An active interface for rapid structural control

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Most natural organisms show fascinating mechanical versatility when interacting with their environments. Stiffness tuning in nature is used as a powerful tool to combine the load carrying functionality of rigid structures with compliance and adaptability. A remarkable example of stiffness tuning can be seen in echinoderms, such as sea cucumbers, where the mechanical stiffness can change by a factor of 10 in less than 1s. Human-made structures are normally designed to meet a specific load carrying requirement. To add other functionalities, additional components are often required; these increase the total weight and cost of the structure and consequently cause limitations in performance, efficiency and safety. Therefore, embedding sensing, actuation and control within a structure is highly desirable. Inspired by stiffness tuning in natural organisms, various synthetic materials have been developed in recent years for active structural control. However, achieving significant stiffness reduction in a short time frame with minimum power requirements but without undermining the load carrying capacity of the structure remain as some of main challenges.In this proposal, we aim to tackle these challenges by exploiting recent advances in optoelectronics and nanotechnology to design, manufacture and evaluate a nano-structured interconnected metallic network embedded in a thermoplastic layer. This layer will be then employed, as an active interface, in a conventional multi-layered structure. Upon activation, it will provide rapid structural control and impact protection capabilities. We will use a combined experimental and numerical approach to investigate the electro-thermo-mechanical response of this interface. Understanding the main physical obstacles that limit the response time and the fundamental parameters controlling the stability and the failure of this interface under harsh electro-thermal loading will help us to better engineer this interface at the micro level to meet the fast response and low power requirements.This new understanding will accelerate the technology readiness level of active structural control technology to be used in future multi-functional and smart structures. This technology has a wide range of application in robotics, morphing and deployable structures, active damping and active impact protection. As a potential representative technology, we aim to employ this active interlayer in laminated glass windscreens for automotive vehicles. Application of this transparent active interface in windscreens will help protect vulnerable road users against head-related injuries and is believed to be a step change toward designing more pedestrian/cyclist-friendly vehicles. To motivate the development of this technology, the University of Surrey is partnering with Pilkington, a member of the NSG group, which is one of the world's largest manufactures of glass and glazing products for architectural, automotive and technical glass sectors to manufacture and test this active transparent interlayer for application in automotive windscreens.