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.

Fiberglass: Lateral Loads from Climatic and Temporary Factors

2021 ◽  
Vol 1031 ◽  
pp. 88-96
Author(s):  
Irina V. Zlobina
Keyword(s):  
Electromagnetic Field ◽  
Environmental Factors ◽  
Bending Strength ◽  
Lateral Loads ◽  
Functional Dependencies ◽  
Initial State ◽  
Term Operation ◽  
The Stability ◽  
Control Samples

The influence of modification of fiberglass in the cured state in the microwave electromagnetic field on the value of the limit stresses is significantly manifested when testing samples in the initial state. The increase in limit voltages is on average 7%. Tests of modified samples after exposure in full-scale conditions showed a decrease in the effect with an increase in the exposure time from 6% for exposure of 3 months to 3% for exposure of 8 months. This significantly increases the uniformity of the bending strength values in the batch, which is manifested in a decrease in the coefficient of variation of limit stresses relative to the control samples by 33%. Functional dependencies in the form of 2nd-order polynomials are obtained, which allow predicting the stability of products made of modified fiberglass for long-term operation under the influence of environmental factors with a confidence of up to 98%.

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.

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 EFFECT OF THE MICROWAVE ELECTROMAGNETIC FIELD ON DEFECT FORMATION UNDER THE INFLUENCE OF ENVIRONMENTAL FACTORS IN CURED CARBON FIBER

2021 ◽  
pp. 34-36
Author(s):  
I. V. Zlobina
Keyword(s):  
Electromagnetic Field ◽  
Carbon Fiber ◽  
Environmental Factors ◽  
Defect Formation ◽  
Strength Characteristics ◽  
Interlaminar Shear ◽  
Kinetics Of ◽  
Maximum Stresses

The article presents the results of researches of influence of modification of the cured CFRP in a microwave electromagnetic field to change the kinetics of defect formation and strength characteristics under the influence of environmental factors, showed the increase of the maximum stresses interlaminar shear specimens after exposure in situ by 16,5% compared with the control.

Influence of Extrusion Temperature on Property of Graphene Oxide-carbon Fiber Hybrid Reinforced Resin Matrix Composites

2021 ◽  
Author(s):  
Yuqin Ma ◽  
Fei Li ◽  
Wei Xu ◽  
Long Yan ◽  
Haiyin Guo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Graphene Oxide ◽  
Carbon Fiber ◽  
Performance Test ◽  
Bending Strength ◽  
Extrusion Temperature ◽  
Resin Matrix ◽  
Strengthening Effect ◽  
Molding Process ◽  
The Matrix

Abstract The graphene oxide-carbon fiber hybrid reinforced resin matrix (GO-CF/EP) composites were prepared by vacuum infiltration hot-pressing molding process. The effects of extrusion temperature on the microstructure, fracture mechanism and mechanical properties of GO-CF/EP composites were investigated by setting different extrusion temperatures. In the experiments, the extrusion temperature was controlled as 30℃, 40℃, 50℃, 60℃ and 70℃ respectively. It was found that the best mechanical property of composites and infiltration effect of matrix in the fiber gap were obtained at the temperature of 50℃. The bending strength of the material reached 977 MPa through the performance test. The results showed the matrix viscosity was high and the fluidity was poor when the extrusion temperature was low. Poor penetration of the matrix resulted in a large number of fibers failing to bond together. The stress was difficult to transfer to other fibers through the matrix and the strengthening effect of graphene oxide (GO) was weak when the composite was subjected to external force. This phenomenon led to poor mechanical properties of composites. Under the condition of higher temperature, the flow speed of the matrix and the curing speed of composites could be improved. As a result, some of the matrix was solidified in advance while being pressed out, which led to cracks and other defects in the process of loading and affects the mechanical properties of the composites. However, the mechanical properties of the composites with higher extrusion temperature were better than those with lower extrusion temperature due to the existence of graphene oxide in the fiber gap.

Primal Study on Mechanical Properties of Phosphate Based Geopolymer

2017 ◽  
Vol 726 ◽  
pp. 490-494
Author(s):  
Zhu Ding ◽  
Can Lu ◽  
Peng Cui ◽  
Wei Ting Xu
Keyword(s):  
Mechanical Properties ◽  
Carbon Fiber ◽  
Concrete Beam ◽  
Bending Strength ◽  
Fiber Composites ◽  
Bottom Surface ◽  
Strengthening Effect ◽  
Test Results ◽  
Inorganic Matrix ◽  
Strength And Ductility

A novel inorganic matrix for fiber composites prepared from phosphate based geopolymer (PBG) was synthesized at ambient temperature. The mechanical property of PBG paste and the carbon fiber reinforced PBG composite was determined. Test results showed that the compressive strength of PBG paste at the age of 28 days was found to be 33.67 MPa. Moreover, the carbon fiber sheets enhanced the bending strength and ductility of PBG paste by up to 1300% and 307% respectively. Finally, the strengthening effect of this new composite on concrete beam was evaluated. The carbon fiber PBG composite applied on the bottom surface of concrete beam increased the bending strength by 183%. Therefore, it is concluded that PBG can be a promising inorganic matrix that can be used to strengthen deteriorated concrete structures.

Effect of Improved ThO2 Particle Dispersion in Nickel on High-Temperature Strength

1970 ◽  
Vol 28 ◽  
pp. 444-445
Author(s):  
E. R. Kimmel ◽  
H. L. Anthony ◽  
W. Scheithauer
Keyword(s):  
High Temperature ◽  
Metal Matrix ◽  
Oxide Particle ◽  
Oxide Phase ◽  
Dislocation Motion ◽  
Particle Dispersion ◽  
High Temperature Strength ◽  
Strengthening Effect ◽  
Oxide Particles ◽  
The Stability

The strengthening effect at high temperature produced by a dispersed oxide phase in a metal matrix is seemingly dependent on at least two major contributors: oxide particle size and spatial distribution, and stability of the worked microstructure. These two are strongly interrelated. The stability of the microstructure is produced by polygonization of the worked structure forming low angle cell boundaries which become anchored by the dispersed oxide particles. The effect of the particles on strength is therefore twofold, in that they stabilize the worked microstructure and also hinder dislocation motion during loading.

Applicability of Instability Index for In vitro Protein Stability Prediction

2019 ◽  
Vol 26 (5) ◽  
pp. 339-347 ◽  
Author(s):  
Dilani G. Gamage ◽  
Ajith Gunaratne ◽  
Gopal R. Periyannan ◽  
Timothy G. Russell
Keyword(s):  
Protein Stability ◽  
Caulobacter Crescentus ◽  
Effect Of Temperature ◽  
Instability Index ◽  
Dipeptide Composition ◽  
Experimental Conditions ◽  
The Stability ◽  
Vitro Protein

Background: The dipeptide composition-based Instability Index (II) is one of the protein primary structure-dependent methods available for in vivo protein stability predictions. As per this method, proteins with II value below 40 are stable proteins. Intracellular protein stability principles guided the original development of the II method. However, the use of the II method for in vitro protein stability predictions raises questions about the validity of applying the II method under experimental conditions that are different from the in vivo setting. Objective: The aim of this study is to experimentally test the validity of the use of II as an in vitro protein stability predictor. Methods: A representative protein CCM (CCM - Caulobacter crescentus metalloprotein) that rapidly degrades under in vitro conditions was used to probe the dipeptide sequence-dependent degradation properties of CCM by generating CCM mutants to represent stable and unstable II values. A comparative degradation analysis was carried out under in vitro conditions using wildtype CCM, CCM mutants and two other candidate proteins: metallo-β-lactamase L1 and α -S1- casein representing stable, borderline stable/unstable, and unstable proteins as per the II predictions. The effect of temperature and a protein stabilizing agent on CCM degradation was also tested. Results: Data support the dipeptide composition-dependent protein stability/instability in wt-CCM and mutants as predicted by the II method under in vitro conditions. However, the II failed to accurately represent the stability of other tested proteins. Data indicate the influence of protein environmental factors on the autoproteolysis of proteins. Conclusion: Broader application of the II method for the prediction of protein stability under in vitro conditions is questionable as the stability of the protein may be dependent not only on the intrinsic nature of the protein but also on the conditions of the protein milieu.

scholarly journals Effect of Organo-Modified Montmorillonite Nanoclay on Mechanical, Thermo-Mechanical, and Thermal Properties of Carbon Fiber-Reinforced Phenolic Composites

Polymers ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 754
Author(s):  
Jantrawan Pumchusak ◽  
Nonthawat Thajina ◽  
Watcharakorn Keawsujai ◽  
Pattarakamon Chaiwan
Keyword(s):  
Thermal Properties ◽  
Carbon Fiber ◽  
Bending Strength ◽  
Mechanical And Thermal Properties ◽  
Fiber Reinforced ◽  
Heat Resistant ◽  
Degradation Temperature ◽  
Modified Montmorillonite ◽  
Carbon Fiber Reinforced ◽  
Montmorillonite Nanoclay

This work aims to explore the effect of organo-modified montmorillonite nanoclay (O-MMT) on the mechanical, thermo-mechanical, and thermal properties of carbon fiber-reinforced phenolic composites (CFRP). CFRP at variable O-MMT contents (from 0 to 2.5 wt%) were prepared. The addition of 1.5 wt% O-MMT was found to give the heat resistant polymer composite optimum properties. Compared to the CFRP, the CFRP with 1.5 wt% O-MMT provided a higher tensile strength of 64 MPa (+20%), higher impact strength of 49 kJ/m2 (+51%), but a little lower bending strength of 162 MPa (−1%). The composite showed a 64% higher storage modulus at 30 °C of 6.4 GPa. It also could reserve its high modulus up to 145 °C. Moreover, it had a higher heat deflection temperature of 152 °C (+1%) and a higher thermal degradation temperature of 630 °C. This composite could maintain its mechanical properties at high temperature and was a good candidate for heat resistant material.

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