Active vortex generator deployed on demand by size independent actuation of shape memory alloy wires integrated in fiber reinforced polymers

2016 ◽  
Author(s):  
M. Hübler ◽  
S. Nissle ◽  
M. Gurka ◽  
J. Wassenaar
Keyword(s):  
Shape Memory Alloy ◽  
Shape Memory ◽  
Vortex Generator ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
On Demand

Active Vortex Generator Deployed on Demand by Active Hybrid Composites From Shape Memory Alloys and Fiber Reinforced Polymers

2017 ◽  
Author(s):  
Martin Gurka ◽  
Sebastian Nissle ◽  
Moritz Hübler ◽  
Max Kaiser
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Flow Separation ◽  
Hybrid Composites ◽  
Vortex Generators ◽  
Fiber Reinforced Polymers ◽  
Fe Model ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
On Demand

High performance airfoils with laminar airflow exhibit minimum drag and maximum lift, but tend to sudden stall due to flow separation at low air speed. This requires an increased approach speed of the aircraft, resulting in less steep approaches and a higher noise exposure of the surroundings. New active vortex generators, deployed only on demand at low speed, energizing the boundary layer of air flow and reducing flow separation, can help to overcome this critical situation. Active hybrid composites, combining the actuation capability of shape memory alloys (SMA) with the possibility of tailoring the compliance of fiber reinforced polymers (FRP) on the materials level, provide an active aerodynamic system with high lightweight potential and small space requirements. Being one of the first applications of active hybrid structures from SMA and FRP we will demonstrate the potential of this new technology with an integrated system of active vortex generators for a glider. In this contribution we present - the design process, based on a FE-model and careful characterization of the actuating SMA and the composite material - manufacturing relevant aspects for reliable series production - the testing of single vortex generators in lab scale under aerodynamic load - and an overview of the whole system.

scholarly journals The influence of carbon nanotubes and shape memory alloy wires to controlled impact resistance of polymer composites

2016 ◽  
Vol 51 (2) ◽  
pp. 273-285 ◽  
Author(s):  
Katerina Sofocleous ◽  
Vasileios M Drakonakis ◽  
Stephen L Ogin ◽  
Charalabos Doumanidis
Keyword(s):  
Carbon Nanotube ◽  
Carbon Fiber ◽  
Shape Memory Alloy ◽  
Shape Memory ◽  
Polymer Composites ◽  
Fiber Reinforced Polymers ◽  
Fiber Reinforced ◽  
Carbon Fiber Reinforced Polymers ◽  
Reinforced Polymers ◽  
Carbon Fiber Reinforced

Matrix as well as interlayer regions of laminated polymer composites have been reinforced with carbon nanotubes, additionally to shape memory alloy wires, in order to further enhance the overall material toughness and introduce the improved impact resistance mechanisms through micro- and nano-engineering. In this work, we examine carbon fiber reinforced polymer composites with constant carbon fiber volume fraction, further reinforced with carbon nanotube and shape memory alloy wires, under controlled impact. Single-type as well as multiple-type impact tests have been carried out, demonstrating that the energy absorption and damage development are similar in both impact tests for the same material. When the carbon nanotube and shape memory alloy wires reinforcements are compared separately, shape memory alloy-reinforced carbon fiber reinforced polymers present higher energy absorption than the carbon nanotube-reinforced carbon fiber reinforced polymers. When they are combined, although the carbon nanotube + shape memory alloy-reinforced carbon fiber reinforced polymers present similar energy absorption improvement to shape memory alloy-only carbon fiber reinforced polymers, the carbon nanotube addition increases toughness, resulting in damage initiation at higher depths of impact penetration.

Integration of Shape Memory Alloy Wires in Fiber Reinforced Polymers for Endless Crash Absorber Structures

2014 ◽  
Author(s):  
Sebastian Nissle ◽  
Moritz Hübler ◽  
Martin Gurka ◽  
Sebastian Schmeer ◽  
Nikolai Voll
Keyword(s):  
Shape Memory Alloys ◽  
Shape Memory ◽  
Energy Absorption ◽  
Tensile Load ◽  
Tensile Loading ◽  
Fiber Reinforced Polymers ◽  
Force Level ◽  
Fiber Reinforced ◽  
Reinforced Polymers ◽  
Metal Elements

Today in most cases crash absorber elements are made of metals. Those materials absorb the energy during a crash event by ductile plastification, as e.g. by buckling. Fiber reinforced polymers (FRP) offer due to their heterogenic structure several failure mechanisms for energy absorption under compressive load, such as fiber-break, matrix-break, delamination, fiber pull-out, fiber-matrix-interphase failure and friction processes. This in combination with the low density leads to significantly better specific energy absorption of FRP absorbers (50 J/g to 200 J/g FRP, 20 J/g steel, 40 J/g aluminum). But in case of tensile load fiber reinforced polymers break brittle and the energy absorption level is low. Today as a consequence of rising energy costs FRP with their good specific mechanic properties are used more and more also for crash relevant structures as in automobiles and aircrafts. For this applications a good crash behavior in both cases, compressive and tensile loading, is important. The integration of metal elements in FRP-structures offers the possibility to improve the tensile crash behavior of fiber reinforced polymers as the metal elements can prevent a catastrophic failure of the structure in case of FRP-break and distributes the load during tensile deformation on a larger FRP volume. The integration of shape memory alloys (SMA) with their pseudoplastic martensitic detwinning plateau allows for manufacturing of an “endless” crash absorber in case of tensile load. Required is a well dimensioned structure of shape memory alloys, e.g. a wire mesh, the FRP component and their interface. Doing so, it is possible to get huge number of breaks in the SMA reinforced FRP. The pseudoplastic detwinning plateau and the huge strain hardening of the SMA material ensure that after a FRP-break and the drop of the force level associated therewith the force level in the whole structure raises again so that another FRP-break is initiated. Also the reinforcement prevents a complete failure of the structure. In this contribution we present a theoretical extrapolation of the behavior of these new hybrid structures under tensile loading, give an estimation of their potential and demonstrate a first experimental validation of this new concept.

scholarly journals On-Demand Photopolymerization of Fiber-Reinforced Polymers Exhibiting the Shape Memory Effect

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4300
Author(s):  
Xavier Allonas ◽  
Johann Pierrel ◽  
Ahmad Ibrahim ◽  
Céline Croutxé-Barghorn
Keyword(s):  
Shape Memory ◽  
Shape Memory Effect ◽  
Memory Effect ◽  
Glass Fibers ◽  
Polymer Chains ◽  
Fiber Reinforced Polymers ◽  
Secondary Amines ◽  
Fiber Reinforced ◽  
One Pot ◽  
Reinforced Polymers

Fiber-reinforced polymers exhibiting the shape memory effect were created on the basis of a one-pot three-step chemical process. The first step is a Michael addition, which creates linear polymer chains. The second step is free radical photopolymerization, which increases the degree of curing of polymers. The last step is post-consolidation due to the reaction of previously formed secondary amines on the residual double bonds. By employing such chemistry to impregnate glass fibers, the final composite exhibits a convincing shape memory effect, as shown by cyclic thermomechanical tests.

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