English

A Martins J,Ferreira I

doi:10.5897/sre2015.6269

Abstract

An unexpected (premature) failure happened in Tail Pulley during operation in field. Consequently, a complete analysis in terms of fracture and fatigue performed. The analysis aimed to determine the failure root-cause by the analysis of the project and materials. The analysis covered the tensions undergone by the pulleys under operation and the material´s mechanical strengths. The results showed the project conforms the classical mechanics calculations. The failure, on the other hand, characterized as ductile fracture – Fatigue - with crack propagating along 45° referencing the cylinder longitudinal axis. The crack initiated at a flaw found at the weldment region, which resulted a shorter lifetime (collapsing). The sharpen flaw generated a shortcut in the failure process and jumped it straight to the phase of fracture - Stage II fatigue – called crack propagation.   Key words: Tag pulley, stress raiser, critical stress, fatigue.  &nbsp

Highlights

Mechanical failure of components is always detrimental to equipments and machines and sometimes catastrophic
The sharpen flaw generated a shortcut in the failure process and jumped it straight to the phase of fracture - Stage II fatigue – called crack propagation
This paper aims to analyse the pulley in terms of design, material application and manufacturing, determining the root cause of its abrupt collapse during operation

Summary

Introduction

Mechanical failure of components is always detrimental to equipments and machines and sometimes catastrophic. In the mining or quarry segments failures bring huge prejudices to companies due to downtime (sometimes production impossibility) and costs involved in corrective maintenances. Pulleys are essential to support and allow the conveying of materials and minerals back and forth in the production. Their failures generate always long stoppage in production. A deep analysis of the failed part is notoriously important to preventively avoid recurrence of such event. In this context, the design reanalysis and a “practice x theory”

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