Abstract

The main aim of this work is to investigate patterns of potential orbital bone fractures due to mechanical injuries. The solution of the main problem is followed by analysis of several testing examples having straight correlation with civil engineering structures, in which materials of wide range of stiffness are applied. To solve the main problem, the three-dimensional finite element method (FEM) model of the orbital region has been built, basing on the real geometry of the human skull, including also the intraorbital soft tissues being the significant part of the entire system. The mechanical properties of so-defined objects have been applied according to the laboratory tests results, as well as using the data available in the literature. Then, the non-linear dynamic analysis has been performed, including the contact effect between bodies having extremely different mechanical properties, that are: stiff-deformable bony thin shell and soft-deformable solid intraorbital tissues. The results obtained during the numerical tests of different load cases have been confronted with the results of clinical tests of patients suffering real orbital injuries – computer tomography (CT) scans. Upon that basis, the most essential patterns of the orbital bone trauma have been identified, while the theory known as the hydraulic model has been verified. The analysis has proved that for investigated scheme of loading the actual nature of the alleged hydraulic mechanism is the direct result of the intraorbital tissues deformation (especially the eyeball deformation) in the perpendicular direction to the applied load. Such procured transfer of the intraorbital pressure concentrates solely at the orbital sidewalls in fact, thus the alleged hydraulic model has been proved to be questionable. In front of the commonly used inaccurate name of the above mechanism, the new name, consistent with the real character of the mentioned mechanism has been proposed – the stretching mechanism.

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