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Journal of Biomechanical Engineering

Triantafyllos Stylianopoulos
Tumor progression and response to treatment is determined in large part by the generation of mechanical stresses that stem from both the solid and the fluid phase of the tumor. Furthermore, elevated solid stress levels can regulate fluid stresses by compressing intratumoral blood and lymphatic vessels. Blood vessel compression reduces tumor perfusion, while compression of lymphatic vessels hinders the ability of the tumor to drain excessive fluid from its interstitial space contributing to the uniform elevation of the interstitial fluid pressure...
October 19, 2016: Journal of Biomechanical Engineering
Corinne R Henak, Lena R Bartell, Itai Cohen, Lawrence J Bonassar
Mechanical damage is central to both initiation and progression of osteoarthritis (OA). However, specific causal links between mechanics and cartilage damage are incompletely understood, which results in an inability to predict failure. The lack of understanding is primarily due to the difficulty in simultaneously resolving the high rates and small length scales relevant to the problem and in correlating such measurements to the resulting fissures. This study leveraged microscopy and high-speed imaging to resolve mechanics on the previously unexamined time and length scales of interest in cartilage damage, and used those mechanics to develop predictive models...
October 19, 2016: Journal of Biomechanical Engineering
Matthew D Parker, Lynette A Jones, Ian W Hunter, A J Taberner, M P Nash, P M F Nielsen
A triaxial force-sensitive microrobot was developed to dynamically perturb skin in multiple deformation modes, in vivo. Wiener static nonlinear identification was used to extract the linear dynamics and static nonlinearity of the force-displacement behavior of skin. Stochastic input forces were applied to the volar forearm and thenar eminence of the hand, producing probe tip perturbations in indentation and extension. Wiener static nonlinear approaches increased the variance accounted for by 0.1 % to 3.4 % over linear approaches, to 94 % to 97 %...
October 19, 2016: Journal of Biomechanical Engineering
Mesude Ozturk, Dimitrios V Papavassiliou, Edgar A O'Rear
In this work, contributing factors for red blood cell damage in turbulence were investigated by simulating jet flow experiments. Results showed that dissipative eddies comparable or smaller in size to the red blood cells cause hemolysis and that hemolysis corresponds to the number and the surface area of eddies that are associated with Kolmogorov length scale smaller than about 10 µm. The size distribution of Kolmogorov scale eddies was used to define a turbulent flow extensive property with eddies serving as a means to assess the turbulence effectiveness in damaging cells, and a new hemolysis model was proposed...
October 19, 2016: Journal of Biomechanical Engineering
S Negin Mortazavi, Donna Geddes, Fatemeh Hassanipour
This work presents a fluid dynamic study of milk flow in lactating human breast. The motivation for this study is in part to improve the fundamental understanding of transport processes in an important but insufficiently studied human organ, and in part to produce a new methodology for the understanding of the pathologies of lactation, which can have a huge impact on the health and well-being of a significant proportion of the population. This collaborative effort among lactation specialists and fluid dynamic engineers starts with a careful, statistically representative measurement of infant suckling patterns...
October 19, 2016: Journal of Biomechanical Engineering
Ronak Dholakia, Chandramouli Sadasivan, David Fiorella, Henry Woo, B Barry Lieber
Cerebral aneurysms are pathological focal evaginations of the arterial wall at and around the junctions of the circle of Willis. Their tenuous walls predispose aneurysms to leak or rupture leading to hemorrhagic strokes with high morbidity and mortality rates. The endovascular treatment of cerebral aneurysms currently includes the implantation of fine-mesh stents, called flow diverters, within the parent artery bearing the aneurysm. By mitigating flow velocities within the aneurysmal sac, the devices preferentially induce thrombus formation in the aneurysm within hours to days...
October 11, 2016: Journal of Biomechanical Engineering
Jeffrey W Holmes, Jessica E Wagenseil
October 4, 2016: Journal of Biomechanical Engineering
Erica R Pursell, Daniela Vélez-Rendón, Daniela Valdez-Jasso
In a MCT induced-PAH rat animal model, the dynamic stress-strain relation was investigated in the circumferential and axial direction using a linear elastic response model within the quasi-linear viscoelasticity theory framework. Right and left pulmonary arterial segments (RPA, LPA) were mechanically tested in a tubular biaxial device at the early stage (1 week post-MCT treatment) and at the advanced stage of the disease (4 weeks post-MCT treatment). The vessels were tested circumferentially at the in vivo axial length with matching in vivo measured pressure ranges...
September 29, 2016: Journal of Biomechanical Engineering
Arthur R Ghigo, Xiao-Fei Wang, Ricardo Armentano, Jose Maria Fullana, Pierre-Yves Lagrée
This work deals with the viscoelasticity of the arterial wall and its influence on the pulse waves. We describe the viscoelasticity by a nonlinear Kelvin-Voigt model in which the coefficients are fitted using experimental time series of pressure and radius measured on a sheep's arterial network. We obtained a good agreement between the results of the nonlinear Kelvin-Voigt model and the experimental measurements. We found that the viscoelastic relaxation time - defined by the ratio between the viscoelastic coefficient and the Young's modulus - is nearly constant throughout the network...
September 29, 2016: Journal of Biomechanical Engineering
Laurent Dumas, Tamara El Bouti, Didier Lucor
Cardiovascular diseases are currently the leading cause of mortality in the population of developed countries, due to the constant increase in cardiovascular risk factors. Numerous prospective and retrospective studies have shown that arterial stiffening is a relevant predictor of these diseases. Unfortunately, arterial stiffness distribution across the human body is difficult to measure experimentally. We propose a numerical approach to determine the arterial stiffness distribution of an arterial network using a subject-specific one-dimensional model...
September 29, 2016: Journal of Biomechanical Engineering
Dermot O'Rourke, Saulo Martelli, Murk Bottema, Mark Taylor
Understanding the sensitivity of FE models to assumptions and uncertainties in geometric parameters and material properties is a fundamental step in understanding the reliability of model predictions. The computational cost of individual simulations and the large number of required models limits comprehensive quantification of model sensitivity. To quickly assess the sensitivity of a FE model, we built linear and Kriging surrogate models of a FE model of the intact hemipelvis. The percentage of the total sum of squares (%TSS) was used to determine the most influential input parameters and their possible interactions on the median, 95th percentile and maximum equivalent strains...
September 29, 2016: Journal of Biomechanical Engineering
Vitaly O Kheyfets, Jamie Dunning, Uyen Truong, Dunbar Ivy, Kendall Hunter, Robin Shandas
In Pulmonary Hypertension (PH) diagnosis and management, many useful functional markers have been proposed that are unfeasible for clinical implementation. In addition to clinical applications, many research projects are hampered by limited retrospective clinical data. The objective of this study was to develop and validate a 0-D computational model, along with an implementation protocol, of the right ventricular-pulmonary artery (RV-PA) axis. The model is validated against pediatric clinical data (N = 111) and utilized to perform a multi-variate statistical study of the complex interplay between functional phenotype and resulting hemodynamics...
September 29, 2016: Journal of Biomechanical Engineering
Mohammad M Faghih, M Keith Sharp
Hemolysis (damage to red blood cells) is a long-standing problem in blood contacting devices, and its prediction has been the goal of considerable research. The most popular model relating hemolysis to fluid stresses is the power-law model, which was developed from experiments in pure shear only. In the absence of better data, this model has been extended to more complex flows by replacing the shear stress in the power-law equation with a von Mises-like scalar stress. While the validity of the scalar stress also remains to be confirmed, inconsistencies exist in its application, in particular, two forms that vary by a factor of 2^0...
September 22, 2016: Journal of Biomechanical Engineering
Fatemeh Fatemifar, Hai-Chao Han
The stability of the arteries under in vivo pressure and axial tension loads is essential to normal arterial function and lumen collapse due to buckling can hinder the blood flow. The objective of this study was to develop the lumen buckling equation for nonlinear anisotropic thick-walled arteries to determine the effect of axial tension. The theoretical equation was developed using exponential Fung strain function and the effects of axial tension and residual stress on the critical buckling pressure were illustrated for porcine coronary arteries...
September 22, 2016: Journal of Biomechanical Engineering
Sergio Ruiz de Galarreta, Aitor Cazón, Raúl Antón, Ender A Finol
An Abdominal Aortic Aneurysm (AAA) is a permanent focal dilatation of the abdominal aorta of at least 1.5 times its normal diameter. Although the criterion of maximum diameter is still used in clinical practice to decide on a timely intervention, numerical studies have demonstrated the importance of other geometric factors. However, the major drawback of numerical studies is that they must be validated experimentally before clinical implementation. This work presents a new methodology to verify wall stress predicted from numerical studies against experimental testing...
September 16, 2016: Journal of Biomechanical Engineering
Sjeng Quicken, Wouter P Donders, Emiel M J van Disseldorp, Kujtim Gashi, Barend M E Mees, Frans van de Vosse, Richard G P Lopata, Tammo Delhaas, Wouter Huberts
When applying models to patient-specific situations, the impact of model input uncertainty on the model output uncertainty has to be assessed. Proper uncertainty quantification (UQ) and sensitivity analysis (SA) techniques are indispensable for this purpose. An efficient approach for UQ and SA is the generalized polynomial chaos expansion (gPCE) method, where model response is expanded into a finite series of polynomials that depend on the model input (i.e. a meta-model). However, because of the intrinsic high computational cost of three-dimensional (3-D) cardiovascular models, performing the number of model evaluations required for the gPCE is often computationally prohibitively expensive...
September 16, 2016: Journal of Biomechanical Engineering
Giulia Mantovani, Mario Lamontagne
The choice of marker set is a source of variability in motion analysis. Studies exist that assess the performance of marker sets when direct kinematics is used, but these results cannot be extrapolated to the inverse kinematic framework. Therefore, the purpose of this study was to examine the sensitivity of kinematic outcomes to inter-marker set variability in an inverse kinematic framework. The compared marker sets were Plug-in-Gait, University of Ottawa Motion Analysis Model and a 3-marker-cluster marker set...
September 16, 2016: Journal of Biomechanical Engineering
Timothy P Holsgrove, Nicolas V Jaumard, Nina Zhu, Nicholas S Stiansen, William C Welch, Beth A Winkelstein
Dynamic cervical spine loading can produce facet capsule injury. Despite a large proportion of neck pain being attributable to the C2/C3 facet capsule, potential mechanisms are not understood. This study replicated low-speed frontal and rear-end traffic collisions in Occiput-C3 human cadaveric cervical spine specimens, and used kinematic and full-field strain analyses to assess injury. Specimens were loaded quasistatically in flexion and extension before and after dynamic rotation of C3 at 100°/sec. Global kinematics in the sagittal plane were tracked at 1kHz and C2/C3 facet capsule full-field strains were measured...
September 16, 2016: Journal of Biomechanical Engineering
Alisdair R MacLeod, Hannah Rose, Harinderjit S Gill
For the first time, an experimentally validated finite element model of a composite femur is presented for use in the three solvers: ABAQUS (Simulia); ANSYS (ANSYS, Inc.) and FEBio (University of Utah). This model is freely available online [web address tbc] along with all supporting validation data. Synthetic biomechanical test specimens are frequently used for pre-clinical evaluation of implant performance, often in combination with numerical modelling such as Finite Element (FE) analysis. The primary aim of the study to conduct a comparison of mesh convergence and strain prediction between three solvers (ABAQUS, ANSYS and FEBio) and to provide validated open-source models of a fourth generation composite femur for use all three FE packages...
September 12, 2016: Journal of Biomechanical Engineering
Jonas Lantz, Lilian Henriksson, Anders Persson, Matts Karlsson, Tino Ebbers
Cardiac hemodynamics can be computed from medical imaging data, and results could potentially aid in cardiac diagnosis and treatment optimization. However, simulations are often based on simplified geometries, ignoring features such as papillary muscles and trabeculae due to their complex shape, limitations in image acquisitions, and challenges in computational modeling. This severely hampers the use of computational fluid dynamics in clinical practice. The overall aim of this study was to develop a novel numerical framework that incorporated these geometrical features...
September 12, 2016: Journal of Biomechanical Engineering
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