Çelik Tel Halatı Mukavemetinin Deniz Ortamındaki Değişikliklerinin İncelenmesi

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Tarih
2015-06-30
Yazarlar
Kandemir, İsmail
Süreli Yayın başlığı
Süreli Yayın ISSN
Cilt Başlığı
Yayınevi
Fen Bilimleri Enstitüsü
Institute of Science and Technology
Özet
Çelik halatlar; her önemli icat gibi bir ihtiyaçtan yola çıkılarak ortaya çıkmış parçalardır ilk örnekleri milattan önce(MÖ) 12000-9000 yılları arasında Mısır medeniyetinde rastlanmıştır ayrıca Finlandiya’da bulunan halatların Mezolitik dönemden (MÖ 9000-3000) kaldığı, Mısırda bulunan ve devetüyünden yapılan halatların ise 4000 yıldan daha eski olduğu varsayılıyor, orta cağda ise birçok binanın, heykelin ve şu an bildiğimiz tarihi simgelerin yapımında kullanılmıştır. Çelik halatların modern uygulamalarına en yakın örnek, madenlerden cevherleri yüzeye taşımak amacıyla Maden Mühendisi August Julius Albert tarafından 1834 yılında kendi ismi ile anılan (Albert Rope) halatı tasarlaması ile ortaya çıkmıştır, ilk üretilen halat madenlerden cevher taşımaya kullanılmıştır, halat üretilirken amaç sağlam olması ve tekrarlanabilir kuvvetler üzerinde dayanım göstermesidir. Deniz ortamındaki uygulamalar en eski ticaret sistemlerinden biri olan deniz yolunda, yükleri elleçlerken veya güvertede taşınan yüklerin güvenliğini sağlarken karşımıza çıkmaktadır. Çelik halatların tasarımı ve fiziksel modelleme çalışmaları 1800’lü yılların başlarından itibaren günümüze kadar birçok çalışmanın konusu olmuştur. Günümüzde çelik tel halatlar; gemilerin yükleme, tahliye ve güvenlik donanımlarının en önemli parçalarından biridirler. Tel halatlar deniz, hava, güneş etkileri altında bulunan ve çalışırken yıpratıcı kuvvetlere en fazla maruz kalan donanımlardır. Can ve mal güvenliğinin söz konusu olduğu şartlar altında çelik tel halatlar, planlı bakım-tutum sistemi içinde çeşitli şekillerde kullanılmakta ve gerektiğinde yenilenmektedirler. Ancak çelik tel halatlar için üretimden itibaren bir kullanım ömrü tanımlanmamış olup kullanılan yerlere göre ömürleri ve dayanıklılıkları tahmini olarak kabul edilmektedir. Bu çalışmada, deniz ortamında bulunan çelik halatlarda meydana gelen fiziki değişiklikler deneysel olarak incelenmiştir. Çeşitli ölçülerdeki çelik halatlar, deniz kıyısında kurulu bir düzenekle oluşturulan ortamda bekletilmiş ve tellerin; sıfır, üç, altı ve dokuz ay süre sonrasında ISO 6892-1 Standardına göre çekme testleri yapılmış ve sonuçlar karşılaştırılarak ortamın tel halatlar üzerindeki etkileri ölçülmüştür.
Steel wire ropes are one of the most important parts of loading, discharging and safety equipments of a ship. Wire ropes are the most effected equipments from the sea, air, sun and are the most exposed equipment to damaging forces. Steel wire ropes are used for planned maintanence system in different types, when safety of life and property are in question, and renewed when necessary. However, expiring date for steel wire rope is not defined, so that their validity and strengths are predicted depent on their using purposes.  Most wire ropes are constructed from either a single strand, or from several strands that are wound around a core. This core may either be a strand in itself or it may be a fibrous or deformable element. The strand is constructed of wires that are wound around a central wire. In single, straight strands, all wound wires are each configured as a single-helix. However, in a wound strand each wire (except for the central wire of the strand) is configured as a double-helix.The design of wire rope cross-sections dates back to the late 1800_s (Sayenga, 1980), and has been continuously improved since. Many analytical studies of a multi-layer single strand construction have been proposed in literature (Cardou and Jolicoeur, 1997). Hruska (1952a,b) and Lanteigne (1985), modeled the mechanical response of a multi-layer single strand construction, assuming a fiber response of each wire (i.e.,ignoring bending and torsion rigidity of the wires). Costello and Phillips (1976), Costello and Miller (1979), All the above studies were limited to a single, straight strand, in which all wound wires are single-helices. Jolicoeur and Cardou (1991) compared the mechanical response of a single strand rope as predicted by all the models mentioned above, and compared these models to experimental measurements of single strands. They showed that the simplifying assumption of fiber-like wires yields good results except for an inaccurate prediction of the torsion stiffness of the single straight strand.However, most cables in use have a more complex cross-section in which most wires are configured as double helices. In order to model the complex cross-section of multi-strand constructions, several modeling approaches (Costello, 1990) have been suggested. Velinsky (1981) and Velinsky et al. (1984) were the first to analyze the mechanical response of a multistrand construction. They extended the procedure developed by Costello and Phillips (1976) and Costello and Miller (1979) to treat a multi-strand construction of frictionless wires. Their modeling procedure is based on the nonlinear equations of equilibrium of a thin helical rod (Love, 1944) and considers the torsion and bending stiffness of the wires. Velinsky et al. computed the resultant tension and torque in a straight strand for uniform elongation and torsion of the straight strand. They then approximated the tension and torque of a wound strand that develop due to extension and twist of the wound strand by the same mechanical relation computed for the straight strand. To complete the model, they included the effect of changes in curvature of the wound strand by an approximation that considered planar bending of a straight strand around a cylinder. Phillips and Costello (1985) generalized Velinskys approach for any kind of wire rope with an Independent Wire Rope Core (IWRC). Their work considered the response of a rope bent over a sheave, and neglected friction forces between adjacent wires. This model was said to be applicable only to well-lubricate ropes or to ropes that are loaded exclusively in tension, without twisting or bending. The models of Velinski and of Philips and Costello give a good approximation of the mechanical response of the rope. However, to obtain complete description of the stress in individual wires there is need to develop a model that will explicitly take into account the double helix construction (e.g., the geometrical treatment of Wang and McKewan (2001)). This complete description will enable to estimate resultant ension, bending and torsion moments, relative displacements and contact forces, and the variations of all these along the individual double-helix wires. This information is essential for predicting fatigue life, wear,and overall mechanical response of the entire rope. It is difficult to conduct an analytical investigation of the mechanical response of wire rope because the kinematics of each wire is very complex. To facilitate an analytic study, it is therefore constructive to assume the kinematics of the wires, calculate the associated mechanical response of the whole construction, and examine the consequences of the assumptions by considering their affect on the validity of the equilibrium equations (Love, 1944). In this thesis, physical changes of steel wire ropes in marine enviroment conditions are investigated experimentally. Steel wire ropes in different sizes,are stored in a place which is built on the shore side and tensile tests of wires are done at the end of the zero, three, six and nine months period of time according to ISO 6892-1 standard, then the effects of environment on wire ropes are measured through comparison of result. Unloading of materials, its safety, installation and demounting of the components, and the status of the steel cables depending on time variations in marine environment are examined. Steel ropes are exposed to many corrosive effect during their use where the most important of these is corrosion and abrasion. Addition of these two effects, the metals are exposed to the fatigue. On the ship, the steel ropes are multi-purpose parts where they are either under constantly the load or no load of entire life and in generally unknown exact a lifetime. In our experiment, exposure of any load to the steel wire with the different diameters non artificial sea environment over a year and the particular regular tensile tests whether the results were evaluated.  Steel ropes exposed to a very corrosive effect as known; that is the reason that we have conducted the experiment in order to achieve results with minimal effects. In order to do that, we have tried the no load condition only overlapping consisting of various diameters to wire rope is waited in the platform we aimed to examine the changes. The use of steel cables in order to create a suitable environment ITU Maritime Faculty on the campus of the area close to the sea has been identified, we choose both the field of observation, we can close both experimental applications, and we can perform a location. Rope for the pin to be able to interact with each other and prevent them from a height of 10 cm from the soil to the wood plastic crates are secured with cable ties. Ropes are secured after the controlled and continuous contact with each other is prevented. Also it is not affected from weather conditions with constantly keeping under control. In the artificial platform, we have started from the day on steel ropes soaked in sea-water twice a day and at the end of the tenth month, sea water, rain, snow, wind, humidity, sun, and most importantly, the effects of the naturally exposed. The test can be done after determining the appropriate size, steel wire rope manufacturer or vendor of the company in ships with ropes which are used more idea you have been exchanged, as a result of our conversations in a bundle 19 of the wire and 6 bundles of hemp concise decision was made on the rope. Tests, Turkish Standards Institute, Gebze Campus in the Laboratory of Machine INSTRON 5589 model and a 60-Tonne towing capacity of the device is 10 mm/minute was carried out rapidly. On the sea-shore device, we got hold of the steel rope 3. Months, and 6. Months and 9. In the months of regular tests, and the results are evaluated.
Açıklama
Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2015
Thesis (M.Sc.) -- İstanbul Technical University, Instıtute of Science and Technology, 2015
Anahtar kelimeler
Çelik Tel Halat, Deniz Ortamı, Korozyon, Çekme Testi, Steel Wire Rope, Marine Environment, Corrision, Tensile Test
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