STUDYING THE EFFECT OF THE SCHEME OF EXPOSURE TO MICROWAVE ELECTROMAGNETIC FIELDS ON THE HARDNESS OF THE CURED CARBON FIBER-REINFORCED PLASTIC WITH LIGHTNING-PROTECTION GRID APPLIED ON ITS SURFACE

2020 ◽  
Vol 0 (4) ◽  
pp. 12-18
Author(s):  
I.V. ZLOBINA ◽  
Keyword(s):  
Electromagnetic Field ◽  
Carbon Fiber ◽  
Wind Turbines ◽  
Field Research ◽  
Carbon Plastic ◽  
Lightning Protection ◽  
Fiber Reinforced ◽  
Short Term ◽  
Short Term Exposure ◽  
Carbon Fiber Reinforced

Currently, the use of fiber-reinforced polymer composite materials (PCM), in particular, carbon plastic and fiberglass, is much promising in manufacturing structural elements of aircrafts and wind turbines. In order to increase the resistance of these materials to static electricity and lightning strikes when passing storm fronts, the structure of the PCM includes various lightning protection coatings (LPC). The most common LPC are in the form of copper grids. The fin assembly and planes of aircrafts and also large-sized blades of wind turbines are exposed to cyclic high-amplitude and low-frequency bending loads as well as vibrations. Collisions with solid objects are quite possible. Thus, hardness is one of the key characteristics of PCM that determines their performance properties. Strength and endurance of PCM components can be increased by short-term exposure to a microwave electromagnetic field. The presence of a built-in metallic structure brings additional uncertainty in the tolerance to operating loads by anisotropic PCM, as well as in the process of their interaction with an ultrahigh frequency electromagnetic field. Research was performed on the hardness of carbon fiber-reinforced plastics with built-in LPC using various exposure schemes to a microwave electromagnetic field: from the side of the LPC, from the side opposite to the LPC and sequential processing from both sides. It was found that short-term processing in a microwave electromagnetic field with energy flux density of (17-18)×104mW/cm2 did not lead to any change in the initial hardness of the surface of the samples. However, the uniformity of hardness distribution on the surface of the samples in- creased by 35.8-70%, thus ensuring a more adequate tolerance to loads of different nature. The obtained results can be used in the development of finishing technologies to post-process PCM components and improve the latter’s stability to dynamic loading.

THE EFFECT OF MICROWAVE ELECTROMAGNETIC FIELD ON THE HARDNESS OF CARBON FIBER-REINFORCED PLASTIC WITH LIGHTNING PROTECTION GRID DISTRIBUTED IN THE SURFACE LAYER

2020 ◽  
Vol 0 (4) ◽  
pp. 5-11
Author(s):  
I.V. ZLOBINA ◽  
Keyword(s):  
Electromagnetic Field ◽  
Surface Layer ◽  
Carbon Fiber ◽  
Surface Hardness ◽  
Lightning Protection ◽  
Fiber Reinforced ◽  
Short Term Exposure ◽  
Structural Density ◽  
Carbon Fiber Reinforced ◽  
The Impact

Based on the analysis of scientific and technical literature and trends in the development of multi-purpose aircrafts, we can see a steady extension of the use of polymer composite materials (PCM) in their design. The importance of lightning protection is noted for aircrafts, the skin of which consists mainly of the PCM, and it is shown that one of the common means is a lightning protection coating (LPC) in the form of a metal grid distributed in the PCM surface layer. Anisotropy of PCM properties and reduced fracture toughness in comparison with metals necessitates the improvement of PCM compositions and technologies of their formation as well as the development of methods for final hardening treatment in the cured state, which can be effectively performed under the effect of microwave electromagnetic field. Consideration is given to the influence of a short-term exposure to microwave electromagnetic field on the stability of carbon fiber-reinforced PCM with PLC against impact loads, as well as on the surface hardness. Our findings show a decrease in the damaged area of the impact zone by 40-60% and the absence of microcracking and delamination as well as an increase in hardness by 7.8%. Particular emphasis is placed on a 3-fold decrease in the spread of hardness values after the microwave exposure, this indicating a significant increase in the uniformity of this important characteristic for the component performance. As a mechanism of these modifications, it is proposed to reduce the pore size and porosity and to increase the number of points of contact interaction between matrix and fiber agglomerates that ensure an increase in the structural density.

Change of Rigidity of PCM Modified in an Ultrahigh Frequencies Electromagnetic Field under the Action of External Factors

2021 ◽  
Vol 1031 ◽  
pp. 234-241
Author(s):  
Irina V. Zlobina
Keyword(s):  
Electromagnetic Field ◽  
Elastic Modulus ◽  
Carbon Fiber ◽  
Experimental Studies ◽  
External Environment ◽  
Carbon Fiber Reinforced Plastic ◽  
Fiber Reinforced ◽  
Fiber Reinforced Plastic ◽  
Reinforced Plastic ◽  
Carbon Fiber Reinforced

Experimental studies of bending deformation of carbon - and fiberglass samples after 8-month exposure in full-scale conditions were performed and the modulus of transverse elasticity was determined. It was found that the influence of the external environment on fiberglass samples is more significant. For carbon fiber, there was an average decrease of 7.1%, and for fiberglass-by 14%. Modification of samples in ultrahigh frequencies (UHF) electromagnetic field reduces the negative influence of the environment: the values of the transverse elastic modulus of carbon fiber and fiberglass samples are reduced by 5% and 11%, respectively. It is shown that the UHF electromagnetic field in rational modes can increase the modulus of transverse elasticity of carbon fiber by (27-30)%, fiberglass – by (20.8-25.6)% with a significant increase in the uniformity of this parameter. Experimental studies of the bending deformation of carbon-and fiberglass specimens after 8-month exposure in natural conditions have been carried out, and the shear elastic modulus has been determined. It has been established that the influence of the external environment on fiberglass samples is more significant. For carbon fiber reinforced plastic, a decrease was noted on average by 7.1%, for fiberglass - by 14%. Modification of samples in a microwave electromagnetic field helps to reduce the negative influence of the external environment: the values ​​of the shear modulus of the prototypes of carbon fiber reinforced plastic and fiberglass are reduced by 5% and 11%, respectively. It is shown that the microwave electromagnetic field in rational modes allows increasing the transverse elastic modulus of carbon fiber reinforced plastic by (27-30)%, fiberglass - by (20.8-25.6)% with a significant increase in the uniformity of this parameter.

Effects of high pressure on the crystallization of carbon fiber reinforced polyetheretherketone (CF/PEEK) laminate composites

1990 ◽  
Vol 48 (4) ◽  
pp. 876-877
Author(s):  
Hong-Ming Lin ◽  
C. H. Liu ◽  
R. F. Lee
Keyword(s):  
High Pressure ◽  
Carbon Fiber ◽  
Sample Surface ◽  
High Yield ◽  
Fiber Reinforced ◽  
Laminate Composites ◽  
Peek Composite ◽  
Continuous Carbon Fiber ◽  
Carbon Fiber Reinforced

Polyetheretherketone (PEEK) is a crystallizable thermoplastic used as composite matrix materials in application which requires high yield stress, high toughness, long term high temperature service, and resistance to solvent and radiation. There have been several reports on the crystallization behavior of neat PEEK and of CF/PEEK composite. Other reports discussed the effects of crystallization on the mechanical properties of PEEK and CF/PEEK composites. However, these reports were all concerned with the crystallization or melting processes at or close to atmospheric pressure. Thus, the effects of high pressure on the crystallization of CF/PEEK will be examined in this study.The continuous carbon fiber reinforced PEEK (CF/PEEK) laminate composite with 68 wt.% of fibers was obtained from Imperial Chemical Industry (ICI). For the high pressure experiments, HIP was used to keep these samples under 1000, 1500 or 2000 atm. Then the samples were slowly cooled from 420 °C to 60 °C in the cooling rate about 1 - 2 degree per minute to induce high pressure crystallization. After the high pressure treatment, the samples were scanned in regular DSC to study the crystallinity and the melting temperature. Following the regular polishing, etching, and gold coating of the sample surface, the scanning electron microscope (SEM) was used to image the microstructure of the crystals. Also the samples about 25mmx5mmx3mm were prepared for the 3-point bending tests.

Restoring Initially Cracked Reinforced Concrete Beams utilizing Carbon Fiber Reinforced Polymer Strips

2019 ◽  
Vol 7 (1) ◽  
pp. 30-34
Author(s):  
A. Ajwad ◽  
U. Ilyas ◽  
N. Khadim ◽  
Abdullah ◽  
M.U. Rashid ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Concrete Beams ◽  
Fiber Reinforced Polymer ◽  
Carbon Fiber Reinforced Polymer ◽  
Fiber Reinforced ◽  
Loading Test ◽  
Control Beam ◽  
Reinforced Polymer ◽  
Cfrp Sheet ◽  
Carbon Fiber Reinforced

Carbon fiber reinforced polymer (CFRP) strips are widely used all over the globe as a repair and strengthening material for concrete elements. This paper looks at comparison of numerous methods to rehabilitate concrete beams with the use of CFRP sheet strips. This research work consists of 4 under-reinforced, properly cured RCC beams under two point loading test. One beam was loaded till failure, which was considered the control beam for comparison. Other 3 beams were load till the appearance of initial crack, which normally occurred at third-quarters of failure load and then repaired with different ratios and design of CFRP sheet strips. Afterwards, the repaired beams were loaded again till failure and the results were compared with control beam. Deflections and ultimate load were noted for all concrete beams. It was found out the use of CFRP sheet strips did increase the maximum load bearing capacity of cracked beams, although their behavior was more brittle as compared with control beam.

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