12,962 research outputs found
Empirical study of the impact energy absorption enhancement of kevlar through STF impregnation
No full textImpact Monitoring of Composite Wing Using Error Outlier Assessment Based Impact Localization Algorithm and FBG Sensors
No full textLow-Velocity Impact Monitoring of Aircraft Wing Structure Using Novel Error Outlier Impact Localization Algorithm
No full textUnveiling the Mechanisms of Improved Stability and Performance via Tetraalkyl-Type Ionic Liquids: Suppression of Organic Solid Electrolyte Interface Formation in Lithium-Mediated Nitrogen Reduction
No full textLithium-mediated nitrogen reduction reaction (Li-NRR) has emerged as a promising alternative to the conventional Haber-Bosch process, enabling modular and decentralized ammonia production. A critical component influencing Li-NRR efficiency is the solid-electrolyte interface (SEI), which modulates reactant transport and controls reaction pathways at the electrode surface. Recently, tetraalkyl organic salts have attracted attention as advantageous proton carriers due to their superior electrochemical stability and structural versatility, offering avenues for optimized SEI control. In this study, we utilized in situ attenuated total reflectance-surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) to dynamically investigate SEI formation during Li-NRR, comparing ethanol (EtOH) and tetrabutylammonium chloride (TBACl) as proton carriers. Distinct differences in SEI composition and morphology were observed, with EtOH promoting rapid and extensive formation of irregular organic SEI layers, predominantly lithium ethoxide (LiOEt) and lithium carbonate (Li2CO3). Conversely, TBACl conditions suppressed organic SEI growth through stable electric double layer formation by TBA+ ions, significantly limiting free THF molecules near the electrode surface and, thus, reducing unwanted organic SEI components. Our results highlight the critical role of proton carrier selection in controlling SEI formation, emphasizing TBACl's advantages for enhancing Li-NRR stability and efficiency.
Investigation of LEO environment exposure monitoring potential using embedded FBG sensors
No full textComposite materials provide many advantages over conventional materials including metals, especially for space applications. However, composites have failure modes that are complex and difficult to identify, and various cracks and delamination are predominantly difficult to detect visually. In this regard, an effective method of monitoring the integrity of composite materials and structures exposed to hazardous space environments is necessary to ensure the long-term reliability of composite materials in aerospace applications. FBG sensors are advantageous for space applications due to their immunity to various environments. In this study, FBG sensors were used to investigate LEO environment exposure monitoring of CFRP
Investigation of Multi-layer Embedded FBG Sensor Response under Simulated LEO Environment Exposure
No full textEffects of the Bonding Length on the Reflected Spectra and Strain Measurement of the Surface Bonded Fiber Bragg Grating Sensor
No full textLow velocity impact monitoring of composite wing structure under simulated wing loading condition using fiber Bragg grating sensors
No full textA low velocity impact onto a composite structure can result in the occurrence of barely visible impact damage (BVID), which is difficult to detect. Therefore, the low velocity impact monitoring of composite structures is highly desirable for impact detection and localization. In this paper, low velocity impacts on a composite wing under a simulated wing loading condition were monitored using six multiplexed fiber Bragg grating (FBG) sensors and localized using error outlier based impact localization algorithm. The impact response signals from the FBG sensors were sampled at a rate of 100 kHz using high-speed interrogator. The impacts were localized with an average error of 18.4 mm
Signal characteristics of the surface bonded fiber Bragg grating sensors by bonding length under different load types
No full textThe surface-bonding method of the fiber Bragg grating(FBG) sensor is easier to handle than embedding method. However surface bonded FBG sensors have the limitation of the signal characteristics being affected by the bonding layer. In this study, the effects of the bonding length on the surface installed FBG sensor signal characteristics under various load types were empirically investigated. To evaluate the stability of the signal characteristics of the FBG sensors, the strain transfer rate and the multiple peaks ratio of the reflected spectrum were calculated and compared. From the experimental results, the strain transfer ratio and multiple peaks ratio varied because of the different strain gradients formed depending on the applied load type. Therefore, it was found that the effective bonding length for respective load types need to be determined to get a stable signal from the surface bonded FBG sensors
Effect of tubing material on conventional and thin FBG sensor for embedded environment impact monitoring of CFRP composites
No full textApplications of composite materials in aerospace structures is increasing due to the outstanding properties, however, monitoring such composite structures exposed to harsh environments is still a posing issue. Low Earth orbit space structures are exposed to property degradation and damage from high-degree vacuum, ultraviolet radiation, thermal cycling, and atomic oxygen attack which are detrimental to composite materials. In this study, FBG sensors for embedding in CFRP composite plates in different thickness locations to provide health and damage monitoring of the material exposed to such environments regarding the overall health of the material with a focus on the exposed surface are explored in comparison to conventional FBG sensors
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