Structural Integrity Assessment and Remaining Fatigue Life Estimation of a Rotary Dryer Shell Using Finite Element and Fracture Mechanics Approaches

Abstract

Rotary dryers are widely used in fertilizer, mineral processing, and chemical industries under cyclic thermo-mechanical loading, making their shells susceptible to fatigue cracking and structural degradation during long-term service. This study evaluates the structural integrity and remaining fatigue life of a rotary dryer shell using an integrated finite element analysis (FEA) and fracture mechanics approach. A global–local finite element model was developed in ANSYS Mechanical to identify critical stress concentration regions, while submodeling was employed to improve local stress evaluation. Semi-elliptical surface cracks were introduced, and the Mode-I Stress Intensity Factor (KI) was determined using the Contour Integral method. Fatigue crack propagation and remaining fatigue life were predicted using Paris Law. The global analysis produced a maximum von Mises stress of 234.13 MPa, whereas the submodel predicted a localized stress of 874.71 MPa at the shell–riding ring welded joint. The calculated KI ranged from 203.61 to 275.72 MPa√mm, with fatigue crack growth rates between 2.67 × 10⁻⁹ and 6.63 × 10⁻⁹ m/cycle. The predicted remaining fatigue life was approximately 1.0 × 10⁷ loading cycles, equivalent to 39,682 operating hours (4.53 years). The proposed framework provides an effective basis for structural integrity assessment and condition-based maintenance planning of rotary dryer shells.