scholarly journals Effects of Boundary Conditions on the Stress Relaxation of Passively Compressed Skeletal Muscle

2020 ◽  
Author(s):  
Anurag Vaidya ◽  
Benjamin Wheatley
Keyword(s):  
Skeletal Muscle ◽  
Stress Relaxation ◽  
Boundary Conditions ◽  
Surgical Planning ◽  
Computational Models ◽  
Strain Rates ◽  
Impact Biomechanics

Computational models of skeletal muscle are useful to study impact biomechanics and surgical-planning. However, the accuracy of these models comes into question as the behavior of muscle in compression is not well understood, specifically in regard to boundary conditions. In this study, we aim to understand how skeletal muscle behaves in different formsof compression (confined and unconfined) at different strain rates. Data from this study will help to develop physiologicallyaccurate computational models of skeletal muscle.

scholarly journals Development and implementation of volumetric compression relaxation testing of skeletal muscle

2020 ◽  
Author(s):  
Anurag Vaidya ◽  
Benjamin Wheatley
Keyword(s):  
Skeletal Muscle ◽  
Boundary Conditions ◽  
Skeletal Muscles ◽  
Computational Models ◽  
Viscoelastic Model ◽  
Confined Compression ◽  
Automobile Safety ◽  
Body Tissues ◽  
Fluid Properties

Computational models of human body— such as the Toyota THUMS model— are frequently used in the automobile safety industry. Such models rely on accurate material properties for body tissues. However, the compressive behavior of skeletal muscle is not fully understood yet, particularly regarding the differences in muscle response to various in vivo loading conditions. It is likely that in vivo muscle experiences a variation between confined and unconfined volumetric boundary conditions, but nearly all previous studies investigating passively compressed tissue have focused on muscle in unconfined compression (UC) or fully confined compression (CC). One study has investigated muscle under anisotropic semi-confined compression (SC). However, the apparatus used by Bol et al. (2016) does not allow testing the effect of interstitial fluid properties on the mechanics of skeletal muscles. Thus, we have developed novel instrumentation that can help to investigate the effects of volumetric boundary conditions (SC and CC) on stress relaxation of skeletal muscles. We also present a viscoelastic model that shows how relaxation behavior differs from boundary conditions.

scholarly journals Novel Volumetric Compression Relaxation Testing of Skeletal Muscles

2020 ◽  
Author(s):  
Anurag Vaidya ◽  
Benjamin Wheatley
Keyword(s):  
Skeletal Muscle ◽  
Stress Relaxation ◽  
Human Body ◽  
Material Properties ◽  
Skeletal Muscles ◽  
Computational Models ◽  
Surrounding Tissue ◽  
Unconfined Compression ◽  
Compressive Behavior

Computational models of the human body – such as those that simulate automotive impact – rely onaccurate material properties for bodily tissues. However, the compressive behavior of skeletal muscle is not fullyunderstood, particularly with regards to compression under confinement by surrounding tissue. For example, itis likely that in vivo muscle experiences a variation between confined and unconfined volumetric boundaryconditions, but nearly all previous studies have focused on muscle in unconfined compression (UC) or fullyconfined compression (CC). Thus, we have developed novel instrumentation to investigate the effects ofvolumetric boundary conditions (SC and CC) on stress relaxation of skeletal muscles.

scholarly journals Effects of volumetric boundary conditions on the compressive mechanics and modeling of passive skeletal muscle

2020 ◽  
Author(s):  
Anurag Vaidya ◽  
Benjamin Wheatley
Keyword(s):  
Skeletal Muscle ◽  
Finite Element ◽  
Boundary Conditions ◽  
Human Body ◽  
Material Properties ◽  
Computational Models ◽  
Compressive Behavior ◽  
Confined Compression ◽  
In Vivo Loading

For over two decades, computational models of human body—such as the Toyota THUMS model— have been used in automobilesafety. These models rely on accurate material properties for eachtissue. However, the compressive behavior of skeletal muscle is notfully understood, particularly regarding the differences in muscleresponse to in vivo loading conditions. It is likely that in vivo muscleexperiences a variation between confined and unconfined volumetricboundary conditions, but nearly all previous studies investigatingpassively compressed tissue have focused on muscle in unconfinedcompression (UC). One study has investigated muscle underanisotropic semi-confined compression, however none have studiedmuscle in fully confined compression (CC). Thus, we have investigatedthe effects of volumetric boundary conditions (UC and CC) on the stressrelaxation of skeletal muscle. Moreover, a finite element modelsimultaneously characterizing muscle behavior in both boundaryconditions is explored.

Tensile Stress—Strain and Stress Relaxation Behavior of Raw Elastomers Using a High Speed Tester

1974 ◽  
Vol 47 (2) ◽  
pp. 307-317 ◽  
Author(s):  
H. H. Bowerman ◽  
E. A. Collins ◽  
N. Nakajima
Keyword(s):  
Stress Relaxation ◽  
High Speed ◽  
Strain Rates ◽  
Time Behavior ◽  
Stress Strain ◽  
Strain Behavior ◽  
Relaxation Measurements ◽  
Ultimate Properties ◽  
Short Time ◽  
Acrylonitrile Copolymers

Abstract A high-speed, tensile-testing device was used to determine the stress—strain behavior of uncompounded butadiene—acrylonitrile copolymers over a range of temperatures and deformation rates. The strain rates were varied from 267 to 26,700 per cent/sec and the temperature was varied from 25 to 97° C. The high-speed tester was also used for stress—relaxation measurements by applying the strain nearly instantly in conformity with theoretical requirements in order to obtain the short time behavior. The WLF equation was obtained from the stress—relaxation data and then used to reduce the ultimate properties to one temperature over four decades of the strain rates. The ultimate properties could be represented by a failure envelope similar to those obtained for vulcanizates.

The mechanical characteristics of a porcine spinal cord under static loading in vitro

2018 ◽  
Vol 23 (2) ◽  
pp. 43-51
Author(s):  
Robert Pasławski ◽  
Monika Jacyna ◽  
Krzysztof Jacyna ◽  
Adrian Janiszewski ◽  
Romuald Będziński
Keyword(s):  
Spinal Cord ◽  
Stress Relaxation ◽  
Strain Rate ◽  
Mechanical Characteristics ◽  
Young Modulus ◽  
Rate Dependence ◽  
Least Square ◽  
Strain Rate Dependence ◽  
Strain Rates

Background – In spite of a number of researchers, it is well known that mechanical behaviour of a spinal cord under loading has not yet been studied extensively enough. Methods - Specimens were loaded at various strain rates: 0.02/s and 0.002/s to 5% and 10% strain. After reaching defined strain value, samples were left at a constant strain for stress relaxation. Findings – The demonstrated tensile testing stress-strain response is a highly non-linear curve corresponding to low stiffness. In the toe region stress increases exponentially with the applied strain. The highest calculated stress value for 10% strain was 0,014 MPa (strain rate 0,02/s) and 0,008 MPa (strain rate 0,002/s). Linear approximation of the stress by the least square method allowed to derive Young modulus of the value: 39,68 kPa at strain rate 0,02/s and 31,07 kPa at strain rate 0,002/s. R squared value for both regressions was above 0,99 and confirmed a good quality of approximation. A and β coefficients were 1,5MPa and 31,3 at 0,02/s strain rates and 1,3MPa and 25,3 at 0,002/s strain rates correspondingly. Relative stress relaxation increased from 20% to 37% after 60 s. Absolute stress relaxation was from 0,4kPa to 2,4kPa, at 0,002/s strain rate by 5% maximum strain and 0,02/s strain rate by 10% respectively. Interpretation - Mechanical characteristics demonstrated a visible strain-rate dependence as stiffness was significantly increasing with an increase of strain rate. Mechanical characteristics demonstrated a visible strain-rate dependence as stiffness was significantly increasing with an increase of strain rate.

A visco-hyperelastic model for skeletal muscle tissue under high strain rates

2010 ◽  
Vol 43 (13) ◽  
pp. 2629-2632 ◽  
Author(s):  
Y.T. Lu ◽  
H.X. Zhu ◽  
S. Richmond ◽  
J. Middleton
Keyword(s):  
Skeletal Muscle ◽  
Muscle Tissue ◽  
High Strain ◽  
Skeletal Muscle Tissue ◽  
Strain Rates ◽  
High Strain Rates ◽  
Hyperelastic Model

Tuning a Multiscale Model of Abdominal Aortic Hemodynamics to Incorporate Patient-Specific Features of Flow and Pressure Waveforms

2009 ◽  
Author(s):  
Ryan L. Spilker ◽  
Charles A. Taylor
Keyword(s):  
Boundary Conditions ◽  
Computational Models ◽  
Multiscale Model ◽  
Patient Specific ◽  
Vascular Walls ◽  
Outflow Boundary Conditions ◽  
Abdominal Aortic ◽  
Cardiovascular Models ◽  
Outflow Boundary ◽  
Aortic Hemodynamics

Computational models enable the calculation of quantities that are impractical or impossible to measure and the prediction of physiological changes due to interventions. In order to be useful, cardiovascular models must be both rooted in physical principles and designed such that measured or otherwise desired features of the cardiovascular system are reproduced. The former requirement has motivated the development of image-based anatomic models, patient-specific inflow boundary conditions, deformable vascular walls, outflow boundary conditions that represent the influence of the downstream circulation, and multiscale models. The development of approaches to address the latter requirement, reproducing desired features of the circulation, is a critical area of modeling research that has received comparatively little attention.

Computational models to predict stenosis growth in carotid arteries: Which is the role of boundary conditions?

2009 ◽  
Vol 12 (1) ◽  
pp. 113-123 ◽  
Author(s):  
R. Balossino ◽  
G. Pennati ◽  
F. Migliavacca ◽  
L. Formaggia ◽  
A. Veneziani ◽  
...  
Keyword(s):  
Boundary Conditions ◽  
Computational Models ◽  
Carotid Arteries
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