*Understanding the effect of load sequence is important in the context of a blade-disc dovetail joint in an aero-engine and many other such applications where, the mating surfaces undergo fretting wear. Typically researchers have analysed the fretting using constant amplitude loading condition. However, due to the variation in rotation speed of the rotors, there is a variable amplitude loading that is related to the rotation speed of the rotor stages. It is important to understand the fretting wear under variable slip amplitude loading conditions.*

*In the present work, a two-dimensional finite element analysis is carried out for a cylinder-on-plate configuration. Both cylinder and plate were modelled with elastic material behavior.*

*Both the cylinder and plate were modelled as deformable bodies with elastic material properties of steel, viz. modulus of elasticity of 200 GPa and Poisson’s ratio of 0.3. A sufficiently refined mesh of size 10x30 um was used in the contact zone with 3-noded (CPE3) and 4-noded (CPE4), first order plane strain elements. The regions away from the contact zone were modelled using a coarser mesh size to reduce the computational effort.* *The loading was applied in two-steps: first a compressive normal load (P) was applied by coupling the top surface of the cylinder with a reference point. Thereafter, oscillatory tangential displacement was applied on the cylinder. During the normal load application, the cylinder was allowed to translate only in Y- direction with rotation being constrained. While during the application of tangential displacement (δ), movement in both in X- and Y- direction were allowed. The bottom face of the plate was constrained in both X- and Y- direction during both normal load and tangential displacement step. The contact interaction between the cylinder is define using master-slave algorithm by choosing plate as master surface while cylinder as slave surface. The frictional interaction was defined using Coulomb’s frictional law assuming a constant friction coefficient (µ). Penalty formulation was used to model both tangential and normal behaviour to avoid convergence issues.*

*An incremental wear modelling algorithm was used to model the wear of cylindrical pad while the plate was assumed as un-worn. This simulates a practical scenario where, generally one of the mating surfaces is sufficiently hardened or an interfacial harder/sacrificial element is inserted to restrict the wear to only one of the surfaces. A Fortran-based ABAQUS® subroutine UMESHMOTION was used to simulate the wear profile for the cylinder. A constant extrapolation technique was used to simulate 18000 cycles of fretting. The finite element analysis results were validated with the analytical solutions and literature data. The fretting wear modelling was carried out for two different slip amplitudes viz., 25 µm and 150 µm, to simulate the low and high slip amplitude loading respectively. Two blocks of alternate low and high slip amplitudes were applied to understand the influence of load sequence. They were organized as Hi-Lo or Lo-HI block of slip amplitudes. Important contact parameters viz., contact pressure, contact stresses and contact slip were extracted. A comparison was made between the low-high and high-low load sequence based on the ablation depth and worn out profiles.* *Hi-Lo load sequence is found more damaging than Lo-Hi load sequence; The wear volume obtained under Lo-Hi and Hi-Lo load sequence lies between the upper and lower bounds obtained using ‘Hi’ load sequence and ‘Lo’ load sequence.*


Finite Element Study of the Effect of Load Sequence on the Fretting Wear

Division / Sponsors: 
Aerospace, Bioengineering, Applied Mechanics, Design Engineering Division, Advanced Energy Systems, Manufacturing Engineering Division, Noise Control and Acoustics, Nondestructive Evaluation, Diagnosis, and Prognosis (NDPD), Nuclear Engineering Division, Process Industries Division, Fluids Engineering, Heat Transfer, Materials, Microelectromechanical Systems, Safety Engineering and Risk Analysis, Computers & Information in Engineering


Paper Proceedings: https://asmedigitalcollection.asme.org/IMECE/IMECE2020/volume/84478

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