Nowadays, most energy absorbing devices used in industry absorb energy through permanent deformation. In some cases, consumers have to repair or even replace energy absorbers even after a mild collision. The work presented in this paper proposes a novel re-usable solution in the form of a hybrid bumper-crush can design where a recoverable structure is integrated into the bumper beam and crush can for a mild collision situation in addition to the traditional energy absorbers recommended for more severe collisions. The main investigation is focused around the performance and optimisation of Negative Stiffness honeycomb, the recoverable structure and honeycomb-filled elements. A comprehensive study was undertaken to investigate numerically the behaviour of these energy absorbing structures under crash conditions, corresponding to real scenarios and simulated using a specially developed finite element model.

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Aluminium composite sandwich panels are widely used to enhance the design of structures subjected to dynamic mechanical loading in thermally harsh environments. Spacecraft structures fall into this category because typical environmental conditions include combined and variable mechanical and thermal loading. Usually mechanical loadings arise as a consequence of localised structural dynamics and the thermal loadings are attributable principally to the effects of solar irradiation and eclipse during the vehicle's orbit. Together these have the potential to influence satellite de-point in particular. Therefore, building a combined physics model which is representative of the thermal and mechanical loadings has emerged as an interesting and useful aim, which can be thought of as defining an important thermoelastic deformation problem in this application. The performance of such a structure loaded in this way could obviously be considered in the context of separate thermodynamic and mechanical interpretations. However, multiphysics modelling is currently in hand based on the premise that the pseudo-static thermal loadings and the mechanical loadings encountered in various operating environments are not necessarily decoupled processes, and this will be the subject of a separate publication. The analytical modelling fully represents both static and dynamic mechanical and thermal loading conditions.It has become clear that predictive accuracy may be compromised by separation of the phenomena, at least without the introduction of a judicious correction factor. Therefore, in this paper an attempt has been made to identify experimentally the presence, and then to understand the attendant effects, of the coupling between the thermal and mechanical effects in an aluminium composite sandwich panel under test. The authors have performed a series of experiments on an aluminium honeycomb composite panel under three-point mechanical bending and controlled environmental temperature. The panel was subjected to a controllable, centrally located, very slowly increasing mechanical load in conjunction with thermal loading in the form of precisely controlled lowered and elevated environmental temperature. The tests were performed on a computer controlled Instron 8801 100 kN test machine for which the rate of change of applied mechanical load was automatically linked through feedback control to the rate of change of displacement. This ensured that the exact load-deflection profile can be obtained, even for materials with highly nonlinear characteristics.Both forms of loading have been shown to influence the displacement of the panel in significant ways, thereby confirming the importance of a combined physics approach.

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This article represents the first step in an attempt to obtain an analytical model of a cymbal transducer. The structure is considered as two mechanically coupled systems (i.e. a piezoelectric disc producing radial motion and end caps amplifying under the compression caused by this radial behaviour). Therefore, an analytical model of the piezoelectric disc, core driver of the cymbal, and its dynamics under an electrical signal are presented in this article. The function describing the radial motion of the disc, distribution of the electrical potential along the thickness, and displacement along the thickness are obtained analytically. The obtained radial motion function will be used for modelling the end cap amplification as a compressive loading.

This paper reports on a first attempt to model the dynamics of an asymmetrical motorised momentum exchange tether for spacecraft payload propulsion, and it also provides some interesting summary results for two novel applications for motorised momentum exchange tethers. The asymmetrical tether analysis is very important because it represents the problematic scenario when payload mass unbalance intrudes, due to unexpected payload loss or failure to retrieve. Mass symmetry is highly desirable both dynamically and logistically, but it is shown in this paper that there is still realistic potential for mission rescue should an asymmetry condition arise. Conceptual designs for tethered payload release from LEO and lunar tether delivery and retrieval are also presented as options for future development.

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