INVESTIGATION OF TIME AND FREQUENCY DOMAIN FATIGUE LIFE CALCULATION METHODS USING FINITE ELEMENT METHOD

Abstract

There are several vibration induced fatigue damage and life calculation methods in time domain and frequency domain. These methods with the use of finite element method play important role in mechanical design process. In this study, Rainflow counting method and Dirlik counting method are investigated using finite element method and it is found that Dirlik method gives minimum fatigue life. If there is not an option to validate the design with tests and the only way to evaluate the design is the finite element analysis, Dirlik method is advantageous because it gives the safest design.   

Keywords

• Rainflow Counting,Dirlik Method,Vibration Fatigue,Random Vibrations,Fatigue

ZAMAN VE FREKANS DÜZLEMİNDE YORULMA ÖMRÜ HESAPLAMA YÖNTEMLERİNİN SONLU ELEMANLAR YÖNTEMİ İLE İNCELENMESİ

Abstract

Maruz kalınan titreşim nedeni ile meydana gelen yorulma hasarı ve ömrünü tespit etmek için zaman düzleminde ve frekans düzleminde hesaplama yapan yöntemler bulunmaktadır. Bu yöntemler sonlu eleman analizleri ile birlikte kullanılarak mekanik tasarımın şekillendirilmesi sürecinde kritik rol oynamaktadır. Bu çalışmada zaman düzleminde yorulma hesaplayan Rainflow yöntemi ve frekans düzleminde yorulma hesaplayan Dirlik yöntemi sonlu elemanlar analizleri yardımı ile incelenmiş ve minimum yorulma ömrünü Dirlik metodunun verdiği görülmüştür. Herhangi bir test ile tasarım doğrulama imkânı bulunmadığında ve tasarım yalnızca sonlu elemanlar yöntemi ile değerlendirileceğinde, Dirlik metodu sonuçları referans alınarak yapılacak tasarımın en güvenli tasarımı vereceği için en avantajlı yöntem olduğu tespit edilmiştir.

Keywords

• Rainflow Yöntemi,Dirlik Yöntemi,Titreşim Kaynaklı Yorulma,Rastlantısal Titreşim,Yorulma

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