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The performance of a model-based tracking controller depends on the quality of the underlying model. Especially for flexible multibody systems, the derivation of a suitable model and the subsequent controller design are challenging tasks. In the paper, it is shown how in a straightforward approach a feed-forward controller for a flexible multibody system is designed based on a simplified model which approximates an elastic beam by a combination of rigid beams and force elements. Furthermore, the modelling error due to this harsh simplification is included as uncertainty in the simplified model and considered in the model-based feed-forward controller design using fuzzy arithmetic. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
995.
The paper deals with the effect of different stress states on damage and failure behavior of ductile materials. To be able to model these effects a continuum damage model has been proposed taking into account the dependence of the stress intensity, the stress triaxiality and the Lode parameter on the constitutive equations. The model is based on the introduction of damaged and fictitious undamaged configurations. Only experiments are not adequate enough to determine all constitutive parameters. Therefore, additional three-dimensional micro-mechanical simulations of representative volume elements have been performed to get more insight in the complex damage mechanisms. These simulations cover a wide range of different void sizes, void shapes and void distributions. After all, the results from the micro-mechanical simulations are used to propose the damage equations and to identify corresponding parameters. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
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997.
This paper presents a basic endochronic plasticity model with isotropic hardening for small strain theory according to Valanis. The key point of this model is a convolution integral over an intrinsic time scale involving past values of the strain measure and a so-called memory kernel which leads to a smooth evolution equation for the internal variable. For the temporal discretization of the underlying constitutive equations and the resulting evolution equation we use higher order accurate variational integrators (VI). The remarkable feature is the fact that we approximate the position vector in terms of velocities according to partitioned Runge-Kutta methods (pRK). As a representative model problem serves a quasistatic, uniaxial tensile testing as well as a dynamic, elastoplastic cantilever beam with a smooth plasticity model according to the Valanis framework. (© 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim) 相似文献
998.
Michael Veith Charu Mathur Volker Hugh 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):489-492
The synthesis of the new heteroleptic heterotrimetallic cluster, [(C5H5)Sn(μ-OBut)2Ge(OBut)Mo(CO)5] (1) has been achieved by a thermally induced CO substitution of the transition metal derivative, Mo(CO)6, by the basic germanium atom of the cyclopentadienyl heterobimetallic alkoxide, [(C5H5)Sn(μ-OBut)2Ge(OBut)]. The microanalysis, molecular weight (monomer in benzene), IR and multinuclear NMR data and X-ray diffraction study is consistent with the formulation of 1. The Sn atom has a trigonal pyramidal coordination environment formed by a aysmmterically π-bonded terminal C5H5 ring and two symmetrically bridged tert-butoxy groups. The four-coordinate Ge atom lies at the centre of a distorted tetrahedron and is terminally attached to a tert-butoxy group and a Mo(CO)55? fragment. 相似文献
999.
Michael Mehring Christian LÖW Ioannis Vrasidas Markus SchÜRmann Klaus Jurkschat 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1):311-318
Recent results are reported on the application of the novel O,C,O-coordinating pincer ligand {2,6-[P(O)(OEt)2]2-4-tert-Bu-C6H2} (A) for the synthesis of hypercoordinate organotin(IV) compounds ASnR3 (R = Ph, Cl), heteroleptic stannylenes ASnR (R = Cl, CH2SiMe3) and intramolecularly coordinated 1,2,5-oxaphosphastannolanes. 相似文献
1000.
Rustem Kamalov Roza Al'myanova Michael Pudovik 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4)
Abstract Isothiocyanatochloromethyl(thio)phosphonates and (thio)-phosphinates 1 (X=O, S; R1 = OPh, CH2Cl, NCS; R2 = H, Cl have been found to be convenient starting material for synthesis of a variety of S (Se), N, P-containing cyclic compounds. They react with different proton containing nucleophiles in the presence of a base with formation of saturated 2 and unsaturated 3 five membered phosphacyclanes. Diisothiocyanatodichloromethylphosphonates 1 (R1 = NCS, R2 =Cl) produce with amines and thiols appropriate bicyclic compounds 4. 相似文献