Copyright © 2009 ICCES ICCES, vol.10, no.2, pp.41-50 Towards standardising the fatigue crack simulation studies on metallic materials S. M. Beden 1 , S. Abdullah 1 and A. K. Ariffin 1 Summary Fatigue crack growth as consequence of service loads depends on many dif- ferent contributing factors. This paper describes the fatigue crack growth behavior of metallic materials under cyclic loading towards standardizing the fatigue crack studies on metallic materials. For the simulation purpose, three points bend (TPB) with span to width ratio 8:1 and compact tension (CT) specimens geometry were used. There are many factors affecting the fatigue crack growth in structures, such as fatigue crack growth model, stress ratio, aspect ratio and type of geometry. The behavior of such cases is shown using different fatigue crack models (Paris, For- man and Austen). These models gave different fatigue crack growth behavior. The fatigue crack growth obtained from two specimens geometry was compared. Dif- ferent values of these factors showed different effects on the fatigue crack growth. For further study need to validate the modelling procedure with experimental work as well as take into account the other factors such as; other types of geometries with fatigue crack models and environmental effects. keywords: Cyclic loading, factors; fatigue crack growth model; geometry; simulation. Introduction The problem of crack growth is a major issue in the prediction and maintenance of aerospace structures, as well as other structural elements in mechanical and civil engineering projects. For the last three decades, fracture mechanics have been the main tool with which such problems have been treated. The fracture mechanics scientists and engineers have made tremendous advances, from the basic practical approach dominated by Paris–Erdogan law (1963), to more and more sophisticated crack growth models. Mathematical and metallurgical models, experimental analy- sis of simple models and testing of complex structures have resulted in thousands of publications, dozens of models for crack growth and life prediction. In some cases the difficulty of machining a full-size specimen has made investigators to design sub-size specimens (Jeelani, Natarajan and Reddy, 1986). There are many factors affecting the fatigue crack growth in structures, such as; stress ratio, thickness of the specimen or aspect ratio, types of specimen’s geometry, fatigue crack growth model etc. A major concern of fracture mechanics is the influence of the load ratio on the behavior of cracks. This is expressed in the stress ratio (R), which is clas- sically defined as: the ratio of minimum to maximum applied stresses (Ellyn and 1 Department of Mechanical and Materials Engineering University KebangsaanMalaysia. E-mail: shahrum@eng.ukm.my (S. Abdullah)