On the cross-well dynamics of a bi-stable composite plate.

Multi-stable composites are a novel type of composites capable of adopting multiple statically stable configurations. Due to the multi-stability property this type of composite material has been considered for several applications, particularly for morphing structures. The change of shape between stable states is achieved by a nonlinear mechanism known as snap-through. Most of the research done on these composites has focused on predicting the configuration after manufacture, its static characteristics and static actuation strategies to induce snap-through. However, these structures will operate subject to dynamic loads. Yet, very little work has been carried out to examine the dynamic behaviour of bi-stable composites. This paper focuses on the study of the cross-well dynamics of a bi-stable composite plate. A simple model previously derived for the dynamics confined to a single stable state is extended to. include cross-well dynamics. The rich dynamics are experimentally investigated, focusing on cross-well oscillations and the key dynamic features of snap-through. Numerical simulations are obtained and compared to the experimental results showing good agreement. In particular, experimentally observed characteristics suggesting chaotic oscillations for cross-well dynamics are captured well by the proposed model. The results herein could be used for implementing control strategies for both configuration morphing and undesired snap-through suppression of bi-stable composites

Dynamic snap-through for morphing of bi-stable composite plates

Composite laminate plates designed to have two statically stable configurations have been the focus of recent research, with a particular emphasis on morphing applications. In this article, we consider how external vibration energy can be used to assist with the actuation between stable states. This is of interest in the case when surface bonded macrofiber composites (MFC) actuators are employed as the actuation system. Typically, these type of actuators have been found to require considerably high voltage inputs to achieve significant levels of actuation authority. Therefore, assisting the actuation process will allow lower voltages and/or stiffer plates to be actuated. Two bi-stable plates with different thickness, [0(4) - 90(4)](T) and [0(2) - 90(2)](T), are tested. The results show a significant reduction in the force required to change state for the case where dynamic excitation provided by an MFC actuator is used to assist the process. This strategy demonstrates the potential of dynamically assisting actuation as a mechanism for morphing of bi-stable composites

Low Order Model for the Dynamics of Bi-Stable Composite Plates

This article presents the derivation and validation of a low order model for the non-linear dynamics of cross-ply bi-stable composite plates focusing on the response of one stable state. The Rayleigh–Ritz method is used to solve the associated linear problem to obtain valuable theoretical insight into how to formulate an approximate non-linear dynamic model. This allows us to follow a Galerkin approach projecting the solution of the non-linear problem onto the mode shapes of the linear problem. The order of the non-linear model is reduced using theoretical results from the linear solution yielding a low order model. The dynamic response of a bi-stable plate specimen is studied to simplify the model further by only keeping the non-linear terms leading to observed oscillations. Simulations for the dynamic response using the derived model are presented showing excellent agreement with the experimentally observed behaviour. Additionally, deflection shapes are measured and compared with the calculated mode shapes, showing good agreement

Virtual tool for the promotion of anaerobic conversion technologies of residual biomass in Colombian rural areas. [Herramienta virtual para la promoción de tecnologías de conversión anaerobia de biomasa residual en zonas rurales del territorio colombiano]

The effects of climate change are more evident and destructive every year, because of this, investments in nonconventional energy sources are increasing rapidly and countries are reinforcing their policies to promote the use, research and implementation of new low-carbon technologies. With this in mind, this paper explores a software for estimating the biogas generation potential of livestock; and its use as a virtual tool to inform the inhabitants of Colombian rural areas of the energy potential of residual biomass with easy to understand indicators and comparisons. Results of the proposed software are based on reported data from scientific sources and results are identical to those calculated by traditional mathematical models. The authors expect to enhance the adoption of anaerobic digestion technologies by releasing this software through governmental, non-governmental and non-profit organizations. © 2020 AISTI