Ultra Yüksek Mukavemetli Çeliklerden Yapılan Mobil Vinçlerdeki Kaynaklı Bağlantıların Yapısal Gerilim Yöntemi Kullanılarak Yorulma Ömrü Tahmini

Öz

Bu çalışmada, mobil vinç tasarım modelinin statik ve dinamik sonlu elemanlar analizi (FEA) yapılmış ve kaynaklı birleştirmelerin gerilmeleri yapısal sıcak nokta yöntemi ile incelenmiştir. Özellikle ultra yüksek dayanımlı çeliklerin (UHSS) kaynağında kaynak parametrelerinin seçimi mekanik özellikleri etkilemektedir. FEA sonuçlarına göre incelenen bölgeler için farklı malzeme ve kaynak parametreleri içeren numuneler hazırlanmış ve bu çalışmada uygulanan tahribatlı testler gerçekleştirilerek bir değerlendirme yaklaşımı önerilmiştir. Bu şekilde tahribatlı test sonuçları ve FEA değerlendirmeleri kullanılarak kaynaklı birleştirmelerin üretimindeki belirsizliklerin önüne geçilmiştir. Analiz sonucunda kaynaklı birleştirmelerin kritik bölgelerindeki maksimum asal gerilme için sıcak nokta değeri 527,54 MPa olarak bulunmuş ve S960QL malzemesi seçilmiştir. Bu çalışmalar sonucunda UHSS malzemeler tercih edilmiş ve kaynaklı birleştirmeler için minimum yorulma ömrü tahmini 13665 çevrim olarak hesaplanarak mobil vinç üretilmiştir.

Anahtar Kelimeler

• Yorulma ömrü tahmini
• sonlu elemanlar analizi
• mobil vinçler
• ultra yüksek dayanımlı çelikler
• kaynaklı bağlantılar.

Fatigue Life Estimation of Welded Joints in Mobile Cranes with Ultra High Strength Steels Using the Structural Stress Method

Abstract

In this study, static and dynamic finite element analysis (FEA) of a mobile crane design model were per-formed and stresses of welded joints were examined by the structural hot spot method. Especially in the welding of ultra high strength steel (UHSS), choice of welding parameters affects mechanical properties. According to the FEA results, specimens containing different materials and welding parameters were prepared for investigated regions and an evaluation approach was proposed by performing destructive tests applied in this study. In this way, uncertainties in the production of welded joints are avoided by using destructive test results and FEA evaluations. As a result of the analysis, the hotspot value for maximum principal stress in critical regions of welded joints was found to be 527.54 MPa, and S960QL material was selected. As a result of these studies, UHSS materials were preferred and the minimum fatigue life estimate for welded joints was calculated as 13665 cycles and a mobile crane was produced.

Keywords

• Fatigue life estimation
• finite element analysis
• mobile cranes
• ultra-high strength steels
• welded joints.

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