Rapid and reliable biomechanical screening of injectable bone cements for autonomous augmentation of osteoporotic vertebral bodies: Appropriate values of elastic constants for finite element models

2007 ◽  
Vol 82B (2) ◽  
pp. 408-417 ◽  
Author(s):  
Gladius Lewis ◽  
Jie Xu
Keyword(s):  
Finite Element ◽  
Elastic Constants ◽  
Finite Element Models ◽  
Bone Cements ◽  
Vertebral Bodies

Micro-CT-Based Large Scale Linear Finite Element Models Predict the Strength of Human Thoracic and Lumbar Vertebral Bodies

2007 ◽  
Author(s):  
Yener N. Yeni ◽  
Do-Gyoon Kim ◽  
Roger R. Zauel ◽  
Evan M. Johnson ◽  
Dianna D. Cody
Keyword(s):  
Finite Element ◽  
Large Scale ◽  
Quantitative Computed Tomography ◽  
Finite Element Models ◽  
Micro Ct ◽  
Linear Finite Element ◽  
Vertebral Strength ◽  
Local Properties ◽  
Vertebral Bodies ◽  
Architectural Detail

Vertebral fractures are among the most common and debilitating fractures. Structural organization of cancellous and cortical bone in a vertebra and their local properties are important factors that determine the strength of a vertebra. Linear finite element models utilizing Quantitative Computed Tomography (QCT) images have proven useful for predicting vertebral strength and are potentially useful in predicting risk of fracture in a clinical setting [1]. However, the amount of architectural detail in these models is not sufficient for studying trabecular stress and strains, and their relationship with the microscopic structure, which is important for understanding the mechanisms behind vertebral fragility.

Quantitative Computed Tomography-Based Finite Element Models of the Human Lumbar Vertebral Body: Effect of Element Size on Stiffness, Damage, and Fracture Strength Predictions

2003 ◽  
Vol 125 (4) ◽  
pp. 434-438 ◽  
Author(s):  
R. Paul Crawford ◽  
William S. Rosenberg ◽  
Tony M. Keaveny
Keyword(s):  
Finite Element ◽  
High Resolution ◽  
Fracture Strength ◽  
Quantitative Computed Tomography ◽  
Finite Element Models ◽  
Voxel Size ◽  
Element Size ◽  
Damage And Fracture ◽  
Vertebral Bodies ◽  
High Resolution Models

This study investigated the numerical convergence characteristics of specimen-specific “voxel-based” finite element models of 14 excised human cadaveric lumbar vertebral bodies (age: 37–87; M=6, F=8) that were generated automatically from clinical-type CT scans. With eventual clinical applications in mind, the ability of the model stiffness to predict the experimentally measured compressive fracture strength of the vertebral bodies was also assessed. The stiffness of “low”-resolution models (3×3×3 mm element size) was on average only 4% greater p=0.03 than for “high”-resolution models (1×1×1.5 mm) despite interspecimen variations that varied over four-fold. Damage predictions using low- vs high-resolution models were significantly different p=0.01 at loads corresponding to an overall strain of 0.5%. Both the high r2=0.94 and low r2=0.92 resolution model stiffness values were highly correlated with the experimentally measured ultimate strength values. Because vertebral stiffness variations in the population are much greater than those that arise from differences in voxel size, these results indicate that imaging resolution is not critical in cross-sectional studies of this parameter. However, longitudinal studies that seek to track more subtle changes in stiffness over time should account for the small but highly significant effects of voxel size. These results also demonstrate that an automated voxel-based finite element modeling technique may provide an excellent noninvasive assessment of vertebral strength.

A Finite Element Analysis of the General Rolling Contact Problem for a Viscoelastic Rubber Cylinder

1988 ◽  
Vol 16 (1) ◽  
pp. 18-43 ◽  
Author(s):  
J. T. Oden ◽  
T. L. Lin ◽  
J. M. Bass
Keyword(s):  
Finite Element ◽  
Variational Principles ◽  
Standing Waves ◽  
Rolling Contact ◽  
Finite Element Models ◽  
Viscoelastic Cylinder ◽  
Element Analysis ◽  
Elastic Rubber ◽  
Frictional Effects ◽  
Rough Foundation

Abstract Mathematical models of finite deformation of a rolling viscoelastic cylinder in contact with a rough foundation are developed in preparation for a general model for rolling tires. Variational principles and finite element models are derived. Numerical results are obtained for a variety of cases, including that of a pure elastic rubber cylinder, a viscoelastic cylinder, the development of standing waves, and frictional effects.

Affordable structural optimization for large-size dynamic finite element models

1997 ◽  
Author(s):  
Francois Hemez ◽  
Emmanuel Pagnacco ◽  
Francois Hemez ◽  
Emmanuel Pagnacco
Keyword(s):  
Finite Element ◽  
Structural Optimization ◽  
Finite Element Models ◽  
Dynamic Finite Element ◽  
Large Size
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