Lynx: A User-Friendly Computer Application for Simulating Fatigue Growth of Planar Cracks Using FEM R. BRANCO, 1 F.V. ANTUNES, 2 J.D. COSTA 2 1 Department of Mechanical Engineering, ISEC, Polytechnic Institute of Coimbra, Coimbra, Portugal 2 CEMUC, Department of Mechanical Engineering, University of Coimbra, Coimbra, Portugal Received 31 March 2011; accepted 13 September 2011 ABSTRACT: People engaged in fracture mechanics education recognise the need to combine theory and effective practice in order to enhance students’ skills in this field. Nevertheless, real experiments are not always possible for education purposes because they require too much time, involve specialised equipment and specimen preparation. In these circumstances, numerical simulation is a valid alternative to guarantee the link between theory and practice. In this article, a computer application capable of simulating the fatigue crack growth (FCG) of planar cracks under mode-I cyclic loading is presented. This tool incorporates an extensive range of real significance problems found in the context of FCG. Besides, an intuitive and user-friendly inter- face was provided in order to improve its functionality and to allow the user to define quickly and easily fundamental input data. Default values are proposed for less experienced users, seeking the minimum effort in numerical model definition. The use of this software in educational context is expected to provide a major insight into FCG phenomenon. ß 2011 Wiley Periodicals, Inc. Comput Appl Eng Educ; View this article online at wileyonlinelibrary.com/journal/cae; DOI 10.1002/cae.20578 Keywords: fatigue crack growth; engineering educational software; finite element analysis INTRODUCTION Fatigue, as a consequence of crack initiation and propagation, remains the major source of failure for mechanical components subjected to cyclically time-varying loading. Modern defect-tol- erant design approaches to fatigue are based on the premise that engineering components are inherently flawed. Designers must be able to predict fatigue life accurately in order to avoid unexpected in-service failures. For that reason, undergraduate and graduate engineering mechanics curricula always focus on this phenomenon. However, due to materials’ opacity and due to the wide range of variables involved, a deep understanding of main concepts is not always achieved by the standard stu- dent. In this context, people engaged in fracture mechanics edu- cation recognise the need to combine theory and effective practice in order to enhance student’s skills in this field. Never- theless, real experiments are not always possible for education purposes because they require too much time, significant finan- cial resources and high-tech equipment. In these circumstances, numerical simulation is a valid al- ternative to guarantee the link between theory and practice. Similar experiences have been carried out in other scientific areas [1–3]. As a matter of fact, different numerical approaches have been successfully used to study fatigue crack growth (FCG) of planar cracks. One of the most efficient ways, widely used in literature, consists of an automatic procedure based on the finite element method. The numerical model is usually gen- erated using commercial finite element packages [4–28]. How- ever, it is a relatively complex and time-consuming task since these programs have been developed for general purposes and not for such specific situations. On the other hand, most of the existing software solutions devoted to FCG are not available commercially, such as ADAPCRACK3D [29], FRANC3D [30], FRANC/FAM [31], CRACKTRACER 3D [32], among others. ZENCRACK [33] is commercial FE software designed for line- ar elastic fracture mechanics problems but is also able to study 3D FCG problems. The uncracked 3D-FE mesh is created using an external FE package and consists of a pure hexahedral mesh in the complete structure. Then, the crack front is inserted into Correspondence to R. Branco (rbranco@isec.pt). ß 2011 Wiley Periodicals, Inc. 1