STRESS CONCENTRATION AND FATIGUE LIFE PREDICTION FOR DISKS CENTRIFUGAL SEPARATORS

Abstract

The paper presents the continuation of a previous study ( Anghel, Iatan, Pasat, 1998) concerning the elastic analysis of disk centrifugal separators. The goals are the state of stress analysis and stress concentration determination in the main critical junctions of the separator´s bowl, subjected to loads corresponding to the main technological conditions. Taking into account the cyclic nature of technological loads (centrifugal forces r omega ²) standard procedures for estimating the fatigue and residual strength of the entire bowl are discussed for prediction of the lifetime. The numerical results presented were obtained for a real small separators bowl. Two numerical analyses were developed to identify the critical junctions of the bowl due to the main loads: central axial load (F_a), centrifugal force (r . omega²) and internal pressure (p). One analysis is based on the extension of the classical thin shell theory and the flexibility matrix method ( Anghel, Iatan, Pasat, 1998) and the second on the finite element method (FEM), using a professional package, COSMOS/M Designer II. The study reveals a reasonable accuracy of the analytical and numerical results, an accurate positioning of the critical junctions and a great number of lifetime service cycles. On the other hand, the study may be a suitable method for preliminary design analysis and load-carrying capacity prediction of such structures.