M. Kirpluks^1*, U. Cabulis¹, A. Ivdre¹, M. Kuranska², M. Zieleniewska³, M. Auguscik³

Journal of Renewable Materials, Vol.4, No.1, pp. 86-100, 2016, DOI:10.7569/JRM.2015.634132

Abstract The most common sustainable solution for polyurethane (PU) materials is their production using renewable resources. Polyols derived from biomass and recycled polymers are the most promising way to do that. This study compares five different sustainable polyols as a possible raw material for production of highdensity rigid PU foams for automotive application. The goal of our study was to show that biobased polyols are a suitable replacement for polyols derived from petrochemical products. The influence of the chemical structure of polyols on the PU polymer matrix and foam properties was investigated. Two sources of PU raw material feedstock were studied:… More >

Aleksander Prociak^*, Elźbieta Malewska, Szymon Bąk

Journal of Renewable Materials, Vol.4, No.1, pp. 78-85, 2016, DOI:10.7569/JRM.2015.634129

Abstract In this article, the results of the foaming process analysis of fl exible polyurethane with different isocyanate indexes are presented. Two types of flexible polyurethane foams (FPURF) were obtained: (1) by using petrochemical components and a rapeseed-oil-based polyol (used in the amount of 20 wt%), (2) by using petrochemical components and cellulose as a natural fi ller in the amount of 3 php (per hundred parts of polyol). The characteristic parameters of the foaming process, such as the foam’s growth velocity, the core temperature and dielectric polarization, were measured using a Foamat device. Moreover, the following properties of flexible polyurethane… More >

Ligia Munteanu¹, Cornel Brisan², Veturia Chiroiu³, Stefania Donescu⁴

CMC-Computers, Materials & Continua, Vol.31, No.2, pp. 127-146, 2012, DOI:10.3970/cmc.2012.031.127

Abstract A modeling of the compression by using the property of Helmholtz equation to be invariant under geometric transformations is presented in this paper. The versatility of the geometric transformations is illustrated in order to obtain a new interpretation of the compression process. The physical spatial compression leads, most of the times, to new materials with inhomogeneous and anisotropic properties. The compression can be theoretically controlled by the geometric transformations. As an example, new architectures for auxetic materials can be built up by applying the geometric transformations. The new versions are finding their full correspondents in the results of the experiments… More >

H. Altenbach¹, V. A. Eremeyev²

CMC-Computers, Materials & Continua, Vol.9, No.2, pp. 153-178, 2009, DOI:10.3970/cmc.2009.009.153

Abstract Within the framework of the direct approach to the plate theory we consider natural oscillations of plates made of functionally graded materials taking into account both the rotatory inertia and the transverse shear stiffness. It is shown that in some cases the results based on the direct approach differ significantly from the classical estimates. The reason for this is the non-classical computation of the transverse shear stiffness. More >

J. Aubry¹, P. Navarro¹, S. Marguet¹, J.-F. Ferrero¹, O. Dorival², L. Sohier³, J.-Y. Cognard³

CMC-Computers, Materials & Continua, Vol.39, No.1, pp. 21-47, 2014, DOI:10.3970/cmc.2014.039.021

Abstract In this paper a numerical model dedicated to the simulation of the mechanical behaviour of polymeric Rohacell foams is presented. The finite elements model is developed at the scale of the microstructure idealized by a representative unit cell: the truncated octahedron. Observations made on micrographs of Rohacell lead to mesh this representative unit cell as a lattice of beam elements. Each beam is assigned a brittle linear elastic mechanical behaviour in tension and an elastoplastic behaviour in compression. The plasticity in compression is introduced as a way to mimic the buckling of the edges of the cells observed in experimental… More >