• FEM simulation of a crack propagation in a round bar under combined tension and torsion fatigue loading

      Citarella, Roberto; Maligno, Angelo; Shlyannikov, Valery; University of Salerno; University of Derby; Russian Academy of Sciences (Italian Group of Fracture, 2015-01)
      An edge crack propagation in a steel bar of circular cross-section undergoing multiaxial fatigue loads is simulated by Finite Element Method (FEM). The variation of crack growth behaviour is studied under axial and combined in phase axial+torsional fatigue loading. Results show that the cyclic Mode III loading superimposed on the cyclic Mode I leads to a fatigue life reduction. Numerical calculations are performed using the FEM software ZENCRACK to determine the crack path and fatigue life. The FEM numerical predictions have been compared against corresponding experimental and numerical data, available from literature, getting satisfactory consistency
    • Retardation effects due to overloads in aluminium-alloy aeronautical components

      Maligno, Angelo; Citarella, Roberto; Silberschmidt, Vadim V.; University of Derby; University of Salerno; University of Loughborough; Institute for Innovation in Sustainable Engineering; University of Derby; Quaker Way, Derby DE1 3HD UK; Department of Industrial Engineering; University of Salerno; via Giovanni Paolo II, Fisciano SA Italy; Wolfson School of Mechanical and Manufacturing Engineering; Loughborough University; Loughborough UK (Wiley, 2017-02-08)
      Fatigue data are generally derived under constant-amplitude loading conditions, but aircraft components are subjected to variable-amplitude loading. Without interaction effects, caused by overloads and underloads intermingled in a loading sequence, it could be relatively easy to establish a crack growth curve by means of a cycle-by-cycle integration. However, load-spectrum effects largely complicate a crack growth under variable-amplitude cycling. In this paper, fatigue crack growth behaviour of aeronautical aluminium alloy 2024-T3 was studied. Effects of various loading conditions such as stress ratio and amplitude loadings were investigated. In particular, the effect of different overloads on the fatigue crack growth was simulated using Zencrack code. Preliminary analyses on Compact Tension (CT) specimens proved that the numerical results generated were in agreement with the results provided by an afgrow code for the same conditions. A case study was carried out on a helicopter component, undergoing repeated overloads, to compare numerical results obtained implementing yield zone models in Zencrack.