Validation experiments on finite element models of an ostrich (Struthio camelus) cranium

The first finite element (FE) validation of a complete avian cranium was performed on an extant palaeognath, the ostrich (Struthio camelus).Ex-vivostrains were collected from the cranial bone and rhamphotheca. These experimental strains were then compared to convergence tested, specimen-specific finite element (FE) models. The FE models contained segmented cortical and trabecular bone, sutures and the keratinous rhamphotheca as identified from micro-CT scan data. Each of these individual materials was assigned isotropic material properties either from the literature or from nanoindentation, and the FE models compared to theex-vivoresults. The FE models generally replicate the location of peak strains and reflect the correct mode of deformation in the rostral region. The models are too stiff in regions of experimentally recorded high strain and too elastic in regions of low experimentally recorded low strain. The mode of deformation in the low strain neurocranial region is not replicated by the FE models, and although the models replicate strain orientations to within 10° in some regions, in most regions the correlation is not strong. Cranial sutures, as has previously been found in other taxa, are important for modifying both strain magnitude and strain patterns across the entire skull, but especially between opposing the sutural junctions. Experimentally, we find that the strains on the surface of the rhamphotheca are much lower than those found on nearby bone. The FE models produce much higher principal strains despite similar strain ratios across the entirety of the rhamphotheca. This study emphasises the importance of attempting to validate FE models, modelling sutures and rhamphothecae in birds, and shows that whilst location of peak strain and patterns of deformation can be modelled, replicating experimental data in digital models of avian crania remains problematic.

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Potential and limitations of finite element modelling in assessing structural integrity of coralline algae under future global change

Biogeosciences ◽

10.5194/bg-12-5871-2015 ◽

2015 ◽

Vol 12 (19) ◽

pp. 5871-5883 ◽

Cited By ~ 7

Author(s):

L. A. Melbourne ◽

J. Griffin ◽

D. N. Schmidt ◽

E. J. Rayfield

Keyword(s):

Climate Change ◽

Finite Element ◽

Structural Integrity ◽

Geometric Model ◽

Algal Growth ◽

Coralline Algae ◽

Rocky Shores ◽

Element Analysis ◽

Scan Data ◽

The Impact

Abstract. Coralline algae are important habitat formers found on all rocky shores. While the impact of future ocean acidification on the physiological performance of the species has been well studied, little research has focused on potential changes in structural integrity in response to climate change. A previous study using 2-D Finite Element Analysis (FEA) suggested increased vulnerability to fracture (by wave action or boring) in algae grown under high CO2 conditions. To assess how realistically 2-D simplified models represent structural performance, a series of increasingly biologically accurate 3-D FE models that represent different aspects of coralline algal growth were developed. Simplified geometric 3-D models of the genus Lithothamnion were compared to models created from computed tomography (CT) scan data of the same genus. The biologically accurate model and the simplified geometric model representing individual cells had similar average stresses and stress distributions, emphasising the importance of the cell walls in dissipating the stress throughout the structure. In contrast models without the accurate representation of the cell geometry resulted in larger stress and strain results. Our more complex 3-D model reiterated the potential of climate change to diminish the structural integrity of the organism. This suggests that under future environmental conditions the weakening of the coralline algal skeleton along with increased external pressures (wave and bioerosion) may negatively influence the ability for coralline algae to maintain a habitat able to sustain high levels of biodiversity.

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Influence of Loading Conditions in Finite Element Analysis Assessed by HR–pQCT on Ex Vivo Fracture Prediction

Bone ◽

10.1016/j.bone.2021.116206 ◽

2021 ◽

pp. 116206

Author(s):

M. Revel ◽

F. Bermond ◽

F. Duboeuf ◽

D. Mitton ◽

H. Follet

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Ex Vivo ◽

Fracture Prediction ◽

Loading Conditions ◽

Element Analysis

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Reliability-Based Assessment Method of Buried Pipeline at Fault Crossings

Volume 2: Pipeline Safety Management Systems; Project Management, Design, Construction, and Environmental Issues; Strain Based Design; Risk and Reliability; Northern, Offshore, and Production Pipelines ◽

10.1115/ipc2020-9609 ◽

2020 ◽

Author(s):

Qian Zheng ◽

Xiaoben Liu ◽

Hong Zhang ◽

Samer Adeeb

Keyword(s):

Neural Network ◽

Finite Element ◽

Finite Element Model ◽

Limit State ◽

Element Model ◽

Normal Operation ◽

Operating Pressure ◽

Peak Strain ◽

Highly Nonlinear ◽

Fault Displacement

Abstract The tectonic fault, which is one of the most common geohazards in field, poses great threat to buried pipe segments. Pipes will process to buckling or fracture due to large strain induced by continuously increasing ground displacements during earthquakes. Therefore, it is imperative to conduct safety analysis on pipes which are buried in seismic areas for the sake of ensuring normal operation. However, the highly nonlinearity of pipe response restricts the proceeding of reliability assessment. In this study, a hybrid procedure combining finite element method and artificial neural network is proposed for reliability-based assessment. First of all, the finite element model is developed on ABAQUS platform to simulate pipe response to strike-slip fault displacements. Thus, the strain demand value (the peak strain value obtained by finite element model in each design case) can be collected for database establishment, which is the preparation for neural network training. Thoroughness of the strain demand database can be achieved by a fully comprehensive calculation with consideration of influencing factors involving pipe diameter and wall thickness, operating pressure, magnitude of fault displacement, intersection angle between pipeline and fault plane, and characteristic value of backfill mechanics. Sequentially, Back Propagation Neural Network (BPNN) with double hidden layers is trained based on the developed database, and the surrogate strain demand prediction model can be obtained after accuracy verification. Hence, the strain-based limit state function can be respectively determined for tensile and compressive conditions. The strain capacity term is simply assumed based on published papers, the strain demand term is naturally superseded by the surrogate BPNN model, and Monte Carlo Simulation is employed to compute the probability of failure (POF). At last, the workability of the proposed approach is tested by a case study in which basic variables are referred to the Second West-to-East natural gas transmission pipeline project. It indicates that ANN is a good solver for reliability problems with implicit limit state functions especially for highly nonlinear problems. The proposed method is capable of computing POFs, which is an exploratory application for reliability research on pipes withstanding fault displacement loads.

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Measurement of bone surface strains on the sheep metacarpus in vivo and ex vivo

Veterinary and Comparative Orthopaedics and Traumatology ◽

10.1055/s-0038-1632754 ◽

2003 ◽

Vol 16 (01) ◽

pp. 38-43 ◽

Cited By ~ 3

Author(s):

R. Steck ◽

C. Gatzka ◽

E. Schneider ◽

P. Niederer ◽

M. L. Tate

Keyword(s):

Ex Vivo ◽

Longitudinal Axis ◽

Peak Strain ◽

Bone Surface ◽

Interstitial Fluid Flow ◽

Ex Vivo Model ◽

Physiological Strain ◽

Bending Load ◽

Walking Speeds

SummaryBone surface strains were measured on the dorsal ovine metacarpus during normal locomotion on a treadmill at different walking speeds to determine physiological strain levels. These measured strains were related to the strains measured in an ex vivo model of the sheep forelimb with two types of load application: loading by two Schanz-screws and loading via the radius. In vivo, the average surface strains were found to be dependent upon body weight as well as the walking speed. The orientation of the peak principal strain corresponded to the longitudinal axis of the bone. Ex vivo, loads applied via Schanz screws in the screw-loading model lead to strains on the dorsal metacarpus that corresponds to strains experienced in vivo during intermittent peak loads. Screw loading imparted primarily a bending load to the metacarpus, with the dorsal aspect in compression and the palmar aspect in tension. Loads, applied via the radius and the hoof in the radius-loading model, resulted in bone surface strains comparable to those measured during slow walking in vivo. In both ex vivo loading situations, peak strain orientation was parallel to the longitudinal axis of the sheep metacarpus. In conclusion, the results show that although the ex vivo loading models do not exactly replicate the load experienced in vivo, the magnitude and orientation of the principal strains on the dorsal metacarpus are within the range of strains occurring during normal physiological loading. These data validate the physiological significance of the ex vivo model and aid in understanding effects of mechanical loading on interstitial fluid flow and mass transport through bone.

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The Application of Digital Volume Correlation (DVC) to Evaluate Strain Predictions Generated by Finite Element Models of the Osteoarthritic Humeral Head

Annals of Biomedical Engineering ◽

10.1007/s10439-020-02549-2 ◽

2020 ◽

Vol 48 (12) ◽

pp. 2859-2869 ◽

Cited By ~ 1

Author(s):

Jonathan Kusins ◽

Nikolas Knowles ◽

Melanie Columbus ◽

Sara Oliviero ◽

Enrico Dall’Ara ◽

...

Keyword(s):

Finite Element ◽

Humeral Head ◽

Total Shoulder Arthroplasty ◽

Mechanical Strain ◽

Digital Volume Correlation ◽

Finite Element Models ◽

Full Field ◽

Loaded State ◽

Microct Imaging ◽

Experimental Strains

AbstractContinuum-level finite element models (FEMs) of the humerus offer the ability to evaluate joint replacement designs preclinically; however, experimental validation of these models is critical to ensure accuracy. The objective of the current study was to quantify experimental full-field strain magnitudes within osteoarthritic (OA) humeral heads by combining mechanical loading with volumetric microCT imaging and digital volume correlation (DVC). The experimental data was used to evaluate the accuracy of corresponding FEMs. Six OA humeral head osteotomies were harvested from patients being treated with total shoulder arthroplasty and mechanical testing was performed within a microCT scanner. MicroCT images (33.5 µm isotropic voxels) were obtained in a pre- and post-loaded state and BoneDVC was used to quantify full-field experimental strains (≈ 1 mm nodal spacing, accuracy = 351 µstrain, precision = 518 µstrain). Continuum-level FEMs with two types of boundary conditions (BCs) were simulated: DVC-driven and force-driven. Accuracy of the FEMs was found to be sensitive to the BC simulated with better agreement found with the use of DVC-driven BCs (slope = 0.83, r2 = 0.80) compared to force-driven BCs (slope = 0.22, r2 = 0.12). This study quantified mechanical strain distributions within OA trabecular bone and demonstrated the importance of BCs to ensure the accuracy of predictions generated by corresponding FEMs.

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Quasi-static and dynamic motions of the columellar footplate in ostrich ( Struthio camelus ) measured ex vivo

Hearing Research ◽

10.1016/j.heares.2017.11.005 ◽

2018 ◽

Vol 357 ◽

pp. 10-24 ◽

Cited By ~ 7

Author(s):

Pieter G.G. Muyshondt ◽

Raf Claes ◽

Peter Aerts ◽

Joris J.J. Dirckx

Keyword(s):

Ex Vivo ◽

Struthio Camelus

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Mitral Valve Finite Element Modeling: Implications of Tissues’ Nonlinear Response and Annular Motion

Journal of Biomechanical Engineering ◽

10.1115/1.4000107 ◽

2009 ◽

Vol 131 (12) ◽

Cited By ~ 27

Author(s):

Marco Stevanella ◽

Emiliano Votta ◽

Alberto Redaelli

Keyword(s):

Finite Element ◽

Finite Element Modeling ◽

Morphological Description ◽

Peak Strain ◽

Papillary Muscles ◽

Anterior Leaflet ◽

Auxiliary Model ◽

Element Modeling ◽

Clinical Scenarios ◽

Tensile Strains

Finite element modeling represents an established method for the comprehension of the mitral function and for the simulation of interesting clinical scenarios. However, current models still do not include all the key aspects of the real system. We implemented a new structural finite element model that considers (i) an accurate morphological description of the valve, (ii) a description of the tissues’ mechanical properties that accounts for anisotropy and nonlinearity, and (iii) dynamic boundary conditions that mimic annulus and papillary muscles’ contraction. The influence of such contraction on valve biomechanics was assessed by comparing the computed results with the ones obtained through an auxiliary model with fixed annulus and papillary muscles. At the systolic peak, the leaflets’ maximum principal stress contour showed peak values in the anterior leaflet at the strut chordae insertion zone (300 kPa) and near the annulus (200–250 kPa), while much lower values were detected in the posterior leaflet. Both leaflets underwent larger tensile strains in the longitudinal direction, while in the circumferential one the anterior leaflet experienced nominal tensile strains up to 18% and the posterior one experienced compressive strains up to 23% associated with the folding of commissures and paracommissures, consistently with tissue redundancy. The force exerted by papillary muscles at the systolic peak was equal to 4.11 N, mainly borne by marginal chordae (76% of the force). Local reaction forces up to 45 mN were calculated on the annulus, leading to tensions of 89 N/m and 54 N/m for its anterior and posterior tracts, respectively. The comparison with the results of the auxiliary model showed that annular contraction mainly affects the leaflets’ circumferential strains. When it was suppressed, no more compressive strains could be observed and peak strain values were located in the belly of the anterior leaflet. Computational results agree to a great extent with experimental data from literature. They provided insight into some of the features characterizing normal mitral function, such as annular contraction and leaflets’ tissue anisotropy and nonlinearity. Some of the computed results may be useful in the design of surgical devices and techniques. In particular, forces applied on the annulus by the surrounding tissues could be considered as an indication for annular prostheses design.

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Improvement and FEA of New Type of Osteointegrated Implant for Higher Amputated Leg Attachment

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.342-343.829 ◽

2007 ◽

Vol 342-343 ◽

pp. 829-832

Author(s):

J.M. Luo ◽

L. Zheng ◽

X.H. Shi ◽

Yao Wu ◽

Xing Dong Zhang

Keyword(s):

Finite Element Analysis ◽

Finite Element ◽

Distal Part ◽

Element Analysis ◽

Bone Stress ◽

Traditional Design ◽

Maximal Stress ◽

New Type ◽

Scan Data ◽

Leg Prosthesis

Stress concentration is one of the main mechanical problems leading to the failure of clinical application for osteointegrated implant of percutaneous osteointegrated prosthesis, which is especially marked for higher amputated leg prosthesis. Traditionally design was composed of only the distal part. To improve the biomechanical safety, a new design with the lag part similar to the lag screw was introduced. Based on CT scan data, relatively accurate model of femur for finite element analysis (FEA) were obtained. The FEA results with the new implant demonstrated that compared to traditional design, the declination of bone stress peak ranged from 15.68% to 28.67%, perpendicular deformation from 34.73% to 72.16%, and maximal stress of implant from 14.51% to 23.36% with the increasing of loads from 3750N to 2000N. So the new design of osteointegrated implant would be more secure mechanically, in the case of higher amputated leg attachment.

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Impaction Loads Resulting in Intraoperative Periprosthetic Femoral Fracture: A Finite Element Study

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.553.299 ◽

2014 ◽

Vol 553 ◽

pp. 299-304

Author(s):

Caleb Christos Ioannidis ◽

Danè Dabirrahmani ◽

Qing Li ◽

Zhong Pu Zhang ◽

Jun Ning Chen ◽

...

Keyword(s):

Finite Element ◽

Extended Finite Element Method ◽

Femoral Stem ◽

Femoral Fractures ◽

Patient Specific ◽

Periprosthetic Femoral Fracture ◽

Extended Finite Element ◽

Bone Damage ◽

Scan Data ◽

And Gender

Intraoperative periprosthetic femoral fractures (IPPFF) occur in approximately 3-5% of all cementless total hip arthroplasty (THA) surgeries. This study aimed to identify the critical impaction load to cause an IPPFF during implant implementation. This critical load may be used as a guideline for surgeons as well as a parameter for the design of future surgical tools and procedures. This study concerned a single femur of a healthy 60 year old female with an anatomical femoral stem implant, thus the effects of patient specific variables (such as osteoporosis, amount of bone resorption, bone damage, implant geometry, age and gender) were not considered. The eXtended Finite Element Method (XFEM) was used to analyse the fracture. From CT scan data, a user-defined subroutine is used to assign heterogeneous isotropic material properties to the femur. It was computed that IPPFF would take place at an impaction load of 18.5 kN.

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