On the Bidirectional Viscoelastic Behavior of the Human Achilles Tendon

2008 ◽  
Author(s):  
Oluseeni A. Komolafe ◽  
Todd C. Doehring
Keyword(s):  
Soft Tissues ◽  
Viscoelastic Behavior ◽  
Daily Activities ◽  
Fiber Bundles ◽  
Ground Substance ◽  
Entire Volume ◽  
Loading And Unloading ◽  
Tissue Orientation ◽  
Climbing Stairs

Soft tissues such as tendons and ligaments are made up of groups of collagen fascicles surrounded by a sheath of epitenon. The friction between these structural fibers and their surrounding ground substance has been suggested to be the main contributor to the observed viscoelastic response of the tissue[1]. During normal daily activities such as walking, climbing stairs or jumping, these tissues are subjected to alternating loading and unloading conditions. Depending on the load and tissue orientation, this alternating loading condition may not be uniformly applied over the entire volume of the tissue. In some instances, certain fiber bundles are in tension (loaded) while others might be unloading. Hence, the development of accurate predictive models requires characterization of not only the loading behavior, but also the unloading behavior. To our knowledge, there are few models that specifically address the unloading behavior of the tissue.

Modeling of soft tissues with damage

2016 ◽  
Vol 231 (1-2) ◽  
pp. 131-139
Author(s):  
João Ferreira ◽  
Marco Parente ◽  
Renato Jorge
Keyword(s):  
Soft Tissues ◽  
Three Dimensional ◽  
Ground Substance ◽  
Computational Framework ◽  
Material Models ◽  
Pathological Conditions ◽  
Subject Variability ◽  
Non Linear ◽  
Multiple Material

The characteristic highly non-linear biomechanics of soft tissues within their physiological range often involve degradation of the material properties. Some evidence shows that the stretch patterns induced in this (bio)structures lead to pathological conditions associated with the continuous degradation of the collagen fibres and ground substance of the material. In this work, a computational framework for modeling local anisotropic damage within non-linear geometrical considerations is proposed. Due to tissue and subject variability observed in the mechanical characterization of these types of materials, we adopt a strongly objective approach able to compute the material response for any functional form of the hyperelastic constitutive equations. The numerical examples of three-dimensional displacement and force-driven boundary value problems describe the capability to use multiple material models within the same computational framework. Particularities in the behaviour of the considered material models and the implications of considering damage effects to represent the Mullins effect are discussed.

Design and validation of a modular micro-robotic system for the mechanical characterization of soft tissues

2021 ◽  
Author(s):  
Andrea Acuna ◽  
Julian M. Jimenez ◽  
Naomi Deneke ◽  
Sean M. Rothenberger ◽  
Sarah Libring ◽  
...  
Keyword(s):  
Soft Tissues ◽  
Mechanical Characterization ◽  
Robotic System

Thumb Injuries and Instabilities. Part 2: Spectrum of Lesions

2021 ◽  
Vol 25 (02) ◽  
pp. 355-365
Author(s):  
Alain G. Blum ◽  
Marnix T. van Holsbeeck ◽  
Stefano Bianchi
Keyword(s):  
Soft Tissues ◽  
Imaging Techniques ◽  
Metacarpophalangeal Joint ◽  
Resonance Imaging ◽  
Ligament Injuries ◽  
First Line ◽  
Collateral Ligament ◽  
Traumatic Injuries ◽  
Line Imaging

AbstractThe motor function of the thumb and its alignment with regard to the hand make it particularly vulnerable to trauma. Pathology encountered in this joint is varied, and imaging techniques play a crucial role in the diagnosis and characterization of injury. Despite advances in imaging technology, acute thumb injuries remain a challenge for radiologists. Currently, standard radiography and ultrasonography are frequently used first-line imaging techniques. Computed tomography is most often indicated for complex fractures and dislocations. Magnetic resonance imaging may be used to optimally characterize soft tissues and bone marrow. In this article, we cover the most common traumatic injuries: fractures, dislocations, collateral ligament injuries of the metacarpophalangeal joint, as well as soft tissue lesions.

Analysis and characterization of high-resolution and high-aspect-ratio imaging fiber bundles

2015 ◽  
Vol 54 (32) ◽  
pp. 9422 ◽  
Author(s):  
Nojan Motamedi ◽  
Salman Karbasi ◽  
Joseph E. Ford ◽  
Vitaliy Lomakin
Keyword(s):  
High Resolution ◽  
Aspect Ratio ◽  
High Aspect Ratio ◽  
Fiber Bundles ◽  
Ratio Imaging

A NEW PARAMETER ESTIMATION METHOD FOR ONLINE SOFT TISSUE CHARACTERIZATION

2016 ◽  
Vol 16 (08) ◽  
pp. 1640019 ◽  
Author(s):  
JAEHYUN SHIN ◽  
YONGMIN ZHONG ◽  
JULIAN SMITH ◽  
CHENGFAN GU
Keyword(s):  
Soft Tissue ◽  
Linear Regression ◽  
Tissue Characterization ◽  
Soft Tissues ◽  
Unscented Kalman Filter ◽  
Estimation Method ◽  
Regression Method ◽  
Linear Regression Method ◽  
Non Linear

Dynamic soft tissue characterization is of importance to robotic-assisted minimally invasive surgery. The traditional linear regression method is unsuited to handle the non-linear Hunt–Crossley (HC) model and its linearization process involves a linearization error. This paper presents a new non-linear estimation method for dynamic characterization of mechanical properties of soft tissues. In order to deal with non-linear and dynamic conditions involved in soft tissue characterization, this method improves the non-linearity and dynamics of the HC model by treating parameter [Formula: see text] as independent variable. Based on this, an unscented Kalman filter is developed for online estimation of soft tissue parameters. Simulations and comparison analysis demonstrate that the proposed method is able to estimate mechanical parameters for both homogeneous tissues and heterogeneous and multi-layer tissues, and the achieved performance is much better than that of the linear regression method.

Combined Statistical-Mechanical Characterization of a Next Generation Textured PTFE for Extreme Environments

2018 ◽  
Author(s):  
Sannmit Shinde ◽  
Ali P. Gordon ◽  
Zachary Poust ◽  
Steve Pitolaj ◽  
Jim Drago ◽  
...  
Keyword(s):  
Extreme Environments ◽  
Viscoelastic Behavior ◽  
Ceramic Particle ◽  
Operating Conditions ◽  
Operating Environments ◽  
Linear Viscoelastic Behavior ◽  
Linear Viscoelastic ◽  
Statistical Mechanical ◽  
Relaxation Responses

Pressurized vessels that transfer media from one location to another often contain a bolted connection. Gaskets are essential for these systems since they confer high levels of leak mitigation across of range of operating environments (i.e., internal pressure and temperature). The balance of both sealability and compressibility must be displayed in candidate gasket materials to be subjected to aggressive operating conditions. Historically, thin gauge gasket (i.e., 1/16” thick) confer high sealability while thick gaskets offer superior compressibility (i.e., 1/8”). Fabricated with skive cut, ceramic particle-reinforced PTFE, these materials display linear viscoelastic behavior that allow consolidation to occur. For example, GYLON® 3504 is filled with Aluminosilicate Microspheres, GYLON®3510 is filled with barium sulfate, respectively, to efficiently fill crevices along the surfaces of the flange. Novel textured PTFE gasket (3504 EPX and 3510 EPX) have been developed to simultaneously confer sealability and compressibility compared to flat products. A design of experiments (DoE) approach is applied to characterize the factors that influence load relaxation responses of the both candidate textured PTFE (dual-face honeycomb) and existing (flat) gasket styles. Using an instrumented test platform analyzed. A new parameter is presented to quantify gasket efficiency. The collection of efficiency measurement methods and approach to re-torque optimization convey a novel framework that designers can invoke to facilitate improved flange performance.

scholarly journals Role of smooth muscle activation in the static and dynamic mechanical characterization of human aortas

2022 ◽  
Vol 119 (3) ◽  
pp. e2117232119
Author(s):  
Giulio Franchini ◽  
Ivan D. Breslavsky ◽  
Francesco Giovanniello ◽  
Ali Kassab ◽  
Gerhard A. Holzapfel ◽  
...  
Keyword(s):  
Experimental Data ◽  
Smooth Muscle ◽  
Muscle Activation ◽  
Mechanical Response ◽  
Mechanical Characterization ◽  
Viscoelastic Behavior ◽  
Material Model ◽  
Suitable Material ◽  
Dynamic Mechanical

Experimental data and a suitable material model for human aortas with smooth muscle activation are not available in the literature despite the need for developing advanced grafts; the present study closes this gap. Mechanical characterization of human descending thoracic aortas was performed with and without vascular smooth muscle (VSM) activation. Specimens were taken from 13 heart-beating donors. The aortic segments were cooled in Belzer UW solution during transport and tested within a few hours after explantation. VSM activation was achieved through the use of potassium depolarization and noradrenaline as vasoactive agents. In addition to isometric activation experiments, the quasistatic passive and active stress–strain curves were obtained for circumferential and longitudinal strips of the aortic material. This characterization made it possible to create an original mechanical model of the active aortic material that accurately fits the experimental data. The dynamic mechanical characterization was executed using cyclic strain at different frequencies of physiological interest. An initial prestretch, which corresponded to the physiological conditions, was applied before cyclic loading. Dynamic tests made it possible to identify the differences in the viscoelastic behavior of the passive and active tissue. This work illustrates the importance of VSM activation for the static and dynamic mechanical response of human aortas. Most importantly, this study provides material data and a material model for the development of a future generation of active aortic grafts that mimic natural behavior and help regulate blood pressure.

scholarly journals Copper Containing Glass-Based Bone Adhesives for Orthopaedic Applications: Glass Characterization and Advanced Mechanical Evaluation

2020 ◽  
Author(s):  
Sahar. Mokhtari ◽  
Anthony.W. Wren
Keyword(s):  
Mechanical Properties ◽  
Photoelectron Spectroscopy ◽  
Structural Changes ◽  
Viscoelastic Behavior ◽  
Polymer Chains ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
X Ray ◽  
Compression Data

AbstractThis study addresses issues with currently used bone adhesives, by producing novel glass based skeletal adhesives through modification of the base glass composition to include copper (Cu) and by characterizing each glass with respect to structural changes. Bioactive glasses have found applications in fields such as orthopedics and dentistry, where they have been utilized for the restoration of bone and teeth. The present work outlines the formation of flexible organic-inorganic polyacrylic acid (PAA) – glass hybrids, commercial forms are known as glass ionomer cements (GICs). Initial stages of this research will involve characterization of the Cu-glasses, significant to evaluate the properties of the resulting adhesives. Scanning electron microscopy (SEM) of annealed Cu glasses indicates the presence of partial crystallization in the glass. The structural analysis of the glass using Raman suggests the formation of CuO nanocrystals on the surface. X-ray diffraction (XRD) pattern and X-ray photoelectron spectroscopy (XPS) further confirmed the formation of crystalline CuO phases on the surface of the annealed Cu-glass. The setting reaction was studied using Fourier transform infrared spectroscopy (ATR-FTIR). The mechanical properties of the Cu containing adhesives exhibited gel viscoelastic behavior and enhanced mechanical properties when compared to the control composition. Compression data indicated the Cu glass adhesives were efficient at energy dissipation due to the reversible interactions between CuO nano particles and PAA polymer chains.

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