PSI - Issue 25

Hassan Mansour Raheem et al. / Procedia Structural Integrity 25 (2020) 3–7 Author name / Structural Integrity Procedia 00 (2019) 000–000

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on the test data (see Fig. 3). It seems that at low strain, i.e. less than 10%, all models predict the same behavior for A2. However, at strain value larger than 10%, FEA results exhibited stiffer behavior than models of hydrogels using SEDFs. Nevertheless, these changes were still within the range of test data. The Ogden model seemed to be the best choice that represents the nonlinear behavior of the hydrogel, because it was stable for small strain and large values as well. These results are in line with Ref. (Yu, Santos, and Campanella 2012).

Fig. 2. General geometry of FEA model.

4 Conclusions The hyperplasic models that represent the mechanical behavior of hydrogel aagrose A2 have been defined. Theoretically, the strain energy models present a good approach to predict the behavior of the viscoelastic materials. The test data were implemented as input to ABAQUS to determine the material responses in tension and compression depending on the SEDFs. The validations of the most known models were performed using a general FE model. Among the models, Ogden (N=1) was found to be the best model that represents the mechanical behavior of the hydrogels. References Ali, Aidy, M Mosseini, and B.B Sahari. 2010. “A Review of Constitutive Models for Rubber-Like Materials.” American J. of Engineering and Applied Sciences 3 (1): 232–39. Buckwalter, J. A. 1995. “Aging and Degeneration of the Human Intervertebral Disc.” Spine 20 (11): 1307–14. Gefen, A., N. Gefen, E. Linder-Ganz, and S. S. Margulies. 2005. “In Vivo Muscle Stiffening Under Bone Compression Promotes Deep Pressure Sores.” Journal of Biomechanical Engineering 127 (3): 512. https://doi.org/10.1115/1.1894386. Pereira, Diana R, Sliva-Correia, Joana, Sofia G Caridade, J. T. Oliveria, R. A. Sousa, Antonio J. Salgado, Joaquim M. Oliveira, J. F. Mano, Nuno Sousa, and Rui L. Reis. 2011. “Development of Gellan Gum-Based Microparticles Hydrogel Matrices for Application in the Intervertebral Disc Regeneration” 17 (10). Previati, G., M. Gobbi, and G. Mastinu. 2017. “Silicone Gels - Comparison by Derivation of Material Model Parameters.” Polymer Testing 58 (April): 270–79. https://doi.org/10.1016/j.polymertesting.2017.01.011. Raheem, Hassan Mansour, Brian Bay, and Skip Rochefort. 2019. “Viscoelastic Properties of a Novel Hydrogel/Foam Composites for Nucleus Pulposus Replacement.” SN Applied Sciences 1 (8): 809. https://doi.org/10.1007/s42452-019-0855-z. Sasson, Aviad, Shachar Patchornik, Rami Eliasy, Dror Robinson, and Rami Haj-Ali. 2012. “Hyperelastic Mechanical Behavior of Chitosan Hydrogels for Nucleus Pulposus Replacement—Experimental Testing and Constitutive Modeling.” Journal of the Mechanical Behavior of Biomedical Materials 8 (April): 143–53. https://doi.org/10.1016/j.jmbbm.2011.12.008. Yu, Jinghu, P.H.S. Santos, and O.H. Campanella. 2012. “A Study to Characterize the Mechanical Behavior of Semisolid Viscoelastic Systems Under Compression Chewing - Case Study of Agar Gel: Mechanical Behavior of Gels Under Compression.” Journal of Texture Studies 43 (6): 459–67. https://doi.org/10.1111/j.1745-4603.2012.00356.x.