Sustainable Implementation of Electrified Roads: Structural and Material Analyses Feng Chen Doctoral Thesis KTH Royal Institute of Technology Engineering Sciences Department of Civil and Architectural Engineering SE -100 44 Stockholm, Sweden TRITA-BKN. BULLETIN 144, 2016 ISSN 1103-4270 ISRN KTH/BKN/B--144--SE ISBN 978-91-7729-193-0 Feng Chen Stockholm 2016 Akademisk avhandling som med tillstånd av KTH i Stockholm framlägges till offentlig granskning för avläggande av teknisk doktorsexamen fredagen den 25 november kl. 10:00 i sal A123, KTH, Osquars backe 5, Stockholm. I Abstract In the future, roads may not only serve for vehicles mobility but could also have the capability of enabling other functions, such as Car-to-Road communication, energy harvesting, autonomous driving or on-the-road charging. These new technologies are often referred to as making the physical road infrastructure multifunctional or ‘smart’, and their applications could promote the sustainable development of society as a whole. An important feature of these smart applications is that all require an intrinsic integration of technologies into the practical roads, and their successful implementation depends significantly on a collective (system) effort. However, our current engineering and research communities do not necessarily allow for an optimal development of such integrated systems. To fill some of the knowledge gaps, this Thesis is focusing on a specific case of the electrified road (also called ‘eRoad’) that allows for on- the-road charging, in which the consequences and possible modifications of the road infrastructure are considered. Given the promise of the Inductive Power Transfer (IPT) technology for eRoad applications, the potential challenges for a successful integration of dynamic IPT technology into the physical road structure are explored extensively in this research work. The Finite Element Method (FEM) is selected for studying the structural performance of an eRoad under operational conditions. In this, an energy-based finite strain constitutive model for asphalt materials is developed and calibrated, to enable the detailed investigation of the structural response and optimization of the considered eRoad. In the context of enabling both dynamic charging and autonomous driving for future electric vehicles, the influences to the pavement (rutting) performance by the changed vehicle behaviour are investigated as well. Moreover, to study the effect on the IPT system by the integration, the potential power loss caused within eRoad pavement materials is further examined by a combined analytic and experimental analysis. The direct research goal of this Thesis is therefore to enhance the possibility of a sustainable implementation of the eRoad solutions into the real society. At the same time, it aims to demonstrate that the road structure itself is an important part of smart infrastructure systems that II can either become a bottleneck or a vessel of opportunities, supporting the successful integration of these complex systems. Keywords Electrified road; Structural performance; Constitutive modelling; Asphalt; Dielectric loss. III Sammanfattning I framtiden kommer vägar inte enbart att nyttjas för rörligheten hos fordon utan kommer även att ha andra funktioner som biltillväg kommunikation, energiinsamling, automatisk körning eller batteri- laddning under färd för eldrivna fordon. Dessa nya tekniker ses ofta som att man gör väginfrastrukturen ”smart” och att kopplade applikationer skulle stödja samhällsutvecklingen totalt sett. Dessa smarta applikationer kräver alla en reell integration av tekniker i praktiken när det gäller själva vägen och för att uppnå en framgångsrik implementation måste man ha ett djupgående gemensam (system)samarbete. Tyvärr tillåter inte dagens ingenjörs- och forskarstukturer en optimal utveckling av sådana integrerade system. För att brygga över kunskapsklyftan fokuserar denna avhandling på ett speciellt fall av elektrifierade vägar, (kallat ”eRoad”) som möjliggör laddning på vägen, i vilket konsekvenserna och möjliga anpassningar av väginfrastrukturen belyses. Givet de förutsättningar som induktiv energiöverföring (IPT Inductive Power Transfer) har för eRoad applikationerna, utforskas möjligheterna för en framgångsrik integration av dynamisk IPT i den fysiska vägkonstruktionen på en djupgående nivå i detta forskningsarbete. Speciellt har finita elementmetoden använts för att studera det strukturella beteendet hos en e-väg under driftsmässiga förhållanden. Inom detta har en energibaserad konstitutiv model för stora töjningar utvecklats och kalibrerats för att möjliggöra detaljerade undersökningar av strukturell respons och optimering av de föreslagna e-vägarna. I samband med att möjliggöra både dynamisk laddning och autonom körning för framtida elektriska fordon, har beläggningars (spårbildnings)egenskaper studerats utifrån de laddande fordonen beteende. Dessutom för att studera effekten av IPT-systemet har den potentiella energiförlusten inom e-vägars beläggningsmaterial undersökts genom en kombinerad analytisk och experimentell undersökning. Som sådant är det direkta forskningsmålet med denna avhandling att utöka möjligheterna för en hållbar implementering av eRoad systemet inom det verkliga samhället. Samtidigt är målet att visa att vägkonstruktionen i sig själv är en viktig del av det smarta infrastruktursystemet som antingen kan bli en flaskhals eller en bärare av IV möjligheter, stödjande en framgångsrik implementering av dessa komplexa system Nyckelord Elektrifierade vägar; Strukturellt beteende; Konstruktivt modellerande; Asfalt; Dielektrisk förlust. V Preface The work in this four-year PhD research project has been carried out at Department of Civil and Architectural Engineering, KTH Royal Institute of Technology, Sweden. Firstly, I would like to express my sincere gratitude to my supervisors Associate Prof. Niki Kringos, Dr. Romain Balieu and Dr. Nathaniel Taylor, for their excellent guidance, valuable discussions and continuous encouragement in this challenging and interesting cross-disciplinary research work. Meanwhile, I would also like to thank my colleagues and friends at KTH for their help and support, as well as providing a very friendly working environment. Thanks go to Prof. Bjorn Birgisson as well for accepting my PhD application at the previous highway engineering division. The financial supports from China Scholarship Council (CSC), the FABRIC project under the EU seventh framework and the CO-OP program under Road2Science (KTH) are gratefully acknowledged. Last but not least, my gratitude goes to my beloved wife Man Yu for her company and support, and my family in China that always believed in me. Feng Chen 陈 丰 Stockholm, Sept. 2016 VII List of appended papers Paper I. Chen F, Taylor N, Kringos N. Electrification of roads: Opportunities and challenges. Applied Energy, 2015, 150: 109-119. Paper II. Chen F, Balieu R, Kringos N. Thermodynamics-based finite strain viscoelastic-viscoplastic model coupled with damage for asphalt material. Submitted to the International Journal of Solids and Structures, 2016. Paper III. Chen F, Balieu R, Córdoba E, Kringos N. Towards an understanding of the structural performance of future smart roads: a case study on eRoad. Submitted to the International Journal of Pavement Engineering, 2016. Paper IV. Chen F, Balieu R, Kringos N. Potential influences on long- term service performance of road infrastructure by automated vehicles. Transportation Research Record: Journal of the Transportation Research Board, 2015, 2550: 72-79. Paper V. Chen F, Taylor N, Kringos N, et al. A study on dielectric response of bitumen in the low-frequency range. Road Materials and Pavement Design, 2015, 16(sup1): 153-169. Paper VI. Chen F, Taylor N, Kringos N. Dynamic applications of the Inductive Power Transfer (IPT) systems in an electrified road: Dielectric power loss due to pavement materials. Submitted to Construction and Building Materials, 2016. The author of this Thesis has done the main work in all papers where he is the first author. The other authors have contributed with some parts to these studies, like the planning of the research, reviewing of the text and discussions about the results. VIII Other related publications In addition to the appended publications, the author of the Thesis has been involved in the following related publications. Conference proceedings: I. Chen F, Kringos N. Towards new infrastructure materials for on-the-road charging. Electric Vehicle Conference (IEVC), 2014 IEEE International. IEEE, 2014: 1-5. II. Chen F, Birgisson B, and Kringos N. Electrification of Roads: An infrastructural perspective. The 94th Annual Meeting of Transportation Research Board, Washington D.C., 2015. III. Córdoba E, Chen F, Balieu R, Kringos N. Towards an understanding of the structural integrity of electrified roads through a combined numerical and experimental approach. Accepted to the 96th annual meeting of Transportation Research Board, Washington D.C., 2017. IV. Balieu, R, Kringos, N, Chen, F, & Córdoba, E (2016). Multiplicative Viscoelastic-Viscoplastic Damage-Healing Model for Asphalt-Concrete Materials. In 8th RILEM International Conference on Mechanisms of Cracking and Debonding in Pavements (pp. 235-240). Springer Netherlands. Reports: Several reports in the FABRIC project that supported and co-funded by EU 7th Framework programme: I. D45.1 Analysis of the road infrastructure and requirements for test sites. II. D45.2 Technical specifications and design of solutions