Workbench 17

The PSO model was imported into Ansys Workbench 17.0. The degree of freedom of sacrum was constrained in all directions, and its X, Y, and Z directions were set to 0 as the boundary condition. Stress on internal fixation, osteotomy plane, and displacement of plane was measured under various workloads, including stand forward flexion and backward extension, left and right flexion, and rotation. A 424.7-N axial load was applied on the T1 vertebral body, and bending, extension, and rotation were achieved with additional 10-Nm moment of force (22 ) (Table 2).
Overall stress distribution and displacement were measured on each internal fixation model and osteotomy planes, and the mechanical distribution of PSO models was compared under different workloads using numerical comparison.

All the material configurations of this study were analysed by FEM analysis; the simulation platform was Ansys Workbench 17.0. 3D linear static simulations were performed.

In ANSYS Workbench 17.0, after the construction of the laminated composite specimen as explained in Section 2.2, the shell element from ACP (Pre) domain was imported into implicit static structural analysis. The updated geometry required mesh generation. Then, the discretization of geometry, whereby the grid dependency tests of mesh elements were conducted. The mesh dependency check is carried out varying the number of elements and the best mesh of quadrilateral elements of 1625 is selected with good quality of 0.20. It should be noted that the maximum skewness of cell quality with the value towards 0 is indicated as the excellent cell quality with ideal and skewed quadrilaterals cell.
For boundary conditions of the tensile specimen, the first boundary condition of fixed support was assigned at the end grip with a tab of the rectangular specimen. While the second boundary condition was set to be towards the Z-axis with a force of 0 N. The other end of the rectangular specimen was assigned as the loading condition of load moving outward with a velocity of 20 mm/s until the specimen failed. The simulation ran for 10 s, with a time step of 0.1 s. The calculation was considered to be accomplished once the specimen failed. The simulation setup replicating the actual experiment for the tensile test is depicted in Figure 4.

In order to compare the range of motion (ROM) of intact AS model with the ROM of normal vertebra in biomechanical experiment, a 7.5 Nm moment and a compression 150N force [22 (link), 23 (link)] were applied at the center of the superior surface of T9. The inferior surface of L5 was immobilized. The ROM of T9-L5 was calculated and the ROM of the corresponding segment was compared with the previous experiment studies (Table 2). For testing the fixation capacity, a compressive load of 400 N force and a 10 Nm moment were applied in all fixation patterns [23 (link)–25 (link)]. Six loading conditions including flexion, extension, left bending, right bending, left axial rotation, and right rotation were simulated. Ansys workbench 17 (ANSYS Inc., PA, USA) was used to set the material properties and simulate the loading conditions.

3D microfluidic model was constructed using Solidworks 2015 (Dassault Systèmes SolidWorks Corp.) and imported to ANSYS Workbench 17 (ANSYS, Inc.) for geometry discretization and numerical simulation using ANSYS FLUENT. Inlet flow velocity was set at 10 μl/min, which corresponded to ∼1 dyn/cm². Non-slip boundary conditions were applied to all channel walls, and outlet was defined as a pressure outlet with atmospheric pressure. The Navier-Stokes equations were solved using 2nd order accuracy. The Semi-Implicit Method for Pressure-Linked Equations (SIMPLE) scheme was used for pressure-velocity decoupling. All simulations were conducted by using an iterative and segregated solution method. A residual sum for continuity and momentum of 1 × 10⁻⁶ was set as a convergence criterion. The working fluid was assumed to be water (homogeneous, single phase, Newtonian fluid, ρ =  993.37 kg/m³, μ  =  0.000692 kg/m s). To reduce computational load, only half of the chip was modelled due to channel symmetry along the midline. Mesh independence study was conducted. The optimized meshes for the 3D stenosis chip with 0%, 50%, and 80% of constrictions consisted of 2160, 86 678, and 137 892 cells, respectively.