CHARACTERIZATION OF DUCTILE FRACTURE LOCI OF ISOTROPIC MATERIALS

Öz

There is no generally accepted ductile fracture criterion by the fracture mechanics community. As a result of the comparison of various ductile fracture criteria proposed in the literature, Maximum Shear Stress (MSS) criterion has been observed to be the most advantageous criterion with respect to the number of calibrated parameters and the accuracy of the model. Nevertheless, recently developed Karr-Akçay Energy Balance (KAEB) criterion was not evaluated in these studies. Therefore, in this study, KAEB criterion and MSS criterion are compared, and the advantages and disadvantages of both criteria are discussed. One of the fundamental shortcomings of MSS criterion is that the criterion is based on Lode angle/parameter only. In contrast, KAEB criterion contains the stress triaxiality and Lode angle/parameter dependence inherently. Both criteria, however, require only one calibration parameter. In this study, KAEB criterion is observed to be more advantageous compared to MSS criterion with respect to the number of calibrated parameters and the accuracy of the model.

Anahtar Kelimeler

• Fracture,Ductility,Plasticity,KAEB,MSS

İZOTROPİK MALZEMELERİN SÜNEK KIRILMA GEZENEKLERİNİN TAYİNİ

Öz

Kırılma mekaniği camiası tarafından genel kabul görmüş bir sünek kırılma kriteri henüz bulunmamaktadır. Literatürdeki çeşitli sünek kırılma kriterlerinin, kalibre edilen parametre sayısı ve modelin doğruluğu göz önünde bulundurularak karşılaştırılması sonucunda Maksimum Kayma Gerilmesi (MSS) kriterinin en avantajlı kriter olduğu gözlemlenmiştir. Buna karşın, bu karşılaştırma çalışmalarında yakın zamanda geliştirilmiş Karr-Akçay Enerji Dengesi (KAEB) kriteri göz önünde bulundurulmamıştır. Dolayısıyla, bu çalışmada, KAEB kriteri ile MSS kriteri deney sonuçları üzerinden karşılaştırılarak, her iki kriterin üstünlükleri ve eksiklikleri tartışılmıştır. MSS kriterinin yalnızca Lode açısına/parametresine bağlı bir kriter olması temel zayıflıklarından bir tanesidir. Buna karşın, KAEB kriteri gerilme üçeksenliliği ve Lode açısı/parametresi bağlılıklarını özünde içermektedir. Bununla birlikte, her iki kriter de yalnızca bir adet kalibrasyon parametresi hesabını gerektirir. Bu çalışmada, kalibre edilen parametre sayısı ve modelin doğruluğu göz önünde bulundurulduğunda, KAEB kriterinin MSS kriterine göre daha avantajlı bir kriter olduğu gözlemlenmiştir.

Anahtar Kelimeler

• Kırılma,Süneklik,Plastisite,KAEB,MSS

Kaynakça

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