Study Of Axial Deformation And Energy Absorption Characteristics Of Composite Foam-filled Thin-walled Tubes

Aluminum foam-filled tube structure is a multiple-materials composite structure with excellent properties.It has the outstanding advantages of independent load-bearing capacity,high stability and can be used in extreme environments,wich make it a great potential in engineering field.In addition,due to its excellent mechanical,physical and chemical properties,carbon nanotubes(CNTs)are ideal reinforcing phases for aluminum foam matrix composites.In recent years,with the continous requirement of high properties for material properties in cutting-edge fields such as aerospace,the research of preparation and performanc of composite foam-filled tubes has become a hot topic.The research contents and results of this paper are as follows:Aluminum foam-filled aluminum alloy tubes were prepared by a direct-filling method.The effect of ambient temperature(25 oC~250 oC)on compression energy absorption and deformation modes of foam-filled tubes were studied.The results show that compared with aluminum foam-filled 6061-O aluminum alloy tubes,aluminum foam-filled 6061-T6 aluminum alloy tubes have higher energy absorption performance but also higher temperature sensitivity of energy absorption.The high temperatures decrease the strength of the aluminum foams,aluminum alloys tubes and foam-filled thin-walled tubes.The mean plateau forces of the aluminum foams and the thin-walled tubes together decide the deformation mode of the foam-filled tubes.The deformation process and failure mechanism of ex-situ aluminum foam-filled carbon fiber reinforced plastic(CFRP)thin-walled tubes were studied by Digital Image Correlation(DIC)technology.The effects of porosity of aluminum foams and service temperature on the mechanical and energy absorption properties of aluminum foam-filled CFRP thin-walled tubes were studied.The results show that the failure of aluminum foam-filled CFRP thin-walled tubes is caused by the failure of fibrous layer.With the increase of porosity of aluminum foams and service temperatures,the mechanical properties of the foam-filled tubes decrease;at 150 oC,the resin matrix of the CFRP tube is severely softened and the extrusion of the aluminum foams on the thin-walled tube aggravates the delamination of the resin matrix and the debonding of the carbon fiber.Composite aluminum foam-filled thin-walled tubes were prepared by an in-situ filling methond.The optimum processing parameters were investigated and the deformation mechanism and strengthening mechanism of the foam-filled tubes were studied.The results show that the foam-filled tubes have best mechanical and energy properties with 6061-O aluminum alloy tubes,cold pressing pressure of 400 MPa,sintering temperature of 610 oC and CNTs contents of composite foams of 2.5 wt%.Metallurgical bonding was formed between the composite foams and the thin-walled tubes and there is an obvious interaction between the compostie foams and thin-walled tubes.The energy absorption of foam-filled tubes increases by 46.1%.