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Two series of Pd–MeOx/Al2O3(Me = Co, La, Ce) catalysts were prepared and tested in reaction of methane combustion. The first series comprises the samples obtained by impregnation of γ-Al2O3with the corresponding salts of La and Ce and additionally modified with Co. For the second series the LaCeAl2O3SG and LaAl2O3SG supports were prepared by the sol–gel method and the cobalt was not included as a modifying element. The aim was to obtain catalysts with comparable activities to that of the Co-containing samples, however the using of cobalt being subject of exclusion due to its high toxicity. The catalysts were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, Temperature programmed reduction and Fourier transform infrared spectroscopy. The modification of alumina with lanthanum and cerium by impregnation, before the cobalt introduction, decreases interaction between the PdO and the support leading to the easy transformation of PdO into the less active Pd, when the catalyst is treated at high temperatures. The cobalt-free samples prepared by sol–gel method exhibit activity and stability comparable with those of the impregnated cobalt containing Pd + Co/LaAl2O3catalyst. The observed high activity is explained by the formation of stable PdO particles, however the needed Pd-content to achieve the same activity as Co-containing samples is remarkably higher.

The paper presents an overview of a finite element approach for the analysis of the thermo-hygro-mechanical-hydration behaviour of concrete structures. The thermo-hygro component considers the mass balance equation of moisture as well as the enthalpy balance equation, and uses two primary variables, namely the capillary pressure and temperature. Heat of hydration is simulated using the approach of Schindler and Folliard. The basic mechanical model simulates directional cracking, rough crack closure and crushing using a plastic-damage-contact approach. Hydration dependency is introduced into the mechanical constitutive model. The material data from the Concrack benchmark are considered with the model. This includes data on adiabatic temperature changes during curing, changing elastic properties during curing, shrinkage and creep. The model, as implemented in the finite element program LUSAS, is used to analyse the Concrack benchmark beam RL1. Particular attention is paid to crack openings and the difference between predicted crack openings from analyses with and without time-dependent effects. It is concluded that ignoring time-dependent effects can result in a significant underestimate of crack openings in the working load range.

Experimental static and fatigue tension-tension tests were carried out on 5HS/RTM6 composite intact coupons and coupons incorporating adhesively-bonded (FM300-2) stepped flush joints. The results show that the adhesive joint, which is widely used in repairs, significantly reduces the static strength as well as the fatigue life of the composite. Both, the static and the fatigue failure of the ‘repaired’ coupons occur at the adhesive joint and involve crack initiation and propagation. The latter is modelled using interface finite elements based on the decohezive zone approach. The material degradation in the interface constitutive law is described by a damage variable, which can evolve due to the applied loads as well as the number of fatigue cycles. The fatigue formulation, based on a published model, is adapted to fit the framework of the pseudotransient formulation that is used as a numerical tool to overcome convergence difficulties. The fatigue model requires three material parameters. Numerical tests show that a single set of these parameters can be used to recover, very accurately, the experimental S-N relationship. Sensitivity studies show that the results are not mesh dependent.

This paper presents a comprehensive model for simulating coupled heat and mass transfer in concrete when it is subjected to a fire. The model considers not only the transport of dry air, water vapour and liquid water but also the evaporation of liquid water and the dehydration of bound water. It can be applied to multidimensional problems. The governing equations describing this coupled heat and mass transfer phenomenon are solved using finite element methods with a standard Galerkin approximation. Results related to temperature, pore pressure, moisture content, the level of evaporation and dehydration of water within concrete for a standard fire curve are given. The influence of the liquid water transport on the spatial distributions of temperature and pore pressure is investigated through the use of parametric studies. The present results can be used to predict the potential of concrete spalling.

An FEM parametric study of the stress distribution in orthotropic beam flanges was performed. Several beam boundary conditions and cross sections were considered explicitly. The practical variations of cross-sectional dimensions were extended in order to cover the case of thin cover plates with stiffeners. In the FE analyses a two-dimensional plane stress model was used. An empirical formula was established for the shear lag coefficient λwhich is used for computing the effective flange width Be= λBfor stress calculations. Longitudinal flange stiffeners can be accounted for by modifying the E/G ratio. The formula is accurate and gives good results even for small Tf/Twand high E/Gratios, as is the case with fiber reinforced laminated composite plates with stiffeners. Several existing analytical solutions, discussed in the paper, are not reliable for this case.