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1

Stochastic local load redistribution in the fibre bundle model of nanopillar arrays

Derda T.

Journal of Applied Mathematics and Computational Mechanics

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2015

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Vol. 14, nr 4

19--30

EN

We study the breakdown of the nanopillar arrays subjected to axial loading. The pillar-strength-thresholds are drawn from a given probability distribution. Pillars are located in the nodes of the supporting regular lattice. In this work we introduce stochastic local load sharing - after pillar breakdown each of its nearest intact neighbours obtains a random fraction of the failing load. Two types of loading procedure are employed, namely quasi-static and finite force. We analyse critical loads, catastrophic avalanches as well as probabilities of cascade and breakdown.

2

Statistical analysis of mechanical damage in arrays of mixed nanopillars

Derda T.

Journal of Applied Mathematics and Computational Mechanics

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2015

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Vol. 14, nr 1

43--53

EN

We apply the Fibre Bundle Model to study critical loads and catastrophic avalanches in arrays of axially loaded nanopillars under so-called local load sharing. Nanopillars with assigned random strength-thresholds are located in the nodes of the supporting square lattice. We analyzed different mixtures of weak and strong pillars, i.e. we use distributions of strength-thresholds drawn from two different uniform distributions.

3

Damage evolution in the anisotropic range variable model of nanopillar array

Derda T.

Journal of Applied Mathematics and Computational Mechanics

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2014

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Vol. 13, nr 3

37--46

EN

We study mechanical-damage avalanches occurring in axially loaded nanopillars located in the nodes of the supporting square lattice. Nanopillars are treated as fibres in the framework of the stochastic Fibre Bundle Model and they are characterised by random strength thresholds. Once an element crashes, its load is transferred to the other intact elements according to a given load transfer rule. In this work we use a modified range variable model including an anisotropic-stress-transfer function. Avalanches of broken nanopillars, critical loads and clusters of damaged nanopillars are analysed by varying both the anisotropy and effective range coefficients.

4

Mechanical annealing model of damage in arrays of nanopillars

Derda T.

Journal of Applied Mathematics and Computational Mechanics

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2013

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Vol. 12, nr 4

31--40

EN

The mechanical damage accumulation occurring in an array of axially loaded nanopillars is studied within the stochastic approach. To each nanopillar, an initial strength--threshold is assigned which is drawn from the Weibull probability distribution. Under the influence of load exceeding the strength-threshold the pillar height is reduced. Then the reduced pillar gets new higher strength-threshold and its load is transferred to other working pillars. We analyse slip loads causing the system height reductions and avalanches of the pillar height reductions.

5

Mikro- i nanostruktury krzemowe jako materiał termoelektryczny

Turczyński M., Lisik Z.

Elektronika : konstrukcje, technologie, zastosowania

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2012

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Vol. 53, nr 9

74-76

PL

Termoelektryczność może stać się kolejnym niekonwencjonalnym źródłem energii bezpośrednio przetwarzającym energię cieplną w energię elektryczną. Każdego dnia ogromna ilość ciepła jest wytwarzana i bezpowrotnie tracona w trakcie procesów przemysłowych, a także w silnikach naszych samochodów. Energia ta może jednak zostać odzyskana przez termoelementy wykorzystujące zjawisko Seebeck'a a następnie przetworzona na elektryczność. Niestety, materiały obecnie wykorzystywane w urządzeniach termoelektrycznych (takie jak BiTe, PbTe, SiGe) są zbyt drogie by mogły być stosowane na dużą skalę, a ich sprawność nie przekracza 5% [1], Stąd zainteresowanie naukowców z całego świata nowymi materiałami oraz rozwiązaniami, a obecnie najbardziej obiecującym kierunkiem badań są mikro- i nanostruktury.

EN

Thermoelectricity can become another widely used unconventional source of energy that converts thermal energy directly into electricity. Every day, an enormous amount of heat is released and lost during industrial processes or in the engines of vehicles. This energy can be recovered by thermoelements due to the Seebeck effect. Unfortunately, nowadays the most common materials for thermoelectric applications, such as BiTe, PbTe or SiGe, are too expensive to use in a large scale, and their performance does not exceed 5%. Hence, the new materials and the new solutions are being explored. The most promising trend in this research area is connected with nanostructures. The aim of this work was to investigate the electrical and thermal properties of silicon nanopillars with respect to possible thermoelectric application.