Papers by Author: U. Galietti

Abstract: This work discusses application of the thermoelastic technique to the stress analysis of Rapid Prototyping (RP) models. The aim is to evaluate the possibility of conducting complete and effective structural tests on prototypes made by means of stereolithography (SLA). The analyzed material is an RP Cure 600 ND epoxy resin. A statistical approach was followed to evaluate the sensitivity of the thermoelastic behaviour of the material to some SLA characteristic parameters. In addition, the effect of load cycle frequency on thermoelastic signal was also analyzed. The experimental work included forty-eight tests on ASTM standardized specimens. A new testing procedure was developed for resin-made models. The new method is based on the application of a loading ramp to SLA standard specimens and on the acquisition of the infrared signal. The thermoelastic constant K is determined using the thermographic signal temporal slope. Results for an engine bracket are presented in the paper.

Abstract: This work presents a set of experimental results based on the measured thermoelastic signal from GRP composite coupons adopting different lay-ups. A comparison is made with the thermoelastic signal predicted by two different analytical models: one based on the classical law of the thermoelastic effect for orthotropic materials, and the other based on a novel theory accounting for the presence of a resin layer on the external surface of the composite structure. The composite coupons were designed such to determine a significant difference in the predictions made by the two theoretical models. Experimental results have shown a far better match with the predictions based on the novel theory accounting for the presence of a surface resin rich layer.