Contact Modeling in Multibody Systems with Elastic Bodies in High-Frequency Applications

This paper discusses the refinement of multibody models by integration of flexible bodies and by considering nonlinearities from contacts. It presents common approaches for contact modeling in multibody simulations and strategies to include flexible bodies. A contact model is implemented in the elastic multibody model. Experimental results show that significant effects of system dynamics can be modeled by use of a multibody model including elastic bodies and contacts. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Tire footprint analysis depending on the elastokinematics of a multi-link suspension system using multi-body dynamics simulation

An automotive suspension system represents one of the most complex and important systems in a passenger vehicle, which has to ensure a robust and optimized contact between the wheels and the road at any time. For improving a suspension system it is important to take an investigative look at the interaction between suspension, tire and road dynamics. Thus a part of a study into aspects of suspension modeling on multi-body simulations of rear multi-link suspension system dynamics with focus on the tire footprint area is presented in this work. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Complete fusion studies of the 20Ne+235U system

The probability for complete fusion has been measured for the ²⁰Ne+²³⁵U system at bombarding energies of 175 and 252 MeV. The fission fragment angular correlation technique was used to obtain both the absolute cross section for complete fusion and relative cross sections for the ratio of complete fusion to incomplete fusion processes. Total reaction cross sections were also determined from elastic scattering measurements. Values of σ_R = 1900±40 and 2810 ± 140 mb were obtained at 175 and 252 MeV, respectively. These measurements yield if$\text{σ}{}_{\mathrm{<mtext>CF</mtext>}}\text{σ}{}_{\mathrm{<mtext>R</mtext>}}\text{= 0.74±0.05}\text{at}\text{175}\text{MeV and}\text{0.48 ±0.06}\text{at}\text{252}\text{MeV}$. The corresponding values of the critical angular momentum are compared with the predictions of several heavy-ion interaction models. It is observed that the l_c values obtained from these data agree well with the current models, although the energy dependence is not as strong as predicted. In addition, it is observed that these values of l_c exceed the limiting value for a charged rotating drop.     

A Two Dimensional Model for the Dynamical Contact of Elastic Rough Surfaces

To model the contact behavior including dynamical effects, a two dimensional mechanical model of elastic rough contact is developed. This model can simulate the contact behaviour between two rough surfaces depending on normal pressure, sliding speed and roughness profiles. The contact between two rough surfaces is reduced to a rough rigid and a rough elastic layer. The elastic layer is modeled by point masses connected by spring-damper elements. The total system is described by coupled ODEs. The number of ODEs and thus the degree of freedom of the model depends on the varying contact conditions. The contact conditions are monitored during the simulation and the simulation interrupts, in case the contact conditions change. The equations of motion are then adapted with respect to the contact constraints. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

High-resolution measurements of beta-delayed protons from 37Ca and 41Ti

Protons with energies from 870 keV to 5.4 MeV have been observed following bombardment of a ⁴⁰Ca target with ³He at beam energies of 29.5, 36.5 and 60 MeV, as well as from 40 MeV ³He bombardment of an ³⁶Ar gas target. These data, and those resulting from 20 MeV proton bombardment of ⁴⁰Ca, permit accurate identification of proton unbound levels in ⁴¹Sc, ³⁷K, and ⁴⁰Ca fed by allowed beta decay from ⁴¹Ti, ³⁷Ca or ⁴⁰Sc, respectively. Absolute ft values have been determined for beta decay to these levels. The half-life of ⁴¹Ti has been remeasured to be 80±2 ms and the log ft for its superallowed decay branch has been found to be 3.35±0.02, indicating an isospin purity for the lowest $\text{T =}\text{3}\text{2}\text{state in}{}^{41}\text{Sc of}\text{≈ 91 \%}$. The $\text{ft}\text{values for}{}^{37}\text{Ca}\text{β}{}^{\mathrm{+}}$ decay are compared to shell-model calculations for beta-decay in A = 37 nuclei.     

Multiobjective Optimization including Safety of Operation Applied to a Linear Drive System

In this contribution, we introduce a multiobjective optimization used to calculate safe optimal working points for a mechatronic system by including stochastic safety-critical signals in an objective function. Our application example consists of a linear drive for a rail-bound vehicle and an actuation unit. The linear drive's secondary part is fixed; the primary part is vehicle-mounted and can be adjusted vertically to account for deviations of the height of the secondary part. A small air gap between both parts improves efficiency, but increases the risk of a collision between the two parts. Using height data of the secondary part, a trajectory for the vertical adjustment of the primary part is calculated. However, unexpected deviations necessitate a readjustment of the air gap. The probability of such unexpected height deviations can be calculated from the readjustment data. The system is equipped with sensors to measure the air gap. Assuming that the sensor noise is normally distributed, noise characteristics are determined. Using this information and the probability distribution of unexpected height deviations, the probability of a collision is determined.T he sensor noise and the probability of a collision between both parts of the linear drive are included in the dynamical model of the system. Using multiobjective optimization, pareto-optimal working points for the controller of the air gap are obtained. By selecting an appropriate working point, safe operation can be ensured. (© 2013 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

Die Herstellung azobenzolgruppenhaltiger α, α′-Azo-[isobuttersäure-nitril]-derivate und ihre Anwendung zur Polymerisation

Zusammenfassung Es wird die Herstellung von Azobenzolgruppen enthaltenden , -Azo-[isobuttersäure-nitril]-derivaten beschrieben. Löst man die Polymerisation von Methacrylsäuremethylester und Styrol radikalisch durch thermischen Zerfall dieser als Starter dienenden Derivate7 und9 g aus, so enthalten die Polymeren covalent gebundene Starterbruchstücke; sie sind colorimetrisch quantitativ meßbar. Jedoch bewirken Nebenreaktionen, daß die Zahl der so bestimmten Starterfragmente nicht identisch ist mit der Zahl der durch Startreaktionen eingeführten Endgruppen.

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Synthesis of azobenzene groups-containing , -azoisobutyronitrile derivatives and their use in polymerization

The preparation of derivates of , -azo-bisisobutyronitrile containing azobenzene groups is described. The thermal decomposition of the derivatives7 and9 g in methyl methacrylate and styrene initiates radicalic polymerisation. The polymers contain covalently bound fragments of the initiators, which can be determined by colorimetry. However due to side reactions the number of the detected initiator fragments is not identical with that of the end groups introduced by initiation.

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Frau Professor Dr.E. Husemann zum 60. Geburtstage gewidmet.     

Eine quantitative,UV-photometrische bestimmung von Endgruppen in polystyrolen

Styrene was polymerized in bulk for 45 min at 70°C under a nitrogen atmosphere to a conversion of 6.16 weight-percent with an aliphatic azo compound, which contained four p-methoxyphenyl groups per molecule. The polystyrene could be purified easily by column chromatography and was then free of initiator and its decomposing products. It was separated into ten fractions by fractional precipitation (toluene/methanol), and the molecular weights of the polystyrenes were determined osmotically. The ultraviolet absorptions of the polystyrene solutions in dioxane were optically constant and followed the Bouguer-Lambert-Beer law. This made it possible to determine the number of absorbing groups per polystyrene molecule, which were constant with a value of 2. Polystyrenes with a number average molecular weight to 10⁶ should be determinable in the same way.