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Finite element modeling

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
Ashish Kumar Singh, Bo-Yang Chen, Vincent B C Tan, Tong-Earn Tay, Heow-Pueh Lee
Linear ultrasonics methods based on the principle of reflection, transmission, dissipation of sound waves have been traditionally used to detect delaminations in composite structures. However, when the delamination is in very early stages such that it is almost closed, or closed due to a compressive load, the linear methods may fail to detect such cases of delaminations. Nonlinear acoustics/ultrasonics have shown potential to identify damages in composite structures which are difficult to detect using conventional linear ultrasonic methods...
October 8, 2016: Ultrasonics
Yunzhu Meng, Wansoo Pak, Berkan Guleyupoglu, Bharath Koya, F Scott Gayzik, Costin D Untaroiu
Child pedestrian protection deserves more attention in vehicle safety design since they are the most vulnerable road users who face the highest mortality rate. Pediatric Finite Element (FE) models could be used to simulate and understand the pedestrian injury mechanisms during crashes in order to mitigate them. Thus, the objective of the study was to develop a computationally efficient (simplified) six-year-old (6YO-PS) pedestrian FE model and validate it based on the latest published pediatric data. The 6YO-PS FE model was developed by morphing the existing GHBMC adult pedestrian model...
October 16, 2016: Accident; Analysis and Prevention
Giordano Tasca, Matteo Selmi, Emiliano Votta, Paola Redaelli, Francesco Sturla, Alberto Redaelli, Amando Gamba
BACKGROUND: Aortic root aneurysm can be treated with valve-sparing procedures. The David and Yacoub techniques have shown excellent long-term results but are technically demanding. Recently, a new and simpler procedure, the Sleeve technique, was proposed with encouraging results. We aimed to quantify the biomechanics of the initially aneurysmal aortic root (AR) after the Sleeve procedure to assess whether it induces abnormal stresses, potentially undermining its durability. METHODS: Two finite element (FE) models of the physiologic and aneurysmal AR were built, accounting for the anatomical asymmetry and the nonlinear and anisotropic mechanical properties of human AR tissues...
October 15, 2016: Annals of Thoracic Surgery
Ling He, Deli Li, Jiwu Zhang, Xiucheng Li, Songhe Lu, Zhihui Tang
OBJECTIVE: The aim of this study was to evaluate cross-sectional area of the abutments, strain distribution in the periimplant bone, stress in the abutments and dental root-analog implant by different abutment design under different loading conditions, through three-dimensional finite element analysis. METHODS: Two three-dimensional finite element models were established. Two types of abutments, oval cross section abutment (OCSA) and circular cross section abutment (CCSA) were designed, keeping the size of the thinnest implant wall 0...
October 13, 2016: Implant Dentistry
Weihua Xie, Songhe Meng, Hua Jin, Chong Du, Libin Wang, Tao Peng, Fabrizio Scarpa, Chenghai Xu
This paper presents a simple methodology to perform a high temperature coupled thermo-mechanical test using ultra-high temperature ceramic material specimens (UHTCs), which are equipped with chemical composition gratings sensors (CCGs). The methodology also considers the presence of coupled loading within the response provided by the CCG sensors. The theoretical strain of the UHTCs specimens calculated with this technique shows a maximum relative error of 2.15% between the analytical and experimental data. To further verify the validity of the results from the tests, a Finite Element (FE) model has been developed to simulate the temperature, stress and strain fields within the UHTC structure equipped with the CCG...
October 13, 2016: Sensors
Jun Qiu, Fang-Fang Li
Mechanical properties of a single cell and its mechanical response under stimulation play an important role in regulating interactions between cell and extracellular matrix and affecting mechanotransduction. Osteocytes exhibit solid-like viscoelastic behavior in response to the interstitial fluid shear resulting from tissue matrix deformation. This study intends to quantitatively describe the mechanical behavior of osteocytes combining in vitro experiment and fluid-structure interaction (FSI) finite element (FE) model...
October 17, 2016: Biomechanics and Modeling in Mechanobiology
Diogo F Almeida, Rui B Ruben, João Folgado, Paulo R Fernandes, Emmanuel Audenaert, Benedict Verhegghe, Matthieu De Beule
Femur segmentation can be an important tool in orthopedic surgical planning. However, in order to overcome the need of an experienced user with extensive knowledge on the techniques, segmentation should be fully automatic. In this paper a new fully automatic femur segmentation method for CT images is presented. This method is also able to define automatically the medullary canal and performs well even in low resolution CT scans. Fully automatic femoral segmentation was performed adapting a template mesh of the femoral volume to medical images...
October 14, 2016: Medical Engineering & Physics
Sadegh Sadeghzadeh
A multi-scale method is employed in this paper to conduct a virtual study of the high-strain behavior of single- and multi-layer graphene sheets and to investigate the design of related graphene-based devices. By bridging the length and time scales by combining the Molecular Dynamics and Finite Element methods together, a comprehensive multiscale model is developed to study the fascinating capabilities of single- and multi-layer graphene sheets in withstanding the impact of ultrafast projectiles. In order to contribute to future developments and innovations in this field, several quantitative and qualitative comparisons are also performed...
October 5, 2016: Journal of Molecular Graphics & Modelling
Leo Fradet, Xiaoyu Wang, Lawrence G Lenke, Carl-Eric Aubin
BACKGROUND: Proximal junctional failure is a severe proximal junctional complication following adult spinal instrumentation and involving acute proximal junctional kyphotic deformity, mechanical failure at the upper instrumented vertebra or just above, and/or proximal junctional osseoligamentous disruption. Clinical studies have identified potential risk factors, but knowledge on their biomechanics is still lacking for addressing the proximal junctional failure issues. The objective of this study was to develop comprehensive computational modeling and simulation techniques to investigate proximal junctional failure...
October 11, 2016: Clinical Biomechanics
Wenhao Song, Dongsheng Zhou, Yu He
BACKGROUND: The aim of this study was to compare the biomechanical characteristics between bilateral and unilateral lumbo-iliac fixation in unilateral comminuted sacral fractures (USF) by finite element analysis. METHODS: A 3-dimensional finite element model of unilateral sacral fractures was simulated. Three kinds of implants were instrumented into the model, including the unilateral lumbopelvic fixation (ULF), bilateral lumbopelvic fixation (BLF), and unilateral iliac fixation with bilateral lumbar pedicle screws (UBF)...
October 2016: Medicine (Baltimore)
Yuta Shimura, Yuji Sato, Noboru Kitagawa, Miyuki Omori
BACKGROUND: Proper implant placement is very important for long-term implant stability. Recently, numerous biomechanical studies have been conducted to clarify the relationship between implant placement and peri-implant stress. The placement of multiple implants in the edentulous posterior mandible has been studied by geometric analysis, three-dimensional finite element analysis (FEA), model experimentation, etc. Offset placement is a technique that reduces peri-implant load. However, few studies have used multiple analyses to clarify the value of the offset placement under identical conditions...
December 2016: Int J Implant Dent
Sho Kayumi, Yoshiyuki Takayama, Atsuro Yokoyama, Nana Ueda
BACKGROUND: The purpose of this study was to investigate the influence of occlusal forces (the contractile force of masticatory muscles) exerted during occlusal adjustment on the distribution of the forces among teeth, implants, and temporomandibular joints (TMJs) in intercuspal clenching in cases with bilateral missing molars and premolars by using finite element analysis. METHODS: A three-dimensional finite element model of the mandible with eight implants in the premolar and molar regions was constructed...
December 2015: Int J Implant Dent
Miyuki Omori, Yuji Sato, Noboru Kitagawa, Yuta Shimura, Manabu Ito
BACKGROUND: Three-dimensional finite element analysis (FEA) is effective in analyzing stress distributions around dental implants. However, FEA of living tissue involves many conditions, and the structures and behaviors are complex; thus, it is difficult to ensure the validity of the results. To verify reproducibility and validity, we embedded implants in experimental models and constructed FEA models; implant displacements were compared under various loading conditions. METHODS: Implants were embedded in the molar regions of artificial mandibles to fabricate three experimental models...
December 2015: Int J Implant Dent
Mansi Manish Oswal, Ulhas N Amasi, Manish S Oswal, Ashish S Bhagat
PURPOSE: Clinical success of implant prosthodontics is dependent in part upon the type of implant thread design. The selection of implant thread design plays an important role in the outcome of the treatment. This study was undertaken to evaluate the pattern of stress distribution using a finite element analysis; hence, the area which would be bearing maximum load for a given design would be arrived. MATERIALS AND METHODS: Three implants with different thread designs, namely V-thread, buttress, and reverse buttress thread designs were considered and dimensions were standardized...
October 2016: Journal of Indian Prosthodontic Society
Stefano C Meliga, Jacob W Coffey, Michael L Crichton, Christopher Flaim, Martin Veidt, Mark A F Kendall
In-depth understanding of skin elastic and rupture behavior is fundamental to enable next-generation biomedical devices to directly access areas rich in cells and biomolecules. However, the paucity of skin mechanical characterization and lack of established fracture models limits their rational design. We present an experimental and numerical study of skin mechanics during dynamic interaction with individual and arrays of micro-penetrators. Initially, micro-indentation of individual skin strata revealed hyperelastic moduli were dramatically rate-dependent, enabling extrapolation of stiffness properties at high velocity regimes (>1 ms(-1))...
October 13, 2016: Acta Biomaterialia
Qing-Hang Zhang, Andrew Cossey, Jie Tong
Periprosthetic bone strain distributions in some of the typical cases of total knee replacement (TKR) were studied with regard to the selection of material, design and the alignments of tibial components to examine which conditions are more forgiving than the others to stress shielding post a TKR. Four tibial components with two implant designs (cruciate sacrificing and cruciate retaining) and material properties (metal-backed (MB) and all-polyethylene (AP)) were considered in a specimen-specific finite element tibia bone model loaded in a neutral position...
October 10, 2016: Medical Engineering & Physics
Sourabh Boruah, Damien L Subit, Glenn R Paskoff, Barry S Shender, Jeff R Crandall, Robert S Salzar
The strength and compliance of the dense cortical layers of the human skull have been examined since the beginning of the 20th century with the wide range in the observed mechanical properties attributed to natural biological variance. Since this variance may be explained by the difference in structural arrangement of bone tissue, micro-computed tomography (µCT) was used in conjunction with mechanical testing to study the relationship between the microstructure of human skull cortical coupons and their mechanical response...
October 1, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Christof B Clemen, Günther E K Benderoth, Andreas Schmidt, Frank Hübner, Thomas J Vogl, Gerhard Silber
In this study, useful methods for active human skeletal muscle material parameter determination are provided. First, a straightforward approach to the implementation of a transversely isotropic hyperelastic continuum mechanical material model in an invariant formulation is presented. This procedure is found to be feasible even if the strain energy is formulated in terms of invariants other than those predetermined by the software's requirements. Next, an appropriate experimental setup for the observation of activation-dependent material behavior, corresponding data acquisition, and evaluation is given...
September 28, 2016: Journal of the Mechanical Behavior of Biomedical Materials
Jakub Żmigrodzki, Szymon Cygan, Beata Leśniak-Plewińska, MirosŁaw Kowalski, Krzysztof KaŁużyński
The identification of a sub-endocardial infarction is of major interest in cardiology. This study evaluates the sensitivity of selected measures to the thickness of such an infarction. Synthetic ultrasonic data (long-axis view) of left ventricular models with inclusions were generated using Field II and meshes obtained from finite-element simulations, which also provided the reference for the estimates obtained from ultrasonic data. The displacements, the first and second component of the principal strain (ε1 and ε2), and several measures derived from these quantities were estimated...
October 13, 2016: Ultrasound in Medicine & Biology
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