PSI - Issue 13

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ScienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Structu al Integrity 13 (2018) 3 4–31 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000 – 000 Available online at www.sciencedirect.com ScienceDirect Structural Int grity Procedia 00 (2018) 000 – 000

www.elsevier.com/locate/procedia www.elsevier.com/locate/procedia

www.elsevier.com/locate/procedia

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 Environmental effects in biaxially orientated Polymethyl Methacrylate Sze Ki Ng a *, Muhammad A. Kamaludin , John P. Dear a , Bamber R. Blackman a a Department of Mechanical E gineering, Imperial Collge London, London,UK SW7 2AZ Abstract Environmental stress cracking (ESC) is commonly found in polymers when submerged in an environment under applied stress. In such conditions, a crack may initiate and propagate from a material defect until it reaches a critical size and causes catastrophic failure. It is known that materials with a denser molecular structure are less prone to ESC, hence amorphous polymers often suffer greatly from this effect. A fracture mechanics approach was employed to investigate the fracture mechanism and crack growth in both air and environment. Two different grades of PMMA (amorphous and biaxially stretched PMMA) were tested in solvents with similar solubility parameters as this is known to hasten crazing. Time for crack initiation and crack speed were obtained and plotted against their corresponding fracture toughness. Thus, the ESC resistance of each material can be compared and component life expectance can also be predicted. To validate the experimental results, scanning electron microscopy (SEM) was used to examine the fracture mechanism of ESC. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: environmental stress cracking; biaxially orientated PMMA; fracture mechanics; crazing 1. Introduction Modern aircraft canopies are constructed from transparent polymers such as Polymethyl Methacrylate (PMMA) as lightweight alternative to glass and an economical substitution to Polycarbonate (PC). However, standard amorphous PMMA exhibits a brittle behaviour under loading or impact and is relatively low in strength in comparison to other transparent materials. One recently developed method to improve their mechanical properties is to pre-stretch and © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. ECF22 - Loading and Environmental effects on Structural Integrity Environmental effects in biaxially orientated Polym thyl Methacrylate Sze Ki Ng a *, Muhammad A. Kamaludin a , John P. Dear a , Bamber R. Blackman a a Department of Mechanical Engineering, Imperial Collge London, London,UK SW7 2AZ Abstract Environmental stress cracking (ESC) is commonly found in polymers when submerged in an environment under applied stress. In such conditions, a crack may initiate and propagate from a material defect until it reaches a critical size an causes catastrophic failure. It is known that materials with a denser molecular structure are less prone to ESC, hence amorphous polymers often suffer greatly fro th s effect. A fracture echanics appro ch was em l y d to investigat the fracture mechanism and crack rowth in both air and environment. Two different grades of PMMA (amorphous and biaxially stretched PMMA) were tested in solvents with similar solubility parameters as this is known to hasten crazing. Time for crack initiation and crack sp ed were obtained and plotted against their corresponding fracture toughness. Thus, the ESC resistance of each material can be compared and component life expectance ca also be predicted. To validate t experimental results, scanning electron microscopy (SEM) was used to examine the fracture mechanism of ESC. © 2018 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the ECF22 organizers. Keywords: environmental stress cracking; biaxially orientated PMMA; fracture mechanics; crazing 1. Introduction Modern aircraft canopies are constructed from transparent polymers such as Polymethyl Methacrylate (PMMA) as lightweight alternative to glass and an economical substitution to Polycarbonate (PC). However, standard amorphous PMMA exhibits a brittle behaviour under loading or impact and is relatively low in strength in comparison to other transparent materials. One recently developed method to improve their mechanical properties is to pre-stretch and © 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.

* Sze Ki Ng. E-mail address: sze.ng11@imperial.ac.uk * Sze Ki Ng. E-mail address: sze.ng11@imperial.ac.uk

* 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.

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.2018.12.051