Wyniki wyszukiwania - BazTech

1

Strength hypotheses - a never ending story

Altenbach H.

Czasopismo Techniczne. Mechanika

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2010

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R. 107, z. 4-M

5-15

EN

Up to now there are a lot of discussions concerning criteria of the limit state of a material. The classical criteria like the Huber-von Mises-Hencky criterion are mostly used by the engineers. With the creation of new materials with non-classical behavior (different limit values at tension and compression, compressibility, Poynting-Swift effect, etc.) the classical criteria fail. It will be shown how new criteria can be created by some unified approach.

PL

Liczne dyskusje dotyczące kryteriów osiągania przez materiał stanów granicznych trwają do dzisiaj. Najczęściej stosowanymi przez inżynierów są takie klasyczne kryteria, jak kryterium Hubera-von Misesa-Hencky'ego. Wraz z powstaniem nowych materiałów, zachowujących się w sposób nieklasyczny (różne wartości graniczne po stronie rozciągania i ściskania, ściśliwość, efekt Poyntinga-Swifta etc.), dotychczasowe klasyczne kryteria stają się niewystarczające. W artykule pokazano, jak stworzyć nowe kryteria za pomocą zunifikowanego podejścia.

2

On the numerical prediction of the anisotropic elastic properties in thin-walled structures madę from short-fiber reinforced plastics

Altenbach H., Naumenko K., Pylypenko S.

Computer Assisted Mechanics and Engineering Sciences

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2005

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Vol. 12, No. 4

329-339

EN

The paper presents a model which allows to estimate the elastic properties of thin-walled structures manufactured by means of injection molding. The starting point is the numerical prediction of the microstructure of a short fiber reinforced composite induced during the filling stage of the manufacturing process. For this purpose the commercial program Moldflow Plastic InsightŽ (MPI) is used. The result of the filling simulation characterizing the fiber microstructure is a second rank orientation tensor. The elastic material properties after the processing are locally dependent on the orientational distribution of the fibers. The constitutive model is formulated by means of the orientational averaging for the given orientation tensor. The tensor of elastic material properties is computed and translated into the format suitable for the stress-strain analysis based on the ANSYSŽ finite element code. The influence of technological manufacture parameters on the microstructure and the elastic properties is discussed with the help of two examples a center-gated disk and a shell of revolution.

3

Trends in engineering plate theories

Altenbach J., Altenbach H.

Eksploatacja i Niezawodność

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2001

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nr 4

21-30

EN

The paper summarises some basic trends in modelling and analysis of refined plate theories not primary from a mathematical aspect but from the viewpoint of engineering application and of an increasing reliability of engineering structure analysis. Shear rigid and shear deformable plate models including shear correction factors or kinematical warping effects can be formulated. An extended two-dimensional theory for transverse shear stress analysis yields improved results, the influence of singularities on the global structure behaviour must be considered and the kinematical degree of freedom of plate models is an important criterion in structural analysis of folded plate structures. Composite materials have become an increasing importance in engineering structures. Multilayered, laminated and sandwich plates are used in aerospace and many other industries. Thin-walled structures composed of composite material have generally a moderate thickness and low transverse stiffness. An adequate modelling of structural plate elements should be given by refined plate theories.

4

A phenomenological creep theory including nonclassical effects and creep-damage coupling

Altenbach J., Altenbach H., Naumenko K.

Applied Mechanics and Engineering

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1999

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Vol. 4, no spec.

11-16

EN

Many engineering components of structures operate at temperatures high enough for creep to be an important design consideration. The paper formulates time-dependent constitutive equations including higher order effects of deformations.