Sonlu Elemanlar Yaklaşımı Kullanılarak Sandviç Yapının Modal Analizi

Öz

Otomotiv, havacılık, denizcilik ve ileri mühendislik uygulamalarında sandviç yapılar, yüksek mukavemet/ağırlık oranı, aşınma direnci ve iyi yüzey kalitesi gibi üstün özelliklerinden dolayı giderek daha fazla tercih edilmektedir. Bu çalışmada, sandviç yapıların doğal frekansları ve mod şekilleri incelenmiş; farklı sınır koşullarının ve malzeme kombinasyonlarının titreşim karakteristikleri üzerine etkileri değerlendirilmiştir. Modal analizler ANSYS yazılımı kullanılarak Sonlu Elemanlar Yöntemi (SEM) ile gerçekleştirilmiş ve üretilen sonlu elemanlar modeli literatür verileriyle karşılaştırılarak doğrulanmıştır. Modelde, üst ve alt yüzeylerde karbon çeliği ve karbon fiber takviyeli plastik (CFRP) malzemeler; çekirdek tabakasında ise poliüretan elastomer matrisli fiber ve PVC köpük kullanılmıştır. Bulgular modelin doğruluğunu ve geçerliliğini ortaya koymakta; ayrıca sınır koşullarının ve malzeme tiplerinin doğal frekanslar üzerindeki etkilerini göstererek mühendislik tasarımlarında yapılacak parametrik analizler için temel oluşturmaktadır.

Anahtar Kelimeler

• Modal Analiz
• Mod Şekli
• Doğal Frekans
• Sandviç Yapı

Modal Analysis of Sandwich Structure Using Finite Element Approach

Abstract

In automotive, aviation, marine and advanced engineering applications, sandwich structures are increasingly preferred due to their superior properties such as high strength to weight ratio, wear resistance, and good surface quality. In this study, the natural frequencies and mode shapes of sandwich structures were investigated, and the effects of different boundary conditions and material combinations on their vibration characteristics were evaluated. Modal analyses were performed using the Finite Element Method (FEM) via ANSYS software, and the generated model was validated by comparing with existing literature data. In the model, carbon steel and carbon fiber reinforced plastic (CFRP) were used as the face sheet materials, while polyurethane elastomer matrix fiber and PVC foam were used as the core material. According to the results, the sandwich structure with a PVC foam core exhibited a 178.6% increase in the first natural frequency compared to the structure with a polyurethane elastomer matrix fiber core. Boundary conditions had a significant impact on natural frequencies, with the completely fixed (C–C–C–C) configuration yielding values 28.6% higher than the completely free (F–F–F–F) condition. Sandwich structures with fully CFRP face sheets showed a 27.7% higher natural frequency than those with hybrid face sheets. These findings demonstrate that the dynamic performance of sandwich structures is highly sensitive to boundary conditions as well as the types of core and face sheet materials, emphasizing the importance of appropriate material and geometric configuration in engineering design.

Keywords

• Modal Analysis
• Mode Shape
• Natural Frequency
• Sandwich Structure

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