A new formulation of two-scale FE2 analysis introduces symmetric stretch tensor as strain measure on macro level instead of asymmetric deformation gradient to determine boundary conditions on embedded microstructure. This significantly reduces computational cost of boundary conditions related sensitivity analysis of microstructure and with it the evaluation of local macroscopic stress tensors and tangent matrices. Various FE2 formulations with isogeometric and standard finite element microanalysis are tested for consistency, accuracy and numerical efficiency on numerical homogenisation examples. Objective performance comparison of different FE2 formulations is enabled with automation of all procedures in symbolic code generation system AceGen. The results obtained in numerical examples show reduced computational cost of the new FE2 formulation without loss of accuracy and comparable numerical efficiency of higher order isogeometric and standard FE2 formulations.
COBISS.SI-ID: 7244129
• Single and two layered solar absorber coatings from pigment particle dispersions • Prototype coil absorber coating for flat absorbers on 800 m aluminium coil • Solar absorptance of 0.905 and thermal emittance of 0.12 on aluminium substrates • Isoconversion kinetics predictions for improving selectivity by heat treatment • Solar absorptance of 0.92 and thermal emittance of 0.075 on aluminium substrates • Superior thermal stability at 500 °C for coatings deposited on stainless steel substrate
COBISS.SI-ID: 7094113
A new semi-analytical procedure is derived for the determination of buckling of the reinforced concrete column exposed to fire. The fire analysis is performed in three separate steps, of which the time development of temperatures in the fire compartment is performed first, followed by the coupled heat and moisture transfer analysis and, finally, by the mechanical analysis. A particular emphasis has been given to the critical buckling time and the remaining critical buckling load at a selected time. For this purpose, a parametric study has been performed by which the influence of different geometric parameters on the buckling load capacity of reinforced concrete columns has been assessed. The results of this study show that the load-carrying capacity of the column reduces significantly with the increasing time of fire exposure and the column slenderness. Moreover, the initial mechanical load has a small, although not negligible effect on the buckling load capacity.
COBISS.SI-ID: 6871137
he results of a laboratory investigation on the early autogenous shrinkage of high strength concrete, and the possibilities of its reduction, are presented. Such concrete demonstrates signiicant autogenous shrinkage, which should, however, be limited in the early stages of its development in order to prevent the occurrence of cracks and/or drop in the load-carrying capacity of concrete structures.he following possibilities for reducing autogenous shrinkagewere investigated: the use of low-heat cement, a shrinkagereducing admixture, steel ibres, premoistened polypropylene ibres, and presoaked lightweight aggregate. In the case of the use of presoaked natural lightweight aggregate, with a fraction from 2 to mm, the early autogenous shrinkage of one-day-old high strength concrete decreased by about 90%, with no change to the concretes compressive strength in comparison with that of the reference concrete.
COBISS.SI-ID: 7248225