Combining specimen-specific finite-element models and optimization in cortical-bone material characterization improves prediction accuracy in three-point bending tests

2018 ◽  
Vol 76 ◽  
pp. 103-111 ◽  
Author(s):  
Guanjun Zhang ◽  
Songyang Xu ◽  
Jie Yang ◽  
Fengjiao Guan ◽  
Libo Cao ◽  
...  
Keyword(s):  
Finite Element ◽  
Cortical Bone ◽  
Material Characterization ◽  
Prediction Accuracy ◽  
Finite Element Models ◽  
Bone Material ◽  
Bending Tests ◽  
Three Point Bending

Novel and simplified optimisation pathway using response surface and design of experiments methodologies for dental implants based on the stress of the cortical bone

2021 ◽  
pp. 095441192110253
Author(s):  
João PO Freitas ◽  
Bruno Agostinho Hernandez ◽  
Paulo J Paupitz Gonçalves ◽  
Edmea C Baptista ◽  
Edson A Capello Sousa
Keyword(s):  
Finite Element ◽  
Stress Distribution ◽  
Design Of Experiments ◽  
Cortical Bone ◽  
Response Surface ◽  
Dental Implants ◽  
Finite Element Models ◽  
Long Term Treatment ◽  
Dimensional Finite Element ◽  
Surrounding Bone

Dental implants are widely used as a long-term treatment solution for missing teeth. A titanium implant is inserted into the jawbone, acting as a replacement for the lost tooth root and can then support a denture, crown or bridge. This allows discreet and high-quality aesthetic and functional improvement, boosting patient confidence. The use of implants also restores normal functions such as speech and mastication. Once an implant is placed, the surrounding bone will fuse to the titanium in a process known as osseointegration. The success of osseointegration is dependent on stress distribution within the surrounding bone and thus implant geometry plays an important role in it. Optimisation analyses are used to identify the geometry which results in the most favourable stress distribution, but the traditional methodology is inefficient, requiring analysis of numerous models and parameter combinations to identify the optimal solution. A proposed improvement to the traditional methodology includes the use of Design of Experiments (DOE) together with Response Surface Methodology (RSM). This would allow for a well-reasoned combination of parameters to be proposed. This study aims to use DOE, RSM and finite element models to develop a simplified optimisation analysis method for dental implant design. Drawing on data and results from previous studies, two-dimensional finite element models of a single Branemark implant, a multi-unit abutment, two prosthetic screws, a prosthetic crown and a region of mandibular bone were built. A small number of combinations of implant diameter and length were set based on the DOE method to analyse the influence of geometry on stress distribution at the bone-implant interface. The results agreed with previous studies and indicated that implant length is the critical parameter in reducing stress on cortical bone. The proposed method represents a more efficient analysis of multiple geometrical combinations with reduced time and computational cost, using fewer than a third of the models required by the traditional methods. Further work should include the application of this methodology to optimisation analyses using three-dimensional finite element models.

Investigation of tensile and flexural behavior of biaxial and rib 1 × 1 weft-knitted composite using experimental tests and multi-scale finite element modeling

2019 ◽  
Vol 53 (23) ◽  
pp. 3201-3215 ◽  
Author(s):  
Reza Hessami ◽  
Aliasghar Alamdar Yazdi ◽  
Abbas Mazidi
Keyword(s):  
Finite Element ◽  
Finite Element Modeling ◽  
Experimental Results ◽  
Flexural Behavior ◽  
Bending Tests ◽  
Three Point Bending ◽  
Element Modeling ◽  
Multi Scale ◽  
Scale Modeling ◽  
Composite Samples

In this study, tensile and flexural behavior of biaxial and rib weft-knitted composite is obtained numerically and experimentally. Multi-scale finite element modeling is employed to simulate the tensile and flexural behavior of composite samples. In the finite element modeling, the geometry of a unit cell of each fabric is initially modeled in ABAQUS software, and then periodic boundary conditions were applied to a unit cell. The stiffness matrix for each structure was obtained by a python code via meso scale modeling and used as input data for the macro modeling. To validate the numerical model, two types of weft-knitted fabrics (rib 1 × 1 and biaxial fabrics) are produced by a flat weft knitting machine. Epoxy resin is used to construct composite by the vacuum injection process (VIP). After that, the tensile and three-point bending tests were applied to composite samples. The experimental results showed that tensile strength and tensile modulus of biaxial composites are greater than rib composites, in both wale and course directions. Moreover, in three-point bending test, biaxial composite showed more strength and more stiffness in comparison to rib composite. Finite element results were compared to experimental results in tensile and bending tests. The results showed that good agreement with experimental results in the linear section of tensile and flexural behavior of composites. Consequently, the current multi-scale modeling can be used to predict the stiffness matrix and mechanical behavior of complex composite structures such as knitted composites.

Finite Element Modeling for Energy Release Rate in Human Cortical Bone

Volume 2 ◽  
2004 ◽  
Author(s):  
Saiphon Charoenphan ◽  
Apiwon Polchai
Keyword(s):  
Finite Element ◽  
Crack Propagation ◽  
Finite Element Modeling ◽  
Energy Release Rate ◽  
Cortical Bone ◽  
Energy Release ◽  
Crack Growth ◽  
Release Rate ◽  
Slow Crack Growth ◽  
Finite Element Models

The energy release rates in human cortical bone are investigated using a hybrid method of experimental and finite element modeling techniques. An explicit finite element analysis was implemented with an energy release rate calculation for evaluating this important fracture property of bones. Comparison of the critical value of the energy release rate, Gc, shows good agreement between the finite element models and analytical solutions. The Gc was found to be approximately 820–1150 J/m2 depending upon the samples. Specimen thickness appears to have little effect on the plane strain condition and pure mode I assumption. Therefore the energy release rate can be regarded as a material constant and geometry independent and can be determined with thinner specimens. In addition, the R curve resulting from the finite element models during slow crack growth shows slight ductility of the bone specimen that indicates an ability to resist crack propagation. Oscillations were found at the onset of the crack growth due to the nodal releasing application in the models. In this study light mass-proportional damping was used to suppress the noises. Although this techniques was found to be efficient for this slow crack growth simulation, other methods to continuously release nodes during the crack growth would be recommended for rapid crack propagation.

Finite Element Analysis of Woven Airbeams

2006 ◽  
Author(s):  
Christopher G. Malm ◽  
William G. Davids ◽  
Michael L. Peterson ◽  
Hui Zhang
Keyword(s):  
Finite Element ◽  
Finite Element Models ◽  
Storage Space ◽  
Element Analysis ◽  
Irreversible Damage ◽  
Three Point Bending ◽  
Finite Element Software ◽  
Mesh Density ◽  
Explicit Solver ◽  
Solution Accuracy

The underlying mechanics of airbeam structures continues to be a topic of current research. Airbeams are attractive because they have the advantage of outstanding strength-to-weight ratios, can deform without causing irreversible damage to the structure, and the deflated storage space is small. Major challenges in the analysis of airbeams include capturing fabric wrinkling under small compressive strains and incorporating the effects of internal pressure. This paper presents results from analyses of cylindrical woven airbeams using the commercial finite element software package ABAQUS. Models are created using a combination of shell and membrane elements, and loaded in three point bending. The models are solved as quasi-static using the ABAQUS/Explicit solver. The effects of mesh density and material damping on solution accuracy are investigated. Results of the finite element models are compared to experimental data.

A new approach for assigning bone material properties from CT images into finite element models

2010 ◽  
Vol 43 (5) ◽  
pp. 1011-1015 ◽  
Author(s):  
G. Chen ◽  
B. Schmutz ◽  
D. Epari ◽  
K. Rathnayaka ◽  
S. Ibrahim ◽  
...  
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Ct Images ◽  
Finite Element Models ◽  
Bone Material ◽  
New Approach ◽  
Bone Material Properties

Development of specimen-specific finite element models of human vertebrae for the analysis of vertebroplasty

2008 ◽  
Vol 222 (2) ◽  
pp. 221-228 ◽  
Author(s):  
V N Wijayathunga ◽  
A C Jones ◽  
R J Oakland ◽  
N R Furtado ◽  
R M Hall ◽  
...  
Keyword(s):  
Finite Element ◽  
Material Properties ◽  
Bulk Material ◽  
Image Data ◽  
Finite Element Models ◽  
Micro Computed Tomography ◽  
Bone Material ◽  
Automated Methods ◽  
Pmma Cement ◽  
Good Agreement

The aim of this study was to determine the accuracy of specimen-specific finite element models of untreated and cement-augmented vertebrae by direct comparison with experimental results. Eleven single cadaveric vertebrae were imaged using micro computed tomography (mCT) and tested to failure in axial compression in the laboratory. Four of the specimens were first augmented with PMMA cement to simulate a prophylactic vertebroplasty. Specimen-specific finite element models were then generated using semi-automated methods. An initial set of three untreated models was used to determine the optimum conversion factors from the image data to the bone material properties. Using these factors, the predicted stiffness and strength were determined for the remaining specimens (four untreated, four augmented). The model predictions were compared with the corresponding experimental data. Good agreement was found with the non-augmented specimens in terms of stiffness (root-mean-square (r.m.s.) error 12.9 per cent) and strength (r.m.s. error 14.4 per cent). With the augmented specimens, the models consistently overestimated both stiffness and strength (r.m.s. errors 65 and 68 per cent). The results indicate that this method has the potential to provide accurate predictions of vertebral behaviour prior to augmentation. However, modelling the augmented bone with bulk material properties is inadequate, and more detailed modelling of the cement region is required to capture the bone—cement interactions if the models are to be used to predict the behaviour following vertebroplasty.

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