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At present, most of the crash performance studies for negative Poisson's ratio (NPR) filled tubes are focused on the axial impact loadings. This paper focused on the transverse impact load response of filled tubes for double-arrowed negative Poisson's ratio (DANPR) structures. The effects of each structural parameter of the double-arrowed cell on the peak collision force (PCF) and specific absorption energy (SEA) of the filled tube were analyzed by numerical simulations and three-point bending experiments. Cell beam thickness, cell half-width, cell long beam angle, cell short beam angle and impact velocity were found to have significant influences on the PCF and SEA and the deformation of the filled tube. The optimal structural parameters of the DANPR filled tubes were obtained by a surrogate model and an optimization algorithm. The results shown that the maximum value of SEA and the minimum value of PCF are contradictory relationships and cannot be obtained simultaneous. However, it can be found that after optimization, the SEA can be changed to about 510 kJ/kg with the same PCF, which is an increase of about 36.45%. If its SEA is kept constant, the PCF becomes about 3.2 kN after optimization, a decrease of about 37.74%. Therefore, the practical manufacturing needs to make tradeoffs according to the weights of both, which also provides a reference for the design of DANPR filled tubes. [ABSTRACT FROM AUTHOR]

Bioinspired structure/material has attracted attentions in engineering fields. In this article, a novel sandwich cylinder inspired by shore horsetail is proposed by introducing the double-arrowed auxetic filler. The energy absorption characteristics of the sandwich cylinder are analysed comprehensively and compared to the conventional structure to show its superiority. The effects of the geometric parameters on the energy absorption characteristics are also discussed. It is found that the number of layers and cells for auxetic structures, thickness of beams and thin-walled tubes, and the radius of the inner tube have great effects on the crushing force, energy absorption, initial peak force and specific energy absorption. The sandwich cylinder will be a great energy absorber after designing. [ABSTRACT FROM AUTHOR]

It is well known that the natural frequencies of a coupled vehicle–bridge interaction system are time-varying. While this knowledge is useful for applications in bridge health monitoring, it does not provide an understanding of the relations between the excitation and coupled system responses, nor leads to developments of effective control strategies to mitigate vibration. In this paper, a novel theoretical framework for the time-varying displacement transmissibility is developed using a time-frozen technique. The time–frequency characteristics of the transmissibility functions are investigated to gain fundamental understanding and insights of the coupling dynamics in relation to the matching of bridge and vehicle natural frequencies. An important aspect of the transmissibility formulation is that it leads to the development of physics-based vibration control strategies in the frequency domain. By applying the principle of fixed points from vibration absorber designs to the transmissibility functions, an optimally tuned vehicle suspension to mitigate bridge vibration is obtained. The tuning strategy depends only on a priori known structural parameters. Thus, the tuning strategy provides useful guidelines in practice and is shown to be effective in reducing the vibrations of both the moving vehicle and the bridge. This work paves a foundation for further research in the design of bridge-friendly vehicles via parameter tuning. [ABSTRACT FROM AUTHOR]