Showing papers by "Rüdiger Schmidt published in 2006"
TL;DR: In this article, the relevance of the five and six-parameter variants of the FOSD hypothesis for large rotation plate and shell problems was discussed, and it was shown that the assumption of constant through-thickness distribution of the transverse normal displacements is acceptable only for small and moderate rotation problems.
Abstract: The paper deals with the geometrically non-linear analysis of laminated composite beams, plates and shells in the framework of the first-order transverse shear deformation (FOSD) theory. A central point of the present paper is the discussion of the relevance of five- and six-parameter variants, respectively, of the FOSD hypothesis for large rotation plate and shell problems. In particular, it is shown that the assumption of constant through-thickness distribution of the transverse normal displacements is acceptable only for small and moderate rotation problems. Implications inherent in this assumption that are incompatible with large rotations are discussed from the point of view of the transverse normal strain–displacement relations as well as in the light of an enhanced, accurate large rotation formulation based on the use of Euler angles. The latter one is implemented as an updating process within a Total Lagrangian formulation of the six-parameter FOSD large rotation plate and shell theory. Numerical solutions are obtained by using isoparametric eight-node Serendipity-type shell finite elements with reduced integration. The Riks–Wempner–Ramm arc-length control method is used to trace primary and secondary equilibrium paths in the pre- and post-buckling range of deformation. A number of sample problems of non-linear, large rotation response of composite laminated plate and shell structures are presented including symmetric and asymmetric snap-through and snap-back problems.
60 citations
01 Jan 2006
TL;DR: In this paper, a geometrically nonlinear finite shell element based on the total Lagrangian formulation was developed for the actuation of piezolaminated plates and shells and the displacement field in transverse direction was assumed to vary linearly according to the Reissner-Mindlin hypothesis.
Abstract: Several numerical examples are presented in which geometrical nonlinearity plays a considerable role when the actuation of piezolaminated plates and shells is considered. In each numerical example the comparison between linear and geometrically nonlinear approximations is drawn. For the numerical simulation of the actuation of piezolaminated shells a geometrically nonlinear finite shell element has been developed based on the total Lagrangian formulation. The strain-displacement relations are based on the assumptions of small strains and moderate rotations of the mid-surface normals. The displacement field in transverse direction is assumed to vary linearly according to the Reissner-Mindlin hypothesis.
3 citations
TL;DR: In this paper, circular metal plates are subjected to impulsive loadings in shock tubes and the damage growth in the plate specimens until failure is predicted by finite element simulations, and the authors validate the applied isotropic and anisotropic damage laws by means of comparisons between calculated and measured deformations.
Abstract: In the present study circular metal plates are subjected to impulsive loadings in shock tubes. The damage growth in the plate specimens until failure is predicted by finite element simulations. The aim is to validate the applied isotropic and anisotropic damage laws by means of comparisons between calculated and measured deformations. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
2 citations
TL;DR: In this article, the hysteresis of a mechanically unconstrained actuator is obtained using the Michelson interferometry and the hysteretic behavior is modelled by a Preisach model.
Abstract: Piezoelectric ceramics are often used as actuators in smart structures technology. In the vast majority of papers dealing with this topic only linear constitutive relations are used. However, the electric field-strain relations of such actuators show hysteretic behaviour, which means that the piezoelectric coupling coefficient is not constant.
In this study the hysteresis of a mechanically unconstrained actuator is obtained using the Michelson interferometry. The hysteretic behaviour is modelled by a Preisach model. Using these experimental data, for the modelling of an active structure with embedded piezoelectric actuators the actual coupling coefficient can then be determined with the help of the Preisach model. With this procedure the actuation strain of an embedded actuator, including the physical nonlinearities, can be calculated using the material characteristics obtained for an unconstrained actuator.
For an experimental validation of the method outlined above, a Lead Zirconate Titanate (PZT) actuator is characterised experimentally and then glued to a cantilever beam. Then, the tip displacement of the actuated beam is determined experimentally and simulated numerically using the above method. The experimental and numerical results agree reasonably well if the shear lag due to the bonding layer between the actuator and the structure is taken into consideration. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)
1 citations