PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at www.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 13 (2018) 255–26 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural I tegrity Procedia 00 (2018) 000 – 000

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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. ECF22 - Loading and Environmental effects on Structural Integrity Intermediate self-similar asymptotic presentation of stress and damage fields in the vicinity of mixed mode crack tip under creep regime Stepanova Larisa a * a Department of Mathematical Modelling in Mechanics, Samara Univeristy, Moskovskoe shosse, 34, Samara 443086 Russia Higher order asymptotic fields of stress, creep strain rate and damage of a mixed mode I/II creep crack tip are obtained and analyzed on the basis of Continuum Damage Mechanics by employing a similarity variable and similarity solution. In the paper the class of the creep mixed mode crack problems in damaged p wer aw materials under creep-damage coupled formulation for plane strain conditions is considered. With the similarity variable and the self-similar representation of the solution for a power law creeping material and the classical Kachanov – Rabotnov power-law damage evolution equation the near crack-tip stresses, creep strain rates and damage distributions for plane strain conditions are obtained. The approximate solutions are based on the idea of the existence of the completely damaged zone near the crack tip. The multi-term asymptotic expansions of the stress and damage fields outside the completely damaged zone are found. It is shown that the asymptotical analysis of the near crack-tip fields results in nonlinear eigenvalue problems. The technique permitting to find all the eigenvalues numerically is proposed and numerical solutions to the nonlinear eigenvalue problems arising from the mixed-mode crack problems in a power-law medium under plane strain conditions are obtained. Using the approach developed the eigenvalues different from the eigenvalues corresponding to the Hutchinson-Rice-Rosengren (HRR) problem are found. For new eigenspectra and eigensolutions obtained the geometry of the completely damaged zone in the vicinity of the crack tip is found for all values of the mixity parameter. Effect of the higher order terms of the asymptotic expansions on the near crack tip field description is elucidated. Special attention is paid to angular distributions of the stress and damage fields for mixed mode loading. ECF22 - Loading and Environmental effects on Structural Integrity Intermediate self-similar asymptotic presentation of stress and damage fields in the vicinity of mixed mode crack tip under creep regime Stepanova Larisa a * a Department of Mathematical Modelling in Mechanics, Samara Univeristy, Moskovskoe shosse, 34, Samara 443086 Russia Abstract Higher order asymptotic fields of stress, creep strain rate and damage of a mixed mode I/II creep crack tip are obtained and analyzed on the basis of Continuum Damage Mechanics by employing a similarity variable and similarity solution. In the paper the class of the creep mixed mode rack problems in damaged power law mate ials un r creep-da age coupled formulation for plane strain conditions is considered. With the similarity variable and the self-similar repres ntation of the solution for a p wer law creepi g material and the classical Kachanov – Rabotnov power-law damage evolution equation the near crack-tip stress s, creep strai rates and damag distributions for plane strain conditions are obtain d. The approximate solutions are based on the id a of the existence of the completely damaged zone near the crack tip. The multi-term symptotic xpansi s of the stress and damage fields outside the completely da aged zone ar found. It is shown that the asymptotical analysis f the near crack-tip fields results in nonlinear eigenvalue problems. The techniq e permitting to find all the eigenvalues umerically is proposed and numerical solutions to the nonlinear eigenvalue problems arising from the mixed-mode crack problems in a power-law medium under plane strain c nditions are obtai ed. Using the approach developed the eig nv lues different from the eigenvalues corresponding to the Hutchi son-Rice-Rosengren (HRR) problem are found. For n w eigenspectra and eigensolutions obtained the geometry of the completely damaged zone in the vicinity of the crack tip is found for all values of the mixity parameter. Effect of the hig er order terms of the asymptotic expa sions on the near crack tip field description is elucidated. Sp cial attention is paid to angular distributions of the stress and damage fields for mixed mode loading. © 2018 The Authors. Published by Els vier B.V. Peer-review under responsibility of the ECF22 organizers. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: Creep crack problem, crack-tip fields, damage field, ixed-mode loading, mixity parameter, similarity .variable, intermediate stress asymptotic behavior, angular distributions of the stresses, totally damaged zone, higher order te ms of asy ptot c expansions. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Keywords: Creep crack problem, crack-tip fields, damage field, mixed-mode loading, mixity parameter, similarity .variable, intermediate stress asymptotic behavior, angular distributions of the stresses, totally damaged zone, higher order terms of asymptotic expansions. Abstract

* Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. 2452-3216 © 2018 The Authors. Published by Elsevier B.V. Peer review under r sponsibility of the ECF22 organizers. * Stepanova Larisa. Tel.: +7 -846 -334-54-41; fax: +7-846-334-54-41. E-mail address: stepanovalv@samsu.ru * Stepanova Larisa. Tel.: +7 -846 -334-54-41; fax: +7-846-334-54-41. E-m il address: stepanovalv@samsu.ru

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. Peer-review under responsibility of the ECF22 organizers. 10.1016/j.prostr.2018.12.043