Fatigue Behavior of VARTM Manufactured Biaxial Braided Composites

2003 ◽  
Author(s):  
Jitendra S. Tate ◽  
Ajit D. Kelkar
Keyword(s):  
Fatigue Behavior ◽  
Low Cost ◽  
Impact Resistance ◽  
Fatigue Loading ◽  
High Volume ◽  
Manufacturing Cost ◽  
Braided Composites ◽  
Structural Applications ◽  
Potential Benefits ◽  
Transportation Applications

Braided composites have good properties in mutually orthogonal directions, more balanced properties than traditional tape laminates, and have potentially better fatigue and impact resistance due to the interlacing. Another benefit is reduced manufacturing cost by reducing part count. Because of these potential benefits braided composites are being considered for various applications ranging from primary/secondary structures for aerospace structures [1]. These material systems are gaining popularity, in particular for the small business jets, where FAA requires taken off weights of 12,500 lb. or less. The new process, Vacuum Assisted Resin Transfer Molding (VARTM), is low cost, affordable and suitable for high volume manufacturing environment. Recently the aircraft industry has been successful in maufacturing wing flaps, using carbon fiber braids and epoxy resin and the VARTM process. To utilize these VARTM manufactured braided materials to the fullest advantage (and hence to avoid underutilization), it is necessary to understand their behavior under different loading and environmental conditions. This will reduce uncertainty and hence reduce the factor of safety in the design. Any typical structural member made of composite material is subjected to different types of loading such as static, impact, cyclic causing fatigue, and environmental effects such as change in temperature and exposure to moisture and other corrosives. It is well known that cyclic loading reduces the strength of a material and its useful life or, the fatigue strength of a material is lower than its static strength. This is true of all materials—metals, plastics, composite materials, etc. In structural applications, fatigue loading is unavoidable especially in aerospace and ground transportation applications. This research addresses the tensiontension fatigue behavior of biaxial braided composites.

Performance Evaluation of Notched Biaxial Braided Composites

2004 ◽  
Author(s):  
Jitendra S. Tate ◽  
Ajit D. Kelkar ◽  
Ronnie Bolick
Keyword(s):  
Composite Structures ◽  
Low Cost ◽  
Impact Resistance ◽  
High Volume ◽  
Manufacturing Cost ◽  
Braided Composites ◽  
Static Tensile Loading ◽  
New Process ◽  
Static Tensile ◽  
Potential Benefits

Braided composites have good properties in mutually orthogonal directions, more balanced properties than traditional tape laminates, and have potentially better fatigue and impact resistance due to the interlacing. Another benefit is reduced manufacturing cost by reducing part count. Because of these potential benefits braided composites are being considered for various applications ranging from primary/secondary structures for aerospace structures [1]. These material systems are gaining popularity, in particular for the small business jets, where FAA requires take off weights of 12,500 lb. or less. The new process, Vacuum Assisted Resin Transfer Molding (VARTM), is low cost, affordable and suitable for high volume manufacturing environment. Recently the aircraft industry has been successful in manufacturing wing flaps, using carbon fiber braids and epoxy resin and the VARTM process. To utilize these VARTM manufactured braided materials to the fullest advantage (and hence to avoid underutilization), it is necessary to understand their behavior under different loading and environmental conditions. This will reduce uncertainty and hence reduce the factor of safety in the design. It is well known fact that the strength of the composite structure reduces because of discontinuities and abrupt change in the cross-section. Accurate knowledge of strength and failure mechanism of notched and unnotched composites is very important for design of composite structures. This research addresses the behavior of notched braided composites under static tensile loading.

Comparative Study of S2 Glass Plain and Twill Woven Composites Under Fatigue Loading

2000 ◽  
Author(s):  
Ajit D. Kelkar ◽  
Sunil S. Shenoy
Keyword(s):  
Fatigue Behavior ◽  
Low Cost ◽  
Impact Resistance ◽  
Fatigue Loading ◽  
High Volume ◽  
Fatigue Tests ◽  
Woven Composites ◽  
Woven Composite ◽  
Resin Infusion ◽  
Structural Applications

Abstract Woven composites have good properties in mutually orthogonal directions, more balanced properties than unidirectional laminates and have better impact resistance. The use of these composites for primary structural applications in place of conventional laminated composites has been increased considerably in the recent years. They are being manufactured by using new processes such as Resin Infusion (VARIM) and Resin Transfer Molding (RTM). These new processes are low cost, affordable and suitable for high volume manufacturing environment. One of the popular plain woven composites is fabricated using S2-Glass and SC-15 resin system components by using Resin Infusion (VARIM) process. These woven composites are being evaluated for Integral Armor applications. These components are expected to be under fatigue loading. To assess the feasibility of this material manufactured through Resin Infusion (VARIM), it is very important to understand the fatigue behavior of these composite materials. The present study provides comparison of the performance evaluation of plain and twill woven composite material for Integral Armor applications. Tension-Compression (R = −1) fatigue experiments were performed. All the fatigue tests are performed at 1 Hz frequency. S-N diagram and stiffness degradation over the fatigue life of the specimens were obtained.

Flexural Behavior of Biaxial Braided Composites

Materials ◽  
2005 ◽  
Author(s):  
Jitendra S. Tate ◽  
Ajit D. Kelkar
Keyword(s):  
Low Cost ◽  
Impact Resistance ◽  
Three Dimensional ◽  
Fatigue Loading ◽  
Woven Fabrics ◽  
Flexural Behavior ◽  
Braided Composites ◽  
Fiber Volume ◽  
Fiber Placement ◽  
Complex Components

Braided composites have more balanced properties than traditional tape laminates, and have potentially better fatigue and impact resistance due to the interlacing. The natural conformability of biaxial braided tubes makes it the ideal preform for three-dimensional complex components. Braid tube fits on complex components with ease just like pulling socks on feet. Thus cutting, stitching, or manipulation of fiber placement is not needed, as in the use of woven fabrics. Biaxial braided composites find applications in aerospace, automotive, construction, medical, and recreational industry. Some of the products are automobile cross beams, lamp and utility poles, prosthetic limbs, hockey sticks, baseball bats, and bicycle components. Vacuum assisted resin transfer molding (VARTM) is a low-cost manufacturing process with the capability of manufacturing complex parts with higher fiber volume fractions than those from hand lay-up. To utilize the braided composites to the fullest advantage (and hence to avoid underutilization), it is necessary to understand their behavior under flexural, impact, and fatigue loading. Flexural loading is dominant in the above-mentioned applications of braided composites. This research addresses the effect of braid angle on flexural behavior and failure mechanisms of biaxial braided composites manufactured using VARTM.

scholarly journals Failure Mechanisms of Mechanically and Thermally Produced Holes in High-Strength Low-Alloy Steel Plates Subjected to Fatigue Loading

Metals ◽  
2020 ◽  
Vol 10 (3) ◽  
pp. 318 ◽  
Author(s):  
Carlos Jiménez-Peña ◽  
Constantinos Goulas ◽  
Johannes Preußner ◽  
Dimitri Debruyne
Keyword(s):  
Yield Strength ◽  
Electron Backscatter Diffraction ◽  
Fatigue Behavior ◽  
Base Material ◽  
High Strength ◽  
Fatigue Loading ◽  
Offshore Structures ◽  
Load Level ◽  
Low Alloy Steels ◽  
Structural Applications

High-strength low-alloy steels (HSLA) are gaining popularity in structural applications in which weight reduction is of interest, such as heavy duty machinery, bridges, and offshore structures. Since the fatigue behavior of welds appears to be almost independent of the base material and displays little improvement when more resistant steel grades are employed, the use of bolted joints is an alternative joining technique which can lead to an increased fatigue performance of HSLA connections. Manufacturing a hole to allocate the fastener elements is an unavoidable step in bolted elements and it might induce defects and tensile residual stresses that could affect its fatigue behavior. This paper studies and compares several mechanical (punching, drilling, and waterjet-cut) and thermal (plasma and laser-cut) hole-making procedures in HSLA structural plates. A series of 63 uniaxial fatigue tests was completed, covering three HSLA grades produced by thermomechanically controlled process (TMCP) with yield strength ranging from 500 to 960 MPa. Samples were tested at single load level, which was considered representative in HSLA typical applications, according to the input received from end users. The manufactured holes were examined by means of optical and electron microscopy, 3D point measurement, micro hardness tests, X-ray diffraction, and electron backscatter diffraction (EBSD). The results give insight on cutting processes in HSLA and indicate how the fatigue failure is dominated by macro defects rather than by the steel grade. It was shown that the higher yield strength of the HSLA grades did not lead to a higher fatigue life. Best fatigue results were achieved with laser-cut specimens while punched samples withstood the lowest amount of cycles.

scholarly journals Fatigue Behavior of 3D Braided Composites Containing an Open-Hole

Polymers ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2147
Author(s):  
Shuangqiang Liang ◽  
Qihong Zhou ◽  
Haiyang Mei ◽  
Ge Chen ◽  
Frank Ko
Keyword(s):  
Cross Section ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Fatigue Properties ◽  
Failure Behavior ◽  
Braided Composites ◽  
Damage Area ◽  
3D Braided Composites ◽  
Mechanical Performances ◽  
Braiding Angle

The static and dynamic mechanical performances of notched and un-notched 3D braided composites were studied. The effect of longitudinal laid-in yarn was investigated in comparison with low braiding angle composites. The specimens were fatigue tested for up to millions of cycles, and the residual strength of the samples that survived millions of cycles was tested. The cross-section of the 3D braided specimens was observed after fatigue loading. It was found that the static and fatigue properties of low angle 3D braided behaved better than longitudinally reinforced 3D braided composites. For failure behavior, pure braids contain damage better and show less damage area than the braids with longitudinal yarns under fatigue loading. More cracks occurred in the 3D braided specimen with axial yarn cross-section along the longitudinal and transverse direction.

Static and Fatigue Strength of Resin Transfer Molded Composites

2002 ◽  
Author(s):  
Youssef Hamidi ◽  
Levent Aktas ◽  
J. David Bladwin ◽  
M. Cengiz Altan
Keyword(s):  
Tensile Strength ◽  
Ultimate Tensile Strength ◽  
Volume Fraction ◽  
Fatigue Behavior ◽  
Fatigue Loading ◽  
Fiber Content ◽  
Fiber Volume ◽  
Neat Polymer ◽  
Volume Fractions ◽  
Structural Applications

Fiber reinforced polymer composites are preferred in many structural applications for their ease of production and high specific strengths. Although fatigue loading is commonly encountered in structural applications, behavior of composites under cyclic loading is less understood compared to fatigue behavior of more conventional metals and their alloys. In this work, the response of resin transfer molded (RTM) glass/epoxy composites to static tensile and fatigue loading is investigated. Center-gated, disk shaped composites are fabricated using EPON 815C epoxy resin and EPICURE 3282 curing agent. A randomly oriented, planar glass fiber preform with 0.459kg/m2 surface density is used as the reinforcement material. Two and six layers of preforms are used to achieve 7.9 and 28.9% fiber volume fractions respectively. In addition, neat polymer parts are molded without performs to study the effect of fiber content on the tensile and fatigue behavior. Initially, ultimate tensile strength (UTS) and stiffness for three different fiber volume fractions (i.e., 0, 7.9, and 28.9%) are reported. Then, fatigue tests are conducted for stress level (σmax/UTS) of 0.5 and stress ratio (σmax/σmin) of 0.1 at a test frequency of 10 Hz. Loss of stiffness and cycles to failure are the two fatigue properties investigated. As the fiber volume fraction increased from 7.9 to 28.9%, the ultimate tensile strength and stiffness increased by 140 and 100%, respectively. During fatigue loading, the stiffness gradually dropped by approximately 13% for 7.9% and 28.9% fiber volume fractions. However, neat polymer samples did not show considerable decrease in stiffness during cycling. It is also shown that the number of cycles before failure significantly increased with the fiber content.

scholarly journals A rapid, accurate, scalable, and portable testing system for COVID-19 diagnosis

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Guanhua Xun ◽  
Stephan Thomas Lane ◽  
Vassily Andrew Petrov ◽  
Brandon Elliott Pepa ◽  
Huimin Zhao
Keyword(s):  
Limit Of Detection ◽  
Low Cost ◽  
High Volume ◽  
N Gene ◽  
Testing System ◽  
Target Sequence ◽  
One Pot ◽  
Sequence Detection ◽  
Highly Sensitive ◽  
Speed Accuracy

AbstractThe need for rapid, accurate, and scalable testing systems for COVID-19 diagnosis is clear and urgent. Here, we report a rapid Scalable and Portable Testing (SPOT) system consisting of a rapid, highly sensitive, and accurate assay and a battery-powered portable device for COVID-19 diagnosis. The SPOT assay comprises a one-pot reverse transcriptase-loop-mediated isothermal amplification (RT-LAMP) followed by PfAgo-based target sequence detection. It is capable of detecting the N gene and E gene in a multiplexed reaction with the limit of detection (LoD) of 0.44 copies/μL and 1.09 copies/μL, respectively, in SARS-CoV-2 virus-spiked saliva samples within 30 min. Moreover, the SPOT system is used to analyze 104 clinical saliva samples and identified 28/30 (93.3% sensitivity) SARS-CoV-2 positive samples (100% sensitivity if LoD is considered) and 73/74 (98.6% specificity) SARS-CoV-2 negative samples. This combination of speed, accuracy, sensitivity, and portability will enable high-volume, low-cost access to areas in need of urgent COVID-19 testing capabilities.

scholarly journals Towards Sustainable Concrete Composites through Waste Valorisation of Plastic Food Trays as Low-Cost Fibrous Materials

2021 ◽  
Vol 13 (4) ◽  
pp. 2073 ◽  
Author(s):  
Hossein Mohammadhosseini ◽  
Rayed Alyousef ◽  
Mahmood Md. Tahir
Keyword(s):  
Compressive Strength ◽  
Low Cost ◽  
Impact Resistance ◽  
Food Tray ◽  
World Population ◽  
Fibrous Materials ◽  
Palm Oil Fuel Ash ◽  
Waste Plastic ◽  
Compressive Strength Of Concrete ◽  
The Impact

Recycling of waste plastics is an essential phase towards cleaner production and circular economy. Plastics in different forms, which are non-biodegradable polymers, have become an indispensable ingredient of human life. The rapid growth of the world population has led to increased demand for commodity plastics such as food packaging. Therefore, to avert environment pollution with plastic wastes, sufficient management to recycle this waste is vital. In this study, experimental investigations and statistical analysis were conducted to assess the feasibility of polypropylene type of waste plastic food tray (WPFT) as fibrous materials on the mechanical and impact resistance of concrete composites. The WPFT fibres with a length of 20 mm were used at dosages of 0–1% in two groups of concrete with 100% ordinary Portland cement (OPC) and 30% palm oil fuel ash (POFA) as partial cement replacement. The results revealed that WPFT fibres had an adverse effect on the workability and compressive strength of concrete mixes. Despite a slight reduction in compressive strength of concrete mixtures, tensile and flexural strengths significantly enhanced up to 25% with the addition of WPFT fibres. The impact resistance and energy absorption values of concrete specimens reinforced with 1% WPFT fibres were found to be about 7.5 times higher than those of plain concrete mix. The utilisation of waste plastic food trays in the production of concrete makes it low-cost and aids in decreasing waste discarding harms. The development of new construction materials using WPFT is significant to the environment and construction industry.

scholarly journals The Influences of Projectile Material and Environmental Temperature on the High Velocity Impact Behavior of Triaxial Braided Composites

2021 ◽  
Vol 11 (8) ◽  
pp. 3466
Author(s):  
Lulu Liu ◽  
Shikai Yin ◽  
Gang Luo ◽  
Zhenhua Zhao ◽  
Wei Chen
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Energy Absorption ◽  
Cryogenic Temperature ◽  
Environmental Temperature ◽  
Impact Resistance ◽  
Matrix Cracking ◽  
Braided Composites ◽  
Damage Pattern ◽  
Braided Composite

Two-dimensional (2D) triaxial braided composites with braiding angle (± 60°/0°) have been used as aero-engine containing casing material. In the current paper, three types of projectile with the same mass and equivalent diameter, including cylinder gelatin projectile, carbon fiber-reinforced plastics (CFRP), and titanium alloy blade-like projectile, were employed to impact on triaxial braided composites panels with thickness of 4.3 mm at room temperature (20 °C) to figure out the influences of projectile materials on the damage pattern and energy absorption behavior. Furthermore, the influences of environmental temperature were also discussed considering the aviation service condition by conducting ballistic impact tests using CFRP projectile at cryogenic temperature (−50 °C) and high temperature (150 °C). The triaxial braided target panel were pre-heated or cooled in a low-temperature chamber before mounted. It is found that soft gelatin project mainly causes global deformation of the target and therefore absorb much more energy. The triaxial braided composite absorb 77.59% more energy when impacted with CFRP projectile than that with titanium alloy projectile, which mainly results in shear fracture. The environmental temperature has influences on the damage pattern and energy absorption of triaxial braided composites. The cryogenic temperature deteriorates the impact resistance of the triaxial braided composite material with matrix cracking damage pattern, while high temperature condition improves its impact resistance with shearing fracture damage pattern.

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