Extraction of Quasi-Linear Viscoelastic Parameters for Lower Limb Soft Tissues From Manual Indentation Experiment

1999 ◽  
Vol 121 (3) ◽  
pp. 330-339 ◽  
Author(s):  
Y. P. Zheng ◽  
A. F. T. Mak
Keyword(s):  
Lower Limb ◽  
Soft Tissues ◽  
Model Parameters ◽  
Viscoelastic Parameters ◽  
Fitting Procedure ◽  
Ultrasound Indentation ◽  
Initial Modulus ◽  
Linear Viscoelastic ◽  
Young Subjects ◽  
Three Body

A manual indentation protocol was established to assess the quasi-linear viscoelastic (QLV) properties of lower limb soft tissues. The QLV parameters were extracted using a curve-fitting procedure on the experimental indentation data. The load-indentation responses were obtained using an ultrasound indentation apparatus with a hand-held pen-sized probe. Limb soft tissues at four sites of eight normal young subjects were tested in three body postures. Four QLV model parameters were extracted from the experimental data. The initial modulus E0 ranged from 0.22 kPa to 58.4 kPa. The nonlinear factor E1 ranged from 21.7 kPa to 547 kPa. The time constant τ ranged from 0.05 s to 8.93 s. The time-dependent material parameter α ranged from 0.029 to 0.277. Large variations of the parameters were noted among subjects, sites, and postures.

Three-Body Segment Dynamic Model of the Human Knee

1993 ◽  
Vol 115 (4A) ◽  
pp. 350-356 ◽  
Author(s):  
Sami Turgut Tu¨mer ◽  
Ali Erkan Engin
Keyword(s):  
Dynamic Model ◽  
Lower Limb ◽  
Knee Extension ◽  
Quadriceps Femoris ◽  
Model Parameters ◽  
Body Segment ◽  
Human Knee ◽  
Applied Forces ◽  
Anterior Cruciate ◽  
Three Body

In this paper, a two-dimensional, three-body segment dynamic model of the human knee is introduced. The model includes tibio-femoral and patello-femoral articulations, and anterior cruciate, posterior cruciate, medial collateral, lateral collateral, and patellar ligaments. It enables one to obtain dynamic response of the knee joint to any one or combination of quadriceps femoris, hamstrings, and gastrocnemius muscle actions, as well as any externally applied forces on the lower leg. A specially developed human knee animation program is utilized in order to fine tune some model parameters. Numerical results are presented for knee extension under the impulsive action of the quadriceps femoris muscle group to simulate a vigorous lower limb activity such as kicking. The model shows that the patella can be subjected to very large transient patello-femoral contact force during a strenuous lower limb activity even under conditions of small knee-flexion angles. The results are discussed and compared with limited data reported in the literature.

scholarly journals Energy absorption at lower limb joints in different foot contact strategies while descending stairs

2021 ◽  
Vol 29 ◽  
pp. 433-440
Author(s):  
Hyeong-Min Jeon ◽  
Ki-Kwang Lee ◽  
Jun-Young Lee ◽  
Ju-Hwan Shin ◽  
Gwang-Moon Eom
Keyword(s):  
Knee Joint ◽  
Potential Energy ◽  
Energy Absorption ◽  
Lower Limb ◽  
Mechanical Energy ◽  
Connective Tissues ◽  
Stair Descent ◽  
Young Subjects ◽  
Power And Energy ◽  
Joint Loads

BACKGROUND: Joint loads in different walking strategies during stair descent have been investigated in terms of the joint moment in association with the risk of osteoarthritis. However, the absorption mechanisms of the potential energy loss are not known. OBJECTIVE: This study aims to compare the mechanical energy absorptions in lower limb joints in different initial foot contact strategies. METHODS: Nineteen young subjects walked down on instrumented stairs with two different strategies, i.e., forefoot and rearfoot strike. Power and energy at lower limb joints during stance phase were compared between strategies. RESULTS: Lower limb joints absorbed 73 ± 11% of the potential energy released by descending stairs and there was no difference between strategies. Rearfoot strategy absorbed less energy than forefoot strategy at the ankle joint in the 1st phase, which was compensated mainly by more energy absorption at the knee in the 2nd phase and less energy generation at the hip joints in the 3rd phase. CONCLUSION: The results suggest that a leg absorbs most of the potential energy while descending stairs irrespective of the walking strategies and that any reduction of energy absorption at one joint is compensated by other joints. Greater energy absorption at the knee joint compared to the other joints suggests high burden of knee joint muscles and connective tissues during stair-descent, which is even more significant for the rearfoot strike strategy.

scholarly journals Effect of time complexities and variation of mass spring model parameters on surgical simulation

2014 ◽  
Vol 9 (4) ◽  
Author(s):  
Salina Sulaiman ◽  
Tan Sing Yee ◽  
Abdullah Bade
Keyword(s):  
Soft Tissue ◽  
Human Liver ◽  
Soft Tissues ◽  
Surgical Simulation ◽  
Model Parameters ◽  
Spring Model ◽  
Surgical Simulator ◽  
Tissue Model ◽  
Mass Spring Model ◽  
Mass Spring

Physically based models assimilate organ-specific material properties, thus they are suitable in developing a surgical simulation. This study uses mass spring model (MSM) to represent the human liver because MSM is a discrete model that is potentially more realistic than the finite element model (FEM). For a high-end computer aided medical technology such as the surgical simulator, the most important issues are to fulfil the basic requirement of a surgical simulator. Novice and experienced surgeons use surgical simulator for surgery training and planning. Therefore, surgical simulation must provide a realistic and fast responding virtual environment. This study focuses on fulfilling the time complexity and realistic of the surgical simulator. In order to have a fast responding simulation, the choice of numerical integration method is crucial. This study shows that MATLAB ode45 is the fastest method compared to 2nd ordered Euler, MATLAB ode113, MATLAB ode23s and MATLAB ode23t. However, the major issue is human liver consists of soft tissues. In modelling a soft tissue model, we need to understand the mechanical response of soft tissues to surgical manipulation. Any interaction between haptic device and the liver model may causes large deformation and topology change in the soft tissue model. Thus, this study investigates and presents the effect of varying mass, damping, stiffness coefficient on the nonlinear liver mass spring model. MATLAB performs and shows simulation results for each of the experiment. Additionally, the observed optimal dataset of liver behaviour is applied in SOFA (Simulation Open Framework Architecture) to visualize the major effect.

scholarly journals Characterizing Vibrating Cantilevers for Liquid Viscosity and Density Sensing

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
Christian Riesch ◽  
Erwin K. Reichel ◽  
Franz Keplinger ◽  
Bernhard Jakoby
Keyword(s):  
Cross Sections ◽  
Quartz Crystal ◽  
Model Parameters ◽  
Additional Mass ◽  
Liquid Loading ◽  
Fitting Procedure ◽  
Saw Devices ◽  
Quartz Crystal Resonators ◽  
Macroscopic Parameters ◽  
Online Process

Miniaturized liquid sensors are essential devices in online process or condition monitoring. In case of viscosity and density sensing, microacoustic sensors such as quartz crystal resonators or SAW devices have proved particularly useful. However, these devices basically measure a thin-film viscosity, which is often not comparable to the macroscopic parameters probed by conventional viscometers. Miniaturized cantilever-based devices are interesting alternatives for such applications, but here the interaction between the liquid and the oscillating beam is more involved. In our contribution, we describe a measurement setup, which allows the investigation of this interaction for different beam cross-sections. We present an analytical model based on an approximation of the immersed cantilever as an oscillating sphere comprising the effective mass and the intrinsic damping of the cantilever and additional mass and damping due to the liquid loading. The model parameters are obtained from measurements with well-known sample liquids by a curve fitting procedure. Finally, we present the measurement of viscosity and density of an unknown sample liquid, demonstrating the feasibility of the model.

scholarly journals Characteristics of Lower Limb Muscle Activity in Elderly Persons After Ergometric Exercise

2020 ◽  
Vol 6 ◽  
pp. 233372142097980
Author(s):  
Kenichi Kaneko ◽  
Hitoshi Makabe ◽  
Kazuyuki Mito ◽  
Kazuyoshi Sakamoto ◽  
Yoshiya Kawanori ◽  
...  
Keyword(s):  
Lower Limb ◽  
Muscle Activity ◽  
The Elderly ◽  
Elderly Subjects ◽  
Elderly Persons ◽  
Lower Limb Muscle ◽  
Limb Muscle ◽  
Lower Limb Muscles ◽  
The Mean ◽  
Young Subjects

This study examined the characteristics of lower limb muscle activity in elderly persons after ergometric pedaling exercise for 1 month. To determine the effect of the exercise, surface electromyography (SEMG) of lower limb muscles was subjected to Daubechies-4 wavelet transformation, and mean wavelet coefficients were compared with the pre-exercise coefficients and the post-exercise coefficients in each wavelet level. The characteristics of muscle activity after pedaling exercise were also compared between the elderly subjects and young subjects. For the elderly subjects, the mean wavelet coefficients were significantly decreased in the tibialis anterior and the gastrocnemius medialis at wavelet levels of 3, 4, and 5 (125–62.5, 62.5–31.25, and 31.25–15.625 Hz, respectively), by pedaling exercise. However, the mean power of wavelet levels of 2 and 3 (250–125 and 125–62.5 Hz) within the rectus femoris and the biceps femoris were significantly increased in the young subjects. The effect of pedaling exercise is different from the effects of heavy-resistance training. It was suggested that the muscle coordination, motor unit (MU) firing frequency, and firing fiber type of lower limb muscles are changed with the different characteristics between elderly and young persons by pedaling exercise for 1 month.

scholarly journals Nonempirical Interactions for the Nuclear Shell Model: An Update

2019 ◽  
Vol 69 (1) ◽  
pp. 307-362 ◽  
Author(s):  
S. Ragnar Stroberg ◽  
Heiko Hergert ◽  
Scott K. Bogner ◽  
Jason D. Holt
Keyword(s):  
Renormalization Group ◽  
Ab Initio ◽  
Shell Model ◽  
Model Parameters ◽  
Nuclear Shell Model ◽  
Many Body ◽  
Similarity Renormalization Group ◽  
Realistic Interaction ◽  
Three Body ◽  
Nuclear Shell

The nuclear shell model has perhaps been the most important conceptual and computational paradigm for the understanding of the structure of atomic nuclei. While the shell model has been used predominantly in a phenomenological context, there have been efforts stretching back more than half a century to derive shell model parameters based on a realistic interaction between nucleons. More recently, several ab initio many-body methods—in particular, many-body perturbation theory, the no-core shell model, the in-medium similarity renormalization group, and coupled-cluster theory—have developed the capability to provide effective shell model Hamiltonians. We provide an update on the status of these methods and investigate the connections between them and their potential strengths and weaknesses, with a particular focus on the in-medium similarity renormalization group approach. Three-body forces are demonstrated to be important for understanding the modifications needed in phenomenological treatments. We then review some applications of these methods to comparisons with recent experimental measurements, and conclude with some remaining challenges in ab initio shell model theory.

A Structural Continuum Constitutive Model for a Two-Phase Soft Tissue

2010 ◽  
Author(s):  
Silvia Wognum ◽  
Michael S. Sacks
Keyword(s):  
Mechanical Behavior ◽  
Soft Tissues ◽  
Bladder Wall ◽  
Constitutive Models ◽  
Tissue Level ◽  
Model Parameters ◽  
Two Phase ◽  
Tissue Properties ◽  
Highly Nonlinear ◽  
Cord Injury

Due to the complexity in determining multi-constituent tissue properties, most structural constitutive models for soft tissues focus on a single constituent. However, many tissues contain multiple load-bearing constituents, such as collagen fibers and smooth muscle (SM) cells. Moreover, to elucidate how observed changes in tissue components are related to altered net mechanical behavior at the tissue level, structural constitutive models require physiological relevant model parameters and formulations for changes in referential configuration when one component is physically removed. As an excellent example application that underscores these issues, we have examined the urinary bladder wall (UBW), which undergoes large deformations and exhibits highly nonlinear and anisotropic mechanical behavior [1,2]. Moreover, it undergoes profound remodeling in response to different pathologies such as spinal cord injury (SCI) [1,2].

scholarly journals Identification and Frequency Dependence of Viscoelastic Parameters during Dynamic Creep Tests on Selected Pome Fruits

2019 ◽  
Vol 1 (3) ◽  
pp. 324-331 ◽  
Author(s):  
Csaba Farkas ◽  
László Fenyvesi ◽  
Károly Petróczki
Keyword(s):  
Viscoelastic Model ◽  
Model Parameters ◽  
Variable Load ◽  
Pome Fruit ◽  
Creep Tests ◽  
Viscoelastic Parameters ◽  
Wide Range ◽  
Dynamic Creep ◽  
Pome Fruits ◽  
Compressive Loads

In this paper, a novel control-loop concept is presented to investigate the viscoelastic properties of different pome fruits. Repeated mechanical effects are one of the most important risk factors during the postharvest procedures, so our work aimed to expand knowledge in the field. The actual investigations involved Golden Delicious apples and Packham pears. The developed model is based on the Poynting–Thomson body and, during the validating dynamic creep tests, different repeated compressive loads were applied. The examined frequencies were chosen from the most common components of the frequency distribution during the transportation process; the given range is responsible for the highest volume of fruit damage and the most extensive losses. The identified mathematical system determines the viscoelastic model parameters with the best fit to the measured creep data. The model properties of the tested fruit textures are compared in six different frequency setups, with the inspected pome species showing different elastic and viscous responses for the adjusted load conditions. The custom testing device with variable load functions and the proposed solution allow system identification with a wide range of setup possibilities. The resulted viscoelastic parameters can be used for further failure analysis and for the comparison of different pome fruit materials.

Hydatid disease of the soft tissues of the lower limb: findings in three cases

1993 ◽  
Vol 22 (7) ◽  
Author(s):  
Julio Martin ◽  
Vicente Marco ◽  
Ahmed Zidan ◽  
Constancio Marco
Keyword(s):  
Hydatid Disease ◽  
Lower Limb ◽  
Soft Tissues
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