PSI - Issue 19

Available online at www.sciencedirect.com Available online at www.sciencedirect.com ScienceDirect Structural Integrity Procedia 00 (2019) 000 – 000 Available online at www.sciencedirect.com S Structural Integrity Procedia 00 (2019) 000 – 000

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ScienceDirect

Procedia Structural Integrity 19 (2019) 4–11

Fatigue Design 2019 Fatigue Strength Assessment for components and subsystems of a lightweight, space saving city car with electric drive Dr.-Ing Thorsten Voigt*, Dr.-Ing. Klaus Lipp, Prof. Dr.-Ing. Tobias Melz Fraunhofer Institute LBF, Bartningstraße 47, 64289 Darmstadt, Germany Fatigue esign 2019 ati e tre t ssess e t f r c e ts a s s ste s f a li t ei t, s ace sa i cit car it electric ri e r.-Ing horsten oigt*, r.-Ing. laus ipp, Prof. r.-Ing. obias elz Fraunhofer Institute LBF, Bartningstraße 47, 64289 Darmstadt, Germany

Abstract Abstract

In the European research project Urban EV, a resource-saving city vehicle with electric drive in a lightweight design was developed. This article presents the concept of durability assessment for this vehicle. It addresses component tests on a rear control arm partially carried out under environmental conditions, as well as studies on a module of the pivoting rear axle. The provision of suitable load spectra was an important prerequisite for carrying out the experiments. Using numerical and experimental stress analyses, the test results are validated on the basis of the local concept In the European research project Urban EV, a resource-saving city vehicle with electric drive in a lightweight design was developed. This article presents the concept of durability assessment for this vehicle. It addresses component tests on a rear control arm partially carried out under environmental conditions, as well as studies on a module of the pivoting rear axle. The provision of suitable load spectra was an important prerequisite for carrying out the experiments. Using numerical and experimental stress analyses, the test results are validated on the basis of the local concept

© 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. © 1 t rs. lis e ls i r . . Peer-re ie er res si ilit f t e ati e esi n r a izers. e t rs. lis e lse ier . . er res si ilit f t e ati e esi r a izers. eer-re ie

Keywords: electric vehicle; customer usage profile; load programme; variable amplitude testing; local concept Keywords: electric vehicle; customer usage profile; load programme; variable amplitude testing; local concept

1. Introduction 1. Introduction

The topics of digitization, climate change and the resulting changes in our societies are currently very controversial. Among other things, it is about how promising transport concepts could be designed. Different approaches for individual and public transport are under discussion in this context. The "Urban EV" research project, funded by the European Union, has in the last few years taken a closer look at a partial aspect of the transformation of modern city traffic. It focused on the development of a small, resource-efficient, electric-powered city vehicle, with strong focal points on occupant safety, energy efficiency and low parking space requirements (Figure 1). The latter requirement has been implemented constructively by equipping the vehicle with a swiveling rear axle, which can be folded when parking (Figure 3). This reduces the vehicle length by approx. 40 cm. The energy-efficient design of the vehicle is mainly due to lightweight body construction throughout. The supporting structure consists of a frame made of aluminium profiles (AlMgSi7, Figure 2) connected to each other by means of nodular elements made of magnesium casting (MgMn6). Aluminium materials were also used for structural components of the chassis. The use of different materials in the supporting structure of the body makes the use of special bonding methods necessary. So called EMPT crimping was used for this purpose (EMPT = Electro Magnetic Pulse Technology). In this method of forming closed profiles, the bonding area is enclosed by an annular coil that is pulsed with rapid high current surges (Schäfer and Pasquale (2009)). The topics of digitization, climate change and the resulting changes in our societies are currently very controversial. Among other things, it is about how promising transport concepts could be designed. Different approaches for individual and public transport are under discussion in this context. The "Urban EV" research project, funded by the European Union, has in the last few years taken a closer look at a partial aspect of the transformation of modern city traffic. It focused on the development of a small, resource-efficient, electric-powered city vehicle, with strong focal points on occupant safety, energy efficiency and low parking space requirements (Figure 1). The latter requirement has been implemented constructively by equipping the vehicle with a swiveling rear axle, which can be folded when parking (Figure 3). This reduces the vehicle length by approx. 40 cm. The energy-efficient design of the vehicle is mainly due to lightweight body construction throughout. The supporting structure consists of a frame made of aluminium profiles (Al gSi7, Figure 2) connected to each other by means of nodular elements made of magnesium casting ( g n6). Aluminium materials were also used for structural components of the chassis. The use of different materials in the supporting structure of the body makes the use of special bonding methods necessary. So called E PT crimping was used for this purpose (E PT = Electro agnetic Pulse Technology). In this method of forming closed profiles, the bonding area is enclosed by an annular coil that is pulsed with rapid high current surges (Schäfer and Pasquale (2009)).

2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 10.1016/j.prostr.2019.12.002 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. 2452-3216 © 2019 The Authors. Published by Elsevier B.V. Peer-review under responsibility of the Fatigue Design 2019 Organizers. * Corresponding author. Tel.: +49 6151 705 8217; fax: +49 6151 705 214. E-mail address: thorsten.voigt@lbf.fraunhofer.de * Corresponding author. Tel.: +49 6151 705 8217; fax: +49 6151 705 214. E-mail address: thorsten.voigt@lbf.fraunhofer.de