Civil Engineering / İnşaat Mühendisliği
Permanent URI for this collectionhttps://hdl.handle.net/11147/13
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Article Citation - WoS: 40Citation - Scopus: 37Investigation of Interlayer Hybridization Effect on Burst Pressure Performance of Composite Overwrapped Pressure Vessels With Load-Sharing Metallic Liner(SAGE Publications, 2020) Kangal, Serkan; Kartav, Osman; Tanoğlu, Metin; Aktaş, Engin; Artem, Hatice SeçilIn this study, multi-layered composite overwrapped pressure vessels for high-pressure gaseous storage were designed, modeled by finite element method and manufactured by filament winding technique. 34CrMo4 steel was selected as a load-sharing metallic liner. Glass and carbon filaments were overwrapped on the liner with a winding angle of [+/- 11 degrees/90 degrees(2)](3) to obtain fully overwrapped composite reinforced vessel with non-identical front and back dome endings. The vessels were loaded with increasing internal pressure up to the burst pressure level. The mechanical performances of pressure vessels, (i) fully overwrapped with glass fibers and (ii) with additional two carbon hoop layers on the cylindrical section, were investigated by both experimental and numerical approaches. In numerical approaches, finite element analysis was performed featuring a simple progressive damage model available in ANSYS software package for the composite section. The metal liner was modeled as elastic-plastic material. The results reveal that the finite element model provides a good correlation between experimental and numerical strain results for the vessels, together with the indication of the positive effect on radial deformation of the COPVs due to the composite interlayer hybridization. The constructed model was also able to predict experimental burst pressures within a range of 8%. However, the experimental and finite element analysis results showed that hybridization of hoop layers did not have any significant impact on the burst pressure performance of the vessels. This finding was attributed to the change of load-sharing capacity of composite layers due to the stiffness difference of carbon and glass fibers.Article Citation - WoS: 16Citation - Scopus: 24Developing Polymer Composite-Based Leaf Spring Systems for Automotive Industry(Walter de Gruyter GmbH, 2018) Öztoprak, Nahit; Güneş, Mehmet Deniz; Tanoğlu, Metin; Aktaş, Engin; Eğilmez, Oğuz Özgür; Şenocak, Çiler; Kulaç, GedizComposite-based mono-leaf spring systems were designed and manufactured to replace existing mono-leaf metal leaf spring in a light commercial vehicle. In this study, experimentally obtained mechanical properties of different fiber-reinforced polymer materials are presented first, followed by the description of the finite element analytical model created in Abaqus 6.12-1 (Dassault Systemes Simulia Corp., RI, US) using the obtained properties. The results from the finite element analysis are presented next and compared with actual size experimental tests conducted on manufactured prototypes. The results demonstrated that the reinforcement type and orientation dramatically influenced the spring rate. The prototypes showed significant weight reduction of about 80% with improved mechanical properties. The hybrid composite systems can be utilized for composite-based leaf springs with considerable mechanical performance.Article Citation - WoS: 4Citation - Scopus: 4Predicting and Measuring Surface Enlargement in Forward Rod Extrusion(The American Society of Mechanical Engineers(ASME), 2016) Duran, Deniz; Özdemir, İzzetSurface enlargement during bulk metal forming processes is one of the key parameters controlling the tribology at the tool-workpiece interface. Not only the surface roughness evolution but also the integrity of the lubricant layer critically reposes on surface enlargement. As an attempt to address this issue, in the first part of this work, a general, deformation gradient based surface enlargement description is implemented in a commercial finite element program. In the second part, forward rod extrusion tests with different area reductions are conducted using customized steel workpieces in which cylindrical copper rods are embedded through the depth. By sectioning the extruded parts and by identifying the position of the copper rods on the lateral surface, average surface enlargement values could be measured locally at different positions along the extrudate. Comparison of experiments and numerical predictions reveal that the deformation gradient based description performs reasonably well in capturing surface enlargement profiles both qualitatively and quantitatively.