SUMMARYThe present study is aimed to overcome difficulties faced with industrial applications of multilevel iterative methods to arbitrary finite element (FE) structural analysis problems. The coarse grid concept, used in multigrid methods, is substituted with an aggregation coarse model based on the mechanical principle. On the base of this approach together with previously developed multilevel preconditioner, an efficient iterative equation solver FELAGS was developed for using in standard comprehensive finite element software systems. Numerical examples for analyses of three-dimensional (3-D) frame structures demonstrate the efficiency of the method. Comparison with incomplete Cholesky conjugate gradient (ICCG) method and direct methods is presented.

Polymere werden im Plasma einer elektrischen Entladung an der Oberflache funktionalisiert (oxydiert) bzw. abgebaut. Daneben wurde jeweils ein signifikanter, auf eine 5 bis 10 pm starke Schicht an der Oberflache beschrankter Volumeneffekt (,,Tiefeneffekt") beobachtet, der durch die Plasma-UV-Strahlung verursacht wird. Diese photolytischen Erscheinungen fuhren zu Anderungen im Polymergefuge wie Vernetzung, Veranderung der Kristallinitat, Radikalbildung usw. Abbildungen von Polymeratzstrukturen spiegeln deshalb in gewissem Umfang die solchermafien veranderte Sekundarstruktur wider. Mccnedooawx no mpaonenu?o nonuwepoo o naaswe. Yacma I : Haael-cexux cmpyKmypaa nonu,wepoo nocne ux mpaonemx o nnmwe Investigations o n plasma etching of polymers. Part I . Structural changes of polymers by plasma etching I n t h e plasma of electrical discharges polymer samples are subjected t o oxidation causing reactive sites or t o degradation.Further, a significant volume (depth) effect in a 5 t o 10 pm surface layer was observed which was caused by plasma UV radiation. These photolytical effects result in changes of the polymer structure, as crosslinking, change of crystallinity, radical formation etc. Therefore, the etching patterns reflect the features of secondary structures formed by these processes.

No abstract

The extended J-integral for 3D linear elastostatic crack problems and its application to mixed mode problems is investigated. In 3D, the decomposition of the J-integral into its parts corresponding to the symmetric mode I and both antisymmetric modes II and III is derived explicitly. The range of validity of the decomposition method is also discussed in the framework of linear elastic fracture mechanics (LEFM). It is shown analytically that in a general mixed mode case the antisymmetric part of the J-integral can be split into the parts associated with mode II and mode III only in the crack near-field.

Ein Reaktionsmodell der Umsetzung von Glycidet ltern mit aromatischen Cyansaureestern wird begrundet. Als Hauptreaktionen wurden die Trimerisierung der Cyansaureester, die Einschubreaktion der Glycidether in die Cyanuratstruktur, die Isomerisierung der Alkylcyanurate, die Oxazolidinonbildung, die Phenolabspaltung und die Phenol/Glycidether-Addition gefunden. Pea~i4uu nomu$ynm+uona.mnb~x a@upos yuatLoeoLi raclornbc c nomq$ynquonmbnbmu Z A U Y U~' M M M L sghpawu. 2 . Moaem peaxyuli AaeTCR 06OCHOBaHHe AJIH MOAeJrH PeaKqMH I' JIHqHAHbIX 3@HpOB C aPOMaTH' IeCKHMM 3@HpaMH U U a H O B O i KMC3IOTbl. r J I a B H b I M H peaKqHHMH flBJIHIOTCR TPHMePH3aqWH 3@HpOB qHaHOBOfi HHCJIOTbI, PeaKllHH BCTaBHH rJIHqHHHbIX @HpOB B C T~Y H T Y P Y qHaHypaTa, m o~e p~3 a q u~ axHumHMx qaaHypaTon, 0 6 p a a o s a~n e O K C~~O J I E I~H H O H~, oTuenneHHe @eHoJra H peaHqm npHcoeAmieHm @eHona H rnHqwHoro 3 @~p a . Reactions of polyfunctional esters of cyanic w i d with polyfunctional glycidylethers. 2. Reaction modelA model of the reaction between glycidylethers and aromatic cyanates is established. It was found that the trimerization of cyanates, the insertion of glycidylethers, the isomerisation of alkylcyanurates, the oxazolidinone build up, t h e abstraction of h e phenols, and the phenol/glycidylether-addition are the main reactions.