2018-01-1829 Published 10 Sep 20 18 © 2018 SAE International. All Rights Reserved.Structural Integrity of In-Wheel Motors Matic Frajnkovic, Senad Omerovic, Uros Rozic, Jurij Kern, Raphael Connes, Kristof Rener, and Matej Biček Elaphe Propulsion Technologies, Ltd. Citation: Frajnkovic, M., Omerovic, S., Rozic, U., Kern, J. et al., “Structural Integrity of In-Wheel Motors,” SAE Technical Paper 2018-01-1829, 2018, doi:10.4271/2018-01-1829. Abstract In-wheel motors offer an optimized solution for novel drive - train architectures of future electric vehicles that could penetrate into the mainstream automotive industry, moving the wheel actuation where it’s required, directly inside the wheels. Obtainable literature mainly deals with optimization of electromagnetically active parts, however, mechanical design of electromagnetically passive parts that indirectly influence motor performance also requires detailed analysis and extensive validation. To meet the optimal performance requirements (also durable) of an in-wheel traction motor, their mechanical design requires topology optimization of housing elements, thermal mapping, geometrical and dimen - sional tolerance checks and selection of proper hub bearings, in order to assure consistent electromagnetic behavior stability The following paper uniquely describes the review of loads acting on an in-wheel motor, the workflow of a typical mechanical design process, testing, and validation processes for achieving the required durability of an in-wheel assembly. Introduction In-wheel motor (IWM) platforms ( Figure 1 ) intrinsically allow design space resourcefulness, lowering vehicle’s center of gravity, reduction of required parts for vehicle traction system [ 1, 2], consequential cost reduction potential [3, 4], higher energy efficiency eliminating drivetrain friction losses, and consequential increased range [ 5, 6, 7]. The wheels become propelled directly with added propulsion tractive redundancy [ 3, 8, 9, 10, 11, 12] while at the same time allowing vehicle and chassis designers to completely change the way cars are designed [ 13, 14] thus enabling more space for passen - gers and cargo [ 9, 10, 11, 12] without increasing the vehicle footprint. As such, in-wheel propulsion platforms are a natural fit for autonomous, connected and shared vehicles that will no doubt dominate the future and will focus on safety, agility and total cost of ownership. In in-wheel motor design, a specific mix of skills and know-how is necessary for combining methods from electro - magnetic design, mechanics, machining and material science, and electronics. Due to lack of literature, legislation, directives and standards regarding IWM technologies, many phases of the design require pioneering innovation and iterative test validation of the design and manufacturing process. The focus of this paper is to identify and investigate loads acting on an in-wheel motor, which mechanical elements of the IWMs are influenced by these loads, which tests should be made to validate their durability and to what extent to overcome the worst-case scenarios that final users might come across to. The mentioned can be united under the expression structural integrity, that covers various predictions of the system response when loads are acting on the system , in this case on an in-wheel motor. Loads Acting on In-Wheel Motors As already pointed out, the conditions in which the IWMs are designed to operate, are quite demanding. Appropriate prediction and evaluation of the structural integrity of an in-wheel motor first requires identification of all the loads acting on it, together with understanding the dynamics of a vehicle in their entirety. This section focuses on identifying these loads and determining how they influence the behavior of an in-wheel motor. Figure 2 illustrates a classification of the identified loads which are acting on the motor. On a primary level, the loads acting on an in-wheel motor c