Smart material

About: Smart material is a research topic. Over the lifetime, 3704 publications have been published within this topic receiving 74280 citations. The topic is also known as: intelligent material & responsive material.

A feasibility study of using smart materials for rotor control

Abstract: Rotor actuation in the rotating system promises a quantum jump in overall rotor craft performance. Smart material actuator technology for operation `on the blade' is now becoming available and has the potential to overcome the size, weight, and complexity issues of hydraulic and electric on-rotor actuation. The present paper is based on the results of a feasibility study to investigate the use of smart materials for primary and active control on the AH-64 helicopter. Based on the results of the study, it is seen that imbedded actuator concepts, i.e. pitch, twist, and camber control, are not practical at this time. Servoflap control, using hinged control surfaces driven by discrete actuators emerges as the most suitable candidate for smart material actuation. Preliminary data show that rotor control using smart materials might be feasible if a combination of smart materials is used and the rotor design is driven towards low control loads and motions.

Characterization, Performance and Optimization of PVDF as a Piezoelectric Film for Advanced Space Mirror Concepts

Abstract: Piezoelectric polymers based on polyvinylidene fluoride (PVDF) are of interest for large aperture space-based telescopes as adaptive or smart materials. Dimensional adjustments of adaptive polymer films depend on controlled charge deposition. Predicting their long-term performance requires a detailed understanding of the piezoelectric material features, expected to suffer due to space environmental degradation. Hence, the degradation and performance of PVDF and its copolymers under various stress environments expected in low Earth orbit has been reviewed and investigated. Various experiments were conducted to expose these polymers to elevated temperature, vacuum UV, {gamma}-radiation and atomic oxygen. The resulting degradative processes were evaluated. The overall materials performance is governed by a combination of chemical and physical degradation processes. Molecular changes are primarily induced via radiative damage, and physical damage from temperature and atomic oxygen exposure is evident as depoling, loss of orientation and surface erosion. The effects of combined vacuum UV radiation and atomic oxygen resulted in expected surface erosion and pitting rates that determine the lifetime of thin films. Interestingly, the piezo responsiveness in the underlying bulk material remained largely unchanged. This study has delivered a comprehensive framework for material properties and degradation sensitivities with variations in individual polymer performances clearly apparent. Themore » results provide guidance for material selection, qualification, optimization strategies, feedback for manufacturing and processing, or alternative materials. Further material qualification should be conducted via experiments under actual space conditions.« less

Hierarchically structured transparent hybrid membranes by in situ growth of mesostructured organosilica in host polymer

Abstract: The elaborate performances characterizing natural materials result from functional hierarchical constructions at scales ranging from nanometres to millimetres, each construction allowing the material to fit the physical or chemical demands occurring at these different levels. Hierarchically structured materials start to demonstrate a high input in numerous promising applied domains such as sensors, catalysis, optics, fuel cells, smart biologic and cosmetic vectors. In particular, hierarchical hybrid materials permit the accommodation of a maximum of elementary functions in a small volume, thereby optimizing complementary possibilities and properties between inorganic and organic components. The reported strategies combine sol-gel chemistry, self-assembly routes using templates that tune the material's architecture and texture with the use of larger inorganic, organic or biological templates such as latex, organogelator-derived fibres, nanolithographic techniques or controlled phase separation. We propose an approach to forming transparent hierarchical hybrid functionalized membranes using in situ generation of mesostructured hybrid phases inside a non-porogenic hydrophobic polymeric host matrix. We demonstrate that the control of the multiple affinities existing between organic and inorganic components allows us to design the length-scale partitioning of hybrid nanomaterials with tuned functionalities and desirable size organization from angstrom to centimetre. After functionalization of the mesoporous hybrid silica component, the resulting membranes have good ionic conductivity offering interesting perspectives for the design of solid electrolytes, fuel cells and other ion-transport microdevices.