Dip-in direct-laser-writing (DLW) optical lithography allows fabricating complex three-dimensional microstructures without the height restrictions of regular DLW. Bow-tie elements assembled into mechanical metamaterials with positive/zero/negative Poisson's ratio and with sufficient overall size for direct mechanical characterization aim at demonstrating the new possibilities with respect to rationally designed effective materials.

In this work, the mechanical behaviour of millimetre-scale, bulk single crystalline, nanoporous gold at room temperature is reported for the first time. Tension and compression tests were performed with a custom-designed test system that accommodates small-scale samples. The absence of grain boundaries in the specimens allowed measurement of the inherent strength of millimetre-scale nanoporous gold in tension. The elastic modulus and strength values in tension and compression were found to be significantly lower than values measured with nanoindentation-based techniques and previously reported in the literature, but close to those reported for millimetre-scale polycrystalline samples tested using traditional compression techniques. Fracture toughness was found to be very low, in agreement with the macroscopic brittleness of nanoporous gold, but this is due to the localization of deformation to a narrow zone of ligaments, which individually exhibit significant plasticity and necking

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Micro electro mechanical systems, coatings, and thin films contain materials that are often subjected to complex loading conditions and high frequencies. Therefore, the implementation of a resonant multiaxial fatigue setup for small-scale samples is of high interest. Finite Element simulations have been used to design small-scale samples which possess very close bending and torsional resonant frequencies.The bending and torsional modes are excited by two piezo actuators working either in or out of phase with one another. The bending and torsional amplitudes are measured independently by a laser and the actuator amplitudes are controlled by a Field Programmable Gate Array. The fatigue setup can be used with a varying range of sample sizes from centimeters down to tens of micrometers. The novel multiaxial resonant micro fatigue setup as well as results (fatigue damage for Ni and lifetime for Cu) from bending small-scale fatigue tests are shown and discussed.

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FATIGUE 53556 (2014) 7-8 © Carl Hanser Verlag, München Materials Testing nal load, and experimental testing is carried out on the fatigue strength of electrical sheets. S-N curves which use various parameters such as dimensions, temperature, and influences on surface condition are the foundation for a fatigue assessment on the basis of the load spectrum from simulation. Load Data Calculation and Stress AnalysisVirtual Load Data Calculation by System Simulation. As a mechatronic system, the electric axle requires a modeling approach which represents both the mechanical as well as the electrical components in a single model. The transmission is depicted using 1D mechanics and takes into consideration the rotatory connectors for the drive and output shafts, as well as the torsional tively among the wheels of the vehicle. The torque vectoring system thus allows better vehicle traction, increased comfort, and improved driving dynamics.Load data and a load spectrum are already required at an early stage in the product development in order to carry out the mechanical design process and the fatigue assessment of subsystems and components. To accomplish this, system models are created which allow the drive train to be integrated into different vehicle classes and to be represented under real driving conditions with variable load and speed scenarios (e. g., handling course). By means of stress analysis which use a the finite element analysis (FEA), the electric motor subsystem is analyzed under exterTogether with development partners, Schaeffler is developing complete 48 V and high-voltage drive systems for various vehicle classes such as plug-in hybrids. One of these products is a modular system for an electric axle drive (electric axle) whose basic construction is shown in Figure 1. The drive power is provided by a traction motor with a maximum output of 65 kW (permanent magnet synchronous motor) and transmitted to the drive shafts via a coaxially arranged two-stage planetary gear and a spur gear differential. The drive train additionally has a so-called integrated electromechanical torque vectoring (function, with which the power of a second electric motor (6 kW max.) can be used to distribute the torque of the drive motor selecIn the present work, a fatigue assessment of the electric motor within the electric axle drive (electric axle) was developed using virtual load data. Now that the electric axle with torque vectoring function has been integrated into multiple vehicle classes, it is possible to create simulation models which allow the drive train to be mapped in various driving scenarios. Validation is performed by means of optical measurement methods (object tracking) which allow to determine load data for subsystems and components under variable torque and speed scenarios (e. g., handling course). In this paper, a load spectrum was created and used for fatigue analysis of the subsystem, namely the traction motor (EM) and torque vectoring motor. Based on the local stress, a finite element analysis (FEA) was carri...

Inhalt: Für die Auslegung von Bauteilen ist die Bewertung der Schädigungsinitiierung von ausschlaggebender Bedeutung. Insbesondere bei zyklischen Betriebsbeanspruchungen ist zu prognostizieren, ob die vorliegende Mikrostruktur weiteres Risswachstum eher begünstigt oder mindert. In Schweißverbindungen ist eine Bewertung aufgrund der prozessbedingt unterschiedlichen Gefügestrukturen besonders schwierig. An Mikroproben hat das Fraunhofer-Institut für Werkstoffmechanik IWM die Rissentstehungsphase in Schweißverbindungen untersucht und ein probabilistisches Bewertungskonzept entwickelt. Das neue Verfahren vermeidet unnötige Konservativitäten und liefert damit eine Verbesserung der Materialausnutzung.