PSI - Issue 12

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2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216  2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Stress Analysis. 10.1016/j.prostr.2018.11.106 ∗ Corresponding author. Tel.: + 39 080 5962704. E-mail address: luciano.a ff errante@poliba.it 2210-7843 c 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 3.0 / ) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Stress Analysis. ∗ Corresponding author. Tel.: + 39 080 5962704. E-mail address: luciano.a ff errante@poliba.it 2210-7843 c 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 3.0 / ) Peer-review u der re ponsibility of Scientific ommitt e of AIAS 2018 Internati al Conference on Stress Analysis. * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt The first study of adhesion between bodies is due to Bradley (1932), which integrated the Lennard-Jones interaction law between rigid spheres finding a total attractive force equal to 2 π ∆ γ R , where ∆ γ is the adhesion surface energy and R is the composite radius of the contacting spheres. In order to study the adhesive contact between elastic spheres, Derjaguin (1934) supposed deformations of the contacting bodies are not a ff ected by attractive interactions, and hence The first study of adhesion between bodies is due to Bradley (1932), which integrated the Lennard-Jones interaction law between rigid spheres finding a total attractive force equal to 2 π ∆ γ R , where ∆ γ is the adhesion surface energy and R is the composite radius of the contacting spheres. In order to study the adhesive contact between elastic spheres, Derjaguin (1934) supposed deformations of the contacting bodies are not a ff ected by attractive interactions, and hence XV Portuguese Conference on Fracture, PCF 2016, 10-12 February 2016, Paço de Arcos, Portugal Thermo-mechanical modeling of a high pressure turbine blade of an airplane gas turbine engine P. Brandão a , V. Infante b , A.M. Deus c * a Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal b IDMEC, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal c CeFEMA, Department of Mechanical Engineering, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1, 1049-001 Lisboa, Portugal Abstract During their operation, modern aircraft engine components are subjected to increasingly demanding operating conditions, especially the high pressure turbine (HPT) blades. Such conditions cause these parts to undergo different types of time-dependent degradation, one of which is creep. A model using the finite element method (FEM) was developed, in order to be able to predict the creep behaviour of HPT blades. Flight data records (FDR) for a specific aircraft, provided by a commercial aviation company, were used to obtain thermal and mechanical data for three different flight cycles. In order to create the 3D model needed for the FEM analysis, a HPT blade scrap was scanned, and its chemical composition and material properties were obtained. The data that was gathered was fed into the FEM model and different simulations were run, first with a simplified 3D rectangular block shape, in order to better establish the model, and then with the real 3D mesh obtained from the blade scrap. The overall expected behaviour in terms of displacement was observed, in particular at the trailing edge of the blade. Therefore such a model can be useful in the goal of predicting turbine blade life, given a set of FDR data. AIAS 2018 International Conference on Stress Analysis On the DMT adhesion theory: from the first studies to the modern applications in rough contacts Guido Violano a , Giuseppe Pompeo Demelio a , Luciano A ff errante a, ∗ a Department of Mechanics, Mathematics and Management, Politecnico of Bari, V.le Japigia, 182, 70126, Bari, Italy Abstract In the last years, i creasing interest has been devoted to the study of the adhesion between rough media. The Derjaguin, Muller & Toporov (DMT) theory is one of the most known models to describe adhesion between hard elastic solids with long range adhesive interactions. However, many versions of the DMT theory can be found in the literature. In the first part of the present work, we try to make order about the various versions of the DMT theory appeared over the years. All models, often confusedly called with the same name ”DMT theory”, are based on the same assumption of neglecting deformations due to the adhesive forces. They predicts the same value of the detachment force at the pull-o ff , but only the so-called DMT force approach correctly captures the evolution trend of the adhesive force during the contact. In the second part of the work, we address the problem to include adhesion in the contact of rough surfaces according to the DMT theory. Specifically, we compare the Maugis’ idea to add adhesion in the Greenwood and Williamson asperity theory, with more recent models: the Interacti g nd Coalescing Hertzian Asperities (ICHA) ne and the Persson’s theory. The two models, which both take account of adhesion according to the DMT force approach, give very similar results, showing that the pull-o ff force is negligibly a ff ected by the shortest wavelength components of the surface roughnes . On th contrary, the Maugis’ mo el stron ly underestimates adhesion and predicts a vanishing pull-o ff force when the upper cut-o ff spatial freq ency f the surface is increased. c 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http: // creativecommons.org / licenses / by-nc-nd / 3.0 / ) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Stress Analysis. Keywords: DMT theory; fractal surfaces; roughness; adhesion. © 2018 The Authors. Published by Els vier B.V. This is an open access articl u de the CC BY-NC-ND licens (http://creativ commons.org/licenses/by-nc-nd/3.0/) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Str ss Analysis. AIAS 2018 International Conference on Stress Analysis n the T adhesion theory: fro the first studies to the odern applications in rough contacts Guido Violano a , Giuseppe Pompeo Demelio a , Luciano A ff errante a, ∗ a Department of Mechanics, Mathematics and Management, Politecnico of Bari, V.le Japigia, 182, 70126, Bari, Italy Abstract In the last years, increasing interest has been devoted to the study of the adhesion between rough media. The Derjaguin, Muller & Toporov (DMT) theory is one of the most known models to describe adhesion between hard elastic solids with long range adhesive interactions. However, many versions of th DMT theory can be found in the literatur . In the first part of the present work, we try to make order abo t the various versions of the DMT theory appeared over the years. All models, often confusedly called with the same name ”DMT theory”, are based on the same assumption of neglecting deformations due to the adhesive forces. They predicts the same value of the detachment force at the pull-o ff , but only the so-called DMT force approach correctly captures the evolution trend of the adhesive force during the contact. In the second part of the work, we address the problem to include adhesion in the contact of rough surfaces according to the DMT theory. Specifically, we compare the Maugis’ idea to add adhesion in the Greenwood and Williamson asperity theory, with more recent models: the Interacting and Coalescing Hertzian Asperities (ICHA) one and the Persson’s theory. The two models, which both take account of adhesion according to the DMT force approach, give very similar results, showing that the pull-o ff force is negligibly a ff ected by the shortest wavelength components of the surface roughness. On the contrary, the Maugis’ model strongly underestimates adhesion and predicts a vanishing pull-o ff force when the upper cut-o ff spatial frequency of the surface is increased. c 2018 The Authors. Published by Elsevier B.V. his is an open a ce s article und r the CC BY-NC-ND licens (http: // creativecommons.org / licenses / by-nc-nd / 3.0 / ) Peer-review under responsibility of the Scientific Committee of AIAS 2018 International Conference on Stress Analysis. Keywords: DMT theory; fractal surfaces; roughness; adhesion. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. 1. Introduction 1. Introduction