Low velocity impact response of CFRP and Al2024-T3 helicopter blade

Abstract

A high level of safety is demanded in response to the foreign object damage (FOD) problem frequently encountered in aviation. For this reason, in this study, the effect of stone impact on a helicopter blade performed within the scope of FOD is investigated. Considering the actual size of the propeller, a stone impact is applied to a certain section and the mechanical behavior of the propeller is examined according to the material type. In this direction, the Bo-105 helicopter blade with the NACA-23012 profile is taken as a reference, and a 3D drawing of the blade is made in the SolidWorks program. The behavioral properties of metal and composite materials frequently preferred in aviation against stone impact are compared. For this purpose, Al2024-T3 and carbon fiber reinforced polymer (CFRP) are selected. These materials are frequently preferred in aviation. To observe the difference between the materials, low-velocity impact analysis is performed on two blade sections with span dimensions of 140 mm and chord dimensions of 310 mm under the same geometry and conditions. The analysis of the simulated action is obtained using the LS-DYNA program. Because it is a mechanical action, the Arbitrary Lagrangian (ALE) method was used accordingly. Within the scope of this method, the stone to be hit by the blade was modeled as a 5 mm solid structure and hit the blade surface with a speed of 3500 mm/s. While the blade with Al2024-T3 material was modeled as a shell, the CFRP blade was modeled as a composite part consisting of six layers at [0-90-0-90-0-90] degrees. Material properties were defined on the blade using 018 Law Plasticity and 54/55 Enhanced Composite Damage material cards for Al2024-T3 and CFRP, respectively. As a result of this analysis, the time-dependent changes in displacement, kinetic energy, and force parameters were acquired. Then, the low-velocity impact responses of the CFRP and the Al2024-T3 blades were compared.

Keywords

• Foreign object damage
• Helicopter blade
• Impact analysis
• Low velocity impact

CFRP ve Al2024-T3 helikopter kanadının düşük hızlı darbe cevabı

Abstract

Havacılık sektöründe sıklıkla karşılaşılan yabancı madde hasarı (YAMAHA) sorununa karşılık yüksek emniyet seviyesi talep edilmektedir. Bu nedenle çalışmada, YAMAHA kapsamında gerçekleştirilen helikopter pali üzerine taş çarpması etkisi araştırılmaktadır. Palin gerçek boyutu göz önüne alınarak taş çarpması belirli bir kesit üzerine uygulanmaktadır ve palin sahip olduğu malzemeye göre göstermiş olduğu mekanik davranış incelenmektedir. Bu doğrultuda NACA-23012 profiline sahip olan Bo-105 helikopter pali referans alınmış olup palin 3B çizimi Solidworks programında yapılmıştır. Çalışmada havacılıkta sıklıkla tercih edilen metal ve kompozit malzemelerin taş çarpmasına karşı davranış özellikleri karşılaştırılmıştır. Bu amaçla çalışmada Al2024-T3 ve Karbon fiber takviyeli polimer (CFRP) tercih edilmiştir. İki malzemenin farkını gözlemlemek üzere aynı geometri ve koşullarda spanı 140 mm ve veteri 310 mm boyutlarına sahip iki pal kesiti üzerine düşük hızlı darbe analizi gerçekleştirilmiştir. Simüle edilen eylemin analizi LS-DYNA programı kullanılarak elde edilmiştir. Mekanik bir eylem olması gerekçesiyle buna uygun olarak Keyfi Lagrange (ALE) metodu kullanılmıştır. Bu metod kapsamında pale çarptırılacak olan taş, 5 mm boyutunda katı bir yapıda modellenmiş olup 3500 mm/s hızıyla pal yüzeyine çarptırılmıştır. Al2024-T3 malzemeye sahip pal kabuk olarak modellenirken CFRP malzemeli pal [0-90-0-90-0-90] açılarında altı katmandan oluşan kompozit part olarak modellenmiştir. Malzeme özellikleri Al2024-T3 ve CFRP için sırasıyla 018 Law Plasticity ve 54/55 Enchanced Composite Damage materyal kartları kullanılarak pal üzerine tanımlanmıştır. Gerçekleştirilen bu analiz sonucunda her iki malzemenin yer değiştirme, kinetik enerji ve kuvvet parametrelerinin zamana bağlı değişimleri incelenmiştir. Böylece havacılık teknolojisinde sıklıkla tercih edilen CFRP ve Al2024-T3 malzemelerinin düşük hızlı darbe karşısındaki mekanik özellikleri karşılaştırılmıştır.

Keywords

• Darbe analizi
• Düşük hızlı darbe
• Helikopter pali
• Yabancı madde hasarı

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