scholarly journals An Elaborate Data Set Characterizing the Mechanical Response of the Foot

2009 ◽  
Vol 131 (9) ◽  
Author(s):  
Ahmet Erdemir ◽  
Pavana A. Sirimamilla ◽  
Jason P. Halloran ◽  
Antonie J. van den Bogert
Keyword(s):  
Mechanical Properties ◽  
Computational Models ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Normal Function ◽  
Combined Loading ◽  
Anatomical Reconstruction ◽  
Imaging Data ◽  
Data Set ◽  
Mechanical Responses

Mechanical properties of the foot are responsible for its normal function and play a role in various clinical problems. Specifically, we are interested in quantification of foot mechanical properties to assist the development of computational models for movement analysis and detailed simulations of tissue deformation. Current available data are specific to a foot region and the loading scenarios are limited to a single direction. A data set that incorporates regional response, to quantify individual function of foot components, as well as the overall response, to illustrate their combined operation, does not exist. Furthermore, the combined three-dimensional loading scenarios while measuring the complete three-dimensional deformation response are lacking. When combined with an anatomical image data set, development of anatomically realistic and mechanically validated models becomes possible. Therefore, the goal of this study was to record and disseminate the mechanical response of a foot specimen, supported by imaging data. Robotic testing was conducted at the rear foot, forefoot, metatarsal heads, and the foot as a whole. Complex foot deformations were induced by single mode loading, e.g., compression, and combined loading, e.g., compression and shear. Small and large indenters were used for heel and metatarsal head loading, an elevated platform was utilized to isolate the rear foot and forefoot, and a full platform compressed the whole foot. Three-dimensional tool movements and reaction loads were recorded simultaneously. Computed tomography scans of the same specimen were collected for anatomical reconstruction a priori. The three-dimensional mechanical response of the specimen was nonlinear and viscoelastic. A low stiffness region was observed starting with contact between the tool and foot regions, increasing with loading. Loading and unloading responses portrayed hysteresis. Loading range ensured capturing the toe and linear regions of the load deformation curves for the dominant loading direction, with the rates approximating those of walking. A large data set was successfully obtained to characterize the overall and the regional mechanical responses of an intact foot specimen under single and combined loads. Medical imaging complemented the mechanical testing data to establish the potential relationship between the anatomical architecture and mechanical responses and to further develop foot models that are mechanically realistic and anatomically consistent. This combined data set has been documented and disseminated in the public domain to promote future development in foot biomechanics.

An efficient approach to converting three-dimensional image data into highly accurate computational models

2008 ◽  
Vol 366 (1878) ◽  
pp. 3155-3173 ◽  
Author(s):  
P.G Young ◽  
T.B.H Beresford-West ◽  
S.R.L Coward ◽  
B Notarberardino ◽  
B Walker ◽  
...  
Keyword(s):  
Mesh Generation ◽  
Computational Models ◽  
Three Dimensional ◽  
Image Data ◽  
Model Material ◽  
Imaging Data ◽  
Material Inhomogeneity ◽  
Dimensional Image ◽  
Wide Range ◽  
Impact Modelling

Image-based meshing is opening up exciting new possibilities for the application of computational continuum mechanics methods (finite-element and computational fluid dynamics) to a wide range of biomechanical and biomedical problems that were previously intractable owing to the difficulty in obtaining suitably realistic models. Innovative surface and volume mesh generation techniques have recently been developed, which convert three-dimensional imaging data, as obtained from magnetic resonance imaging, computed tomography, micro-CT and ultrasound, for example, directly into meshes suitable for use in physics-based simulations. These techniques have several key advantages, including the ability to robustly generate meshes for topologies of arbitrary complexity (such as bioscaffolds or composite micro-architectures) and with any number of constituent materials (multi-part modelling), providing meshes in which the geometric accuracy of mesh domains is only dependent on the image accuracy (image-based accuracy) and the ability for certain problems to model material inhomogeneity by assigning the properties based on image signal strength. Commonly used mesh generation techniques will be compared with the proposed enhanced volumetric marching cubes (EVoMaCs) approach and some issues specific to simulations based on three-dimensional image data will be discussed. A number of case studies will be presented to illustrate how these techniques can be used effectively across a wide range of problems from characterization of micro-scaffolds through to head impact modelling.

scholarly journals Method for Calibration of Left Ventricle Material Properties Using Three-Dimensional Echocardiography Endocardial Strains

2019 ◽  
Vol 141 (9) ◽  
Author(s):  
Yaghoub Dabiri ◽  
Kevin L. Sack ◽  
Nuno Rebelo ◽  
Peter Wang ◽  
Yunjie Wang ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Left Ventricle ◽  
Diffusion Tensor ◽  
Diastolic Pressure ◽  
Three Dimensional ◽  
Heart Association ◽  
Mean Difference ◽  
Imaging Data ◽  
The Mean

We sought to calibrate mechanical properties of left ventricle (LV) based on three-dimensional (3D) speckle tracking echocardiographic imaging data recorded from 16 segments defined by American Heart Association (AHA). The in vivo data were used to create finite element (FE) LV and biventricular (BV) models. The orientation of the fibers in the LV model was rule based, but diffusion tensor magnetic resonance imaging (MRI) data were used for the fiber directions in the BV model. A nonlinear fiber-reinforced constitutive equation was used to describe the passive behavior of the myocardium, whereas the active tension was described by a model based on tissue contraction (Tmax). isight was used for optimization, which used abaqus as the forward solver (Simulia, Providence, RI). The calibration of passive properties based on the end diastolic pressure volume relation (EDPVR) curve resulted in relatively good agreement (mean error = −0.04 ml). The difference between the experimental and computational strains decreased after segmental strain metrics, rather than global metrics, were used for calibration: for the LV model, the mean difference reduced from 0.129 to 0.046 (circumferential) and from 0.076 to 0.059 (longitudinal); for the BV model, the mean difference nearly did not change in the circumferential direction (0.061) but reduced in the longitudinal direction from 0.076 to 0.055. The calibration of mechanical properties for myocardium can be improved using segmental strain metrics. The importance of realistic fiber orientation and geometry for modeling of the LV was shown.

Three-dimensional echocardiography

2016 ◽  
Author(s):  
Luigi P. Badano ◽  
Roberto M. Lang ◽  
Alexandra Goncalves
Keyword(s):  
Three Dimensional ◽  
Digital Processing ◽  
Surface Rendering ◽  
Imaging Data ◽  
Data Set ◽  
Clinical Scenarios ◽  
Dimensional Echocardiography ◽  
Three Dimensional Echocardiography ◽  
Two Dimensional Echocardiography ◽  
Echocardiographic Technique

The advent of fully-sampled matrix array transthoracic transducers has enabled advanced digital processing and improved image formation algorithms and brought three-dimensional echocardiography (3DE) technology into clinical practice. Currently, 3DE is recognized as an important echocardiographic technique, demonstrated to be superior to two-dimensional echocardiography in various clinical scenarios. This chapter focuses on the technology of 3DE matrix transducers, physics of 3D imaging, data set acquisition (multiplane, real-time, full-volume, zoom, and colour), and display (volume rendering, surface rendering and multislice) modalities. The chapter also addresses the issues of training in 3DE, and main clinical indications and reporting of transthoracic and transoesophageal 3DE.

Three-Dimensional Modeling of Reduced Material Properties in Ceramics With Added Porosity

2019 ◽  
Author(s):  
Stephanie A. Wimmer ◽  
Virginia G. DeGiorgi ◽  
Edward P. Gorzkowski ◽  
Heonjune Ryou
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Finite Element ◽  
Computational Modeling ◽  
Computational Models ◽  
Thermal Protection ◽  
Turbine Blades ◽  
Three Dimensional ◽  
Ceramic Coatings ◽  
Grain Structure

Abstract Manufacturing methods to create ceramic coatings with tailored thermal conductivity are crucial to the development of thermal protection systems for many components including turbine blades in high temperature engines. A designed microstructure of grains, pores, and other defects can reduce the thermal conductivity of the ceramic. However, the same microstructure characteristics can reduce mechanical properties to the point of failure. This work is part of a larger program with the goal of optimizing ceramic coating microstructure for thermal protection while retaining sufficient mechanical strength for the intended application. Processing parameters have been examined to identify methods designed to maintain a nano-sized grain structure of yttria-stabilized zirconia while controlling the added porosity with a specific shape and size. In this paper computational modeling is used to evaluate the effects of porosity on coating performance, both thermal and structural. Coating porosity is incorporated in the computational models by randomly placing empty spaces or defects in the shape of spherical voids, oblate pores, or penny cracks. In addition to computational modeling, prototype coatings are developed in the laboratory with specific porosity. The size and orientation of defects in the computational modeling effort are statistically generated to match experiments. The locations of the defects are totally random. Finite element models are created which include various levels of porosity to calculate effective thermal and mechanical properties. Comparisons are made between three-dimensional finite-element simulations and measured data. The influences of pore size as well as three dimensional computational modeling artifacts are examined.

scholarly journals Pore Geometry Optimization of Titanium (Ti6Al4V) Alloy, for Its Application in the Fabrication of Customized Hip Implants

2014 ◽  
Vol 2014 ◽  
pp. 1-12 ◽  
Author(s):  
Sandipan Roy ◽  
Debojyoti Panda ◽  
Niloy Khutia ◽  
Amit Roy Chowdhury
Keyword(s):  
Mechanical Response ◽  
Geometry Optimization ◽  
Combined Loading ◽  
Hip Implants ◽  
Loading Conditions ◽  
Mechanical Responses ◽  
Porous Ti ◽  
Physiological Loading ◽  
Solid Implants

The present study investigates the mechanical response of representative volume elements of porous Ti-6Al-4V alloy, to arrive at a desired range of pore geometries that would optimize the reduction in stiffness necessary for biocompatibility with the stress concentration arising around the pore periphery, under physiological loading conditions with respect to orthopedic hip implants. A comparative study of the two is performed with the aid of a newly defined optimizing parameter called pore efficiency that takes into consideration both the stiffness quantity and the stress localization around pores. To perform a detailed analysis of the response of the porous structure over the entire spectrum of loading conditions that a hip implant is subjected toin vivo, the mechanical responses of 3D finite element models of cubic and rectangular parallelepiped geometries, with porosities varying over a range of 10% to 60%, are simulated under representative compressive, flexural as well as combined loading conditions. The results that are obtained are used to suggest a range of pore diameters that lower the effective stiffness and modulus of the implant to around 60% of the stiffness and modulus of dense solid implants while keeping the stress levels within permissible limits.

scholarly journals Efficient Shape Estimation of Transparent Microdefects with Manifold Learning and Regression on a Set of Saturated Images

2020 ◽  
Vol 10 (1) ◽  
pp. 385
Author(s):  
Yuanlong Deng ◽  
Xizhou Pan ◽  
Xiaopin Zhong
Keyword(s):  
Three Dimensional ◽  
Measurement Data ◽  
Estimation Method ◽  
Support Vector ◽  
Measuring Instruments ◽  
Imaging Data ◽  
Shape Estimation ◽  
Data Set ◽  
3D Shape ◽  
Accuracy Requirement

In the industry of polymer film products such as polarizers, measuring the three-dimensional (3D) contour of the transparent microdefects, the most common defects, can crucially affect what further treatment should be taken. In this paper, we propose an efficient method for estimating the 3D shape of defects based on regression by converting the problem of direct measurement into an estimation problem using two-dimensional imaging. The basic idea involves acquiring structured-light saturated imaging data on transparent microdefects; integrating confocal microscopy measurement data to create a labeled data set, on which dimensionality reduction is performed; using support vector regression on a low-dimensional small-set space to establish the relationship between the saturated image and defects’ 3D attributes; and predicting the shape of new defect samples by applying the learned relationship to their saturated images. In the discriminant subspace, the manifold of saturated images can clearly show the changing attributes of defects’ 3D shape, such as depth and width. The experimental results show that the mean relative error (MRE) of the defect depth is 3.64% and the MRE of the defect width is 1.96%. The estimation time consumed in the Matlab platform is less than 0.01 s. Compared with precision measuring instruments such as confocal microscopes, our estimation method greatly improves the efficiency of quality control and meets the accuracy requirement of automated defect identification. It is therefore suitable for complete inspection of products.

Experimental and Theoretical Study of Bovine Aorta and its Elastin

2008 ◽  
Author(s):  
Yu Zou ◽  
Katherine Yanhang Zhang
Keyword(s):  
Mechanical Properties ◽  
Blood Vessels ◽  
Biaxial Loading ◽  
Theoretical Study ◽  
Three Dimensional ◽  
Physiological Functions ◽  
Mechanical Responses ◽  
Pathological Conditions

Blood vessels are complex organs with hierarchical ultrastructures. Different kinds of structural supporting fibers, such as collagen and elastin fibers, are cross-linked in a three-dimensional manner to provide stiffness of the tissue. Elastin networks endow blood vessels critical mechanical properties, and are essential to accommodate deformations encountered during physiological functions. Many Pathological conditions involve significant changes in elastin. Therefore it is important to fully characterize and understand the mechanical properties of aorta and its elastin networks. Here we studied, both experimentally and theoretically, the mechanical responses of bovine aorta and its elastin under biaxial loading.

scholarly journals Three-Dimensional Additively Manufactured Microstructures and Their Mechanical Properties

JOM ◽  
2019 ◽  
Vol 72 (1) ◽  
pp. 75-82 ◽  
Author(s):  
Theron M. Rodgers ◽  
Hojun Lim ◽  
Judith A. Brown
Keyword(s):  
Mechanical Properties ◽  
Kinetic Monte Carlo ◽  
Plastic Anisotropy ◽  
Three Dimensional ◽  
Grain Morphology ◽  
Element Model ◽  
Mechanical Responses ◽  
Highly Sensitive ◽  
Complex Parts ◽  
Metal Additive

Abstract Metal additive manufacturing (AM) allows for the freeform creation of complex parts. However, AM microstructures are highly sensitive to the process parameters used. Resulting microstructures vary significantly from typical metal alloys in grain morphology distributions, defect populations and crystallographic texture. AM microstructures are often anisotropic and possess three-dimensional features. These microstructural features determine the mechanical properties of AM parts. Here, we reproduce three “canonical” AM microstructures from the literature and investigate their mechanical responses. Stochastic volume elements are generated with a kinetic Monte Carlo process simulation. A crystal plasticity-finite element model is then used to simulate plastic deformation of the AM microstructures and a reference equiaxed microstructure. Results demonstrate that AM microstructures possess significant variability in strength and plastic anisotropy compared with conventional equiaxed microstructures.

scholarly journals Nano measurements with micro-devices: mechanical properties of hydrated collagen fibrils

2005 ◽  
Vol 3 (6) ◽  
pp. 117-121 ◽  
Author(s):  
S.J Eppell ◽  
B.N Smith ◽  
H Kahn ◽  
R Ballarini
Keyword(s):  
Mechanical Properties ◽  
Computational Models ◽  
Microelectromechanical Systems ◽  
Mechanical Response ◽  
Strain Curve ◽  
Fatigue Behaviour ◽  
Hierarchical Architecture ◽  
Fatigue Properties ◽  
Applied Forces ◽  
Made In

The mechanical response of a biological material to applied forces reflects deformation mechanisms occurring within a hierarchical architecture extending over several distinct length scales. Characterizing and in turn predicting the behaviour of such a material requires an understanding of the mechanical properties of the substructures within the hierarchy, the interaction between the substructures, and the relative influence of each substructure on the overall behaviour. While significant progress has been made in mechanical testing of micrometre to millimetre sized biological specimens, quantitative reproducible experimental techniques for making mechanical measurements on specimens with characteristic dimensions in the smaller range of 10–1000 nm are lacking. Filling this void in experimentation is a necessary step towards the development of realistic multiscale computational models useful to predict and mitigate the risk of bone fracture, design improved synthetic replacements for bones, tendons and ligaments, and engineer bioinspired efficient and environmentally friendly structures. Here, we describe a microelectromechanical systems device for directly measuring the tensile strength, stiffness and fatigue behaviour of nanoscale fibres. We used the device to obtain the first stress–strain curve of an isolated collagen fibril producing the modulus and some fatigue properties of this soft nanofibril.

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