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The Department of Applied Mechanics of the Royal Institution of Engineers in the Netherlands (Koninklijk Instituut van Ingenieurs) organised on April 2-4, 1990 the first National Applied Mechanics Congress about the theme: "Integration of Theory and Applications in Applied Mechanics" The idea behind this initiative was to bring together the Applied Mechanics communities in The Netherlands and Belgium and to create an environment in which new developments in the field could be discussed and in which connections to other disciplines could be established. Among an extensive list of possible subjects the following were selected as congress topics: - non-linear material behaviour, - chaos, - mechatronics, - liquid-solid interactions, - mathematics and applied mechanics, - integration of Applied Mechanics and other disciplines. Applied Mechanics comprises both solid mechanics and fluid mechanics. These can be subdivided further into: rheology, plasticity, theory of plates and shells, theory of elasticity, multibody dynamics, dynamics of continuous media, stability of the elastic equilibrium, etc. Applied Mechanics is of tremendous practical significance and it proves its value almost daily in applications such as the calculation of the strength and stiffness of constructions, like e. g.
E-Book Content
INTEGRATION OF THEORY AND APPLICATIONS IN APPLIED MECHANICS The National Mechanics Congress has been sponsored by: DSM Research Eindhoven University of Technology KIVI - Afdeling voor Mechanica Oce - Vander Grinten B. V. Philips Research Shell Nederland B.V. Integration of Theory and Applications in Applied Mechanics Choice of papers presented ar the First National Mechanics Congress. April 2-4. 1990. Rolduc. Kerkrade. The Netherlands Edited by J. F. DIJKSMAN Philips Lighting BY.. Eindhoven and F. T. M. NIEUWSTADT Laboratory for Aero and Hydrodynamics. Technical University of Delft KLUWER ACADEMIC PUBLISHERS DORDRECHT ! BOSTON! LONDON Library of Congress Cataloging in Publication Data Natlonal MeChanICS Cong;-ess !Jm - - --;,---==-'---;;d' - ad I a:cst - 2 E 10Z(1 - d,)2 Where [Jm denotes the mean value through the thickness. From experimental results it follows that the governing quantities of damage evolution are : '[ = ~~ [Y d + bY d,]l!2 '[' = ~~ = [Y'd]1/2 where b is a material constant. Experimentally, one obtains: Y- YO d= < ~="">+ ifd< 1="" ;="" d="1" otherwise="" d'=""> if d' < 1=""> '[' < y'c="" ;="" d'="1"> 21 Figure 6 : Material curve for the evolution of d Models with delay effects are also used [13]. They differ from the previous one if the damage rates are very high only. To describe the anelastic phenomena due to damage one uses a plasticity model. Details can be founded in [11] [12] [13]. The identification of the material parameters has been done for severallarninates. Results for T300 - 914 and IM6 - 914 are given in [13] [6]. This modelling has been checked out on numerous experimental tests. ~ : Near the edges it is necessary to take out-plane stresses into account In order to simplify Young's modulus E3 and the shear modulus G13 and G 23 are taken constant and thus damage effects of out-plane stresses are assumed to affect interface behavior only. For the interface which is a mechanical surface entity similar modelling is used [13] [1] [12]. S. RUPTURE COMPUTATION The rupture phenomenon happens after two phases. In a first step, the micro-voids and micro-cracks growth is nearly uniform: it is the initiation stage. From the critical point (or from a point just beside) the strain and also the damages become more and more localized; a macro-crack appears and growths until becoming unstable. If the ftrSt stage 22 is well described thanks