PSI - Issue 5

ScienceDirect Available online at www.sciencedirect.com Av ilable o line at ww.sciencedire t.com ienceDirect Structural Integrity Procedia 00 (2016) 000 – 000 Procedia Struc ural Integrity 5 (2017) 1425–1432 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2017) 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. 2nd International Conference on Structural Integrity, ICSI 2017, 4-7 September 2017, Funchal, Madeira, Portugal T nsile and Fatigue Behaviour of AA6022-T4 to IF Steel Resistance Spot Welds Jidong Kang a *, Harish M. Rao a , David R. Sigler b , Blair E. Carlson b a CanmetMATERIALS, 183 Longwood Road South, Hamilton, ON L8P 0A5, Canada b General Motors Global R&D Center, 30500 Mound Road, Warren, MI 48090-9055, USA Abstract Vehicle light weighting plays an integral role in achieving the mandatory fuel efficiency requirements as established in the Corporate Average Fuel Economy Standards (CAFE), USA. To optimize vehicle structures for both performance and mass savings, materials such as aluminum alloys may be used in combination with steels, especially advanced high strength steels. Although joining dissimilar materials is a challenge, General Motors (GM) has recently succeeded in developing a proprietary resistance spot welding process using a multi-ring, domed (MRD) electrode geometry that is capable of producing welds between aluminum alloys and steel materials with acceptable joint strength. In this work, tensile and fatigue properties are presented of welds produced between dissimilar materials in lap-shear configuration. The dissimilar metal resistance spot welds (RSWs) were composed of wrought aluminum 1.2-mm thick AA6022-T4 sheet and 2.0-mm thick IF steel. For comparison, similar metal lap-shear RSWs were made and tested of 1.2-mm and 2.0-mm thick AA6022-T4. Average lap-shear strengths of 4400 N and 3200 N were observed for AA6022-T4 to IF steel welds and AA6022-T4 to AA6022-T4 welds, respectively. In load-controlled fatigue testing, limited scatter in fatigue life was observed for both stack-ups tested at maximum fatigue loads below 1500 N. The overall fatigue life was lower for the AA6022-T4 to AA6022-T4 welds compared to AA6022-T4 to IF steel welds. Failure modes for both stack-ups, particularly at long lives, were primarily a result of crack growth through the thickness direction in the AA6022-T4 sheet around the outer edge of the weld nugget. The superior performance of the AA6022-T4 to IF steel welds was most likely primarily due to the larger size of the weld nuggets created in that joint. Also contributing to the superior performance of the Al-steel welds was a more favourable notch root opening geometry that reduced stress concentration as well as a microstructure in the region of the crack path that contained fine, columnar grains alloyed with iron that SEM analyses indicated slowed fatigue crack growth. Using the structural stress concept, it was found that the fatigue life of lap-shear AA60222-T4 to AA6022-T4 and AA6022-T4 to IF steel welds falls onto a master curve indicating that the nugget size dominates the fatigue life. © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017. Keywords: resistance spot welding; fatigue; dissimilar joint; aluminum to steel; al a a b b . e © 2017 The Authors. Published y Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017 © 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.

* Corresponding author. E-mail address: jidong.kang@canada.ca

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216  2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017 10.1016/j.prostr.2017.07.207 * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt 2452-3216 © 2017 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of ICSI 2017.