Lateral compression behavior of expanded polypropylene foam-filled carbon fiber reinforced polymer and aluminum/carbon fiber reinforced polymer composite tubes: An experimental study

Abstract

This study investigates the energy-absorbing capability of the circular cross-section carbon fiber reinforced polymer (CFRP) and Aluminum/CFRP (Al/CFRP) composite tubular structures under quasi-static lateral compression. The CFRP composite tubes were manufactured with the 6, 8, and 10 layers to observe the thickness effect. A specially designed and manufactured polymer mold was used to manufacture identical CFRP composite tubes. Expanded polypropylene (EPP) foam with densities of 30 kg/m3, 60 kg/m3, and 75 kg/m3 was chosen as a filler material to enhance the energy absorption and efficiency because of its superior properties of high strength-to-weight ratio. The experiments revealed that the carbon fiber layer number directly affected CFRP and Al/CFRP composite tubes' force and the absorbed energy values. The increase in the maximum and average force values is more evident than in the Al/CFRP tubes due to using aluminum tubes constraining the effect of the carbon woven part. Additionally, EPP foam filling significantly contributes to the tubes' absorbed energy. The absorbed energy increased proportional to the foam density, and the 10-layer Al/CFRP tube filled with 75 kg/m3 sample absorbed the highest energy value as 257 J. However, considering the crashworthiness parameters (i.e., specific energy absorption, crush force efficiency, and work effectiveness), the best sample combination did not absorb the highest energy. Although the 6-layer CFRP composite tube absorbed the lowest energy, it has higher specific energy absorption and work effectiveness. According to the crashworthiness parameters, the best efficiency was obtained in the 10-layer composite tubes filled with 75 kg/m3.