Kadir Gok

Comparison of the biomechanical effects of pertrochanteric fixator and dynamic hip screw on an intertrochanteric femoral fracture using the finite element method

This study was conducted to examine and compare the pertrochanteric fixator (PTF) and dynamic hip screw (DHS).

Three-dimensional finite element modeling of effect on the cutting forces of rake angle and approach angle in milling

In this study, milling operations were carried out using AISI 1040 specimens steel in dry cutting conditions. The cutting tools used in the experiment include P20 tool steel and they also have three different approach angles (45°, 60°, 75°) and rake angles (0°, −6°, −12°). In milling experiments, cutting parameters with a depth of cut of 1.5 mm, cutting speed of 193 m/min, and feed rate of 313 mm/min were selected. A comparison was presented between the force values which were obtained by measured value and predicted with numerical simulations, and then a good agreement was found between measured and predicted force values. As result of, it was observed that the rake and approach angles were effective in milling operations.

Comparison of effects of different screw materials in the triangle fixation of femoral neck fractures

In this study, biomechanical behaviors of three different screw materials (stainless steel, titanium and cobalt–chromium) have analyzed to fix with triangle fixation under axial loading in femoral neck fracture and which material is best has been investigated. Point cloud obtained after scanning the human femoral model with the three dimensional (3D) scanner and this point cloud has been converted to 3D femoral model by Geomagic Studio software. Femoral neck fracture was modeled by SolidWorks software for only triangle configuration and computer-aided numerical analyses of three different materials have been carried out by AnsysWorkbench finite element analysis (FEA) software. The loading, boundary conditions and material properties have prepared for FEA and Von-Misses stress values on upper and lower proximity of the femur and screws have been calculated. At the end of numerical analyses, the best advantageous screw material has calculated as titanium because it creates minimum stress at the upper and lower proximity of the fracture line.Graphical Abstract

The Effect on the Cemented Carbide Cutting Tool of Austempering Process

Austempered ductile irons (ADI) have been developed for an increasing number of the engineering applications such as crankshaft, gears, and other mechanic equipments because of its combination of strength and toughness. Therefore, austempering process has important effects on the mechanical properties of ADI. In this study, we have investigated the effect of austempering process on the cutting tool stresses. The cutting forces (main cutting force, feed force and thrust force) obtained from experimental studies have been applied to rake face, main cutting edge, auxiliary cutting edge on the cutting tool, and then the stresses (von-Mises, shear stress, normal stresses in the X, Y and Z directions) occurred on the cutting tool has been analyzed based on finite element method using ANSYS Workbench commercial software. It is also observed that analytical process of Frocht for the stresses on cutting tool tip. The results obtained show that the austempering process is the significant factor affecting cutting tool stresses.

NUMERICAL ANALYSIS OF TEMPERATURE, SCREWING MOMENT AND THRUST FORCE USING FINITE ELEMENT METHOD IN BONE SCREWING PROCESS

In this study, the bone screwing process carried out with M3.5 cortex screw for stabilization after reduction of femur shaft fracture was investigated both experimentally and numerically. The numerical analyses were performed based on the finite element method using Deform-3D software. The friction, material model, the loading and boundary conditions were exactly identified for finite element analyses. An analytic model and software were developed, which calculate the process parameters such as screwing power and thrust power, heat transfer coefficients in order to determine the temperature distributions occurring in the screw and bone material (sawbones) during screwing process. As a result, the screwing moment and thrust force values decrease with increasing of spindle speed. On the contrary, temperature values of screw and sawbones increase with increasing of spindle speed. A good consistence between the results obtained from both experimental and numeric simulations was found during the bone screwing process.

Response concerning ‘Letter to editor’ by Ni et al. (2017), Arch Orthop Trauma Surg. DOI 10.1007/s00402-017-2710-2

1. Gok K, Inal S, Gok A, Gulbandilar E (2017) Comparison of effects of different screw materials in the triangle fixation of femoral neck fractures. J Mater Sci Mater Med 28(5):81 2. Ni J, Wang X, Yuang Y, Liu H, Zhou L (2017) Letter to the editor concerning ‘‘Femoral neck fracture osteosynthesis by the biplane double-supported screw fixation method (BDSF) reduces the risk of fixation failure: clinical outcomes in 207 patients’’ by Filipov O, Sommer C et al (2017). Arch Orthop Trauma Surg. doi:10.1007/s00402-017-2710-2 3. Gok K, Inal S (2015) Biomechanical comparison using finite element analysis of different screw configurations in the fixation of femoral neck fractures. Mech Sci. 6(2):173–179. doi:10.5194/ ms-6-173-2015 Dear Editor,