PSI - Issue 28

Hassan Mansour Raheem et al. / Procedia Structural Integrity 28 (2020) 1755–1760 Hassan Mansour Raheem et al. / Structural Integrity Procedia 00 (2019) 000–000

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Table1. Material properties

Component

Young modulus (MPa) Poisson ratio

Bulk Modulus (MPa)

Shear Modulus (MPa)

Annulus fibrosus Nucleus pulpous

4.2

0.45

14

1.448 0.334

1

0.499

166.7

Fig. 2. The meshing of the intervertebral disc, the central compartment is the nucleus pulposus.

2.3. Validation of the model To validate the model, the responses of the model under axial compression loads were compared with those of literature results for the human spinal disc (Joshi et al. 2006) and with those of simulated data of the lumbar disc (Shirazi-Adl, Shrivastava, and Ahmed 1984). The two literature results were for the denucleated disc (disc without nucleus pulposus) to eliminate any uncertainty of the response due to the variability of the nucleus pulposus related to many factors, such as age, the grade of the nucleus pulposus, and to run the model independent of pressurization effects of the nucleus pulposus on the surrounded tissue, i.e. the annulus fibrosus. Figure 3 shows a comparison between the behaviors of the model with literature data. It seems that the results of the model agree with the reported data.

Fig. 3. Validation of the model enables the quality and reliability of the FEA and the modeling methodology. The validation of this work compared with literature data (the disc without NP) (Joshi et al. 2006; Shirazi-Adl et al. 1984).