Improved Prediction of Local Trabecular Strain Enhances Non-Invasive Assessment of Micro Bone Strength Using a Surface Smoothing Technique in FEA

2007 ◽  
Author(s):  
Suzanne L. Ferreri ◽  
Yi-Xian Qin
Keyword(s):  
Finite Element ◽  
Nondestructive Evaluation ◽  
Bone Quality ◽  
Peak Stress ◽  
Bone Volume ◽  
Micro Ct ◽  
Smoothing Technique ◽  
Surface Smoothing ◽  
Non Invasive

One key issue in clinical, non-invasive assessment of bone quality and fracture risk is the accurate prediction of localized trabecular strength through the determination of peak stress values and locations. Additionally, it has been suggested that peak stress/strain concentrations may play an important role in driving the bone remodeling process. Micro-CT based voxel finite element (FE) meshes have been widely used in nondestructive evaluation of global stiffness. Subsequently, this technique has been advantageous in studies addressing changes in bone volume and microstructure.

scholarly journals Determination of anisotropic elastic parameters from morphological parameters of cancellous bone for osteoporotic lumbar spine

2021 ◽  
Author(s):  
Christoph Oefner ◽  
Elena Riemer ◽  
Kerstin Funke ◽  
Michael Werner ◽  
Christoph-Eckhard Heyde ◽  
...  
Keyword(s):  
Finite Element ◽  
Lumbar Spine ◽  
Cancellous Bone ◽  
Elastic Constants ◽  
Bone Volume ◽  
Human Bone ◽  
Homogenization Theory ◽  
Elastic Parameters ◽  
Anisotropic Elastic

AbstractIn biomechanics, large finite element models with macroscopic representation of several bones or joints are necessary to analyze implant failure mechanisms. In order to handle large simulation models of human bone, it is crucial to homogenize the trabecular structure regarding the mechanical behavior without losing information about the realistic material properties. Accordingly, morphology and fabric measurements of 60 vertebral cancellous bone samples from three osteoporotic lumbar spines were performed on the basis of X-ray microtomography (μCT) images to determine anisotropic elastic parameters as a function of bone density in the area of pedicle screw anchorage. The fabric tensor was mapped in cubic bone volumes by a 3D mean-intercept-length method. Fabric measurements resulted in a high degree of anisotropy (DA = 0.554). For the Young’s and shear moduli as a function of bone volume fraction (BV/TV, bone volume/total volume), an individually fit function was determined and high correlations were found (97.3 ≤ R2 ≤ 99.1,p < 0.005). The results suggest that the mathematical formulation for the relationship between anisotropic elastic constants and BV/TV is applicable to current μCT data of cancellous bone in the osteoporotic lumbar spine. In combination with the obtained results and findings, the developed routine allows determination of elastic constants of osteoporotic lumbar spine. Based on this, the elastic constants determined using homogenization theory can enable efficient investigation of human bone using finite element analysis (FEA).

Effects of Thresholding Techniques on μCT-Based Finite Element Models of Trabecular Bone

2006 ◽  
Vol 129 (4) ◽  
pp. 481-486 ◽  
Author(s):  
Chi Hyun Kim ◽  
Henry Zhang ◽  
George Mikhail ◽  
Dietrich von Stechow ◽  
Ralph Müller ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Trabecular Bone ◽  
Volume Fraction ◽  
Ct Images ◽  
Bone Volume ◽  
Finite Element Models ◽  
Micro Ct ◽  
Bone Volume Fraction ◽  
Element Analysis

Microimaging based finite element analysis is widely used to predict the mechanical properties of trabecular bone. The choice of thresholding technique, a necessary step in converting grayscale images to finite element models, can significantly influence the predicted bone volume fraction and mechanical properties. Therefore, we investigated the effects of thresholding techniques on microcomputed tomography (micro-CT) based finite element models of trabecular bone. Three types of thresholding techniques were applied to 16-bit micro-CT images of trabecular bone to create three different models per specimen. Bone volume fractions and apparent moduli were predicted and compared to experimental results. In addition, trabecular tissue mechanical parameters and morphological parameters were compared among different models. Our findings suggest that predictions of apparent mechanical properties and structural properties agree well with experimental measurements regardless of the choice of thresholding methods or the format of micro-CT images.

Bending Stresses at Longitudinal Weld Joints of Pressurized Cylindrical Shells due to Angular Distortion

1996 ◽  
Vol 118 (3) ◽  
pp. 369-373 ◽  
Author(s):  
L. S. Ong ◽  
K. H. Hoon
Keyword(s):  
Finite Element ◽  
Weld Joint ◽  
Welded Joint ◽  
Peak Stress ◽  
Present Theory ◽  
Order Theory ◽  
Angular Distortion ◽  
Bending Stresses ◽  
The One

This article presents a simple second-order theory for the determination of bending stresses which arise at the longitudinal welded joint of a pressurized, cylindrical shell subject to peaking, i.e., angular misalignment. Although this problem has been studied quite extensively over the years by a few authors and a few versions of simple formulas are available for the calculations of bending stresses at the welded joint, it is noted these formulas show considerable discrepancies when compared with the finite element solutions. As the additional bending stresses at the weld joint will lead to a shorter fatigue life of the joint, an improved theory to predict the peak stress at the weld joint, such as the one presented in this article, would be important and of interest to the design engineer and vessel inspector. The present theory has been validated against finite element results and shown to be extremely accurate.

Comparative Study of Mechanical Properties of Bone Tissue Based on the CT and the µCT Slices

2012 ◽  
Vol 232 ◽  
pp. 152-156 ◽  
Author(s):  
Eva Prášilová ◽  
Petr Marcián ◽  
David Krpalek ◽  
Kamil Řehák ◽  
Radomír Malina ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Image Processing ◽  
Bone Density ◽  
Bone Tissue ◽  
Bone Quality ◽  
Cancellous Bone ◽  
Strain Analysis ◽  
Micro Ct ◽  
Non Invasive ◽  
Density Analysis

This article deals with presentation of data processing obtained from imaging CT (computer tomography) and micro CT devices. These methods enable to perform bone tissue density analysis by non-invasive way. The image processing methods, by which it is possible to determine mechanical properties of bone tissue, are described in this paper. Further, a creation of a computational model with different bone density of cancellous tissue is described and afterwards the stress strain analysis is performed. The mandible segments with different bone density were used as samples. Results show significantly higher stresses are reached in a cancellous bone tissue with worse bone quality.

scholarly journals Assessment of Bone Quality using Finite Element Analysis Based upon Micro-CT Images

2009 ◽  
Vol 1 (1) ◽  
pp. 40 ◽  
Author(s):  
Yumie Rhee ◽  
June-Huyck Hur ◽  
Ye-Yeon Won ◽  
Sung-Kil Lim ◽  
Myong-Hyun Beak ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Bone Quality ◽  
Ct Images ◽  
Micro Ct ◽  
Element Analysis

INFLUENCE OF OFFICE BLEACHING SYSTEMS ON THE RESISTANCE OF HARD TOOTH TISSUES

2020 ◽  
pp. 119-125
Author(s):  
Magsumova O.A. ◽  
Postnikov M.A. ◽  
Ryskina E.A. ◽  
Tkach T.M. ◽  
Polkanova V.A.
Keyword(s):  
Informed Consent ◽  
Oral Fluid ◽  
Personal Data ◽  
Acid Resistance ◽  
Non Invasive ◽  
Hard Tissues ◽  
Voluntary Informed Consent

One of the non-invasive methods for treating discoloration of hard tooth tissues is teeth whitening. The aim of this work is to assess the dynamics of changes in the acid resistance of enamel and hard tissues of teeth and the rate of its remineralization after the procedure of office teeth whitening. The study involved 123 patients aged 18 to 35 years with discoloration of various origins, with the color of hard tooth tissues on the Vita Classic A2 scale and darker. Before performing the office, teeth whitening procedure, all patients gave their written voluntary informed consent to participate in this study, as well as consent to the processing of personal data. Depending on the chosen method of office teeth whitening, patients were divided into 3 groups. The resistance of hard tooth tissues was judged based on the determination of TOER and CASRE tests. These indicators were determined at various times (5 days before the office teeth whitening procedure, 5 days after it, after 14, 30 days and 6 months). Regardless of the chosen whitening system, the office teeth whitening procedure is accompanied by a decrease in the enamel's resistance to acids and a decrease in the rate of its remineralization. The remineralizing function of oral fluid promotes the positive dynamics of the studied parameters after 14 days and after 30 days values increased due to the appointment of remineralizing therapy to all patients in 2 weeks after the teeth whitening procedure. After 6 months, all patients had high enamel resistance and the rate of its remineralization.

Optimization of Extraction Parameters of Reverse Iontophoretic Determination of Blood Glucose in an Artificial Skin Model

2020 ◽  
Vol 16 (6) ◽  
pp. 722-737
Author(s):  
Cigdem Yengin ◽  
Emrah Kilinc ◽  
Fatma Gulay Der ◽  
Mehmet Can Sezgin ◽  
Ilayda Alcin
Keyword(s):  
Ionic Strength ◽  
Body Fluids ◽  
Extraction Time ◽  
Artificial Skin ◽  
Dialysis Membrane ◽  
Skin Model ◽  
Non Invasive ◽  
Electrode Distance ◽  
Experimental Parameters

Background: Reverse İontophoresis (RI) is one of the promising non-invasive technologies. It relies on the transition of low magnitude current through the skin and thus glucose measurement becomes possible as it is extracted from the surface during this porter current flow. Objective: This paper deals with the development and optimization of an RI determination method for glucose. CE dialysis membrane based artificial skin model was developed and the dependence of RI extraction on various experimental parameters was investigated. Method: Dependence of RI extraction performance on noble electrodes (platinum, silver, palladium, ruthenium, rhodium) was checked with CA, CV and DPV, in a wide pH and ionic strength range. Optimizations on inter-electrode distance, potential type and magnitude, extraction time, gel type, membrane MWCO, usage frequency, pretreatment, artificial body fluids were performed. Results: According to the optimized results, the inter-electrode distance was 7.0 mm and silver was the optimum noble metal. Optimum pH and ionic strength were achieved with 0.05M PBS at pH 7.4. Higher glucose yields were obtained with DPV, while CA and CV achieved almost the same levels. During CA, +0.5V achieved the highest glucose yield and higher potential even caused a decrease. Glucose levels could be monitored for 24 hours. CMC gel was the optimum collection media. Pretreated CE membrane with 12kD MWCO was the artificial skin model. Pretreatment affected the yields while its condition caused no significant difference. Except PBS solution (simulated as artificial plasma), among the various artificial simulated body fluids, intestinal juice formulation (AI) and urine formulation U2 were the optimum extraction media, respectively. Conclusion: In this study, various experimental parameters (pretereatment procedure, type and MWCO values of membranes, inter-electrode distance, electrode material, extraction medium solvents, ionic strength and pH, collection medium gel type, extraction potential type and magnitude, extraction time and etc) were optimized for the non-invasive RI determination of glucose in a CE dialysis membrane-based artificial skin model and various simulated artificial body fluids.

Determination of the thermal properties of leaves by non-invasive contact‑free laser probing

2016 ◽  
Vol 217 ◽  
pp. 100-108 ◽  
Author(s):  
J.F. Buyel ◽  
H.M. Gruchow ◽  
N. Tödter ◽  
M. Wehner
Keyword(s):  
Thermal Properties ◽  
Non Invasive ◽  
Laser Probing ◽  
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