scholarly journals Determination of the hyperelastic material behavior of hydrogel specimens for expandable lens implants

2019 ◽  
Vol 5 (1) ◽  
pp. 351
Author(s):  
Heiner Martin ◽  
Olga Sahmel ◽  
Thomas Eickner ◽  
Niels Grabow ◽  
Christine Kreiner ◽  
...  
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Material Properties ◽  
Element Model ◽  
Material Behavior ◽  
Hyperelastic Material ◽  
Human Lens ◽  
Experimental Investigations

Abstract Theoretical and experimental investigations were carried out for development of human lens implants made from hydrogel material. The material properties were measured and implemented in a Finite element model. Though the material is still too stiff for accommodative lenses, the theoretical and experimental foundations for the implant development were established.

scholarly journals A novel finite element model of the ovine lumbar intervertebral disc with anisotropic hyperelastic material properties

PLoS ONE ◽  
2017 ◽  
Vol 12 (5) ◽  
pp. e0177088 ◽  
Author(s):  
Gloria Casaroli ◽  
Fabio Galbusera ◽  
René Jonas ◽  
Benedikt Schlager ◽  
Hans-Joachim Wilke ◽  
...  
Keyword(s):  
Finite Element ◽  
Intervertebral Disc ◽  
Finite Element Model ◽  
Material Properties ◽  
Element Model ◽  
Hyperelastic Material ◽  
Lumbar Intervertebral Disc

Dynamic Analysis of a Turbocharger Centrifugal Compressor Impeller

1991 ◽  
Author(s):  
V. Ramamurti ◽  
D. A. Subramani ◽  
K. Sridhara
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Centrifugal Compressor ◽  
Element Model ◽  
Simplified Model ◽  
Cyclic Symmetry ◽  
Compressor Impeller ◽  
Cyclic Symmetric ◽  
The Finite Element Model

Abstract Stress analysis and determination of eigen pairs of a typical turbocharger compressor impeller have been carried out using the concept of cyclic symmetry. A simplified model treating the blade and the hub as isolated elements has also been attempted. The limitations of the simplified model have been brought out. The results of the finite element model using the cyclic symmetric approach have been discussed.

FEBio finite element model of a pediatric cervical spine

2021 ◽  
pp. 1-7
Author(s):  
Sean M. Finley ◽  
J. Harley Astin ◽  
Evan Joyce ◽  
Andrew T. Dailey ◽  
Douglas L. Brockmeyer ◽  
...  
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Material Properties ◽  
Surgical Simulation ◽  
Element Model ◽  
Axial Stiffness ◽  
Published Data ◽  
Axial Tension ◽  
Flexion Extension

OBJECTIVE The underlying biomechanical differences between the pediatric and adult cervical spine are incompletely understood. Computational spine modeling can address that knowledge gap. Using a computational method known as finite element modeling, the authors describe the creation and evaluation of a complete pediatric cervical spine model. METHODS Using a thin-slice CT scan of the cervical spine from a 5-year-old boy, a 3D model was created for finite element analysis. The material properties and boundary and loading conditions were created and model analysis performed using open-source software. Because the precise material properties of the pediatric cervical spine are not known, a published parametric approach of scaling adult properties by 50%, 25%, and 10% was used. Each scaled finite element model (FEM) underwent two types of simulations for pediatric cadaver testing (axial tension and cardinal ranges of motion [ROMs]) to assess axial stiffness, ROM, and facet joint force (FJF). The authors evaluated the axial stiffness and flexion-extension ROM predicted by the model using previously published experimental measurements obtained from pediatric cadaveric tissues. RESULTS In the axial tension simulation, the model with 50% adult ligamentous and annulus material properties predicted an axial stiffness of 49 N/mm, which corresponded with previously published data from similarly aged cadavers (46.1 ± 9.6 N/mm). In the flexion-extension simulation, the same 50% model predicted an ROM that was within the range of the similarly aged cohort of cadavers. The subaxial FJFs predicted by the model in extension, lateral bending, and axial rotation were in the range of 1–4 N and, as expected, tended to increase as the ligament and disc material properties decreased. CONCLUSIONS A pediatric cervical spine FEM was created that accurately predicts axial tension and flexion-extension ROM when ligamentous and annulus material properties are reduced to 50% of published adult properties. This model shows promise for use in surgical simulation procedures and as a normal comparison for disease-specific FEMs.

A FINITE ELEMENT MODEL FOR COMPRESSIVE ICE LOADS BASED ON A MOHR-COULOMB MATERIAL AND THE NODE SPLITTING TECHNIQUE

2021 ◽  
pp. 1-33
Author(s):  
Hauke Herrnring ◽  
Søren Ehlers
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Material Behavior ◽  
Double Pendulum ◽  
Strain Rates ◽  
Splitting Technique ◽  
Structure Interaction ◽  
Node Splitting ◽  
Brittle Mode

Abstract This paper presents a finite element model for the simulation of ice-structure interaction problems, which are dominated by crushing. The failure mode of ice depends significantly on the strain rate. At low strain rates the ice behaves ductile, whereas at high strain rates ice reacts in brittle mode. This paper focuses on the brittle mode, which is the dominating mode for ship-ice interactions. A multitude of numerical approaches for the simulation of ice can be found in the literature. Nevertheless, the literature approaches do not seem suitable for the simulation of continuous ice-structure interaction processes at low and high confinement ratios in brittle mode. Therefore, this paper seeks to simulate the ice-structure interaction with the finite element method (FEM). The objective of the here introduced Mohr-Coulomb Nodal Split (MCNS) model is to represent the essential material behavior of ice in an efficient formulation. To preserve mass and energy as much as possible, the node splitting technique is applied, instead of the frequently used element erosion technique. The intention of the presented model is not to reproduce individual cracks with high accuracy, because this is not possible with a reasonable element size, due to the large number of crack fronts forming during the ice-structure interaction process. To validate the findings of the model, the simulated maximum ice forces and contact pressures are compared with ice-extrusion and double pendulum tests. During validation, the MCNS model shows a very good agreement with these experimental values.

Determination of wire resistance caused by skin effect using modified 3D finite element model

2020 ◽  
Vol 102 (3) ◽  
pp. 1513-1520
Author(s):  
Jorge Rafael González-Teodoro ◽  
Enrique Romero-Cadaval ◽  
Rafael Asensi ◽  
Vladimir Kindl
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Skin Effect ◽  
Element Model ◽  
3D Finite Element ◽  
3D Finite Element Model ◽  
Wire Resistance

Identification Scheme to Assess the Role of Interfacial Damage in a Hemp-Starch Biocomposite

2014 ◽  
Vol 875-877 ◽  
pp. 524-528
Author(s):  
Sofiane Guessasma ◽  
Mohameden Hbib ◽  
David Bassir
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Precise Determination ◽  
Mechanical Parameters ◽  
Interfacial Damage ◽  
Failure Properties ◽  
Experimental Response

This paper aims at studying the effect of interfacial damage on the mechanical behavior of starch - hemp composite. The procedure encompasses an experimental investigation towards the determination of microstructural features and mechanical testing of the material. A finite element model is developed to account for a particular damage kinetics that triggers failure properties. Our results show that the experimental evidence of interfacial damage driven failure is achieved. Finite element model is able to capture this feature using an abrupt damage criterion. But in order to identify the observed behavior, the experimental response is matched with the numerical one. This process tunes the mechanical parameters to fit the experimental response. The optimization process conducted in this way leads to a precise determination of the mechanical parameters that quantifies the observed ultimate properties.

A Comparative Study of the Human Body Finite Element Model Under Blast Loadings

2012 ◽  
Author(s):  
X. G. Tan ◽  
R. Kannan ◽  
Andrzej J. Przekwas
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Human Body ◽  
Material Properties ◽  
Complex Geometry ◽  
Blast Loading ◽  
Element Model ◽  
Stress Wave Propagation ◽  
Brain Response ◽  
Time Step

Until today the modeling of human body biomechanics poses many great challenges because of the complex geometry and the substantial heterogeneity of human body. We developed a detailed human body finite element model in which the human body is represented realistically in both the geometry and the material properties. The model includes the detailed head (face, skull, brain, and spinal cord), the skeleton, and air cavities (including the lung). Hence it can be used to accurately acquire the stress wave propagation in the human body under various loading conditions. The blast loading on the human surface was generated from the simulated C4 blast explosions, via a novel combination of 1-D and 3-D numerical formulations. We used the explicit finite element solver in the multi-physics code CoBi for the human body biomechanics. This is capable of solving the resulting large system containing millions of unknowns in an extremely scalable fashion. The meshes generated for these simulations are of good quality. This enables us to employ relatively large time step sizes, without resorting to the artificial time scaling treatment. In order to study the human body dynamic response under the blast loading, we also developed an interface to apply the blast pressure loading on the external human body surface. These newly developed models were used to conduct parametric simulations to find out the brain biomechanical response when the blasts impact the human body. Under the same blast loading we also show the differences of brain response when having different material properties for the skeleton, the existence of other body parts such as torso.

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