Keywords: ultrasonic mapping, stacker boom luffing pulleys, BS 7910, Irwin equation, failure, heavy–duty pulleys, fracture toughness, stress, finite element method, FEM, critical crack size, metallic structures, structural flaws, flaw acceptability, welding, modelling
Case study of an evaluation of a Stacker Boom Luffing Pulley by Irwin's model and under BS 7910 guidance
A case study on evaluation of a heavy–duty Stacker Boom Luffing Pulley was presented. Irwin's fracture toughness method and the British Standard were used to help in the decision–making process. Using inspection, discontinuities were found at the first look in the cylinder cross–section at the region of welding of the cylinder ends. A more detailed analysis was conducted by ultrasonic mapping, crossing the cylinder transverse thickness and longitudinal to its length. The final decision took into account accurate analysis of the stress σ
1(Principal Stress) from Finite Element Method (FEM) and σ
refbased on British Standard, and comparing the defect real size and the critical crack size calculated by Irwin equation.