A simplified intervertebral disc finite-element model with a fiber-composite annulus

1982 ◽  
Vol 15 (4) ◽  
pp. 343
Author(s):  
R.L. Spilker ◽  
D.M. Daugirda
2016 ◽  
Vol 34 (7) ◽  
pp. 1264-1273 ◽  
Author(s):  
Brent L. Showalter ◽  
John F. DeLucca ◽  
John M. Peloquin ◽  
Daniel H. Cortes ◽  
Jonathon H. Yoder ◽  
...  

1986 ◽  
Vol 108 (1) ◽  
pp. 1-11 ◽  
Author(s):  
R. L. Spilker ◽  
D. M. Jakobs ◽  
A. B. Schultz

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.


Author(s):  
Francis Hauris ◽  
Onur Bilgen

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.


PLoS ONE ◽  
2017 ◽  
Vol 12 (5) ◽  
pp. e0177088 ◽  
Author(s):  
Gloria Casaroli ◽  
Fabio Galbusera ◽  
René Jonas ◽  
Benedikt Schlager ◽  
Hans-Joachim Wilke ◽  
...  

2013 ◽  
Vol 2013 ◽  
pp. 1-6 ◽  
Author(s):  
Mark Driscoll ◽  
Jean-Marc Mac-Thiong ◽  
Hubert Labelle ◽  
Stefan Parent

A large spectrum of medical devices exists; it aims to correct deformities associated with spinal disorders. The development of a detailed volumetric finite element model of the osteoligamentous spine would serve as a valuable tool to assess, compare, and optimize spinal devices. Thus the purpose of the study was to develop and initiate validation of a detailed osteoligamentous finite element model of the spine with simulated correction from spinal instrumentation. A finite element of the spine from T1 to L5 was developed using properties and geometry from the published literature and patient data. Spinal instrumentation, consisting of segmental translation of a scoliotic spine, was emulated. Postoperative patient and relevant published data of intervertebral disc stress, screw/vertebra pullout forces, and spinal profiles was used to evaluate the models validity. Intervertebral disc and vertebral reaction stresses respected publishedin vivo,ex vivo, andin silicovalues. Screw/vertebra reaction forces agreed with accepted pullout threshold values. Cobb angle measurements of spinal deformity following simulated surgical instrumentation corroborated with patient data. This computational biomechanical analysis validated a detailed volumetric spine model. Future studies seek to exploit the model to explore the performance of corrective spinal devices.


Author(s):  
Kai-ming Hu ◽  
Hua Li

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.


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