Modeling the stress-strain state of a dynamic implant for vertebral stabilization with an intermediate elastic element
DOI:
https://doi.org/10.33271/crpnmu/86.340Keywords:
dynamic spinal stabilization, implant, elastomer, silicone, rubber, linear low-density polyethylene, titanium alloy, Autodesk Fusion 360, finite element method, stress-strain state, stress concentration.Abstract
Purpose. Substantiation of the structural configuration of a dynamic implant with an intermediate elastic element and analysis of the influence of the material selected for this element on the stress-strain state of the stabilization device model under specified static loads.
Research methodology. Analysis of the TOPS™ system design as a functional prototype; parametric 3D modeling of the implant and numerical analysis of its stress-strain state using Autodesk Fusion 360. Three material options for the intermediate elastic element were compared: rubber, silicone elastomer, and linear low-density polyethylene (LLDPE).
Findings. Under a load of 1000 N applied to the two upper arms of the structure, the maximum displacements were 39.327, 26.697, and 2.222 mm for rubber, silicone elastomer, and linear low-density polyethylene, respectively. The maximum von Mises equivalent stresses obtained from the numerical analysis reached 5,022.786, 3,359.223, and 1,336.859 MPa, respectively. Under a lateral force of 50 N applied to one upper arm, the calculated displacements were 25.104 mm for rubber and 16.887 mm for silicone elastomer. The highest equivalent stress concentrations were identified in the regions where the fastening arms are connected to the implant body.
Scientific novelty. Based on a comparative analysis of the numerical simulation results for the stress-strain state of the dynamic implant, the relationships between the mechanical properties of the intermediate elastic element material and the overall structural compliance were established. It was shown that, under the two investigated static loading conditions, the maximum displacements of the structure with a rubber element were approximately 1.5 times greater than those obtained with a silicone element, whereas the use of linear low-density polyethylene significantly reduced the structural deformability under symmetric loading. Criteria for further verification of the numerical model were formulated to assess the mechanical performance of the implant.
Practical significance. The results can be used at the conceptual design stage to identify directions for geometric optimization, determine the appropriate positioning of the elastic insert, evaluate the fastening assemblies, and develop a program of numerical simulations and experimental bench tests.
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