Wyniki wyszukiwania - BazTech

1

Optimal parameters of a dynamically loaded patch/layer structure against the elastic-brittle interface debonding

Ivanova J., Petrova T., Kirilova E., Becker W.

Engineering Transactions

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2017

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Vol. 65, iss. 1

97--103

EN

A one-dimensional shear-lag model was developed to study the high frequency, dynamic, time-harmonic mechanical behavior of the overlap zone of a piezoelastic patch attached to an elastic host layer and subjected to electric, temperature and moisture excitation. It was interesting to see that the change of the geometry of the overlap zone leads to different solutions after some frequency, which is responsible for different dynamic behavior of the considered structure. Furthermore, the model was involved in an optimization framework (genetic algorithm-GA) in order to find the optimal values of the model parameters of the patch/layer configuration.

2

Cracked bi-material structure subjected to monotanically increasing thermal loading. Determination of the interfacial shear and peeling stresses

Nikolova G., Ivanova J.

Journal of Theoretical and Applied Mechanics

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2015

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Vol. 53 nr 4

1019--1028

EN

A modified analytical shear lag model is used for the evaluation of the interfacial shear and peeling stresses in a cracked bi-material structure composed of two elastic plates bonded together by an interface zero thickness material and subjected to monotonically increasing thermal loading. The “peeling” stress can be determined by the aid of the interfacial shear stress and is proportional to deflections of the thinner plate of the structure. The interface is assumed to exhibit brittle failure when the shear stress reaches the critical value. The analytical solution and the length of the debonding and intact zones as well as the interfacial shear and peeling stresses for given material properties and thermal loading are discussed and illustrated in figures.

3

Interfacial shear and peeling stresses in a two-plate structure subjected to monotanically increasing thermal loading

Nikolova G., Ivanova J.

Journal of Theoretical and Applied Mechanics

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2013

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Vol. 51 nr 4

937--947

EN

An approximate analytical model is developed for the evaluation of the interfacial shear and peeling stresses in a bi-material element composed of two elastic plates bonded together by an interface zero thickness material and subjected to monotonically increasing thermal loading. Thermal peeling stress is caused by thermal and elastic mismatch of a two-plate structure undergo a temperature change. The “peeling” stress can be determined from the evaluated interfacial shear stress and is proportional to deflections of the thinner plate of the structure, i.e. to its displacements with respect to the thicker plate. The interface is assumed to exhibit brittle failure at the critical shear stress value. The analytical solution qualitatively shows delamination and ultimate failure. The results are illustrated in figures and discussed.

4

BEM and Shear lag method for interface problem of bi-material structure under static loading

Valeva V., Ivanova J., Gambin B.

Journal of Theoretical and Applied Mechanics

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2011

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Vol. 49 nr 1

17-29

EN

The behaviour of the interface of a pre-cracked bi-material ceramic-metal structure under static axial loading is an object of interest in the present paper. To solve the problem for interface delamination of the structure and to determine the debond length along the interface, a 2D BEM code was created and applied. The interface plate is assumed as a very thin plate comparing with the others two. The parametric (geometric and elastic) analysis of the debond length and interface shear stress is done. First, the obtained numerical results are compared with analytical ones from 1D. Shear lag analysis of the considered structure. The respective comparison is illustrated in figures and shows a good agreement. The comparison between the calculated using 2D BEM code elastic-brittle debond lengths with Song's experimental data for the bi-material structure Zinc/Steel as well as with respective results from FEM simulation shows good coincidence.

PL

W pracy badano zachowanie się na granicy pomiędzy warstwami metalu i ceramiki pod wpływem statycznego obciążenia przyłożonego w kierunku równoległym do połączenia pasm, w przypadku istnienia początkowego nacięcia w jednej z warstw prostopadłego do powierzchni połączenia. W celu rozwiązania zagadnienia delaminacji wzdłuż powierzchni łączącej oba materiały i wyznaczenia długości odspojenia został stworzony i zastosowany kod Metody Elementów Brzegowych – zagadnienie 2-wymiarowe. Warstwa łącząca dwa materiały została potraktowana jako bardzo cienka płyta, w porównaniu do grubości obu warstw materiałowych. Przeprowadzono parametryczną (geometrycznaą i sprężystą) analizę długości odspojenia (delaminacji) i naprężenia stycznego. Otrzymane rezultaty numeryczne porównano z analitycznymi rozwiązaniami 1-wymiarowej analizy tzw. metodą "shear lag". Otrzymane wyniki, zilustrowane na rysunkach, wykazują wzajemną zgodność. Pokazano również, że wyniki uzyskane przy użyciu Metody Elementów Brzegowych są zgodne z wynikami eksperymentu Song'a przeprowadzonego dla dwuwarstwowego elementu kompozytowego pomiędzy warstwą cynku i stali, a także z wynikami uzyskanymi w Metodzie Elementów Skończonych.