A New Mesostructural Soft Tissue Testing System With Multiaxial Loading and Local Strain Measurement Capabilities

2004 ◽  
Author(s):  
Todd C. Doehring ◽  
Michael Kahelin ◽  
Ivan Vesely
Keyword(s):  
Feature Tracking ◽  
Soft Tissues ◽  
Local Strain ◽  
Local Deformation ◽  
Fiber Bundles ◽  
Testing System ◽  
Multiaxial Loading ◽  
Computer Controlled ◽  
Key Features ◽  
Measurement Capabilities

A new mesostructural testing system (MSTS) has been developed to measure structural and material properties of soft tissues at an intermediate, or “mesostructural” scale (i.e. ~ .01 to 10 mm). Key features of this new system are biaxial computer controlled loading and synchronized high-resolution microscopic digital imaging. The system uses a marker-less feature tracking algorithm to measure local deformation of mesostructures such as the fiber bundles of the aortic valve. Validation and bioengineering applications are described.

Marker-Less Measurement and Analysis of Collagen Uncrimping, Orientation, and Local Deformation Patterns Under Controlled Loads

2004 ◽  
Author(s):  
Todd C. Doehring
Keyword(s):  
High Resolution ◽  
Fiber Orientation ◽  
Feature Tracking ◽  
Soft Tissues ◽  
Local Deformation ◽  
Testing System ◽  
High Resolution Imaging ◽  
Measurement And Analysis ◽  
Resolution Imaging ◽  
Deformation Patterns

Deformation, crimp, and alignment patterns of collagen fibers in soft tissues have been measured using a novel testing system combining controlled loading with synchronized high-resolution imaging. Marker-less feature tracking was used to measure 2-D local deformations, and a radon transform was used to compute quantitative maps of crimp patterns and local tissue fiber orientation. We found highly nonuniform deformation and crimp patterns, with the highest strains near the clamps, and the lowest strains in the midsubstance region.

Axial-Torsional Testing System for Clay with Local Strain Measurement

1998 ◽  
Vol 1614 (1) ◽  
pp. 24-32
Author(s):  
Antonio E. Abrantes ◽  
Dayakar Penumadu
Keyword(s):  
Hollow Cylinder ◽  
Local Strain ◽  
Confining Pressure ◽  
Cohesive Soil ◽  
Local Deformation ◽  
Testing System ◽  
Test Results ◽  
Torsional Loading ◽  
Torsional Shear ◽  
Torsional Testing

An axial-torsional testing system, consisting of an MTS loading frame (9.8 kN/113 N-m) and TestWare-SX control, was developed for evaluating the multiaxial behavior of cohesive soil. The capabilities of the testing system include automated control of three axes (axial load/displacement, torque/rotation, and confining pressure) under static and dynamic conditions. Description of a custom-designed triaxial-torsional shear cell developed for this study is presented. Uniform and reproducible specimens (hollow and full cylinder) were obtained with a slurry consolidation technique. As an example for implementing software control, procedures are described for performing K o consolidation with an electropneumatic transducer in conjunction with an automated volume change device. An optical technique developed by the authors for measuring local strains under axial-torsional loading is also described. Initial test results associated with an undrained constant rate of strain axial and pure torsional shear testing on isotropically consolidated hollow-cylinder kaolin clay are presented. Aspects associated with repeatability are discussed. The test results are being used to evaluate the influence of the inclination of major principal stress on the shear strength and pore pressure behavior of isotropically consolidated clay. A qualitative discussion related to global versus local deformation patterns of hollow-cylinder specimens under axial and torsional loading is also presented.

An Energy-Based Method for Testing Cushioning Durability of Running Shoes

1993 ◽  
Vol 9 (1) ◽  
pp. 27-46 ◽  
Author(s):  
John F. Swigart ◽  
Arthur G. Erdman ◽  
Patrick J. Cain
Keyword(s):  
Maximum Energy ◽  
Test Method ◽  
New Method ◽  
Testing System ◽  
Materials Testing ◽  
Wear Factor ◽  
Time Profiles ◽  
Running Shoes ◽  
Computer Controlled ◽  
Force Time

A new method for quantifying shoe cushioning durability was developed. This method used a computer-controlled, closed-loop materials testing system to subject the shoes to force-time profiles that were indicative of running. The change in the magnitude of the maximum energy absorbed by a shoe and the change in the magnitude of the energy balance of the shoe were quantified after the shoe had been worn running for a given distance. A shoe that changed very little in these quantities had a small energy wear factor and was deemed to have durable cushioning. The test method was roughly validated through comparison of three shoes of different midsole constructions with known relative durabilities. The shoes were tested at four simulated running speeds for energy properties when they were new and after they were run in for 161 km. The relative durabilities of the tested shoes were consistent with expectations based on the shoes' materials and constructions, showing that the new method has promise in predicting shoe cushioning durability, and thus more complete studies of the method may prove useful.

A Device for Evaluating the Multiaxial Finite Strain Thermomechanical Behavior of Elastomers and Soft Tissues

1999 ◽  
Vol 67 (3) ◽  
pp. 465-471 ◽  
Author(s):  
E. M. Ortt ◽  
D. J. Doss ◽  
E. Legall ◽  
N. T. Wright ◽  
J. D. Humphrey
Keyword(s):  
Thermal Diffusivity ◽  
Plane Stress ◽  
Finite Strain ◽  
Soft Tissues ◽  
Polymeric Materials ◽  
Thermomechanical Behavior ◽  
Finite Deformations ◽  
Out Of Plane ◽  
Computer Controlled ◽  
Stretch Response

Described here is the design and development of a computer-controlled device capable of measuring the finite strain thermomechanical behavior of a general class of polymeric materials including elastomers and biological soft tissues. The utility of this device for thermoelastic and thermophysical investigations is demonstrated by the measurement of the in-plane stress-stretch response and in-plane and out-of-plane components of thermal diffusivity of neoprene rubber undergoing finite deformations.[S0021-8936(00)01603-2]

scholarly journals Visualizing mineralization processes and fossil anatomy using synchronous synchrotron X-ray fluorescence and X-ray diffraction mapping

2020 ◽  
Vol 17 (169) ◽  
pp. 20200216 ◽  
Author(s):  
Pierre Gueriau ◽  
Solenn Réguer ◽  
Nicolas Leclercq ◽  
Camila Cupello ◽  
Paulo M. Brito ◽  
...  
Keyword(s):  
Cross Sections ◽  
Soft Tissues ◽  
Local Strain ◽  
Phase Identification ◽  
X Ray Diffraction ◽  
X Ray ◽  
Area Detector ◽  
Transmission Geometry ◽  
Mineralization Processes ◽  
Elemental Data

Fossils, including those that occasionally preserve decay-prone soft tissues, are mostly made of minerals. Accessing their chemical composition provides unique insight into their past biology and/or the mechanisms by which they preserve, leading to a series of developments in chemical and elemental imaging. However, the mineral composition of fossils, particularly where soft tissues are preserved, is often only inferred indirectly from elemental data, while X-ray diffraction that specifically provides phase identification received little attention. Here, we show the use of synchrotron radiation to generate not only X-ray fluorescence elemental maps of a fossil, but also mineralogical maps in transmission geometry using a two-dimensional area detector placed behind the fossil. This innovative approach was applied to millimetre-thick cross-sections prepared through three-dimensionally preserved fossils, as well as to compressed fossils. It identifies and maps mineral phases and their distribution at the microscale over centimetre-sized areas, benefitting from the elemental information collected synchronously, and further informs on texture (preferential orientation), crystallite size and local strain. Probing such crystallographic information is instrumental in defining mineralization sequences, reconstructing the fossilization environment and constraining preservation biases. Similarly, this approach could potentially provide new knowledge on other (bio)mineralization processes in environmental sciences. We also illustrate that mineralogical contrasts between fossil tissues and/or the encasing sedimentary matrix can be used to visualize hidden anatomies in fossils.

A Physically-Based Anisotropic Discrete Fiber Model for Fibrous Soft Tissues

2010 ◽  
Author(s):  
C. Flynn ◽  
M. B. Rubin ◽  
P. M. F. Nielsen
Keyword(s):  
Soft Tissues ◽  
Mechanical Response ◽  
Continuous Distribution ◽  
Collagen Fibers ◽  
Fiber Bundles ◽  
Parameter Study ◽  
Rabbit Skin ◽  
Pig Skin ◽  
Proposed Model ◽  
Physically Based

Physically-based fibrous soft tissue models often consider the tissue to be a collection of fibers with a continuous distribution function to represent their orientations. This study proposes a simple model for the response of fibrous connective tissues in terms of a discrete number of fiber bundles. The proposed model consists of six weighted fiber bundles orientated such that they pass through opposing vertices of an icosahedron. A novel aspect of the proposed model is the use of a simple analytical function to represent the undulation distribution of the collagen fibers. The mechanical response of the elastin fiber is represented by a neo-Hookean hyperelastic equation. A parameter study was performed to analyze the effect of each parameter on the overall response of the model. The proposed model accurately simulated the uniaxial stretching of pig skin with an 8% error-of-fit for stretch ratios up to 1.8. The model also accurately simulated the biaxial stretching of rabbit skin with a 10% error-of-fit for stretch ratios up to 1.9. The stiffness of the collagen fibers determined by the model was about 100 MPa for the rabbit skin and 900 MPa for the pig skin, which are comparable with values reported in the literature. The stiffness of the elastin fibers in the model was about 2 kPa.

Axial Strain Measurements in Skeletal Muscle at Various Strain Rates

1995 ◽  
Vol 117 (3) ◽  
pp. 262-265 ◽  
Author(s):  
T. M. Best ◽  
J. H. McElhaney ◽  
W. E. Garrett ◽  
B. S. Myers
Keyword(s):  
Skeletal Muscle ◽  
Strain Field ◽  
High Speed ◽  
Soft Tissues ◽  
Axial Strain ◽  
Local Strain ◽  
Optical Systems ◽  
Rate Dependent ◽  
Strain Formulation ◽  
Tissue Deformations

A noncontact optical system using high speed image analysis to measure local tissue deformations and axial strains along skeletal muscle is described. The spatial resolution of the system was 20 pixels/cm and the accuracy was ±0.125mm. In order to minimize the error associated with discrete data used to characterize a continuous strain field, the displacement data were fitted with a third order polynomial and the fitted data differentiated to measure surface strains using a Lagrangian finite strain formulation. The distribution of axial strain along the muscle-tendon unit was nonuniform and rate dependent. Despite a variation in local strain distribution with strain rate, the maximum axial strain, Exx = 0.614 ± 0.045 mm/mm, was rate insensitive and occurred at the failure site for all tests. The frequency response of the video system (1000 Hz) and the measurement of a continuous strain field along the entire length of the structure improve upon previous noncontact optical systems for measurement of surface strains in soft tissues.

Cross-Sectional Profiles and Volume Reconstructions of Soft Tissues Using Laser Beam Measurements

2004 ◽  
Vol 126 (6) ◽  
pp. 796-802 ◽  
Author(s):  
Eve Langelier ◽  
Daniel Dupuis ◽  
Michel Guillot ◽  
Francine Goulet ◽  
Denis Rancourt
Keyword(s):  
Cross Sections ◽  
Soft Tissues ◽  
Optical Methods ◽  
Mechanical Contact ◽  
Cross Sectional ◽  
Collagen Matrices ◽  
Geometric Reconstruction ◽  
Computer Controlled ◽  
Beam Motion ◽  
Collimated Beam

Precise geometric reconstruction is a valuable tool in the study of soft tissues biomechanics. Optical methods have been developed to determine the tissue cross section without mechanical contact with the specimen. An adaptation of the laser micrometer developed by Lee and Woo [ASME J. Biomech. Eng., 110 (2), pp. 110–114]. is proposed in which the laser-collimated beam rotates around and moves along a fixed specimen to reconstruct its cross sections and volume. Beam motion is computer controlled to accelerate data acquisition and improve beam positioning accuracy. It minimizes time-dependent shape modifications and increases global reconstruction precision. The technique is also competent for the measurement of immersed collagen matrices.

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