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In this current study, the producibility of 3D printed walnut shell composite is investigated. PLA granules and untreated ground walnut shells were mixed priorly and then extruded by using a single screw extruder to produce filaments for 3D printing. Then, pristine and walnut shell doped PLA filaments were 3D-printed by using the fused filament fabrication (FFF) method. The thermal decomposition behaviour of the filaments and the morphology of 3D printed parts are examined by Thermo-gravimetric analysis (TGA) and scanning electron microscopy (SEM), respectively. SEM micrographs presented non-adhesion between the particle and the polymer and also non- homogeneous particle distribution. TGA data revealed that the moisture content of PLA increased, and both pristine and doped PLA filament can resist to extrusion processes which take place at 200C.

HDPE is a newly used thermoplastic for additive manufacturing but there is some problem to overcome. They need to be strengthened with various micro size additives. The distribution of the fibers in the matrix is of vital importance. The production process is affected by many parameters such as temperature, extrusion speed, cooling rate, matrix, and fiber particle size. In this study, a comparison was made by using single and twin-screw extruders to produce 10% glass and carbon and reinforced HDPE filaments. Mechanical properties were evaluated based on tensile tests. Reinforcing fiber to the HDPE matrix increases the tensile strength. If the matrix and fiber particle size are reduced to 250µ before the extrusion, it is possible to achieve high tensile results close to twin screw extrusion with single screw extrusion, but homogeneous distribution of fibers in the matrix is not satisfactory.

For the sustainable boat production, a new composite material consisting ofPLA and wood was introduced in the study. Wood, yellow pine from the forests of theMediterranean region of Turkey, was in two form in the study: (1) 8% in weight in thecomposite and (2) solid wood. From the both kind of the material, specimens were produced by additive manufacturing technique in two (parallel and cross) printing directions and after that, the specimens were subjected to accelerated aging processes representing long-term effects of marine environmental agents such as humidity, salt andtemperature in four conditions namely: (1) without, (2) one-week, (3) two weeks and (4)four weeks aging. Tensile and compressive testing were performed for all the samplesand the results were given comparatively. A scanning electron microscope (SEM) analysis and thermal analysis were also performed to appreciate the bonding performance ofthe materials and the environmental effects on the composite. According to the results,newly introduced PLA/wood composite material was found usable for the interior designelements whose the complex form and the limited exposure to the marine environment.&nbsp

The existing and potential uses of HDPE in marine industry have been introduced in detail, in this study. The methods of manufacturing with HDPE have been compared in terms of usage characteristics such as design approach, cost, time, and performance by experts and users opionions. Apart from these conventional methods, additivemanufacturing methods (AMMs) has come into prominence today’s small craft industryand HDPE has been considered as a potential material for this method in spite of itsobstacles. The ways of improvement of HDPE for AMMs such as “reinforcements withglass or carbon fibres” has been also introduced based on early experimental results.

Reinforcement of polymer matrix with natural fibre can provide an increase in mechanical properties of the related composite. Since thermoplastics, especially biocomposite materials are recyclable, they contribute to a sustainable ecosystem. In this study, 10% by weight hemp-reinforced polylactic acid (PLA) matrix compounds were produced. Tensile test specimens were performed in two different infill patterns, parallel and +/- 45° cross, using the Fused Filament Fabrication (FFF) method from the developed biocomposite filaments. Ultimate tensile stress increases by approximately 20%. It has been observed that the geometry of the infill pattern greatly affects the tensile strength. In addition, through optical and scanningelectron microscopy (SEM) the produced composite filaments were examined. Surface interactions and homogeneous fibre distribution between PLA and hemp were investigated. As a result, hemp was used as a reinforcement material in the study. Homogeneous distribution is very important in the preparation of the compounds and a twin-screw extruder was used to achieve this. However, it has been observed that the interface between fibre and matrix is insufficient. This situation negatively affects structural performance. On the other hand, the addition of hemp decreases the thermal resistance and melting temperature and increases the glass transition temperature compared to pure PLA.

Thisstudy aims to determine the material performance of additive manufacturingmethods, which enable flexible designs against rapidly changing market needswith a high benefit/cost ratio to meet the increasing defense needs ofcountries. In addition, the design of an unmanned surface vehicle (UVS)resistant to sea conditions has been realized and produced by additivemanufacturing. Advantages such as freedom of design, on-site manufacturing, andlow cost in low-volume production have made additive manufacturing methods thefocus of today's production method and research topic. Among the additivemanufacturing methods, Fused Filament Fabrication (FFF) is the mostcost-effective and widely used method. In today's small craft sector, boatsmade of thermoplastic material are replacing metal hulls and thermosettingmatrix composite hull boats day by day. Although composite boats withthermoplastic or thermosetting matrix have limitations in terms of size, it canbe said that they are ideal for small USV. In this study, resistance analysisof the forms of 3 different boats was made with finite element and empiricalmethods. The hull form, which exhibits the lowest resistance value, wasproduced using the FFF method using PETG co-polymer developed fromenvironmentally friendly PET material. Cruise and field tests were carried out.Material performances were determined to be used in the production ofsmall-scale USVs with the FFF method, and the mini-scale USV was produced usingthe PETG material with the FFF method. The suitability of PETG material formarine uses was emphasized.

Prototip ve ürün üretim hızı, tasarımcılara sağladığı form geliştirme özgürlüğü, görece düşük kapasitedeki üretim ihtiyaçları için rekabetçi maliyeti, iyi kaliteye hızlı ulaşım olanaklarıyla, bilgisayar destekli tasarım ve üç boyutlu yazıcı teknolojisi temelindeki eklemeli imalat yöntemi, denizcilik endüstrisini de kapsayacak şekilde yaygın bir ilgi görmektedir. Bu ilginin temel kanıtı, eklemeli imalat yöntemine ilişkin araştırma, geliştirme etkinlikleri ve bilimsel yayın sayılarındaki ciddi artıştır. Esnek tasarımların sıklıkla güncellenmesiyle rekabetçiliği sürdürülebilir kılınabilecek küçük tekne endüstrisinin anılan avantajları nedeniyle eklemeli imalat yöntemine yönelmesi kaçınılmazdır. Eklemeli imalat yöntemi, teknelerin tasarım ve üretim sürecini verimli kılmakla birlikte, bu yöntemden iyi sonuç alabilmek onun bileşenleri üzerinde uygulamayla elde edilmiş deneyimlere dayanan verileri gereksinir. Bu çalışma kapsamında eklemeli imalat yönteminin önemli bileşenlerinden dolgu yoğunluğu ve örüntüsünün nihai ürünün temel mekanik özelliklerinden çekme mukavemeti üzerindeki etkisi deneysel olarak incelenmiştir. Üç boyutlu yazım teknolojileri temelinde yaygın olarak kullanılan polimerlerden polilaktik asitin (PLA) 13 farklı basım örüntüsü ve %10, 25, 50, 75 ve 100 olmak üzere beş farklı dolgu yoğunluğundan oluşan deney matrisi uyarınca çekme deneyleri Dokuz Eylül Üniversitesi (DEÜ) Kompozit Laboratuvarı’nda yapılmıştır. Sonuçlar, mekanik niteliklerin üzerinde durulan parametrelere çok duyarlı olduğu, “kübik” örüntünün incelenen yoğunluklarda genel olarak en iyi mekanik niteliklere ulaşmakta etkin olduğunu göstermiştir. Bu örüntü ve %25 yoğunluktan yararlanılarak 1/5 ölçeğinde bir yelkenli tekne gövdesi PLA polimer kullanılarak eklemeli imalat yöntemiyle DEÜ Deniz Bilimleri ve Teknolojileri Eklemeli imalat Laboratuvarı’nda üretilmiştir., The additive manufacturing method based on computer-aided design and three-dimensional printing technology, its speed, design freedom provided for the designers, the cost-effectiveness and competitive for relatively low-capacity production needs, the possibilities of achieving good quality; has gained a popularity with the industries, including the maritime sector. The main proof of this interest is the significant increase in the number of research and development activities and scientific publications on this topic. Due to above mentioned advantages, it is inevitable for the small-marine craft industry, whose competitiveness can be made sustainable by frequently updating flexible designs, to adopt their technology to the additive manufacturing method. While it makes the design and manufacturing process of boats efficient, for getting more effective results; it requires past driven data approach on practical experience. In this study, the effect of infill density and pattern, which are important parameters of the additive manufacturing method, on the tensile strength of the final product's basic mechanical properties was investigated experimentally. Tensile tests with 13 different printing patterns and 5 different infill densities of polylactic acid (PLA), one of the polymers widely used based on three-dimensional printing technologies, and a test matrix consisting of five different filling densities as 10%, 25%, 50%, 75% and 100%, were performed in Dokuz Eylul University’s (DEU) Composite Laboratory. The results showed that the mechanical properties were very sensitive to these parameters, and the cubic pattern was generally effective in achieving the best mechanical properties at the investigated densities. Using this pattern and 25% density, sailboat hull with a scale of 1/5 was produced in DEU Institute of Marine Sciences and Technologies Additive Manufacturing Laboratory, using PLA polymer by additive manufacturing.

Bu çalışma; yüksek yoğunluklu polietilen bir karina ve cam takviyelipolyester (CTP) bir üst yapıdan oluşan melez bir tekne için birleşim detayıgeliştirmeyi hedeflemektedir. Buradaki ana amaç; daha çevreci, kullanımömrü uzun olan ve estetik olarak daha çekici bir tekne tasarlamaktır. Bu çalışma HDPE ve CTP ile diğer gemi inşaat malzemelerini nitel venicel olarak karşılaştırmaktadır. HDPE ve CTP materlyallerinin gemiinşaattaki avantaj ve dezavantajları detaylı olarak açıklanmıştır. Üç farklıbirleşim detayı için çekme testleri gerçekleştirilmiştir. Test numuneleriningerilme noktalarına gerinim ölçerler konulmuştur. ANSYS yazılımıkullanılarak sonlu elemanlar analizi uygulanmış ve ideal ortamda testlercanlandırılmıştır. Ayrıca olası tekne kullanıcılarının HDPE karina içeren bu yeni tasarımhakkındaki görüşlerini anlamak için 152 kişiyle bir anket yapılmıştır. Anketsonuçları, kullanıcıların daha güvenli ve çevreye duyarlı olması nedeniyleHDPE karinayı tercih edebileceğini göstermiştir. Bu çalışma HDPE – CTPmelez teknenin gelecekte denizcilik sektöründe tercih edilen bir seçenekolabileceğini göstermiştir. This study aims to design a hybrid high density polyethylene (HDPE)boat with glass reinforced plastic (GRP) superstructure, through thedevelopment of a joint between those two materials. The main goal is todesign a more environmental friendly, longer lasting boats with betteraesthetics and appeal. This research compares HDPE and GRP and other hull materials withqualitative and quantitative methods. The advantages and disadvantages ofboth HDPE and GRP are explained in detail. Specimen testing for threedifferent joint types were conducted. The specimens were attached withstrain gauges in order to plot the stress distribution at critical points and theparts. ANSYS software and Finite Element Analysis (FEA) were used to createthe same strain tests in a virtual environment to compare experimental testresults. Furthermore a survey was held in order understand the opinion of 152potential boat users about this new design that involves HDPE hulls.According to the survey, users may prefer HDPE hulls because it is moresafer and more environmental friendly. This study indicates that a hybridHDPE-GRP boats could be a viable alternative for the future marine industry. 99