constrictions, pillars or wings. Here, we experimentally study heat conduction in silicon nanowires with periodic wings, called fishbone nanowires. We find that like in pristine nanowires, the nanowire cross-section controls thermal conductivity of fishbone nanowires. However, the periodic wings further reduce the thermal conductivity...
March 13, 2018: Scientific Reports
Valessa F Carvalho, Priscilla Bf Soares, Crisnicaw Verissimo, Roberto S Pessoa, Antheunis Versluis, Carlos J Soares
PURPOSE: The purpose of this study was to evaluate mouthguard shock absorption ability, strain, and stress generation during impact on dental implants placed in the anterior maxilla. The mouthguard material was also characterized. MATERIALS AND METHODS: Sixty experimental models were created and divided into six groups (n = 10): implant type, external hexagon (EH) and Morse taper (MT); without and with two mouthguards (MTG), EVA custom-fitted (Ct-MTG) and standard self-adapted (St-MTG)...
March 2018: International Journal of Oral & Maxillofacial Implants
Sung-Yong Cho, Yun-Hyuk Huh, Chan-Jin Park, Lee-Ra Cho
PURPOSE: To investigate the stress distribution in an implant-abutment complex with a preloaded abutment screw by comparing implant-abutment engagement features using three-dimensional finite element analysis (FEA). MATERIALS AND METHODS: For FEA modeling, two implants-one with a single (S) engagement system and the other with a double (D) engagement system-were placed in the human mandibular molar region. Two types of abutments (hexagonal, conical) were connected to the implants...
March 2018: International Journal of Oral & Maxillofacial Implants
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