A Microscale Collagen-Fibrin Interacting Network Model With Comparison to Experimental Results

2012 ◽  
Author(s):  
Jeffrey D. Hyypio ◽  
Mohammad F. Hadi ◽  
Victor K. Lai ◽  
Victor H. Barocas
Keyword(s):  
Mechanical Loading ◽  
Network Model ◽  
Computer Model ◽  
Soft Tissues ◽  
Uniaxial Extension ◽  
Tissue Mechanics ◽  
Experimental Results ◽  
Large Strains ◽  
Heterogeneous Nature ◽  
Engineered Tissue

Many native and bioengineered soft tissues are composed of two or more types of biopolymer networks that mechanically define and support the material [1]. Modeling the response of multi-network soft tissues to mechanical loading can be difficult due to the heterogeneous nature of these materials and the large strains (>1) involved. As tissues deform, the different biopolymer networks interact with one another and determine the overall stress-strain outcome for the tissue. Capturing this interaction could help improve the accuracy of a computer model to simulate the microscale behavior of soft tissues under load. We have developed a two-network model to reflect interactions between collagen and fibrin biopolymer networks loaded in uniaxial extension. The model can help improve our understanding of native and engineered tissue mechanics.

A Model for Nonlinear Viscoelastic Mechanical Responses of Collagenous Soft Tissues

2005 ◽  
Vol 898 ◽  
Author(s):  
Michelle Oyen
Keyword(s):  
Stress Relaxation ◽  
Mechanical Behavior ◽  
Soft Tissues ◽  
Applied Strain ◽  
Monotonic Loading ◽  
Experimental Results ◽  
Strain Level ◽  
Time Dependent ◽  
Large Strains ◽  
Mechanical Responses

AbstractExperimental observations of the time-dependent mechanical responses of collagenous tissues have demonstrated behavior that deviates from standard treatments of linear or quasi-linear viscoelasticity. In particular, time-dependent deformation can be strongly coupled to strain level, and strain-rate independence can be observed under monotonic loading, even for a tissue with dramatic stress relaxation. It was postulated that this nonlinearity is fundamentally associated with gradual recruitment of individual collagen fibrils during applied mechanical loading. Based on previously observed experimental results for the time-dependent response of collagenous soft tissues, a model is developed to describe the mechanical behavior of these tissues under uniaxial loading. Tissue stresses, under applied strain-controlled loading, are assumed to be a sum of elastic and viscoelastic stress contributions. The relative contributions of elastic and viscoelastic stresses is assumed to vary with strain level, leading to strain- and time-dependent mechanical behavior. The model formulation is examined under conditions of monotonic loading at varying constant strain rates and stress-relaxation at different applied strain levels. The model is compared with experimental data for a membranous biological soft tissue, the amniotic sac, and is found to agree well with experimental results. The limiting behavior of the novel model, at large strains relative to the collagen recruitment, is consistent with the quasi-linear viscoelastic approach.

scholarly journals Astral hydrogels mimic tissue mechanics by aster-aster interpenetration

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Qingqiao Xie ◽  
Yuandi Zhuang ◽  
Gaojun Ye ◽  
Tiankuo Wang ◽  
Yi Cao ◽  
...  
Keyword(s):  
Common Core ◽  
Self Assembly ◽  
Master Curve ◽  
Soft Tissues ◽  
Tissue Mechanics ◽  
Fresh Perspective ◽  
Single Master Curve ◽  
Unique Mechanism ◽  
Gel Network

AbstractMany soft tissues are compression-stiffening and extension-softening in response to axial strains, but common hydrogels are either inert (for ideal chains) or tissue-opposite (for semiflexible polymers). Herein, we report a class of astral hydrogels that are structurally distinct from tissues but mechanically tissue-like. Specifically, hierarchical self-assembly of amphiphilic gemini molecules produces radial asters with a common core and divergently growing, semiflexible ribbons; adjacent asters moderately interpenetrate each other via interlacement of their peripheral ribbons to form a gel network. Resembling tissues, the astral gels stiffen in compression and soften in extension with all the experimental data across different gel compositions collapsing onto a single master curve. We put forward a minimal model to reproduce the master curve quantitatively, underlying the determinant role of aster-aster interpenetration. Compression significantly expands the interpenetration region, during which the number of effective crosslinks is increased and the network strengthened, while extension does the opposite. Looking forward, we expect this unique mechanism of interpenetration to provide a fresh perspective for designing and constructing mechanically tissue-like materials.

A Multiscale Approach to Modeling the Passive Mechanical Contribution of Cells in Tissues

2013 ◽  
Author(s):  
Victor K. Lai ◽  
Mohammad F. Hadi ◽  
Robert T. Tranquillo ◽  
Victor H. Barocas
Keyword(s):  
Extracellular Matrix ◽  
Soft Tissues ◽  
Multiscale Model ◽  
Tissue Mechanics ◽  
Multiscale Approach ◽  
Cellular Solids ◽  
Comprehensive Model ◽  
Modeling Framework ◽  
Tissue Biomechanics ◽  
Tensegrity Model

In addition to their obvious biological roles in tissue function, cells often play a significant mechanical role through a combination of passive and active behaviors. Phenomenological and continuum modeling approaches to understand tissue biomechanics have included improved constitutive laws that incorporate anisotropy in the extracellular matrix (ECM) and/or cellular phenomenon, e.g, [1]. The lack of microstructural detail in these models, however, limits their ability to explore the respective contributions and interactions between different components within a tissue. In contrast, structural approaches attempt to understand tissue biomechanics by incorporating microstructural details directly into the model, e.g., the tensegrity model [2], cellular solids models [3], or biopolymer models [4]. Research in our group focuses on developing a comprehensive model to predict the mechanical behavior of soft tissues via a multiscale approach, a technique that allows integration of the microstructural details of different components into the modeling framework. A significant gap in our previous models, however, is the absence of cells. The current work represents an improvement of the multiscale model via the addition of cells, and investigates the passive mechanical contribution of cells to overall tissue mechanics.

An Analysis of Conventional and Self-Aligned four Terminal Resistor Structures for The Determination of The Contact Resistivity from End Resistance Measurements

1986 ◽  
Vol 71 ◽  
Author(s):  
I. Suni ◽  
M. Finetti ◽  
K. Grahn
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Computer Model ◽  
Contact Resistivity ◽  
Experimental Results ◽  
The Finite Element Method ◽  
Model Based ◽  
A Value ◽  
And Diffusion

AbstractA computer model based on the finite element method has been applied to evaluate the effect of the parasitic area between contact and diffusion edges on end resistance measurements in four terminal Kelvin resistor structures. The model is then applied to Al/Ti/n+ Si contacts and a value of contact resistivity of Qc = 1.8×10−7.Ωcm2 is derived. For comparison, the use of a self-aligned structure to avoid parasitic effects is presented and the first experimental results obtained on Al/Ti/n+Si and Al/CoSi2/n+Si contacts are shown and discussed.

scholarly journals Facial pressure zones of an oronasal interface for noninvasive ventilation: a computer model analysis

2014 ◽  
Vol 40 (6) ◽  
pp. 652-657 ◽  
Author(s):  
Luana Souto Barros ◽  
Pedro Talaia ◽  
Marta Drummond ◽  
Renato Natal-Jorge
Keyword(s):  
Computer Simulation ◽  
Skin Lesion ◽  
Computer Model ◽  
Noninvasive Ventilation ◽  
Laser Scanning ◽  
Soft Tissues ◽  
Geometric Model ◽  
Human Face ◽  
Nasal Bridge ◽  
Nasal Cartilage

OBJECTIVE: To study the effects of an oronasal interface (OI) for noninvasive ventilation, using a three-dimensional (3D) computational model with the ability to simulate and evaluate the main pressure zones (PZs) of the OI on the human face. METHODS: We used a 3D digital model of the human face, based on a pre-established geometric model. The model simulated soft tissues, skull, and nasal cartilage. The geometric model was obtained by 3D laser scanning and post-processed for use in the model created, with the objective of separating the cushion from the frame. A computer simulation was performed to determine the pressure required in order to create the facial PZs. We obtained descriptive graphical images of the PZs and their intensity. RESULTS: For the graphical analyses of each face-OI model pair and their respective evaluations, we ran 21 simulations. The computer model identified several high-impact PZs in the nasal bridge and paranasal regions. The variation in soft tissue depth had a direct impact on the amount of pressure applied (438-724 cmH2O). CONCLUSIONS: The computer simulation results indicate that, in patients submitted to noninvasive ventilation with an OI, the probability of skin lesion is higher in the nasal bridge and paranasal regions. This methodology could increase the applicability of biomechanical research on noninvasive ventilation interfaces, providing the information needed in order to choose the interface that best minimizes the risk of skin lesion.

scholarly journals Computer Assisted Chord Detection Using Deep Learning and YOLOV4 Neural Network Model

2021 ◽  
Vol 2083 (4) ◽  
pp. 042017
Author(s):  
Yingdong Ru
Keyword(s):  
Neural Network ◽  
Network Model ◽  
Neural Network Model ◽  
Training Model ◽  
Experimental Results ◽  
Fine Tuning ◽  
Computer Assisted ◽  
Single Voice ◽  
Music Information ◽  
Chord Recognition

Abstract Music symbol recognition is an important part of Optical Music Recognition (OMR), Chord recognition is one of the most important research contents in the field of music information retrieval. It plays an important role in information processing, music structure analysis, and recommendation systems. Aiming at the problem of low chord recognition accuracy in the OMR recognition model, the article proposes a chord recognition method based on the YOLOV4 neural network model. First, the YOLOV4 network model is used to train single-voice scores to obtain the best training model. Then, the scores containing chords are trained through neural network fine-tuning technology. The experimental results show that the method recognizes the chords with great results, the model was tested on the test set generated by MuseScore. The experimental results show that the accuracy of note recognition is high, which can reach the accuracy of duration value of 0.96 which is higher than the accuracy of note recognition of other score recognition models.

scholarly journals Exploiting the Relationship between Pruning Ratio and Compression Effect for Neural Network Model Based on TensorFlow

2020 ◽  
Vol 2020 ◽  
pp. 1-8
Author(s):  
Bo Liu ◽  
Qilin Wu ◽  
Yiwen Zhang ◽  
Qian Cao
Keyword(s):  
Neural Network ◽  
Network Model ◽  
Neural Network Model ◽  
Prediction Accuracy ◽  
Computing Time ◽  
Experimental Results ◽  
Data Set ◽  
Compression Effect ◽  
Model Based ◽  
The Relationship

Pruning is a method of compressing the size of a neural network model, which affects the accuracy and computing time when the model makes a prediction. In this paper, the hypothesis that the pruning proportion is positively correlated with the compression scale of the model but not with the prediction accuracy and calculation time is put forward. For testing the hypothesis, a group of experiments are designed, and MNIST is used as the data set to train a neural network model based on TensorFlow. Based on this model, pruning experiments are carried out to investigate the relationship between pruning proportion and compression effect. For comparison, six different pruning proportions are set, and the experimental results confirm the above hypothesis.

On the Origin of Stiffening in Biopolymers

2005 ◽  
Vol 874 ◽  
Author(s):  
Erik Van der Giessen ◽  
Teun Koeman ◽  
Teun Van Dillen ◽  
Patrick Onck
Keyword(s):  
Network Model ◽  
Finite Strain ◽  
Strain Analysis ◽  
Large Strains ◽  
Minor Effect ◽  
Two Dimensional ◽  
Thermally Induced ◽  
Small Strains ◽  
Dimensional Network ◽  
A Minor

AbstractStrain stiffening of protein networks is explored by means of a finite strain analysis of a two-dimensional network model of cross-linked semiflexible filaments. The results show that stiffening is caused by non-affine network rearrangements that govern a transition from a bending dominated response at small strains to a stretching dominated response at large strains. Thermally-induced filament undulations only have a minor effect; they merely postpone the transition.

Computer Aided Finite Element Simulation of the Developed Driller System for Bone Drilling Process in Orthopedic Surgery

2019 ◽  
Vol 18 (04) ◽  
pp. 583-594 ◽  
Author(s):  
Kadir Gok ◽  
Arif Gok ◽  
Yasin Kisioglu
Keyword(s):  
Finite Element ◽  
Temperature Rise ◽  
Orthopedic Surgery ◽  
Soft Tissues ◽  
Experimental Results ◽  
Drilling Process ◽  
Drill Bit ◽  
Bone Drilling ◽  
Computer Aided ◽  
Driller System

Heat reveals during the bone drilling operations in orthopedic surgery because of friction between bone and surgical drill bit. The heating causes extremely important damages in bone and soft tissues. The heating has a critical threshold and it is known as 47∘C. If bone temperature value exceeds 47∘C, osteonecrosis occurs in bones and soft tissues. Many factors such as surgical drill bit geometry and material, drilling parameters, coolant has important roles for the temperature rise. Many methods are used to decrease the temperature rise. The most effective method among them is to use the coolant internally. Numeric simulations of a new driller system to avoid the overheating during the orthopedic operating processes were performed in this study. The numerical simulation with/without coolant was also performed using the finite element based software. Computer aided simulation studies were used to measure the bone temperatures occurred during the bone drilling processes. The outcomes from the simulations were compared with the experimental results. A good temperature level agreement between the experimental results and FEA simulations was found during the bone drilling process.

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