Hasarlı polietilen AFO ortezin onarımı ve kullanılabilirliği
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Ortopedik özürlüler doğuştan veya herhangi bir hastalık ya da kaza sonucu iskelet, kas ve sinir sisteminde arıza meydana gelmesi ve buna bağlı olarak normal yaşam ve aktivitelerini gerçekleştiremeyecek derecede fiziksel yetersizliğe sahip olan kişilerdir. Ortez özürlülerin yaşamlarını yeterli şekilde sürdürebilmeleri amacıyla kullanmakta oldukları cihazlardan birisidir ve özürlü organa göre şekillendirilebilir. AFO ortezler özellikle bilek bölgesinin iki yanında zamanla çatlak oluşumu ve devamında başlangıcı bu noktalar olan kırılma sonucu kullanılamaz hale gelmektedirler. Çalışmada böyle bir hasarın onarılabilmesi için öncelikle aynı malzemeden farklı iki tabakanın ve iki tabaka arasına takviye elemanı cam elyaf lifleri yerleştirilmiş hallerinde, ısıl işlem uygulanması, içyapı görüntüleri alınarak yapının tek parça halinde birleştirilebilirliği incelendi. İlave olarak çekme deneyleri yapılarak birleştirilmiş yapıların dayanımları belirlendi. Polietilen tabakalara endirekt ısı uygulanması, artan sıcaklıkla malzemenin alev almadan tam şeffaflaşıp peltemsi hale geldiğinde, tabakalar arasına belirli oranda elyaf lifin takviye olarak serilmesi, bu andan itibaren oda sıcaklığında soğumaya kadar baskı uygulanması yapılan işlemlerdir. Polietilen plakaların bu uygulamalar neticesi, en iyi içyapı oluşumuyla birlikte çekme dayanımı yüksek yapılar olarak birleştirilebildiği tespit edilmiştir.Polyethylene is a widely used orthosis material which fits best for the foot movements of people. The aim of the study is to repair a damaged polyethylene AFO orthosis firstly and then to expand its endurance period. To this end, changes observed in polyethylene material when exposed to heat have been analyzed. The procedure of combining a two-layer polyethylene material into one layer polyethylene has been performed in the study. Polyethylene material has been exposed to direct flame for heating purposes in Phase I and partially in Phase 2. Throughout the heating process, gradual transparency and deflagration has been observed with the heat increase in the material which was dull white under room temperature. Transparency is an important phase and occurs before degradation phase. At this point, the material is in a #8220;molten jellylike #8221; form and combination is possible without any loss in the structure. However, it is quite difficult to control transparency moment in this and other phases of direct heat application. In indirect heat application, as applied to polyethylene material in Phase II and III, time between initial heating-transparencydegradation phases has been able to be extended. Heat application has revealed more optimal temperature and total time values. Since temperature increases or decreases happen slowly in all phases of indirect heat application, development of combinations with more regular inner structures can be ensured. Literature values have been produced during the heat applications in the scope of the study as well. Temperatures in 210ºC - 230ºC interval can be suggested as the appropriate temperature values for the targeted indirect heat application, the full transparency in the specified phases and study interval. The temperature which starts deflagration process of the material is 250°C and higher temperatures for indirect heat application. In the scope of the meaning of #8220;transparency #8221; in this sense, we mean performance of combination process by indirect heat application, before the material deflagrates and not after the material loses its transparency and turn into molten form as under the room temperature. Combination via heat application has also been analyzed by placing supportive elements between two polyethylene layers with the aim of increasing the endurance of combined structure. The aim of this procedure is to examine the damage preventive effects of supportive elements in the orthosis. Internal structure images obtained via optical microscope are in line with the above explained situation. Internal structure images of directly or indirectly heated and dense fiber supported samples have revealed that melting is not at a sufficient level to cover all the fibers in the dense fiber structure and that there are gaps in the contact point of two structures. Internal structure images of the less fibrous samples have shown that fibers are covered by the material and a gap-free structure has been created in such less fibrous structures. It can easily be concluded that a specific ratio should be determined between the main material and the supportive material for supported structures. In the formation of fibrous structure via indirect heat application, the time between 210ºC - 230ºC interval has been enough for placing supportive elements for the studied dimensions. Said temperature interval can be extended with the help of a sensible and automatically controlled circuit. In this way, a more regular heat application can be ensured, which enables a more regular composition (when compared with fast heat application) of the structures tried to be combined. It has been revealed during the tensile tests conducted in the scope of the study that #8220;unavoidable gaps in the structures combined by using directly or indirectly heated dense fiber negatively affect the tensile strength #8221; and that #8220;more strong combinations can be created with less fibrous and indirectly heated structures since fibers distributed loosely between the layers can be covered by the molten polyethylene material #8221;. Sheet sample in Phase I has been used to enable comparisons between tensile strengths of polyethylene material. By analyzing the tested samples, it has been found out that the fracture observed in a fiber supported sound combination is similar to a fracture in a brittle material. In the light of the data obtained in the experimental study, phases such as the repair of damaged polyethylene orthosis, use of the orthosis in daily life and evaluation of the life cycle of orthosis can be complementary applications of the study. In addition, conduct of bending, pressure and fatigue tests and interpretation of the orthosis model with exhaustion analysis software can enable making of a better evaluation on the material combination through orthosis repair and its subsequent usability.