Influence of Arctic seawater exposure on the flexural behavior of woven carbon/vinyl ester composites

2017 ◽  
Vol 21 (3) ◽  
pp. 1190-1208 ◽  
Author(s):  
R Garcia ◽  
AG Castellanos ◽  
P Prabhakar
Keyword(s):  
Flexural Strength ◽  
Vinyl Ester ◽  
Structural Damage ◽  
Failure Modes ◽  
Sea Water ◽  
Water Saturation ◽  
Flexural Modulus ◽  
Flexural Behavior ◽  
Failure Behavior ◽  
Material System

In this paper, the adverse effects of sea water environment and arctic temperatures on woven carbon fiber/vinyl ester composites are explored in the form of moisture uptake, impact on flexural modulus, strength, and structural damage. The research presented here attempts to relate failure modes to the flexural behavior of these composites exposed to three key environmental conditions: sea water, arctic temperature and combined sea water/arctic condition. Sea water saturation in general degrades the flexural strength up to ≈19.45%. Microstructures of dry and saturated samples are compared using scanning electron microscopy, where a saturated surface with distinctive hue for wet samples is observed as compared to a rough (parched) surface in the dry samples, implying large concentrations of sea water in a thin layer at the specimen boundaries. Arctic exposure and combined condition on these laminates increase the flexural strength by about 23.1% and 36.2%, respectively. However, they tend to shift the post peak behavior from progressive to brittle-type failure as compared to dry samples, which is attributed to matrix and fiber embrittlement in the material system caused by exposure to low temperature. Further, relatively large variations are observed in the flexural strength values of samples exposed to the combined condition (sea water saturated + arctic), which can be attributed to the freezing of sea water that was entrapped during sea water saturation. Variation in the quantity and location of sea water entrapped can alter the flexural strength significantly. Due to the aforementioned flexural responses and failure behavior observed in woven carbon/vinyl ester composites exposed to sea water arctic environment, special consideration is required while designing critical load bearing components in naval applications to avoid possible catastrophic structural failure.

scholarly journals A Pilot Study on the Flexural Properties of Vinyl Ester Composites Filled with Glass Powder

2010 ◽  
Vol 123-125 ◽  
pp. 3-6
Author(s):  
Harry Ku ◽  
Mohan Trada ◽  
Rezwanul Huq
Keyword(s):  
Flexural Strength ◽  
Vinyl Ester ◽  
Glass Powder ◽  
Filler Content ◽  
Flexural Modulus ◽  
Research Centre ◽  
Flexural Properties ◽  
Structural Applications ◽  
Flexural Tests ◽  
Sufficient Strength

Vinyl ester resin was filled with of glass powder with a view to increasing the flexural strength of the composites for civil and structural applications by a research Centre on composites, University of Southern Queensland (USQ). In order to reduce costs, the Centre wishes to fill as much glass powder as possible to the resin subject to maintaining sufficient strength of the composites in civil and structural applications. This project varies the percentage by weight of the glass powder in the composites, which are then subjected to flexural tests. The flexural strength and strain of the glass powder filled vinyl ester composites decreased with increasing filler content but the flexural modulus was highest at 20 w/t % of glass powder. Scanning Electron Microscope (SEM) was used to analyze the fractured samples and it was found that the fractured surfaces examined were correlated with the flexural properties.

scholarly journals Bending behavior of single hat-shaped composite T-joints under out-of-plane loading for lightweight automobile structures

2018 ◽  
Vol 37 (12) ◽  
pp. 808-823 ◽  
Author(s):  
Wenbin Hou ◽  
Xianzhe Xu ◽  
Haifeng Wang ◽  
Liyong Tong
Keyword(s):  
Failure Mode ◽  
Failure Modes ◽  
Flexural Modulus ◽  
Peak Load ◽  
Failure Criteria ◽  
Failure Behavior ◽  
Molding Process ◽  
T Joints ◽  
Final Failure ◽  
Out Of Plane

This paper presents an analytical, numerical, and experimental study on the failure behavior of single hat-shaped T-joints made of plain woven carbon fiber polymer (T300/epoxy 618) and subjected to out-of-plane bending. The T-joint is manufactured by vacuum bag molding process at room temperature. An analytical model is developed to analyze the experimental results and to establish the associated failure criteria. Two failure modes: (a) laminate buckling and (b) laminate crushing are considered, and the theoretical relationships for predicting the failure load associated with each of the two modes were developed. The experimental data correlate closely with the analytically predicted behavior, including failure mode and bending stiffness. In particular, both laminate buckling and laminate crushing are observed during the experiment with laminate crushing being the final failure mode, which can be considered to be the most important failure mode of the fabricated T-joint. In addition, numerical simulations based on the finite element method and the Hashin damage criteria also accurately predict the flexural modulus, the peak load, and failure locations of the T-joint obtained in the test.

scholarly journals FLEXURAL BEHAVIOR OF FRP BARS AFTER BEING EXPOSED TO ELEVATED TEMPERATURES

2021 ◽  
Vol 18 (1) ◽  
pp. 12-19
Author(s):  
Dr. Sherif El-Gamal ◽  
Abdulrahman M. Al-Fahdi ◽  
Mohammed Meddah ◽  
Abdullah Al-Saidy ◽  
Kazi Md Abu Sohel
Keyword(s):  
Flexural Strength ◽  
Elevated Temperatures ◽  
Flexural Modulus ◽  
Flexural Behavior ◽  
Test Results ◽  
Gfrp Bars ◽  
Reinforced Polymer ◽  
Significant Strength ◽  
Glass Frp ◽  
Frp Bars

This research study investigates the flexural behavior of fiber reinforced polymer (FRP) bars after being subjected to different levels of elevated temperatures (100, 200 and 300°C). Three types of glass FRP bars (ribbed, sand coated, and helically wrapped) and one type of carbon FRP bars (sand coated) were used in this study. Two testing scenarios were used: a) testing specimens immediately after heating and b) keeping specimens to cool down before testing. Test results showed that as the temperature increased the flexural strength and modulus of the tested FRP bars decreased. At temperatures higher than the glass transition temperature (Tg), significant flexural strength and modulus losses were recorded. Smaller diameter bars showed better residual flexural strength and modulus than larger diameter bars. The immediately tested bars showed significant strength and modulus losses compared to bars tested after cooling. Different types of GFRP bars showed comparable results. However, the helically wrapped bars showed the highest flexural strength losses (37 and 60%) while the sand coated bars showed the lowest losses (29 and 39%) after exposure to 200 and 300℃, respectively. The carbon FRP bars showed residual flexural strengths comparable to those recorded for the GFRP bars; however, they showed lower residual flexural modulus after being subjected to 200 and 300℃.

scholarly journals Flexural fatigue life of woven carbon/vinyl ester composites under sea water saturation

2020 ◽  
Vol 137 ◽  
pp. 105641 ◽  
Author(s):  
Pavana Prabhakar ◽  
Ricardo Garcia ◽  
Muhammad Ali Imam ◽  
Vinay Damodaran
Keyword(s):  
Fatigue Life ◽  
Vinyl Ester ◽  
Sea Water ◽  
Water Saturation ◽  
Flexural Fatigue

Application and Prospect of Bamboo/Steel Composite Material in Civil Engineering Structure

2010 ◽  
Vol 113-116 ◽  
pp. 989-993 ◽  
Author(s):  
Huang Ying Shen ◽  
Yu Shun Li ◽  
Zhen Wen Zhang ◽  
Tian Yuan Jiang ◽  
Jun Zhe Liu
Keyword(s):  
Composite Material ◽  
Failure Modes ◽  
Civil Engineering ◽  
Failure Process ◽  
Composite Beams ◽  
Flexural Behavior ◽  
Material System ◽  
Composite Slabs ◽  
Steel Composite ◽  
Cold Formed Steel

The objective of this research was to develop a new composite material/system in structural civil engineering. To use of mechanical properties of bamboo-based panel and cold-formed steel, this study composite two kind of materials above-mentioned together utilizing structural adhesives. The research developed various of bamboo/steel composite members, such as composite slabs, composite walls, composite beams and composite columns. And the paper emphasized mechanical performance of bamboo/steel composite slabs and composite beams. Experimental studies on flexural behavior of 6 composite slabs and 9 composite beams were carried out and the failure process, failure modes and failure mechanism were investigated. Experiment results indicates that the bamboo plywood and cold-formed steel can form an excellent composite cross-section; Load vs. mid-span deflection curves of composite slabs and composite beams show linear on serviceability limit state. The maximum ultimate strength of composite slabs and beams have reached 30.0 kN•m and 36.13 kN•m respectively. The study shows that bamboo-steel composite members have good prospects in building structures of China.

scholarly journals A Study on the Effect of Hollow Tubular Flange Sections on the Behavior of Cold-Formed Steel Built-Up Beams

2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Balaji Shanmugam ◽  
Manikandan Palanisamy ◽  
Paul O. Awoyera ◽  
Senthilnathan Chinnasamy ◽  
Mahalakshmi Subramaniam
Keyword(s):  
Flexural Strength ◽  
Failure Modes ◽  
Flexural Behavior ◽  
Test Results ◽  
Structural Members ◽  
Iron And Steel ◽  
Loading System ◽  
Failure Loads ◽  
Cold Formed Steel ◽  
The Web

This paper deals with a study conducted on flexural behavior of cold-formed steel built-up I-beams with hollow tubular flange sections. There were two types of test sections, namely, built-up sections that were assembled with either stiffened or unstiffened channels coupling back-to-back at the web and a hollow tubular rectangular flange at the top and bottom of the web to form built-up I-beam. The flexural behavior along with the strength and failure modes of the built-up sections was examined using the four-point loading system. Nonlinear finite element (FE) models were formulated and validated with the experimental test results. It was observed that the developed FE models had precisely predicted the behavior of built-up I-beams. Further, the verified FE models were used to conduct a detailed parametric study on cold-formed steel built-up beam sections with respect to thickness, depth, and yield stress of the material. The flexural strength of the beams was designed using the direct strength method as specified in American Iron and Steel Institute (AISI) for the design of cold-formed steel structural members and was compared with the experimental results and the failure loads predicted from FE models. Since the results were not conservative, a new customized design equation had been mooted and delineated in the study for determining the flexural strength of cold-formed steel built-up beams with hollow tubular flange sections.

scholarly journals Thermal and Mechanical Properties of Vinyl Ester Hybrid Composites with Carbon Black and Glass Reinforcement

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Geetanjali S. Guggari ◽  
S. Shivakumar ◽  
G. A. Manjunath ◽  
R. Nikhil ◽  
Alagar Karthick ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Flexural Strength ◽  
Carbon Black ◽  
Vinyl Ester ◽  
Flexural Modulus ◽  
Thermal And Mechanical Properties ◽  
Degradation Temperature

The objective of the work is to investigate both thermal and mechanical properties of vinyl ester/glass composites incorporated with different percentages of carbon black reinforcements through experimental approaches. Analysis of glass transition temperature, thermogravimetric analysis (TGA), degradation temperature, hardness, flexural strength, etc. is performed using differential scanning calorimeter, X-ray diffraction, tensile machine, and flexural machine, respectively. The scanning electron microscope was used for surface fracture studies. The degradation temperature reduces initially with the percentage of carbon black and then increases. Glass transition temperature increases with the percentage of carbon black while above 500°C temperature, the weight percentage of composite drops. The results also reveal that 4% of carbon with vinyl ester improved the tensile strength by 30%, hardness by 35%, flexural strength by 45%, flexural modulus by 66%, and interlaminate shear strength by 44% when compared with the other percentage of carbon black.

scholarly journals Environmental effects on mode II fracture toughness of unidirectional E-glass/vinyl ester laminated composites

2021 ◽  
Vol 28 (1) ◽  
pp. 382-393
Author(s):  
Mazaher Salamt-Talab ◽  
Fatemeh Delzendehrooy ◽  
Alireza Akhavan-Safar ◽  
Mahdi Safari ◽  
Hossein Bahrami-Manesh ◽  
...  
Keyword(s):  
Fracture Toughness ◽  
Sulfuric Acid ◽  
Vinyl Ester ◽  
Cohesive Zone Model ◽  
Flexural Modulus ◽  
Mode Ii ◽  
Zone Model ◽  
Sharp Drop ◽  
Mode Ii Fracture ◽  
Mode Ii Fracture Toughness

Abstract In this article, mode II fracture toughness ( G IIc {G}_{\text{IIc}} ) of unidirectional E-glass/vinyl ester composites subjected to sulfuric acid aging is studied at two different temperatures (25 and 90°C). Specimens were manufactured using the hand lay-up method with the [ 0 ] 20 {{[}0]}_{20} stacking sequence. To study the effects of environmental conditions, samples were exposed to 30 wt% sulfuric acid at room temperature (25°C) for 0, 1, 2, 4, and 8 weeks. Some samples were also placed in the same solution but at 90°C and for 3, 6, 9, and 12 days to determine the interlaminar fracture toughness at different aging conditions. Fracture tests were conducted using end notched flexure (ENF) specimens according to ASTM D7905. The results obtained at 25°C showed that mode II fracture toughness increases for the first 2 weeks of aging and then it decreases for the last 8 weeks. It was also found that the flexural modulus changes with the same trend. Based on the results of the specimens aged at 90°C, a sharp drop in fracture toughness and flexural modulus with a significant decrease in maximum load have been observed due to the aging. Finite element simulations were performed using the cohesive zone model (CZM) to predict the global response of the tested beams.

Effect of long-term moisture exposure on impact response of glass-reinforced vinylester

2021 ◽  
pp. 147509022199616
Author(s):  
Fatemeh Alizadeh ◽  
Navid Kharghani ◽  
Carlos Guedes Soares
Keyword(s):  
Water Uptake ◽  
Failure Modes ◽  
Sea Water ◽  
Composite Plates ◽  
Impact Response ◽  
Low Velocity Impact ◽  
Water Type ◽  
Interfacial Damage ◽  
Impact Properties ◽  
The Impact

Glass/Vinylester composite laminates are comprehensively characterised to assess its impact response behaviour under moisture exposure in marine structures. An instrumented drop weight impact machine is utilised to determine the impact responses of dry and immersed specimens in normal, salted and sea water. The specimens, which had three different thicknesses, were subjected to water exposure for a very long period of over 20 months before tested in a low-velocity impact experiment. Water uptake was measured primarily to study the degradation profiles of GRP laminates after being permeated by water. Matrix dissolution and interfacial damage observed on the laminates after prolonged moisture exposure while the absorption behaviour was found typically non-Fickian. The weight of the composite plates firstly increased because of water diffusion up to month 15 and then decreased due to matrix degradation. The specimens with 3, 6 and 9 mm thickness exhibited maximum water absorption corresponding to 2.6%, 0.7% and 0.5% weight gain, respectively. In general, the results indicated that water uptake and impact properties were affected by thickness and less by water type. Impact properties of prolonged immersed specimens reduced remarkably, and intense failure modes detected almost in all cases. The least sensitive to impact damage were wet specimens with 9 mm thickness as they indicated similar maximum load and absorbed energy for different impact energies.

scholarly journals Fatigue Resistance and Failure Behavior of Penetration and Non-Penetration Laser Welded Lap Joints

2021 ◽  
Vol 34 (1) ◽  
Author(s):  
Xiangzhong Guo ◽  
Wei Liu ◽  
Xiqing Li ◽  
Haowen Shi ◽  
Zhikun Song
Keyword(s):  
Fatigue Resistance ◽  
Failure Modes ◽  
Plate Thickness ◽  
High Stress ◽  
Lap Joints ◽  
Failure Behavior ◽  
Passenger Cars ◽  
Plate Fracture ◽  
The Difference ◽  
Railway Passenger

AbstractPenetration and non-penetration lap laser welding is the joining method for assembling side facade panels of railway passenger cars, while their fatigue performances and the difference between them are not completely understood. In this study, the fatigue resistance and failure behavior of penetration 1.5+0.8-P and non-penetration 0.8+1.5-N laser welded lap joints prepared with 0.8 mm and 1.5 mm cold-rolled 301L plates were investigated. The weld beads showed a solidification microstructure of primary ferrite with good thermal cracking resistance, and their hardness was lower than that of the plates. The 1.5+0.8-P joint exhibited better fatigue resistance to low stress amplitudes, whereas the 0.8+1.5-N joint showed greater resistance to high stress amplitudes. The failure modes of 0.8+1.5-N and 1.5+0.8-P joints were 1.5 mm and 0.8 mm lower lap plate fracture, respectively, and the primary cracks were initiated at welding fusion lines on the lap surface. There were long plastic ribs on the penetration plate fracture, but not on the non-penetration plate fracture. The fatigue resistance stresses in the crack initiation area of the penetration and non-penetration plates calculated based on the mean fatigue limits are 408 MPa and 326 MPa, respectively, which can be used as reference stress for the fatigue design of the laser welded structures. The main reason for the difference in fatigue performance between the two laser welded joints was that the asymmetrical heating in the non-penetration plate thickness resulted in higher residual stress near the welding fusion line.

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