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Finite element modeling

Qi Wu, Tomotaka Ogasawara, Nobuhiro Yoshikawa, Hongzhou Zhai
Amorphous thermoplastics, as a type of engineering plastic material, are used in various industrial sectors. In order to manufacture high-performance products, it is important to optimize their forming process to mitigate residual stresses. However, stress in a plate is difficult to measure, therefore, modeling provides a powerful way to investigate and understand the evolution of stress. In this study, the forming process of a polyetherimide (PEI) plate was modelled using finite element analysis, and then validated through a comparison with a warpage experiment...
March 21, 2018: Materials
Hou-Zhen Wei, Dong-Sheng Xu, Qing-Shan Meng
A novel fiber-optic based earth pressure sensor (FPS) with an adjustable measurement range and high sensitivity is developed to measure earth pressures for civil infrastructures. The new FPS combines a cantilever beam with fiber Bragg grating (FBG) sensors and a flexible membrane. Compared with a traditional pressure transducer with a dual diaphragm design, the proposed FPS has a larger measurement range and shows high accuracy. The working principles, parameter design, fabrication methods, and laboratory calibration tests are explained in this paper...
March 21, 2018: Sensors
Robert Gibbs, Gregory Moreton, Turgut Meydan, Paul Williams
The investigation of planar coils of differing topologies, when combined with a magnetostrictive amorphous ribbon to form a stress-sensitive self-inductor, is an active research area for applications as stress or pressure sensors. Four topologies of planar coil (Circular, Mesh, Meander, and Square) have been constructed using copper track on 30 mm wide PCB substrate. The coils are energized to draw 0.4 A and the resulting magnetic field distribution is observed with a newly developed three-dimensional magnetic field scanner...
March 21, 2018: Sensors
Bing Wang, Zhanqiang Liu, Xin Hou, Jinfu Zhao
The paper aims to investigate the influences of material constitutive and fracture parameters in addition to cutting speed on chip formation during high-speed cutting of Inconel 718. Finite element analyses for chip formation are conducted with Johnson-Cook constitutive and fracture models. Meanwhile, experiments of high-speed orthogonal cutting are performed to verify the simulation results with cutting speeds ranging from 50 m/min to 7000 m/min. The research indicates that the chip morphology transforms from serrated to fragmented at the cutting speed of 7000 m/min due to embrittlement of the workpiece material under ultra-high cutting speeds...
March 21, 2018: Materials
Chung-Hsuan Huang, Satish Kumar
Transfer of liquid from one surface to another plays a vital role in printing processes. During liquid transfer, a liquid bridge is formed and subjected to substantial extension, but incomplete liquid transfer can produce defects that are detrimental to the operation of printed electronic devices. One strategy for minimizing these defects is to apply an electric field, a technique known as electrostatic assist (ESA). However, the physical mechanisms underlying ESA remain a mystery. To better understand these mechanisms, slender-jet models are developed for both perfect dielectric and leaky dielectric axisymmetric Newtonian liquid bridges with moving contact lines...
March 21, 2018: Langmuir: the ACS Journal of Surfaces and Colloids
Victor Soltwisch, Philipp Hönicke, Yves Kayser, Janis Eilbracht, Jürgen Probst, Frank Scholze, Burkhard Beckhoff
The geometry of a Si3N4 lamellar grating was investigated experimentally with reference-free grazing-incidence X-ray fluorescence analysis. While simple layered systems are usually treated with the matrix formalism to determine the X-ray standing-wave field, this approach fails for laterally structured surfaces. Maxwell solvers based on finite elements are often used to model electrical field strengths for any 2D or 3D structures in the optical spectral range. We show that this approach can also be applied in the field of X-rays...
March 21, 2018: Nanoscale
Azuma Takahashi, Xiaodong Zhu, Yusuke Aoyama, Mitsuo Umezu, Kiyotaka Iwasaki
The evaluation of strain induced in a blood vessel owing to contact with a medical device is of significance to examine the causes leading to vascular injury and rupture. The development of a method to assess strain in largely deformed elastic materials is expected. This study's scope was to measure strain in deformed tubular elastic mock vessels using tomographic particle image velocimetry (tomo-PIV), and to show the applicability of this measurement method by comparing the results with data derived from a finite element analysis (FEA)...
March 20, 2018: Cardiovascular Engineering and Technology
Caitlin Weaver, Alexander Baker, Matthew Davis, Anna Miller, Joel D Stitzel
Pelvic fractures are serious injuries resulting in high mortality and morbidity. The objective of this study is to develop and validate local pelvic anatomical, cross-section-based injury risk metrics for a finite element (FE) model of the human body. Cross-sectional instrumentation was implemented in the pelvic region of the Global Human Body Models Consortium (GHBMC M50-O) 50th percentile detailed male FE model (v4.3). In total, 25 lateral impact FE simulations were performed using input data from cadaveric lateral impact tests performed by Bouquet et al...
February 20, 2018: Journal of Biomechanical Engineering
Wolfram Wiest, Alexander Rack, Simon Zabler, Alex Schaer, Michael Swain, Katja Nelson
State-of-the art, two-piece dental implants made from titanium alloys exhibit a complex micromechanical behavior under dynamical load. Its understanding, especially the formation of microgaps, is of crucial importance in order to predict and improve the long-term performance of such implants. Microgap formation in a loaded dental implant with a conical implant-abutment connection can be studied and quantified by synchrotron radiography with micrometer accuracy. Due to the high costs and limited access to synchrotron radiation sources, alternative approaches are needed in order to depict the microgap formation...
February 2018: Heliyon
Hung-Wei Hsu, Maxim Bashkuev, Matthias Pumberger, Hendrik Schmidt
Lumbar interbody fusion is currently the gold standard in treating patients with disc degeneration or segmental instability. Despite it having been used for several decades, the non-union rate remains high. A failed fusion is frequently attributed to an inadequate mechanical environment after instrumentation. Finite element (FE) models can provide insights into the mechanics of the fusion process. Previous fusion simulations using FE models showed that the geometries and material of the cage can greatly influence the fusion outcome...
March 15, 2018: Journal of Biomechanics
Erin J Sanchez, Lee F Gabler, Ann B Good, James R Funk, Jeff R Crandall, Matthew B Panzer
BACKGROUND: Head kinematics generated by laboratory reconstructions of professional football helmet impacts have been applied to computational models to study the biomechanics of concussion. Since the original publication of this data, techniques for evaluating accelerometer consistency and error correction have been developed. This study applies these techniques to the original reconstruction data and reanalyzes the results given the current state of concussion biomechanics. METHODS: Consistency checks were applied to the sensor data collected in the head of each test dummy...
March 14, 2018: Clinical Biomechanics
Sermsak Sumanont, Supachoke Nopamassiri, Artit Boonrod, Punyawat Apiwatanakul, Arunnit Boonrod, Chanakarn Phornphutkul
BACKGROUND: Suspension suture button fixation was frequently used to treat acromioclavicular joint (ACJ) dislocation. However, there were many studies reporting about complications and residual horizontal instability after fixation. Our study compared the stability of ACJ after fixation between coracoclavicular (CC) fixation alone and CC fixation combined with ACJ repair by using finite element analysis (FEA). MATERIALS AND METHODS: A finite element model was created by using CT images from the normal shoulder...
March 20, 2018: European Journal of Orthopaedic Surgery & Traumatology: Orthopédie Traumatologie
Yuan Luo, Parinaz Abiri, Shell Zhang, Chih-Chiang Chang, Amir H Kaboodrangi, Rongsong Li, Ashish K Sahib, Alex Bui, Rajesh Kumar, Mary Woo, Zhaoping Li, René R Sevag Packard, Yu-Chong Tai, Tzung K Hsiai
Introduction: Obesity is associated with an increased risk of nonalcoholic fatty liver disease (NAFLD). While Magnetic Resonance Imaging (MRI) is a non-invasive gold standard to detect fatty liver, we demonstrate a low-cost and portable electrical impedance tomography (EIT) approach with circumferential abdominal electrodes for liver conductivity measurements. Methods and Results: A finite element model (FEM) was established to simulate decremental liver conductivity in response to incremental liver lipid content...
2018: Theranostics
Yang Tian, Zhilin Liu, Xiaoqian Li, Lihua Zhang, Ruiqing Li, Ripeng Jiang, Fang Dong
Ultrasonic sonotrodes play an essential role in transmitting power ultrasound into the large-scale metallic casting. However, cavitation erosion considerably impairs the in-service performance of ultrasonic sonotrodes, leading to marginal microstructural refinement. In this work, the cavitation erosion behaviour of ultrasonic sonotrodes in large-scale castings was explored using the industry-level experiments of Al alloy cylindrical ingots (i.e. 630 mm in diameter and 6000 mm in length). When introducing power ultrasound, severe cavitation erosion was found to reproducibly occur at some specific positions on ultrasonic sonotrodes...
May 2018: Ultrasonics Sonochemistry
Kristoffer Johansen, Jae Hee Song, Paul Prentice
We describe the design, construction and characterisation of a broadband passive cavitation detector, with the specific aim of detecting low frequency components of periodic shock waves, with high sensitivity. A finite element model is used to guide selection of matching and backing layers for the shock wave passive cavitation detector (swPCD), and the performance is evaluated against a commercially available device. Validation of the model, and characterisation of the swPCD is achieved through experimental detection of laser-plasma bubble collapse shock waves...
May 2018: Ultrasonics Sonochemistry
William McCartney, Bryan MacDonald, Ciprian Andrei Ober, Rubén Lostado-Lorza, Fátima Somovilla Gómez
BACKGROUND: Finite element analysis was used to compare fixation methods for double pelvic osteotomy (DPO). Using 3D scanning a stereolithography (stl) image was produced of a canine pelvis and this was subsequently refined in computer aided design (CAD). Using the CAD files, the images were imported in MSC Marc software to produce a working finite element (FE) model with 3 dimensional tetrahedral elements with linear shaped functions. The dimensions of a precontoured pelvic osteotomy plate with eight screws and a twisted seven screw straight plate were used to build the 2 fixations implants for the FE models...
March 20, 2018: BMC Veterinary Research
Agnes Beckmann, Yousef Heider, Marcus Stoffel, Bernd Markert
The underlying research work introduces a study of the mechanical properties of polycarbonate urethane (PCU), used in the construction of various medical devices. This comprises the discussion of a suitable material model, the application of elemental experiments to identify the related parameters and the numerical simulation of the applied experiments in order to calibrate and validate the mathematical model. In particular, the model of choice for the simulation of PCU response is the non-linear viscoelastic Bergström-Boyce material model, applied in the finite-element (FE) package Abaqus®...
March 9, 2018: Journal of the Mechanical Behavior of Biomedical Materials
Robert J Cooper, Sophie Williams, Marlène Mengoni, Alison C Jones
BACKGROUND: Impingement resulting in soft tissue damage has been observed in hips with abnormal morphologies. Geometric parameterisation can be used to automatically generate a range of bone geometries for use in computational models, including femurs with cam deformity on the femoral neck. METHODS: This study verified patient-specific parametric finite element models of 20 patients with cam deformity (10 female, 10 male) through comparison to their patient-specific segmentation-based equivalents...
March 14, 2018: Clinical Biomechanics
Chanyuan Jiang, Yilue Zheng, Ningbei Yin, Tao Song
The aim of this study was to investigate the anatomical features of the maxillae and vomer in patients with bilateral cleft lip and palate (BCLP). Craniofacial measurements of 24 adult BCLP patients (GB) and 32 normal adult controls (GN) were carried out. We measured the width and length of the maxillae, their relative positions with respect to the coronal plane passing through the basion, and the volume, length, cross-sectional area, and mean width of the vomer. Between-group differences were assessed using independent-sample t tests...
March 16, 2018: Journal of Craniofacial Surgery
Sheikh Mohammad Shavik, Zhenxiang Jiang, Seungik Baek, Lik Chuan Lee
While it has long been recognized that bi-directional interaction between the heart and the vasculature plays a critical role in the proper functioning of the cardiovascular system, a comprehensive study of this interaction has largely been hampered by a lack of modeling framework capable of simultaneously accommodating high-resolution models of the heart and vasculature. Here, we address this issue and present a computational modeling framework that couples finite element (FE) models of the left ventricle (LV) and aorta to elucidate ventricular-arterial coupling in the systemic circulation...
2018: Frontiers in Physiology
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