Ricerc@Sapienza

We prove that any function in GSBD p (Ω) , with Ω a n-dimensional open bounded set with finite perimeter, is approximated by functions u k ∈ SBV(Ω ; R n ) ∩ L ∞ (Ω ; R n ) whose jump is a finite union of C 1 hypersurfaces. The approximation takes place in the sense of Griffith-type energies ∫ Ω W(e(u)) dx + H n-1 (J u ) , e(u) and J u being the approximate symmetric gradient and the jump set of u, and W a nonnegative function with p-growth, p > 1.

The disposal of fibre reinforced composite materials is a problem widely debated in the literature. This work explores the ability to restore the mechanical properties of thermally conditioned basalt fibres through chemical treatments. Inorganic acid (HF) and alkaline (NaOH) treatments proved to be effective in regenerating the mechanical strength of recycled basalt fibres, with up to 94% recovery of the strength on treatment with NaOH.

This article presents an experimental investigation to quantify the effects of high temperature exposure (400–600 °C) on the mechanical properties of single basalt fibres. To this purpose, a combination of single edge notch tension and nanoindentation micro-pillar splitting methods was used to provide an assessment of the fracture toughness of as-received and thermally treated basalt fibres. Similar values were obtained by the two different methods, and interestingly both highlighted an increase in KIc after heat treatment, up to 22% after exposure at 600 °C for 1h (1.59±0.06MPam).