PSI - Issue 14

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 14 (2019) 168–175 Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2018) 000–000 Available online at www.sciencedirect.com ScienceDirect Structural Integrity 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. 2nd International Conference on Structural Integrity and Exhibition 2018 Designing the interphase in carbon fiber polymer composites using carbon nanotubes Harpreet Singh Bedi, Prabhat K. Agnihotri* Mechanics of Advanced Materials Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India Abstract Experiments are conducted to quantitatively assess the effect of carbon nanotubes (CNTs) on the interfacial properties in carbon fiber/epoxy composites by directly growing CNTs on the surface of carbon fiber (CF). Wetting behavior of single carbon fiber filaments with epoxy matrix before and after CNT grafting is investigated through contact angle measurements. An improvement in wettability is bserved after the incorporation of CNTs o the fiber surfac . Effect of wettability on the size and properties f int r hase is studied th ough well d signed micro-mechanical tests on single fiber composit s processed with unsized and CNT grafted c rb n fib rs. While nanoindentati n test is performed for quantitative determination of interphase size and stiffness, single fib r micro-debond tests are us d to evaluate th interfacial shear strength (IFSS) in unsized carbon fiber/epoxy and CNT grafted carbon fiber/epoxy composites. Consistent with the wettability analysis, CNT grafting enhances th size, stiffness and IFSS of CF/epoxy composites. In addition, it is shown that even though larger CNT growth time on the surface of carbon fiber provides thicker interphase region but tends to degrade the stiffness of interphase and IFSS of CNT grafted carbon fiber/epoxy multiscale composites. Scanning electron microscopy (SEM) analysis of pulled-out and debonded fibers reveal different interfacial failure mechanism in the presence and absence of CNTs on the surface of CF. The present study quantitatively shows the presence of an interphase region surrounding the carbon fiber after CNT grafting on their surface. The existence of interphase is important from the view point of structural integrity of composites as it eliminates the unwanted stress concentration at the fiber/polymer interface by gradual transformation of properties from highly stiff fiber to comparatively weaker matrix. Moreover, the present study provides us a tool to design the interphase in hybrid composites as per the requirement of a specific application. 2nd International Conference on Structural Integrity and Exhibition 2018 Designing the interphase i carbon fiber pol mer composites using carbon nanotubes Harpreet Singh Bedi, Prabhat K. Agnihotri* Mechanics of Advanced Materials Laboratory, Department of Mechanical Engineering, Indian Institute of Technology Ropar, Rupnagar, Punjab 140001, India Abstract Experiments are conducted to quantitatively assess the effect of carbon nanotubes (CNTs) on the interfacial properties in carbon fi er/epoxy composites by directly growing CNTs on the surface of carbon fiber (CF). Wetting behavior of single carbon fiber filaments with epoxy matrix before and after CNT grafting is investigated through contact angle measurements. An improvement in w ttability is observed af er the incorporation of CNTs on the fi er surface. Effect of wettability on the size and properties f int phase is studied through wel designed micro-mec anical tests on single fiber composi es processed with unsized and CNT gr fted carbon fibers. While nanoindent tion testin is performed for quantitative determination of interphase size and stiffness, singl fiber m cr -d bond tests a e used t evaluate the interfacial shear strength (IFSS) in unsized c rbon f b r/epoxy and CNT grafted c rbon fiber/e oxy compos t . Consistent with the wettability analysis, CNT grafting nhan e the size, stif ness IFSS of CF/epoxy compo ites. In additio , it is shown that ev n though larger CNT growth time on the surface f carb n fiber provides thick r interphase regi but ends to degrade the stiffness o interp ase and IFSS of CNT grafted carbon fiber/epoxy multiscale composites. Scanning electr n micro copy (SEM) analysis of pul ed-out and debonded fibers reveal different interfaci l failure mechanism in the pres nce and absence of CNTs on the surface of CF. The present study quantitatively shows the presence of an interphase region surrounding the carbon fiber after CNT grafti g on th ir surface. The existenc of interphas is importan from the view point of structural integrity of composites as it eliminates the unw ted stress concentration t the fiber/polymer interface by gr dual transformation of prop rti s rom highly stiff ib r to comparatively weaker ma rix. Moreover, t e present study provides us a tool to design the interphase n hybrid composites as per the requirement of a p cific application. Keywords: Carbon fiber reinforced p lymer composites; Carbon nanotubes; Wettability; Interphase; Interf cial shear strength. © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. © 2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. Keywords: High Pressure Turbine Blade; Creep; Finite Element Method; 3D Model; Simulation. Keywords: Carbon fiber reinforced polymer composites; Carbon nanotubes; Wettability; Interphase; Interfacial shear strength.

* Corresponding author. Tel.: +91-1881-242257; fax: +91-1881-223395. E-mail address: prabhat@iitrpr.ac.in

2452-3216 © 2016 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Scientific Committee of PCF 2016. 2452-3216  2019 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. 10.1016/j.prostr.2019.05.022 2452-3216 © 2018 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsi ility of Peer-review under responsibility of the SICE 2018 organizers. 2452-3216 © 2018 The Authors. Published by Elsevier B.V. This is n open access rticle under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0/) Selection and peer-review under responsibility of Peer-review under responsibility of the SICE 2018 organizers. * Corresponding author. Tel.: +351 218419991. E-mail address: amd@tecnico.ulisboa.pt * Corresponding author. Tel.: +91-1881-242257; fax: +91-1881-223395. E-mail address: prabhat@iitrpr.ac.in