| Thin-walled tubes are commonly used in the energy absorption components of automobile anti-collision,and absorb energy through the destruction of the self-structure.Compared with metal tubes,Carbon fiber reinforced polymer(CFRP)tubes have many advantages,such as lightweight,high-strength,corrosion-resistant and earthquake-resistant.The closed-cell aluminum foam is an ideal filling material for tube fitting because of its excellent performance of absorbing energy and buffering.aluminum foam-filled CFRP circular tubes(FFCT)has strong crashworthiness and energy absorption,which has a broad application prospect in the automobile industry.the current research on the axial collapse behavior of FFCT is limited to the macroscopic scale,and there is no unified conclusion on the interaction mechanism between the two materials in the collapsing process.In addition,the energy absorption capacity of FFCT is better than the sum of the two materials used alone,but the overall energy absorption mechanism is not explicit.in the meantime,There is a lack of research on the influence of important structural parameters and specific theoretical model about FFCT to guide the engineering application and structural optimization design.It is an urgent problem to study the axial crushing deformation mode of FFCT,explore the interaction and the energy absorption mechanism between CFRP and aluminum foam structure,establish the theoretical model of the overall structure energy absorption in the design of FFCT structure.In order to solve the above problems,this paper studied the axial collapse deformation mechanism and energy absorption characteristics of FFCT from three aspects,which is experiment,simulation and theoretical analysis.Established the mesoscopic finite element model of FFCT.Analyzed the influence of important structure parameters on the deformation,pressure and energy absorption characteristics of FFCT.Established the theoretical models of axial crushing force of single CFRP tubes,single aluminum foam and FFCT.Firstly,the axial collapse experiments and simulations of single CFRP circular tube,aluminum foam cylinder and the FFCT are carried out in this paper.Conducted axial crushing experiments of FFCT,which fills the foam aluminums with different densities.Studied the influence of aluminum foam density on energy absorption of FFCT.Established specific porosity and pore diameter parameters of aluminum foam three-dimensional Voronoi model.Established the finite element model of mesoscopic aluminum foam-filled CFRP circular tubes under axial collapse and verified its validity.Studied the deformation failure mechanism of two materials in FFCT,analyzed the source of energy absorption advantages of FFCT.Secondly,the influence of structural parameters such as aluminum foam density,aluminum foam cell diameter,CFRP tube wall thickness and the diameter of the FFCT on the deformation,pressure and energy absorption characteristics of the FFCT was investigated.analyzed the deformation modes of CFRP tube and aluminum foam with various parameters.The trend of typical load-displacement curve at each stage of FFCT and its variation with parameters were studied,which lays the foundation for establishing the theoretical model of axial crushing force of FFCT.Calculated the energy absorption ratio of each material to analyze the overall energy absorption mechanism of FFCT.Finally,the axial crushing energy dissipation mechanism of CFRP tube in the progressive crushing stage was analyzed in detail.The energy balance formula is established according to the simplified deformation model of the wall crushing zone.Obtained the theoretical model of axial crushing force of CFRP tube,and verified its validity.Added aluminum foam aperture dependency to modify the plastic hardening constitutive model(R-PH model).Fitted the unknown parameters in the model and verified the validity of model.A two-stage theoretical model of axial collapsing force of FFCT was established.Fitted the unknown parameters in the model and verified validity of the model. |
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