Article
Materials Science, Multidisciplinary
B. S. L. da Costa, L. C. S. Nunes
Summary: Understanding the highly nonlinear behavior of crimped collagen fibers is crucial for medical diagnosis. A proposed model, based on a explicit scalar potential and Weibull distribution, proved to better describe tendon behavior compared to existing models. Experimental data validation and investigation of stress-strain curves further supported the effectiveness of the proposed model.
MECHANICS OF MATERIALS
(2022)
Article
Materials Science, Multidisciplinary
Nino Horvat, Lana Virag, Gerhard A. Holzapfel, Igor Karsaj
Summary: This study introduces a fiber dispersion model into a growth and remodeling model of the aortic wall, along with a new definition of the fiber pre-stretch tensor. Results show that changes in fiber dispersions and mean fiber angles significantly affect aneurysm evolution and stress distribution. Increased fiber dispersion in certain layers can slow aneurysm growth, while a mean fiber direction closer to the circumferential direction results in a stiffer response and decreased aneurysm growth rate.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2021)
Article
Biophysics
Nandan N. Pitre, J. B. Moses, Edith Tzeng, Steven Abramowitch, Sachin S. Velankar
Summary: Composites of crimped fibers embedded in a soft matrix can mimic the strain-hardening behavior of collagen tissues. Finite element simulations show that large crimped fibers straighten significantly at small strain and bear increasing load at large strain. A shear lag model can capture the stress-transfer mechanics and estimate the modulus of the composite.
BIOMECHANICS AND MODELING IN MECHANOBIOLOGY
(2023)
Article
Ophthalmology
Fengting Ji, Manik Bansal, Bingrui Wang, Yi Hua, Mohammad R. Islam, Felix Matuschke, Markus Axer, Ian A. Sigal
Summary: The microstructure and mechanical behavior of sclera collagen fibers are crucial for eye physiology and pathology. Most existing models have limitations in describing the interwoven and interacting nature of the fibers. In this study, a new computational modeling approach, called direct fiber modeling, was introduced to accurately represent the fibrous microstructure of the sclera while capturing its macroscale behavior. The results demonstrate the potential of direct fiber models in providing unique insights into tissue behavior questions inaccessible with continuum approaches.
EXPERIMENTAL EYE RESEARCH
(2023)
Article
Ophthalmology
Fengting Ji, Marissa Quinn, Yi Hua, Po-Yi Lee, Ian A. Sigal
Summary: Collagen fiber organization in the corneoscleral shell is not uniformly in-plane, but exhibits a wide range of in-depth orientations, with fibers more aligned in-plane in the anterior parts of the globe. Regions of the posterior globe have a higher percentage of inclined fibers and a larger range of inclination angles.
EXPERIMENTAL EYE RESEARCH
(2023)
Article
Chemistry, Multidisciplinary
Brandon G. Gerberich, Amy J. Wood-Yang, Afsane Radmand, Lauren M. Nichols, Amir Hejri, Elisa Schrader Echeverri, Hannah G. Gersch, Mark R. Prausnitz
Summary: A computational model was developed to predict the crosslinking efficiency of visible/near infrared photosensitizers in the sclera for the treatment of myopia and glaucoma. The study validated photocrosslinking against riboflavin corneal crosslinking experimental studies and simulated the treatment using methylene blue administered by retrobulbar injection and irradiated with a transpupillary light beam. Optimal ranges for treatment parameters were determined and the sensitivity of crosslinking to various parameters was quantified, with oxygen concentration in the injection solution, scleral thickness, and injection volume being the most sensitive parameters.
JOURNAL OF CONTROLLED RELEASE
(2022)
Article
Ophthalmology
Tian Yong Foong, Yi Hua, Rouzbeh Amini, Ian A. Sigal
Summary: Collagen fibers in the cornea and sclera undergo recruitment when stretched, which leads to straightening and increased load-bearing capacity. This recruitment process is essential for the nonlinear behavior of the corneoscleral shell. Our study aimed to determine the fraction of recruited fibers in different regions of the corneoscleral shell under various levels of intraocular pressure. We developed a model based on experimentally-measured collagen fiber properties and simulated the deformation of the corneoscleral shell under varying pressure levels.
EXPERIMENTAL EYE RESEARCH
(2023)
Article
Biophysics
Zhongwei Sun, Changwen Mi
Summary: Due to the complicated structure of the elastic fiber network in annulus fibrosus, existing studies have either simplified or overlooked its distribution pattern. However, both experimental and simulation results show that elastic fibers play a crucial role in maintaining the structural integrity and load-bearing ability of intervertebral discs. This study develops a biphasic annulus fibrosus model that incorporates the accurate distribution pattern of collagen and elastic fibers, successfully identified through microscopy anatomy and micromechanical testing. The model's simulation results agree well with experimental and simulation data, and it reveals the significant influence of elastic fibers on various mechanical performances of annulus fibrosus.
JOURNAL OF BIOMECHANICS
(2023)
Article
Biology
Turki Almubrad, Rita Mencucci, Adrian Smedowski, Ramachandran Samivel, Essam Almutleb, Aljoharah Alkanaan, Adnan Ali Khan, Ali Masmali, Saeed Akhtar
Summary: Electron microscopy revealed that iontophoresis-ultraviolet A (UVA) cross-linking (CXL) with hypotonic riboflavin solution preserved collagen fibril diameter and proteoglycan area size better in the peripheral cornea compared to the central cornea. Riboflavin + UVA application at 3 mW/cm^2 for 30 min and 10 mW/cm(2) for 9 min were effective CXL methods, with the former improving collagen fibril organization and size.
SAUDI JOURNAL OF BIOLOGICAL SCIENCES
(2021)
Article
Biophysics
Salil Pai, Jinha Kwon, Bowen Liang, Hanna Cho, Soheil Soghrati
Summary: The piezoelectric response of bone at the submicron scale was analyzed using the finite element method, with a new algorithm proposed to virtually reconstruct bone nanostructures. The study found that the piezoelectric response showed a linear variation with fibrils volume fraction when fibrils were aligned, while more oscillations were observed in results when fibrils were misaligned, with negligible differences in lateral compression and shear loadings. However, under longitudinal compression, the electric field associated with misaligned fibrils was notably higher than that of aligned fibrils for the same volume fraction.
BIOMECHANICS AND MODELING IN MECHANOBIOLOGY
(2021)
Article
Multidisciplinary Sciences
Hamed Babaei, Emilio A. Mendiola, Sunder Neelakantan, Qian Xiang, Alexander Vang, Richard A. F. Dixon, Dipan J. Shah, Peter Vanderslice, Gaurav Choudhary, Reza Avazmohammadi
Summary: This paper introduces a machine learning model that can accurately predict the passive properties of the myocardium, bypassing the tedious steps of traditional finite element inverse problems. The model performs excellently in predicting stiffness parameters related to fiber direction. The ML model's predictions demonstrate good agreement with both rat-specific and patient-specific data.
SCIENTIFIC REPORTS
(2022)
Article
Engineering, Biomedical
Ryan R. Mahutga, Victor H. Barocas, Patrick W. Alford
Summary: Multiscale mechanical models in biomaterials research often simplify microstructures to enable large-scale simulations. However, these simplifications can lead to problematic assumptions and approximations, particularly in fiber embedded materials where fiber distributions and deformation greatly impact mechanical behavior. In this work, a technique is proposed to couple non-affine network models to finite element solvers, allowing for simulation of microstructural phenomena in complex geometries. The developed plugin is open-source and compatible with the bio-focused finite element software FEBio.
JOURNAL OF THE MECHANICAL BEHAVIOR OF BIOMEDICAL MATERIALS
(2023)
Article
Engineering, Civil
Feng Zhou, Lalita Lama, Kaizhu Zhao
Summary: This paper presents a concrete filled double-skin tubular (CFDST) stub column, with outer stainless steel circular hollow section (CHS) and inner carbon steel CHS. Finite element analysis is conducted to verify the structural performance and investigate the mechanical properties of the sandwiched concrete. Different design methods are assessed to evaluate their applicability and accuracy, and a new design method for calculating the ultimate bearing capacity of the CFDST stub column is proposed.
ENGINEERING STRUCTURES
(2023)
Article
Materials Science, Multidisciplinary
Milad Mahdian, Alireza Seifzadeh, Ali Mokhtarian, Farideh Doroodgar
Summary: This study addresses the potential problems in utilizing material laws in numerical simulations due to geometric and material nonlinearities. By obtaining material parameters through finite element-optimization analysis and experimental data, the model shows promising accuracy and stability in predicting corneal tissue behavior, providing an unprecedented opportunity for accurate numerical simulations in corneal microsurgery. The J-shape behavior of the samples under tensile test can be justified by the model used, demonstrating the model's capability in predicting human corneal behavior.
MATERIALS TODAY COMMUNICATIONS
(2021)
Article
Engineering, Multidisciplinary
Shannon Ryan, Julian Berk, Santu Rana, Brodie McDonald, Svetha Venkatesh
Summary: This article presents an inverse methodology for deriving viscoplasticity constitutive model parameters and using functional experiments in explicit finite element simulations. By utilizing Bayesian optimization and experiments with a wide range of loading conditions, the resulting constitutive model parameters are applicable across various conditions and exhibit superior predictive accuracy.
DEFENCE TECHNOLOGY
(2022)
Article
Engineering, Multidisciplinary
Ildar Khisamitov, Guenther Meschke
Summary: This paper extends the variational interface fracture model to model fluid driven fracture in porous materials, coupling fluid flow with fracture initiation and propagation using a damage variable. The proposed model is validated with analytical solutions and demonstrated through numerical examples.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2021)
Article
Construction & Building Technology
Jelena Ninic, Abdullah Alsahly, Andre Vonthron, Hoang-Giang Bui, Christian Koch, Markus Koenig, Guenther Meschke
Summary: Large infrastructure projects in urban areas, especially involving tunnel construction, require advanced building and construction information modelling as well as computational design assessment tools. This paper presents two automated data exchange workflows to improve the efficiency of modelling and ensure error-free information exchange.
TUNNELLING AND UNDERGROUND SPACE TECHNOLOGY
(2021)
Article
Ophthalmology
Massimo A. Fazio, Stuart K. Gardiner, Luigi Bruno, Meredith Hubbard, Gianfranco Bianco, Udayakumar Karuppanan, Jihee Kim, Mustapha El Hamdaoui, Rafael Grytz, J. Crawford Downs, Christopher A. Girkin
Summary: The 3D morphology of the deep load-bearing structures of the human optic nerve head revealed in vivo by spectral domain optical coherence tomography (SDOCT) shows promising correspondence to ex vivo quantitative 3D histology. However, significant shrinkage artifact and effects of exsanguination of the choroid in fixed tissues may impact the quantification of ex vivo histoarchitecture, highlighting important limitations when developing models and biomarkers based on ex vivo imaging of fixed tissue. Additionally, lack of visibility of most of the lamina surface in SDOCT images is a crucial limitation to metrics and biomarkers based on in vivo images of the deep tissues of the optic nerve head.
EXPERIMENTAL EYE RESEARCH
(2021)
Article
Chemistry, Physical
Vijaya Holla, Giao Vu, Jithender J. Timothy, Fabian Diewald, Christoph Gehlen, Guenther Meschke
Summary: This study introduces a computational tool for generating realistic virtual concrete morphologies, which are calibrated and validated using laboratory measurements, and ultimately trains a neural network to generate elastic properties directly from voxel data.
Article
Chemistry, Physical
Giao Vu, Fabian Diewald, Jithender J. Timothy, Christoph Gehlen, Guenther Meschke
Summary: A reduced order multiscale model for simulating microcracking-induced damage in concrete is proposed, allowing for early identification of failure precursors and application of suitable precautionary measures to reduce repair and maintenance costs. The model simulates microcrack growth in concrete using a two-scale computational methodology and is validated through uniaxial compression tests.
Article
Chemistry, Physical
Claudia Finger, Leslie Saydak, Giao Vu, Jithender J. Timothy, Gunther Meschke, Erik H. Saenger
Summary: This study investigates the sensitivity of Coda Wave Interferometry (CWI) to different types of concrete mesostructures and their damage levels, using numerical simulations to study the effect of ultrasonic measurements on concrete. The results show that different damage scenarios exhibit varying slopes in waveform decorrelation and observed reduction in velocities in the material.
Article
Engineering, Geological
Hoang-Giang Bui, Jelena Ninic, Ngoc-Anh Do, Daniel Dias, Guenther Meschke
Summary: This technical note presents a consistent finite element formulation for tunnel linings design by introducing a variational consistently linearized formulation to consider nonlinear interaction between lining structure and ground. The proposed VHRM model allows for more efficient solution of nonlinear system equations and is applicable for various types of finite elements.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2022)
Article
Biochemical Research Methods
Rafael Grytz, Mustapha El Hamdaoui, Preston A. Fuchs, Massimo A. Fazio, Ryan P. McNabb, Anthony N. Kuo, Christopher A. Girkin, Brian C. Samuels
Summary: In this study, an empirical distortion correction approach is proposed for optical coherence tomography (OCT) devices that use a fan-scanning pattern. The approach utilizes two types of reference markers to estimate the distortion correction method, and the results show that it effectively reduces distortions.
BIOMEDICAL OPTICS EXPRESS
(2022)
Article
Computer Science, Interdisciplinary Applications
Hoang-Giang Bui, Dominik Schillinger, Yaman Zendaki, Gunther Meschke
Summary: This paper presents a computational framework based on the cut finite element method (CutFEM) for process-oriented simulation in mechanized tunneling. The framework allows for the modeling, discretization, and coupling of various components and enables the analysis of multiple tunnel alignment variants using the same mesh. It facilitates the integration of geometric, building information, and simulation models in early stages of a tunnel project.
COMPUTERS AND GEOTECHNICS
(2022)
Article
Engineering, Civil
Gerrit E. Neu, Philipp Edler, Steffen Freitag, Vladislav Gudzulic, Gunther Meschke
Summary: This paper presents a numerical model that directly tracks the influence of important design parameters on the structural response of steel-fibre reinforced segments. The model combines submodels on the single fibre level into a crack bridging model and integrates them into a finite element model for numerical structural analysis. An optimization procedure is also carried out to determine a robust and cost-effective design of a fibre reinforced segmental linings.
ENGINEERING STRUCTURES
(2022)
Article
Ophthalmology
Mustapha El Hamdaoui, Alexander M. Levy, Aaron B. Stuber, Christopher A. Girkin, Timothy W. Kraft, Brian C. Samuels, Rafael Grytz
Summary: Scleral crosslinking using genipin is a promising treatment option for myopia control, but its safety is still unclear. This study investigated the effects of retrobulbar injections of genipin on retinal structure and function in tree shrews. The results showed that genipin injections caused retinal thinning and reduced retinal function, with higher doses leading to noticeable tissue degeneration.
EXPERIMENTAL EYE RESEARCH
(2022)
Article
Engineering, Multidisciplinary
Janis Reinold, Gunther Meschke
Summary: This article proposes a consistent finite strain model for handling large deformations of aging materials during extrusion and deposition processes. By decomposing the deformation gradient into elastic and non-recoverable aging parts and adopting a hyperelastic potential, the problem of evolving stiffness is addressed. The proposed model is highly applicable and can be easily integrated into existing numerical models.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2022)
Article
Engineering, Multidisciplinary
Chen Xu, Ba Trung Cao, Yong Yuan, Guenther Meschke
Summary: Recently, the physics-informed neural networks (PINNs), a class of machine learning methods, have been widely used in solving scientific computing problems by embedding physical laws into the loss function. This paper presents a multi-task learning method that utilizes uncertainty weighting to improve the efficiency and accuracy of PINNs for inverse problems in linear elasticity and hyperelasticity. The approach is demonstrated through the prediction of external loads in engineering structures based on limited displacement monitoring points, and shows robustness and better performance compared to traditional analysis methods.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Engineering, Geological
Abdiel Ramon Leon Bal, Guenther Meschke
Summary: A two-phase velocity-pressure stabilized formulation is proposed for the numerical analysis of mechanized excavations in partially saturated soft soils using the Particle Finite Element Method (PFEM). The PFEM methodology, combined with a hypoplastic constitutive model for deformable soil skeleton, enables the modeling of large deformations. The PFEM model is validated and applied to excavation tests and parametric investigations, demonstrating its suitability for 3D excavation problems.
INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS
(2023)
Article
Ophthalmology
Ramkumar Ramamirtham, James D. Akula, Amber-Lee K. Curran, Justyna Szczygiel, Annie M. Lancos, Rafael Grytz, R. Daniel Ferguson, Anne B. Fulton
Summary: The purpose of the study was to create a simplified model of the eye to determine the power of the crystalline lens. Measurements of cycloplegic refraction and axial length were obtained and a numerical ray tracing model was used to calculate the posterior lens curvature. The posterior retinal curvature remained fixed regardless of refractive error.
OPHTHALMIC AND PHYSIOLOGICAL OPTICS
(2023)
