Gökdeniz Neşer

Heavy metals contamination levels at the Coast of Aliağa (Turkey) ship recycling zone

Aliağa Bay is one of the most important maritime zones of Turkey where shipping activity, shipbreaking industry, steel works and petrochemical complexes exist together. Concentrations of heavy metals and organic carbon in sediment of the Aliağa Bay were investigated to evaluate an environmental risk assessment from metals contamination in 2009-2010. Comparison of the metal concentrations with average shale and Mediterranean background levels revealed that most of the samples from the Aliağa were polluted with Hg, Cd, Pb, Cr, Cu, Zn, Mn and Ni. It was found that Hg, Pb, Cu, Zn and Ni levels in Aliağa Bay exceeded the PEL values. Sediments, contaminated with Pb, Cr, Cu, Zn and Ni were considered as heavily polluted per the SQG.

Polycyclic aromatic and aliphatic hydrocarbons pollution at the coast of Aliaga (Turkey) ship recycling zone.

Aliağa Bay is one of the most important maritime zones of Turkey where shipping activity, shipbreaking industry, steel works and petrochemical complexes exist together. Polycyclic aromatic hydrocarbons (PAHs) and aliphatic hydrocarbons in sediment of the Aliağa Bay were investigated to evaluate an environmental risk assessment from PAHs contamination in 2009-2010. Aliphatic and PAHs diagnostic ratios were showed to be mainly petroleum-originated and pyrolitic contaminations, respectively. The TEL/PEL analysis suggests that Aliağa sediments were likely to be contaminated by acutely toxic PAH compounds.

Effect of T-Joint Geometry on the Performance of a GRP/PVC Sandwich System Subjected to Tension

Mechanical performances of six sandwich type T-joints, used in marine applications subjected to tensile load, have been investigated both numerically and experimentally in this study T-joints, each with different geometries, have been manufactured, Type A: continuous core in join with right angle; Type B: core removed at joint; Type C: core with wedge fillet; Type D: core with 25 mm radius fillet; Type E: core with 70 mm radius fillet and Type F: DK-CND1 of Toftegaard and Lystrup with overlaminate. The skin was a 5mm thick orthophitalic polyester/glass laminated composite and the core was PVC (Divinycell H80). Due to absolute values of the maximum strain values of the T-joints, Type E shows promising performance under tension while Type B is the weakest. It is not recommended to use Type B in the structures subjected to tension. Grading from the strongest to the weakest of T-joints is Type C, D, A and F. Results of the numerical modelling and tests also affirm the utility of the 2D FE models for further studies of the strain distribution in such sandwich T-joints.

Seawater exposure effect on the fracture toughness of low-density woods/GRP sandwich systems

The effect of seawater exposure on the fracture toughness of balsa (Ochroma pyramidale L.) and end-grain balsa cores that are widely used in small-craft constructive members has been investigated experimentally in this study. The interfacial fracture toughness was determined using mode I cracked sandwich beam (CSB) tests. Additionally, the same tests were performed for poplar (Populus tremula L.), easily available because of its natural distribution along the coast of Turkey and more cost-effective than balsa and its derivatives, to see if it is a proper alternative. It was found that balsa and poplar cores that can be classified as low-density cores have much lower fracture toughness values than end-grain balsa cores. Additionally, there was a positive effect of seawater exposure on their fracture toughness as opposed to that of the end-grain core. From the aspect of fracture toughness, the poplar core can be considered much more reliable than the balsa core where delamination loads occur.

On the Interlaminar Fracture Toughness of Some Softwood Cores

The interlaminar fracture toughnesses of balsa and end-grain balsa cores with glass-reinforced plastics (GRP) face elements widely used as constructive members, has been investigated experimentally in this study. The interfacial fracture toughness is determined using a mode-I cracked sandwich beam (CSB) test. Some tests have been performed for the poplar (easily available because of its natural distribution along the coast of Turkey and more cost effective than balsa and its derivatives) in order to see if it is a viable alternative to balsa. Ayous, a low density wood, was also tested additionally to understand its interlaminar fracture behavior as a softwood core. It has been found that ayous, poplar, and balsa, classified as low density cores, have much lower fracture toughness values than end-grain balsa cores. To achieve lighter structures with high fracture toughness by using the cores investigated in this study, it can be seen that the best alternatives in due order are end-grain balsa, ayous, poplar, and balsa, respectively.