Improvement of the mechanical properties in hybrid structures by polyurethane rigid foams reinforcement in aluminium profiles

Abstract

One of the biggest challenges in transport industry is weight reduction. The objective is both economic and environmental: cost reduction together with a reduction in the use of fuel and CO2 emissions. Multi-material design, with rigid foams as local reinforcements, suppose a great opportunity to success this challenges, being a versatile solution for cost and weight saving. Among them, polyurethane rigid foams (PUR) not only present structural and energy absorption advantages, but also improveme other properties, as corrosion resistance and vibration and noise reduction. In the present work, extruded profiles (series 6xxx-T6) were reinforced with PUR foams manufactured by CETEC. The influence of the next factors on the structural strength has been evaluated: profiles wall thickness (from 1.6 to 4 mm), filling method (manual or injection), PUR density (from 100 to 300 kg/m3), amount of material inside the profiles (from 70 to 90%) and influence of the temperature in the PUR foaming. Improvement in the structural strength (maximum load and energy absorption) was characterised by 3-point bending test. In conclusion, it has been observed an improvement in the load and energy absorption with the inclusion of PUR, with a dependence on the wall tickness and foam density. Furthermore, injected profiles presented improved structural results due to the better control over the manufacturing process.