Three-dimensional printing used to be a rapid prototyping process, but nowadays it is establishing as an additive manufacturing (AM) process. One of these AM techniques is selective laser sintering (SLS), which most often involves partial melting of the particles and therefore belongs to the category of powder bed fusion processes. Much progress has been made in this field by research on process parameters like laser power, hatch distance, and scanning speed while still lacking a fundamental understanding of the powder deposition and its influence on parts. A critical issue for economic manufacturing is the building time of parts with good mechanical properties, which can be reduced by lower surface roughness due to less or missing post processing. Therefore, the influence of three blade shapes on powder bed surface roughness has been evaluated for PA12 powder with three different grain size distributions by using advanced X-ray micro computed tomography (XMT) and a confocal laser scanning microscope (LSM). Along with those methods, new techniques for powder characterization were tested and compared. Lowest roughness has been achieved with a flat blade, based on a higher compression due to a larger contact zone between blade and powder bed. Furthermore, an anisotropic effect of the mechanical properties resulting from different building directions has been detected which can be explained by varying amounts of solid contact paths through the powder bed depending on powder application direction. In addition, an optimal combination of process parameters with an even compression of the powder bed leads to low surface roughness, complementing the advantages of additive manufacturing.

Recently, various alternative battery pack design studies have been conducted to achieve the safety requirements of an electric vehicle (EV). This article assesses the performance of a mechanical battery pack structure on the basis of energy absorption and packaging efficiency, thus enabling optimization of the EV’s overall performance in addition to the actual crash performance. Commercially available battery pack structure is evaluated in competition with alternative geometric concepts. The study determines the maximum possible packing efficiency on the basis of geometric considerations and also evaluates its energy absorption characteristics using crashworthiness indicators. The method is limited to the evaluation of the battery pack structures at component level using the finite element method subjected to static and dynamic simulations under the side pole impacts according to international crash standards. During the dynamic simulations, the energy absorbed by the battery cells is also evaluated using simplified crushable foam material.

The spread of all-electric drives is steadily increasing in all sectors of road transport. Due to the constantly increasing demands on efficiency and performance by legislation and customers, it is necessary to continuously push the system limits of the powertrains. This paper presents an approach that performs an initial thermal system analysis based on a first gearbox configuration and efficiency calculation. Here, the componentwise loss calculation is used to identify thermal hotspots within the gearbox stage. The basis of this analysis is the thermal network method. For the approach, the gearbox elements gear, bearing, shaft, seal and housing are broken down into standard thermal elements to be created automatically for any subsequent gearbox configuration. The linking of these elements to each other is also standardised and automated comparably. An extensive simulation study is carried out using the smoothed particle hydrodynamics method to consider the load point-dependent oil distribution, which enables an initial estimate of the oil distribution. The thermal network filled in this way is then solved on a time-step basis, allowing dynamic load cases to be considered. The quality of the method is validated within the paper using the VW ID 3 gearbox as an example. Due to the use of a series gearbox, the validation was carried out on the basis of the accessible housing temperatures. These already show good convergence of the method compared to other existing approaches, which reinforces the necessity of conducting further experimental studies.

Freight transport accounts for about half of all distances travelled in Europe. Therefore, freight transport is one of the decisive factors for reducing greenhouse gases and air pollutants. For this reason, the electrification of road freight transport is being promoted as part of the project “BEV Goes eHighway—[BEE]”. The data basis for the modelling used in this project is an electric drive axle for a heavy commercial vehicle, which was developed in the “Concept-ELV²” project. Based on the results of the previous project, the methodological tools that were developed are presented in this paper. These allow a wide range of possible powertrain topologies to be considered at the concept stage of development based on an estimation of future system characteristics. For this purpose, the components are automatically designed taking into account the mutual influence of the requirements and are evaluated in the context of the holistic system. This publication focuses on the efficiency and thermal evaluation of the transmission stages of the addressed electric drive units and validates the developed models using a pototypically designed electric commercial vehicle axle.

EBook: Concept ELV² – Development of an Electric Drive Axle for Heavy Commercial Vehicles (ISBN 978-3-18-092384-0) von aus dem Jahr 2021