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Öğe Investigation of low velocity impact behaviors of honeycomb sandwich composites(SpringerLink, 2018-08-09) Topkaya, Tolga; Solmaz, Murat YavuzHoneycomb sandwich composites are used as significant structural members in advanced engineering applications. Thus, it is critical to determine how they behave under impact loading, in addition to other loads. In this study, low velocity impact loading behaviors of honeycomb sandwich composites were experimentally investigated. Almost all of the design parameters of honeycomb sandwich composites were investigated. The results indicated that the core thickness of honeycomb had no effect on the strength of the composite, and the parameter influencing the impact behavior of the specimen the most was the face sheet thickness. When the face sheet thickness of the specimen was increased, the most apparent strength increase was observed in the models using carbon fiber-reinforced composite face sheets. For all face sheet types subject to impact energy of 10 Joules, the upper face sheets of 0.5 mm-thick specimens were perforatedÖğe Finite element analysis of the stress distributions in peri-implant bone in modified and standard-threaded dental implants(Taylor & Francis, 2016-01) Topkaya, Tolga; Dündar, Serkan; Solmaz, Murat Yavuz; Yaman, Ferhan; Atalay, Yusuf; Saybak, Arif; Asutay, Fatih; Çakmak, ÖmerThe aim of this study was to examine the stress distributions with three different loads in two different geometric and threaded types of dental implants by finite element analysis. For this purpose, two different implant models, Nobel Replace and Nobel Active (Nobel Biocare, Zurich, Switzerland), which are currently used in clinical cases, were constructed by using ANSYS Workbench 12.1. The stress distributions on components of the implant system under three different static loadings were analysed for the two models. The maximum stress values that occurred in all components were observed in FIII (300 N). The maximum stress values occurred in FIII (300 N) when the Nobel Replace implant is used, whereas the lowest ones, in the case of FI (150 N) loading in the Nobel Active implant. In all models, the maximum tensions were observed to be in the neck region of the implants. Increasing the connection between the implant and the bone surface may allow more uniform distribution of the forces of the dental implant and may protect the bone around the implant. Thus, the implant could remain in the mouth for longer periods. Variable-thread tapered implants can increase the implant and bone contact.Öğe Progressive failure analysis in adhesively, riveted, and hybrid bonded double-lap joints(Taylor & Francis, 2013-11) Topkaya, Tolga; Solmaz, Murat YavuzOne of the important processes in structural design is the joining technique. Failure of composite joints involves different failure mechanisms depending upon the joining technique. In this study, a progressive failure analysis was performed on adhesively, riveted, and hybrid bonded double-lap joints. In the joints, a woven-type fiberglass-reinforced composite material was used as the main material; AV 2015 was used as the adhesive, and steel as the rivet material. The analyses were performed using ANSYS 12.1 finite element package software via software written using parametric design language (APDL) codes. At the end of the progressive failure analysis, failure loads and failure modes were determined for 30-, 45-, and 60-mm overlap lengths in accordance with the Maximum Shear Stress Theory and Hashin Criteria. For 45-mm overlap lengths, the joint strength of hybrid joints proved to be 2.72 and 1.145 times higher, respectively, than adhesive and fastening joints. Results showed that the failure load of the joint increased when the overlap length increased. In riveted joints, the failure occurring in the composite plates began around the rivet hole and the catastrophic failure of these types of joints resulted from fiber tensile failure.Öğe The flexural fatigue behavior of honeycomb sandwich composites following low velocity impacts(MDPI, 2020-01-13) Topkaya, Tolga; Solmaz, Murat YavuzThis study experimentally investigated the flexural fatigue behaviors of honeycomb sandwich composites subjected to low velocity impact damage by considering the type and thickness of the face sheet material, the cell size and the core height parameters. Carbon-fiber reinforced composite and the aluminum alloy was used as the face sheet material. First, the static strength of undamaged and damaged specimens was determined by three-point bending loads. Secondly, the fatigue behaviors of the damaged and undamaged specimens were determined. Low velocity impact damage decreased the flexural strength and fatigue lives but increased the damping ratio for all specimens. Maximum damping ratio values were observed on specimens with a aluminum face sheet.Öğe Stress distribution in a femoral implant with and without bone cement and at different inclination angles(Materialpruefung/Materials Testing, 2018-04) Topkaya, Tolga; Solmaz, Murat Yavuz; Turgut, Aydın; Dündar, Serkan; Şanlıtürk, İsmail HakkıThe purpose of this study was to investigate numerically the effects of the inclination (collodiaphyseal) angle and bone cement (polymethylmethacrylate) filling on the stress distribution of human femurs and implants after the implementation of a partial endoprotez arthroplasty. Ti6Al4V, which is the most commonly used implant material, was choosen for this study. In the numerical study, solid models of implants and femurs were created using the SolidWorks 2010 package program, then stress analyses were carried out at five different inclination angles, 120°, 125°, 130°, 135° and 140°, with and without bone cement (polymethylmethacrylate), using the ANSYS Workbench 12.0 package program. The anteversion angle was assumed to be 12.5° for all models. As a result of the increase in the inclination angle and the addition of bone cement, it was determined that the stress values of the femurs and implants were reduced. Within the limitations of this study it has been shown that parameters like bone cement, anteversion angle, and an appropriate inclination angle should be tested previous to partial endoprosthesis arthroplasty surgery necessary as a result of damage to the human femur.Öğe Numerical analysis of the effect of implant geometry to stress distributions of the three different commercial dental implant system(Sivas Cumhuriyet Üniversitesi, 2015-02-11) Topkaya, Tolga; Solmaz, Murat Yavuz; Dündar, Serkan; Eltas, AbubekirObjectives: The success of dental implants is related to the quality, quantity of local bones, implant design and surgical technique. Implant diameter and length are accepted as key factors. Present work focuses to investigate the effect of titanium implant geometry to stress distributions in implant system. Materials and Methods: For this purpose three different implant models which are currently being used in clinical cases constructed by using ANSYS Workbench 12.1. The stress distributions on components of implant system under static loadings were analyzed for all models. Results: The maximum stress values that occurred in all components happen in the case of loading in which the Nucleoss T-4 (Nucleoss, Turkiye) implant is used, but the occurred lowest stress values happen in the case of Fı loading in which Nobel Active (Nobel Biocare, Zurich, Switzerland) implant is used. In all models, the maximum tensions have occurred in the neck region of the implants. Conclusions: The crestal bone loss in the neck region of the implants reduced the long-term survival rate of implants.The length and the size of the implant are the two important factors in the stress distribution.Öğe The effect of implant number and position on the stress behavior of mandibular implant retained overdentures: A three-dimensional finite element analysis(Elsevier, 2015-07-16) Topkaya, Tolga; Solmaz, Murat YavuzThe present study evaluated the effects of ball anchor abutment attached to implants with a 4.30 mm diameter and 11 mm insert length on stress distribution in a patient without any remaining teeth in the lower jaw. In the study, the stress analysis was performed for five different configurations (2 with 4 implant-supported and 3 with 2 implant-supported) and three different loading types using ANSYS Workbench software. The stresses measured in the 4 implant-supported models were lower compared to the stresses measured in the 2 implant-supported models. The stresses on the implants intensified on the cervical region of the implants. When the effects of the loading sites on the stress were examined, the loading on the first molar tooth produced the highest stresses on the implants.
