Numerical simulations and experimental measurements of the stress intensity factor in perforated plates Antonino Cirello a , Franco Furgiuele b , Carmine Maletta b, * , Antonino Pasta a a Department of Mechanical Engineering, University of Palermo, Viale delle Scienze, 90128 Palermo, Italy b Department of Mechanical Engineering, University of Calabria, P. Bucci 44C, 87030 Arcavacata di Rende (CS), Cosenza, Italy article info Article history: Received 13 April 2007 Received in revised form 1 May 2008 Accepted 23 May 2008 Available online 6 June 2008 Keywords: Perforated plate Hybrid finite element Stress intensity factor Photoelasticity abstract A numerical procedure, which combines two hybrid finite element formulations, was developed to analyse the stress intensity factors in cracked perforated plates with a peri- odic distribution of holes and square representative volume elements. The accuracy of the method in predicting the stress intensity factor was verified by a comparison with experimental measurements, carried out by a photoelasticity method, and by commercial finite element software. Several simulations were executed by varying both the crack length and the hole diameters, and the effects of the holes on the stress intensity factor are illustrated. The method shows high accuracy and efficiency, as small differences were observed when compared with the traditional finite element method, notwithstanding a strong reduction in degrees of freedom and mesh complexity. Ó 2008 Elsevier Ltd. All rights reserved. 1. Introduction Perforated plates are widely used in many branches of engineering applications, particularly in power generating and chemical processing plants, where they are commonly employed in heat exchangers, pressure vessels, steam generators, etc. For this reason a specific ASME Boiler and Pressure Vessel Code [1] is available for the design of perforated plates, which is based on the elastic theory of plates and includes the required safety factors for the maximum allowable stresses. How- ever, owing to the great relevance of perforated plates in the aforementioned technically demanding applications, many re- search activities have been addressed to the study of such plates in the last five decades, with the aim of analysing their thermo-mechanical response, as well as of evaluating the safety margins and the failure mechanisms in specific conditions or emergency situations. In this regard, the contribution made by Gardner [2,3], which was the first to introduce the concept of equivalent solid plate for the design of perforated plates, is of great significance and the subsequently theoretical work done by other researchers are worth mentioning [4–9]. More recently the Finite Element Method (FEM) and Boundary Ele- ment Method (BEM) were widely used to analyse the thermo-mechanical behaviour of perforated plates, in terms of effective properties as well as the interactions between cracks and holes [10–18]. Unfortunately, these investigations indicate that the accuracy of the results strongly depends on the mesh size, especially in modelling the presence of cracks, and consequently high computational costs are involved. To overcome some of the limitations discussed above, Ghosh et al. developed a numerical method, known as VCFEM (Voronoi Cell Finite Element Method) [19], to analyze heterogeneous materials contain- ing inclusions or voids, in which a simple mesh can be generated by using the Dirichlet tessellation method. The method was also extended to study the effects of cracks and interfacial debonding in composite materials [20–22]. Special n-sided hybrid 0013-7944/$ - see front matter Ó 2008 Elsevier Ltd. All rights reserved. doi:10.1016/j.engfracmech.2008.05.007 * Corresponding author. Tel: +39 0984 494662; fax: +39 0984 494673. E-mail address: carmine.maletta@unical.it (C. Maletta). Engineering Fracture Mechanics 75 (2008) 4383–4393 Contents lists available at ScienceDirect Engineering Fracture Mechanics journal homepage: www.elsevier.com/locate/engfracmech