Issue 39

M. Shariati et alii, Frattura ed Integrità Strutturale, 39 (2017) 166-180; DOI: 10.3221/IGF-ESIS.39.17 166 Investigation of stress intensity factor for internal cracks in FG cylinders under static and dynamic loading Mahmoud Shariati Ferdowsi University of Mashhad, Mashhad, Iran mshariati44@um.ac.ir, http://orcid.org/0000-0001-8742-2975 Masoud Mahdizadeh Rokhi Shahrood University of Technology, Shahrood, Iran mmrokhi@shahroodut.ac.ir, http://orcid.org/ 0000-0001-6973-8431 Hassan Rayegan University of Birjand, Birjand, Iran hassanrayegan@yahoo.com A BSTRACT . This paper investigates the variations of mode I stress intensity factor ( K I ) for inner penny-shaped and circumferential cracks in functionally graded solid and hollow thick walled cylinders, respectively with the changes of crack geometry, material gradation and loading conditions. The functionally graded material of cylinders consists of epoxy and glass. It is assumed that the mechanical properties vary with a power law in the radial direction of cylinders. Micromechanical models for conventional composites are used to estimate the material properties of functionally graded cylinders. The equations of motion obtained from the extended finite element discretization are solved by the Newmark method in the time domain. The interaction integral method is employed to calculate the mode I stress intensity factor ( K I ). The MATLAB programming environment was implemented to solve the problem. K EYWORDS . Stress intensity factor; Functionally graded cylinders; Penny- shaped cracks; Circumferential cracks; Extended finite element method; Rotational speed. Citation: Shariati, M., Mahdizadeh Rokhi, M., Rayegan, H., Investigation of stress intensity factor for internal cracks in FG cylinders under static and dynamic loading, Frattura ed Integrità Strutturale, 39 (2017) 166-180. Received: 12.06.2016 Accepted: 11.10.2016 Published: 01.01.2017 Copyright: © 2017 This is an open access article under the terms of the CC-BY 4.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. I NTRODUCTION unctionally graded materials (FGMs) are a new class of composite materials in which their composition and structure gradually change resulting in a corresponding change in their properties. These materials are used extensively in applications such as thermal barrier coatings are exposed to severe stress gradients induced by F