Material Constants for a Finite Element Model of the Intervertebral Disk With a Fiber Composite Annulus

1986 ◽  
Vol 108 (1) ◽  
pp. 1-11 ◽  
Author(s):  
R. L. Spilker ◽  
D. M. Jakobs ◽  
A. B. Schultz
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fiber Composite ◽  
Element Model ◽  
Intervertebral Disk ◽  
Material Constants ◽  
Reinforced Composite ◽  
Vertebral Bodies ◽  
Anisotropic Layers ◽  
Selection Of

A simple axisymmetric finite element model of a human spine segment containing two adjacent vertebrae and the intervening intervertebral disk was constructed. The model incorporated four substructures: one to represent each of the vertebral bodies, the annulus fibrosus, and the nucleus pulposus. A semi-analytic technique was used to maintain the computational economies of a two-dimensional analysis when nonaxisymmetric loads were imposed on the model. The annulus material was represented as a layered fiber-reinforced composite. This paper describes the selection of material constants to represent the anisotropic layers of the annulus. It shows that a single set of material constants can be chosen so that model predictions of gross disk behavior under compression, torsion, shear, and moment loading are in reasonable agreement with the mean and range of experimentally measured disk behaviors. It also examines the effects of varying annular material properties.

Induced Strain Actuation for Solid-State Ornithopters: Pitch and Heave Coupling

2017 ◽  
Author(s):  
Francis Hauris ◽  
Onur Bilgen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fiber Composite ◽  
Leading Edge ◽  
Theoretical Models ◽  
Element Model ◽  
Harmonic Excitation ◽  
Edge Stiffener ◽  
Modes Of Vibration ◽  
Composite Wing

This paper investigates the heaving and pitching of a wing-like parameterized cantilevered plate with a leading edge stiffener and clamp variation when actuated with a surface-bonded piezoelectric actuator. The response is analyzed using a finite element model that is validated by comparison with known analytical solutions. The validated finite-element model is subjected to a harmonic excitation parametric analysis. The parameters varied in the model are the root clamped percentage, leading edge stiffener thickness, and the aspect ratio of the plate. The model is examined at the first two Eigen frequencies. Metrics of heaving and pitching are developed using surface fitting methods and their amplitudes and phases are reported throughout the parameter space. Emphasis is placed on the interaction and coupling of the first two modes of vibration with respect to the parameters. A piezo-composite wing prototype is fabricated and actuated harmonically with a Macro-Fiber Composite actuator while leading edge stiffener thickness and root clamped percentage is varied. The resulting experimental data is used to further validate the theoretical models.

Shock-Resistance Research of Ship Structural Subjected to Underwater Explosion

2014 ◽  
Vol 945-949 ◽  
pp. 1180-1184
Author(s):  
Yao Guo Xie
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Cross Section ◽  
Critical Radius ◽  
Underwater Explosion ◽  
Element Model ◽  
Current Standard ◽  
Envelope Analysis ◽  
Shock Resistance ◽  
Selection Of

A finite element model ships, for example design test condition of the underwater explosion, selection of explosive package quantity is 1000KG TNT, the explosive location along the direction of the ship with the bow, midship and stern, the angle of attack in three exploded cross section have 90 degrees, 60 degrees, 45 degrees, 30 degrees and 0 degrees. According to the current standard to calculate the ship damage radius, critical radius and safety radius of specific values under the effect of underwater explosion, interpolation calculation and draw the envelope. Analysis shows that the vitality of ships and shock-resistance is not only related to the explosive distance, also related to the attack position.

Finite Element Model of the Human Lower Cervical Spine: Parametric Analysis of the C4-C6 Unit

1997 ◽  
Vol 119 (1) ◽  
pp. 87-92 ◽  
Author(s):  
N. Yoganandan ◽  
S. Kumaresan ◽  
L. Voo ◽  
F. A. Pintar
Keyword(s):  
Finite Element ◽  
Cervical Spine ◽  
Finite Element Model ◽  
Compressive Stress ◽  
Vertebral Body ◽  
Element Model ◽  
Intervertebral Disk ◽  
Von Mises Stress ◽  
Lower Cervical Spine ◽  
Intervertebral Disks

In this study, a three-dimensional finite element model of the human lower cervical spine (C4-C6) was constructed. The mathematical model was based on close-up CT scans from a young human cadaver. Cortical shell, cancellous core, endplates, and posterior elements including the lateral masses, pedicle, lamina, and transverse and spinous processes, and the intervertebral disks, were simulated. Using the material properties from literature, the 10,371-element model was exercised under an axial compressive mode of loading. The finite element model response agreed with literature. As a logical step, a parametric study was conducted by evaluating the biomechanical response secondary to changes in the elastic moduli of the intervertebral disk and the endplates. In the stress analysis, the minimum principal compressive stress was used for the cancellous core of the vertebral body and von Mises stress was used for the endplate component. The model output indicated that an increase in the elastic modulii of the disk resulted in an increase in the endplate stresses at all the three spinal levels. In addition, the inferior endplate of the middle vertebral body responded with the highest mean compressive stress followed by its superior counterpart. Furthermore, the middle vertebral body produced the highest compressive stresses compared to its counterparts. These findings appear to correlate with experimental results as well as common clinical experience wherein cervical fractures are induced due to external compressive forces. As a first step, this model will lead to more advanced simulations as additional data become available.

Large deformation mechanical modeling with bilinear stiffness for Macro-Fiber Composite bimorph based on extending mixing rules

2020 ◽  
pp. 1045389X2095125
Author(s):  
Kai-ming Hu ◽  
Hua Li
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Large Deformation ◽  
Composite Structures ◽  
Fiber Composite ◽  
Three Dimensional ◽  
Element Model ◽  
Fiber Composites ◽  
Mixing Rules ◽  
Macro Fiber Composite

Macro-Fiber Composite bimorph is a kind of piezoelectric actuator that allow large bending deformation. However, macro-fiber composites exhibit strong stiffness nonlinearity in their operation range, so it is difficult to accurately estimate their large deformation behavior based on a linear constitutive model. In addition, the macro-fiber composites have active and inactive parts, that significantly differ in their material sizes and properties, so it is not reasonable to consider them as uniform material. Thus, it is necessary develop an accurate modeling and analysis method for the large deformation macro-fiber composite structures. First, the mixing rules are extended to derive the three-dimensional homogenized mechanical and electrical parameters of the macro-fiber composite active part; based on these parameters, the actuation results of linear finite element model is in good agreement with the official data. Then a finite element model of the axially compressed macro-fiber composite bimorph is established, the bilinear tensile stiffness of macro-fiber composite is realized by secondary development in ANSYS. Comparison with the experimental results reveals high accuracy of the established finite element model. Thus, the developed method can be effectively used for the performance evaluation and design of the macro-fiber composite devices with large deformation.

Finite Element Model Updating of a Steel Jacket Scale Model

2012 ◽  
Vol 166-169 ◽  
pp. 588-592
Author(s):  
Zhi Gang Li ◽  
Ying Chao Li ◽  
Shu Qing Wang ◽  
Bin Yang
Keyword(s):  
Sensitivity Analysis ◽  
Finite Element ◽  
Finite Element Model ◽  
Model Updating ◽  
Element Model ◽  
Scale Model ◽  
Cross Model ◽  
Steel Jacket ◽  
The Finite Element Model ◽  
Selection Of

In this paper, the finite element model of a steel jacket scale model is updated using modal parameters identified by modal test. Updating parameters are selected based on sensitivity analysis by solving modal energies. And then, a two-steps updating process is carried out using different parameters and the Cross-Model Cross-Mode (CMCM) model updating method is applied in each step. Results indicate that with selection of updating parameters and sensitivity analysis, CMCM method can update the finite element model with physical meanings.

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