Analysis of the spreader track wheels premature damages Miodrag A. Arsic ´ a , Sr - dan M. Bošnjak b,⇑ , Zoran D. Odanovic ´ a , Momc ˇilo M. Dunjic ´ b , Aleksandar M. Simonovic ´ b a Institute for Testing of Materials IMS, Bulevar Vojvode Mišic ´a 43, 11000 Belgrade, Serbia b University of Belgrade, Faculty of Mechanical Engineering, Kraljice Marije 16, 11120 Belgrade 35, Serbia article info Article history: Received 25 May 2011 Received in revised form 25 October 2011 Accepted 7 November 2011 Available online 15 November 2011 Keywords: Spreader Track wheels Damage diagnostics Stress analysis Experimental investigations abstract The superstructure of the ARs 2000 spreader leans on three crawlers of identical length, width and height. Serious damage to the track wheels threads occurred already during the spreader’s travel from the erection site to the open pit mine as well as immediately after the overburden system exploitation started. The goal of the study presented in this paper was to diagnose the cause of the track wheels premature damage. Contact stresses on the track wheel bearing surface are defined by applying Hertz’s theory and FEM. In order to clarify the causes of the damages, experimental investigations were performed with the purpose of defining the chemical composition, tensile properties, impact toughness and macro and microhardness of the track wheel material. Metallographic examinations were also conducted. Based on the results of the analytical–numerical–experimental analysis, it can be concluded that track wheels failures are predominantly caused by the ‘design-in’ and ‘manufacturing-in’ defects. Ó 2011 Elsevier Ltd. All rights reserved. 1. Introduction Although the wheel design and manufacturing history is very long, even today a relatively large number of researchers are occupied with different problems regarding wheels [1–5], traveling mechanisms and belonging substructures [6–18]. The introduction of the crawler [19,20] undoubtedly presents a milestone in the development and various usage possi- bilities of working machines. Today, crawlers became the dominant traveling mechanism design for open-cast mining ma- chines. The spreader, Fig. 1, presents the final link in the system for continuous overburden removal in the open pit mine ‘‘Kostolac’’ – Serbia. Its superstructure leans on three crawlers of the same length L = 11,570 mm, width B = 4100 mm and height H = 3292 mm. Two steering crawlers enable the spreader curve travel. Every crawler has six two-wheel bogies, Fig. 1. Serious track wheels threads damages, Fig. 2, occurred already during the spreader’s travel from the erection site to the open pit mine and also immediately after the beginning of the overburden system exploitation (after only 1000 work- ing hours or about 3 months). Although infrequently, failures of high performance machines’ (HPM) traveling mechanisms may lead to very serious [9,10] or even disastrous consequences [21], similar to those resulting from failures of vital superstructure parts [22–25]. However, even in cases when consequences are not catastrophic, failures of the HPM traveling mechanisms cause high finan- cial losses [6,26,27]. Furthermore, the replacement of damaged parts is executed on site, often in hard working conditions, Fig. 3, by that essentially prolonging the downtime of the complete surface mining system. Losses caused by machine down- time i.e. the system as a whole, may exceed direct material damage several times, Table 1. 1350-6307/$ - see front matter Ó 2011 Elsevier Ltd. All rights reserved. doi:10.1016/j.engfailanal.2011.11.005 ⇑ Corresponding author. Tel.: +381 11 3370831; fax: +381 11 3370364. E-mail address: sbosnjak@mas.bg.ac.rs (S.M. Bošnjak). Engineering Failure Analysis 20 (2012) 118–136 Contents lists available at SciVerse ScienceDirect Engineering Failure Analysis journal homepage: www.elsevier.com/locate/engfailanal