scholarly journals Reflection based Strain Sensing using Metamaterials

2020 ◽  
Vol 3 (1) ◽  
pp. 25-33
Author(s):  
Toni Dirk Großmann ◽  
Ricardo Decker ◽  
Steffen Kurth ◽  
Lothar Kroll ◽  
Thomas Otto
Keyword(s):  
Tensile Test ◽  
Structural Changes ◽  
Microwave Frequency ◽  
Test Machine ◽  
Strain Sensing ◽  
Lightweight Structures ◽  
Reflection Measurement ◽  
Glass Fibre Reinforced Plastic ◽  
Glass Fibre Reinforced ◽  
Resonator Arrays

Resonator arrays of periodicially arranged electromagnetic sub-wavelength resonators show a strong frequency filter behaviour which can be controlled by the geometry, size and arrangement of the resonators. The use of several resonator arrays and their integration into a polymer matrix allows the realisation of metamaterials with a specific resonance behaviour. The resonance behaviour can be influenced by material and structural changes enabling a passive sensor function. The considered sensor approach based on metamaterials is investigated to enable structural health monitoring of lightweight structures. In the present case, a double-layer Jerusalem cross (JC) resonator array (RA) is integrated into a glass fibre reinforced plastic (GFRP) to analyse the change of the resonance behaviour under load (strain) using a reflection measurement. The CST (Computer Simulation Technology) Microwave Studio was used to model the resonator array for operation in the microwave frequency range between 15 GHz and 35 GHz as well as for the numerical analysis of the resonance behaviour under load. The numerical results were validated by a tensile test using a tensile test machine (type TIRATEST 28100, Tira GmbH) and by a reflection measurement using two standard gain horn antennas (type Standard Gain Horn Series 862, ARRA Inc) and a vector network analyser (type ZVA50, Rohde&Schwarz). The reflection measurement shows a reflection minimum at 28.6 GHz which moves to higher frequencies under load of the GFRP laminate. With the shift of the minimum, the quality factor decreases and the dip widens. The investigation shows that it is possible to provide a GFRP laminate with a specific electromagnetic behaviour by integrating resonator arrays. It is also shown that the specific electromagnetic behaviour can be influenced by structural changes and thus opens up the possibility of monitoring the condition of lightweight structures.

scholarly journals Seawater effects on static loads and interlayer cracking performance for polyvinyl chloride foam-cored sandwich composites

2018 ◽  
Vol 10 (11) ◽  
pp. 168781401880734
Author(s):  
Jian He ◽  
Dongyuan Xie ◽  
Qichao Xue ◽  
Yangyang Zhan
Keyword(s):  
Energy Release ◽  
Polyvinyl Chloride ◽  
Glass Fibre ◽  
Critical Energy ◽  
Bending Tests ◽  
Rate Dependent ◽  
Reinforced Plastic ◽  
Glass Fibre Reinforced Plastic ◽  
Glass Fibre Reinforced ◽  
Cantilever Bending

The diffusion influence of seawater on the static and interlayer cracking properties of a polyvinyl chloride foam sandwich structure is investigated in this study. After soaking specimens in seawater for various durations, various comparison tests are performed to investigate the effects of seawater. Compression tests for H60 and H200 polyvinyl chloride foam specimens are conducted to study strength and modulus degradation, and the results show that immerging time and temperature have significant effects on polyvinyl chloride foam properties. Tensile tests for glass-fibre-reinforced plastic panels, four-point bending tests and double cantilever bending tests for polyvinyl chloride foam sandwich specimens are also performed. The results show that seawater immerging treatment has a noticeable influence on glass-fibre-reinforced plastic tensile properties and interlayer critical energy release rate values, but has almost no effect on bending properties of foam sandwich specimen. Furthermore, a rate-dependent phenomenon is observed in double cantilever bending tests, in which higher loading rate will lead to larger critical energy release values. Numerical simulation is also performed to illustrate the cracking process of double cantilever bending tests and shows a certain accuracy. The simulation also demonstrates that the viscoelasticity of foam material after immerging treatment results in the rate-dependent characterization of double cantilever bending tests.

Sandwich Structures for Naval Ships: Design and Experience

2000 ◽  
Author(s):  
Karl-Axel Olsson
Keyword(s):  
Lightweight Design ◽  
Weight Ratio ◽  
Point Of View ◽  
Economic Point ◽  
Plastic Foams ◽  
Reinforced Plastics ◽  
Sandwich Construction ◽  
Glass Fibre Reinforced Plastic ◽  
Glass Fibre Reinforced ◽  
Common Face

Abstract In Sweden we have a long experience with different types of vehicles and ships in sandwich construction, especially Navy ships such as minesweepers, mine-counter-measure-vessels and corvettes. GRP (Glass fibre Reinforced Plastic) and FRP (Fibre Reinforced Plastics) have been the most common face materials, but metallic materials such as Al-alloys, coated carbon steel and stainless steel have also been used. Core materials have usually been cellular plastic foams of cross-linked PVC (Polyvinyl-chloride), but also extruded PS (Poly-styrene), PUR (Poly-urethane), PEI (Poly-ether-imide) and PMI (Poly-methacryl-imide). Different continuous and discontinuous manufacturing processes have been used. Vacuum assisted infusion has been introduced recently, because it is a closed process, gives high fibre content and a good quality of the laminates. Sandwich design has mainly been used in the transportation area, where lightweight design is needed to give higher performance and load bearing capacity. The use of sandwich construction will give high stiffness- and strength-to weight ratio. This is usually not enough from an economic point of view to justify the introduction of sandwich construction, but other integrated functions must be considered, i.e. insulation, energy consumption, damping, fewer components, lower manufacturing costs, low maintenance, signature effects (military) etc.

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