Browsing by Author "Hammond, D. W."

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    Fatigue fracture in the presence of shot peening residual stresses: initiation, propagation and relaxation phenomena
    (1988-09) Hammond, D. W.; Meguid, S. A.
    This thesis describes both experimental and theoretical work performed in order to analyse fatigue fracture in the presence of shot-peening induced residual stresses. In the study, four contrasting alloys were examined by fatigue testing and use was made of different test techniques to illustrate some of the phenomena associated with fatigue fracture in shot-peened components. The results demonstrate that in order to characterise the process of fatigue in a component bearing residual stresses, it is necessary to consider three groups of variables. These are the applied and residual stress state, the geometry of the component and the flaws it contains and the nature of the alloy itself, including any propensity to work harden, recover or undergo phase changes due to peening or fatigue loading.
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    A new test apparatus to measure the adhesive shear strength of impact ice on titanium 6Al-4V alloy
    (Elsevier, 2019-02-18) Pervier, Marie L. A.; Gurrutxaga Lerma, B.; Piles Moncholi, Eduardo; Hammond, D. W.
    We present a new shear test which may be used in an icing environment. Ice is formed on a jig containing the sample material and this is then loaded by a forcing mechanism to effect the adhesive test. It allows impact (atmospheric) ice adhesive shear tests to be undertaken without disturbance or delay, in icing conditions. Finite element analysis is used in order to evaluate the controlling shear stresses in the most highly stressed zone of the ice/substrate interface and some sample experimental data is given for the adhesion of some impact ices to Ti-6Al-4V alloy with different surface finishes. The adhesion forces reported, represent peak values rather than spatially averaged stress values. Therefore values of adhesive shear strength obtained are higher than previous authors (in the range from 2 to 14 MPa instead of 0.05 to 0.5 MPa).