Re-disseny d’utillatge i anàlisi de vinclament per l’assaig de compressió en laminats prims

El grup de recerca AMADE de la Universitat de Girona està especialitzat en la caracteritzacióde materials compòsits. Per avaluar la resistència i la tolerància al dany d'aquestes estructures,típicament es realitzen dos assajos: impacte a baixa velocitat i compressió després d'impacte(CAI per les sigles en anglès de Compression After Impact), respectivament. L'objectiu del'assaig CAI és obtenir la resistència residual a compressió de l'estructura.L'objectiu d'aquest treball és el de crear una adaptació per l'utillatge capaç d'assajar plaquesamb baix gruix . La modelització amb el mètode dels elements finits serveix per avaluar quantitativament el valorde les càrregues crítiques de vinclament per diferents gruixos de placa.Les plaques d'assaig són plaques de material compòsit amb làmines unidireccionals amb apilamentsimètric i balancejat

Bio-based composites from stone groundwood applied to new product development

This paper deals with the product design, engineering, and material selection intended for the manufacturing of an eco-friendly chair. The final product is expected to combine design attributes with technical and legal feasibility with the implementation of new bio-based materials. Considering the industrial design, a range of objectives and trends were determined after setting the market requirements, and the final concept was proposed and modeled. The product geometry, production technology, and legal specifications were the input data for product engineering. The material selection was based on the technical requirements. Polypropylene (PP) composite materials based on coupled-fiberglass, sized-fiberglass, and coupled-stone ground wood reinforcements were prepared and characterized. Final formulations based on these PP composites are proposed and justified

Analytical investigation of the atmospheric radiation limits in semigray atmospheres in radiative equilibrium

We model the wavelength-dependent absorption of atmospheric gases by assuming constant mass absorption coefficients in finite-width spectral bands. Such a semigray atmosphere is analytically solved by a discrete ordinate method. The general solution is analyzed for a water vapor saturated atmosphere that also contains a carbon dioxide-like absorbing gas in the infrared. A multiple stable equilibrium with a relative upper limit in the outgoing long-wave radiation is found. Differing from previous radiative–convective models, we find that the amount of carbon dioxide strongly modifies the value of this relative upper limit. This result is also obtained in a gray (i.e., equal absorption of radiation at all infrared wavelengths) water vapor saturated atmosphere. The destabilizing effect of carbon dioxide implies that massive carbon dioxide atmospheres are more likely to reach a runaway greenhouse state than thin carbon dioxide ones