CORRELATION DEPENDENCES OF THE BENDING STRENGTH OF POLYMER COMPOSITE MATERIALS MODIFIED IN A MICROWAVE ELECTROMAGNETIC FIELD ON THE MOISTURE CONTENT DURING EXPOSURE IN FULL-SCALE CONDITIONS

2021 ◽  
pp. 3-9
Author(s):  
I. V. Zlobina ◽  
I. S. Katsuba
Keyword(s):  
Electromagnetic Field ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Moisture Content ◽  
Bending Strength ◽  
Climatic Factors ◽  
Experimental Studies ◽  
Three Point Bending ◽  
Treated Carbon ◽  
Control Samples

Experimental studies of the influence of external climatic factors, taking into account exposure, on the change in the bending strength of control and microwave – treated carbon and fiberglass samples in the cured state were performed. An increase in the limit stresses of three – point bending of experimental carbon fiber samples compared to the control ones was found by 7…12 %, and fiberglassby 4…7 %. It is shown that with an increase in exposure to 14 months, the strength of control samples of carbon and fiberglass decreases by an average of 10 %. At the same time, the strength of the prototypes is reduced only by 4.4 %. With an increase in the moisture content of both control and experimental samples, a decrease in their strength is observed. In this case, the linear correlation is average (from– 0.44 to – 0.615). It is established that for experimental samples, the influence of the amount of absorbed moisture on the strength is manifested to a much lesser extent. For carbon fiber, the reduction is 16.6 %, for fiberglass – 12 %.

scholarly journals THE TREATMENT EFFECT IN A MICROWAVE ELECTROMAGNETIC FIELD TO CHANGE THE FLEXURAL STRENGTH OF STRUCTURAL ELEMENTS OF THE CURED CARBON-FIBER COMPOSITES UNDER THE INFLUENCE OF ENVIRONMENTAL FACTORS

2020 ◽  
pp. 20-22
Author(s):  
I. Zlobina ◽  
N. Bekrenev ◽  
I. Katsuba
Keyword(s):  
Electromagnetic Field ◽  
Carbon Fiber ◽  
Environmental Factors ◽  
Bending Strength ◽  
Climatic Factors ◽  
Fiber Composites ◽  
Carbon Fiber Composites ◽  
Structural Elements ◽  
Comparative Tests ◽  
Three Point Bending

The article describes the results of comparative tests for three-point bending of carbon fiber samples processed in a microwave electromagnetic field after being exposed to environmental factors for 3 months. It is shown that the influence of external climatic factors leads to a decrease in the bending strength of control and experimental samples by 3.7% and 1.4%, respectively. At the same time, the strength of the test samples increases by 8% in comparison with the control ones.

scholarly journals REDUCING THE INFLUENCE OF ENVIRONMENTAL FACTORS ON THE BENDING DEFORMATION OF CURED CARBON FIBER BY MICROWAVE PROCESSING

2021 ◽  
pp. 56-58
Author(s):  
I. V. Zlobina
Keyword(s):  
Electromagnetic Field ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Environmental Factors ◽  
Flux Density ◽  
Environmental Conditions ◽  
Climatic Factors ◽  
Transverse Load ◽  
Bending Deformation ◽  
Energy Flux Density

The article discusses the results of a study of bending deformation and creep under transverse load of cured polymer composite materials (PCM), which were located for 8 months in full-scale environmental conditions in Saratov. It was found that being under the influence of natural climatic factors for the specified time leads to an increase in the bending deformation of samples from 13,5 to 25,4%, depending on the load. Processing in a microwave electromagnetic field with a frequency of 2450 MHz with an energy flux density of (17-18) x10 mW / cm for 2 minutes reduces bending deformation by (9-18)%, and creep - up to 4 times.

THE INFLUENCE OF CLIMATIC FACTORS ON RESIDUAL STRESSES IN NANOMODIFIED CYANATE ESTER-BASED CFRP

2021 ◽  
pp. 104-112
Author(s):  
V.O. Startsev ◽  
◽  
E.V. Nikolaev ◽  
A.M. Vardanyan ◽  
A.A. Nechaev ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Residual Stresses ◽  
Bending Strength ◽  
Climatic Factors ◽  
Linear Thermal Expansion ◽  
Cold Climate ◽  
Cyanate Ester ◽  
Three Point Bending ◽  
Reinforced Plastic ◽  
Climatic Testing

The residual stresses in carbon fiber reinforced plastic (CFRP), based on VTkU-2.200 carbon fiber and VSC-14 cyanate ester resin, modified by nanoscale additives (astralen) were studied. Natural exposure was performed in a moderately cold climate. The influence of nanoadditives on mechanical and physical CFRP’s properties after 9 months of climatic testing was studied using the following properties: three-point bending strength, compression strength, coefficient of linear thermal expansion, glass transition temperature and residual stresses parameters. The increase of residual stresses after climatic testing was revealed.

Effect of Moisture Absorption on the Bending Strength of CFRP

2012 ◽  
Vol 450-451 ◽  
pp. 482-485 ◽  
Author(s):  
A Ying Zhang ◽  
Di Hong Li ◽  
Dong Xing Zhang
Keyword(s):  
Moisture Content ◽  
Composite Laminates ◽  
Immersion Time ◽  
Moisture Absorption ◽  
Bending Strength ◽  
Experimental Results ◽  
Bending Tests ◽  
Three Point Bending ◽  
Damage Propagation ◽  
Effect Of Moisture

The effects of moisture content on the bending strength of T300/914 composite laminates that immersed in water for 7 days and 14 days was discussed in this paper. The three-point bending tests were conducted on the composite laminates. Experimental results reveal that the moisture content in the laminates increased with immersion time and that moisture absorption accelerated damage propagation in the composite laminates. The bending strength of the unaged, aged specimens were characterized and analyzed. Compared to the unaged specimens, the bending strength of the composite laminates immersed for 7 and 14 days decreased by 6.62% and 16.98%, respectively. The results revealed that the bending strength of the aged specimens decreased with the increasing immersion time.

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.

IMPACT OF HIGH VOLTAGE ELECTRIC DISCHARGES ON THE CURED POLYMER COMPOSITE MATERIALS, MODIFIED IN A MICROWAVE ELECTROMAGNETIC FIELD

2020 ◽  
pp. 6-12
Author(s):  
I. V. Zlobina ◽  
A. A. Korotich
Keyword(s):  
Electromagnetic Field ◽  
Surface Layer ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Minimum Wage ◽  
Polymer Composite ◽  
High Voltage ◽  
Polymer Composite Materials ◽  
Structural Elements ◽  
The Impact

Due to the widespread use of carbon fiber-reinforced polymer composite materials (PCM) in the structural elements of aircraft with a distributed surface layer of lightning-proof coating (MFP) in the form of metal grids to reduce the risk of lightning strikes and the possibility of increasing their strength characteristics by processing in the microwave electromagnetic field, the need to study the impact of this method of processing on the resistance of PCM to high voltage electrical discharges. The studies of the impact of the discharge voltage 180…200 kV on samples of PCM with the minimum wage and no minimum wage. It is established that pretreatment of samples of the cured polymer composite MW in a microwave electromagnetic field energy flux density (17…18)104 µw/cm2 does not degrade their molniezaschita characteristics and contributes to reducing the size of the damaged area up to 1.5 times. Samples processed in the microwave electromagnetic field without MSP do not have delaminations and burns in contrast to the control ones. The obtained results indicate the possibility of strengthening treatment in the microwave electromagnetic field of structural elements of carbon fiber distributed in the surface layer of the MSP in the form of a metal grid.

Composite Materials with the Coating to Detect Barely Visible Impact Based on the Retroreflective Film

2021 ◽  
Vol 316 ◽  
pp. 949-954
Author(s):  
Olga Buslaeva ◽  
Sergei Sapozhnikov
Keyword(s):  
Composite Materials ◽  
Contact Pressure ◽  
Residual Strength ◽  
Experimental Studies ◽  
New Method ◽  
Composite Specimen ◽  
Dark Spot ◽  
Spot Diameter ◽  
Three Point Bending ◽  
Strength And Stiffness

A new method of indicating contact damage of composite materials, using a polymer retroreflective film (PRF) with micro-prisms, is proposed. Impact contact action leads to deformation of microprisms and with directed lighting allows seeing the place of impact in the form of a dark spot. In experimental studies, using STEF fibreglass as an example, the dependences of the spot diameter on the contact pressure up to 530 MPa were studied. An assessment of the residual strength and stiffness of a composite specimen-beam with a contact defect was obtained with three-point bending. It is shown that, during bending, the strength of STEF with contact defects decreases from 615 to 386 MPa. The data obtained allow to assess the danger of contact pressure by the known diameter of the dark spot on the PRF.

ASSESSMENT OF THE STABILITY OF CARBON FIBER TO THE ACTION OF TRANSVERSE LOADS TAKING INTO ACCOUNT TIME AND CLIMATE FACTORS

2021 ◽  
pp. 3-11
Author(s):  
I. V. Zlobina
Keyword(s):  
Electromagnetic Field ◽  
Carbon Fiber ◽  
Environmental Factors ◽  
Bending Strength ◽  
Negative Influence ◽  
Strengthening Effect ◽  
Functional Dependencies ◽  
Experimental Conditions ◽  
Term Operation ◽  
The Stability

The relevance of research in the development of physical methods for increasing the stability of products made of polymer composite materials (PCM) to the influence of environmental factors, taking into account its duration, is shown. The influence of exposure of carbon fiber samples on an epoxy matrix in the natural conditions of the climate zone of Saratov on the change in the limit stresses of three-point bending was studied. Comparative tests of samples premodified in a microwave electromagnetic field with a frequency of 2.45 GHz with an energy flux density (17…18)×104 µw/cm2 were performed. It is shown that the influence of environmental factors leads to a decrease in the limit stresses by (3,7…10,4) % depending on the exposure. Modification of carbon fiber in the cured state in the microwave electromagnetic field reduces the negative influence of the external environment by reducing the strength by (44.3…73) %. It was found that the strengthening effect of microwave modification increases with increasing exposure from 6 % to 11.5 % under the accepted experimental conditions, while the uniformity of the bending strength values in the batch increases significantly, which is manifested in a decrease in the coefficient of variation of limit stresses by (70.2…77.8) %. Functional dependencies in the form of 2nd-order polynomials are obtained, allowing with confidence (98…99) % predict the stability of products made of modified carbon fiber during long-term operation under the influence of environmental factors.

scholarly journals Polymer Composite Materials Fiber-Reinforced for the Reinforcement/Repair of Concrete Structures

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2058 ◽  
Author(s):  
George Soupionis ◽  
Pantelitsa Georgiou ◽  
Loukas Zoumpoulakis
Keyword(s):  
Mechanical Properties ◽  
Heat Treatment ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Epoxy Resin ◽  
Compression Strength ◽  
Artificial Aging ◽  
Bending Strength ◽  
Resin Matrix ◽  
Epoxy Resin Matrix

The present paper deals with the use of polymeric matrix composite materials reinforced with carbon fiber as concrete shear reinforcement materials. Accordingly, cement specimens were manufactured and coated with various types of carbon fabrics and epoxy resin in liquid and solid form (paste). Additionally, composite materials of epoxy resin matrix reinforced with carbon fiber fabrics were manufactured. In all the specimens, the mechanical properties were estimated; the cement samples coated with composite materials of epoxy resin matrix reinforced with carbon fiber fabrics were tested for compressive strength, while the other specimens were tested for shear and bending strength. The specimens were subjected to artificial aging through heat treatment for 8, 12 and 16 days. During the process of artificial aging, the temperature in the chamber reached the range of 65–75 °C. These composite materials exhibited high mechanical properties combined with adaptability. Both an external deterioration of the materials as well as a reduction in mechanical properties during their artificial aging heat treatment were observed. This was shown in the specimens that were not subjected to artificial aging, with an applied compression strength of 74 MPa, and after the artificial aging, there was a decrease of ~7%, with the compression strength being reduced to 68 MPa.

The Influence of Electromagnatic Field Microwave on Physical and Mechanical Characteristics of CFRP (Carbon Fiber Reinforced Polymer) Structural

2016 ◽  
Vol 870 ◽  
pp. 101-106 ◽  
Author(s):  
I.V. Zlobina ◽  
N.V. Bekrenev
Keyword(s):  
Electromagnetic Field ◽  
Composite Materials ◽  
Carbon Fiber ◽  
Power Density ◽  
Mechanical Characteristics ◽  
Peak Load ◽  
Laminated Composite ◽  
Scientific Publications ◽  
Laminated Composite Materials ◽  
Physical And Mechanical Characteristics

Based on the analysis of the development trends of modern transport equipment the prospect of structural composite materials usage, for example CFRP structural, is shown. In this regard, the expediency of conducting research to improve the strength characteristics of these materials is established. It is shown that, despite the large amount of scientific publications on the application of electro-technological methods and microwave technologies for modification of composite materials, applied to heterogeneous materials, such as carbon fiber, in Russia and abroad there are still some unsolved theoretical and practical questions. The studies of the effect of microwave electromagnetic field power density on different physical and mechanical characteristics of laminated composite materials in order to establish the opportunities to improve their performance, in particular their strength, were made. The example of carbon is used to show that the microwave electromagnetic field power density of 17.5 W/cm3 at a frequency of 2450 MHz exposure time of 2 minutes causes an increase in the shear strength of 38 – 40 % and an increase in the duration of the construction operation of carbon under the action of the peak load of 1.5 up to 4.5 times, wherein the change in flexural strength and modulus of elasticity was 2.6 %.

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