DÜZLEMSEL OLMAYAN ÇATLAK ILERLEME PROBLEMLERININ ÜÇ BOYUTLU ANALIZI

Oğuzhan Demir, Ali Osman Ayhan
529 80

Öz


Enerji, Savunma, Havacılık ve Uzay teknolojileri, ülkeler için kritik öneme sahip olup, bilim ve teknoloji düzeyinin gelişmesinde öncü rol oynayan alanların başında gelmektedir. Ar-Ge ve yatırım maliyetlerinin yüksek olduğu bu alanlarda, kullanılan ekipmanlar da hem mali açıdan hem de malzeme güvenilirliği açısından büyük önem kazanmaktadır. Malzemelerde oluşabilecek hasarları en aza indirebilmek ve çatlak içeren yapıların emniyetli çalışabilmesini sağlamak için son yıllarda kırılma mekaniği alanında yapılan çalışmalar ağırlık kazanmıştır. Tasarım aşamasından başlayarak hasar/çatlak toleransları ve ömürleri tahmin edilerek iyileştirme çalışmaları gerçekleştirilmektedir. Havacılık ve uzay alanında en saygın kuruluşlar arasında yer alan NASA (National Aeronautics and Space Administration), uzay araçlarının kaynak bağlantılı bileşenlerinde, yüksek basınç ve sıcaklığa maruz kalan modüllerde ve çevrimli yüklere maruz kalan yapılarda karşılaşılan kırılma problemlerini kontrol etme, önleme ve buna benzer çatlaklı yapıların emniyetli çalışabilmesini sağlamaya yönelik yöntem ve standartlar geliştirerek bu konular üzerinde ciddi çalışmalar yürütmektedir.

Bu çalışmada, çatlaklı yapıların mod-I kırılma tokluğunu (KIC) belirlemede kullanılan standart CT (compact tension) numunesine eğik çatlak yerleştirilerek mod-I dış yüklemesi altında çatlağın üç boyutlu modelleme ve çatlak ilerleme simülasyonları gerçekleştirilmiştir. Kırılma ve çatlak ilerleme analizleri FCPAS (Fracture and Crack Propagation Analysis System) programı ile gerçekleştirilmiştir. Bu çalışma, FCPAS ile üç boyutlu karışık modlu çatlak ilerleme olgusunun modellenmesinin ilk adımını oluşturmaktadır.


Anahtar kelimeler


Sonlu Elemanlar Yöntemi, Çatlak ilerleme analizi, Karışık Mod-I/III, Düzlemsel olmayan çatlak ilerlemesi

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