The scope of this work was to verify the importance of different material structures and test parameters on the penetration energy Up of E-glass fibre reinforced plastics (GFRP). To this aim, quasi-static and impact tests were carried out on three types of GFRPs having different fibre architectures and orientations, and resin content. Two of the laminates were made of fabric layers, and the third was an in-plane isotropic SMC. From the results, GFRP is strongly sensitive to the loading speed, with higher loading speeds resulting in a sensibly higher capacity of energy absorption. The effect of the support diameter on Up was quite small, yielding a 10% increase in Up for Ds varying in the range 40 to 100 mm. Apart the loading speed, the most effective parameters affecting Up were the panel thickness, t, and tup diameter, Dt. The dependence of the penetration energy on them was clearly more than linear, following a power law of exponent 1.36. This suggested that the true parameter influencing Up for a given material could be the product (t•Dt). The data generated supported this hypothesis, with all the experimental points converging to a single curve, irrespective of the material thickness and tup diameter adopted. In order to compare the response of the different materials tested, yet accounting for the difference in matrix content, a normalisation procedure, successfully applied by previous researchers, was followed: the panel thickness times the fibre content by volume, Vf, was used, instead of the actual t value. All the data collapsed on a master curve, indicating that the total fibre content, rather than their architecture and orientations, is really important when the penetration energy is wanted. Consequently, a formula was proposed, allowing the calculation of Up as a function of the quantity (t•Vf•Dt). This relationship is expected to be valid for whichever GFRP laminate, provided its anisotropy ratio is not too high and the elastic energy stored in the structure is negligible compared to the one expended in penetrating the material. Further, this formula should be helpful in comparing low-velocity impact data obtained from panels of different thickness and fibre content, tested by different impactor diameters.
Factors affecting the penetration energy of glass fibre reinforced plastics subjected to a concentrated transverse load / Caprino, Giancarlo; Lopresto, Valentina. - European Conference on Composite Materials ECCM9:(2000), pp. 1-5. (Intervento presentato al convegno European Conference on Composite Materials ECCM9 tenutosi a Brighton nel 4-7 giugno 2000).
Factors affecting the penetration energy of glass fibre reinforced plastics subjected to a concentrated transverse load
CAPRINO, GIANCARLO;LOPRESTO, VALENTINA
2000
Abstract
The scope of this work was to verify the importance of different material structures and test parameters on the penetration energy Up of E-glass fibre reinforced plastics (GFRP). To this aim, quasi-static and impact tests were carried out on three types of GFRPs having different fibre architectures and orientations, and resin content. Two of the laminates were made of fabric layers, and the third was an in-plane isotropic SMC. From the results, GFRP is strongly sensitive to the loading speed, with higher loading speeds resulting in a sensibly higher capacity of energy absorption. The effect of the support diameter on Up was quite small, yielding a 10% increase in Up for Ds varying in the range 40 to 100 mm. Apart the loading speed, the most effective parameters affecting Up were the panel thickness, t, and tup diameter, Dt. The dependence of the penetration energy on them was clearly more than linear, following a power law of exponent 1.36. This suggested that the true parameter influencing Up for a given material could be the product (t•Dt). The data generated supported this hypothesis, with all the experimental points converging to a single curve, irrespective of the material thickness and tup diameter adopted. In order to compare the response of the different materials tested, yet accounting for the difference in matrix content, a normalisation procedure, successfully applied by previous researchers, was followed: the panel thickness times the fibre content by volume, Vf, was used, instead of the actual t value. All the data collapsed on a master curve, indicating that the total fibre content, rather than their architecture and orientations, is really important when the penetration energy is wanted. Consequently, a formula was proposed, allowing the calculation of Up as a function of the quantity (t•Vf•Dt). This relationship is expected to be valid for whichever GFRP laminate, provided its anisotropy ratio is not too high and the elastic energy stored in the structure is negligible compared to the one expended in penetrating the material. Further, this formula should be helpful in comparing low-velocity impact data obtained from panels of different thickness and fibre content, tested by different impactor diameters.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
