ACHIEVING REALISTIC TOW FIBER VOLUME FRACTIONS IN TEXTILE COMPOSITE MODELS BY INDUCING FIBER ENTANGLEMENT

2021 ◽  
Author(s):  
GEORGE BARLOW ◽  
MATHEW SCHEY ◽  
SCOTT STAPLETON
Keyword(s):  
Process Simulation ◽  
Manufacturing Process ◽  
Fiber Bundle ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Simulation Method ◽  
Textile Composite ◽  
Compression Pressure ◽  
Fiber Volume ◽  
Composite Models

Modeling composites can be an effective way to understand how a part will perform without requiring the destruction of costly specimens. By combining artificial fiber entanglement with manufacturing process simulation, a method was developed to create fiber bundle models using entanglement to control the fiber volume fraction. This fiber entanglement generation uses three parameters, probability of swapping (p_(r_S )), swapping radius standard deviation (r_(σ_S )), and the swapping plane spacing (l_S), to control the amount of entanglement within the fiber bundle. A parametric study was conducted and found that the more entanglement within a fiber bundle, the more compression mold pressure required to compact the fiber bundle to the same fiber volume fraction as that required for a less entangled bundle. This artificial fiber entanglement and manufacturing process simulation method for creating fiber bundles shows the potential to be able to create bundles with controlled final volume fraction using a desired mold compression pressure.

Transverse Elastic Deformation Behavior of Aligned Fiber Bundles under Bulk Compressive Pressure and Longitudinal Stress

2010 ◽  
Vol 97-101 ◽  
pp. 1689-1692
Author(s):  
Jing Zhong Xing ◽  
Li Chen ◽  
Jin Chao Li
Keyword(s):  
Fiber Bundle ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
High Volume ◽  
Longitudinal Stress ◽  
Compaction Process ◽  
Fiber Volume ◽  
High Fiber ◽  
Compressive Pressure ◽  
Initial Fiber

Advanced composite materials generally use fiber in very high volume fraction, compression of textile/perform is adopted in manufacture processes. The major role of the compaction process is to obtain high fiber volume fraction in final parts. During the compaction process, transverse compaction of textile/perform is the main deformation form, where the compaction behavior of a fiber bundle is the most basis issue. In this paper, a micromechanical model of aligned fiber bundle with high fiber volume fraction was developed to investigate elastic deformation behavior under bulk compressive pressure and longitudinal stress. Bending characteristics of a waved fiber was established to describe the transverse bulk compression and the longitudinal deformations of a bundle. A wave amplitude was introduced to describe initial distance between fibers, which affects the initial fiber volume fraction and the transverse deformation feature. An improved representative fiber cell was present to get the deflection of a bending fiber under transverse and axial force. Randomly distributed directions of waved fibers lead to a more reasonable representative fiber cell, which influences initial fiber volume fraction and leads to logical deformation explanation and symmetric constitutive relation for aligned fiber bundle with high volume fraction. Analytical formulae to describe the constitutive relationship of fiber bundle under transverse and longitudinal stress were present. Numerical results show that the transverse bulk compressive stress and its deformation are related to wave amplitude and available fiber volume fraction. The comparison to present literatures was given to show the improvement of the model.

Monitoring of mechanical properties of prestressed glass fiber epoxy composites over 12 months after fabrication

2021 ◽  
pp. 002199832110047
Author(s):  
Mahmoud Mohamed ◽  
Siddhartha Brahma ◽  
Haibin Ning ◽  
Selvum Pillay
Keyword(s):  
Mechanical Properties ◽  
Residual Stress ◽  
Flexural Strength ◽  
Compressive Residual Stress ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Epoxy Composites ◽  
Flexural Properties ◽  
Initial Increase ◽  
Fiber Volume

Fiber prestressing during matrix curing can significantly improve the mechanical properties of fiber-reinforced polymer composites. One primary reason behind this improvement is the generated compressive residual stress within the cured matrix, which impedes cracks initiation and propagation. However, the prestressing force might diminish progressively with time due to the creep of the compressed matrix and the relaxation of the tensioned fiber. As a result, the initial compressive residual stress and the acquired improvement in mechanical properties are prone to decline over time. Therefore, it is necessary to evaluate the mechanical properties of the prestressed composites as time proceeds. This study monitors the change in the tensile and flexural properties of unidirectional prestressed glass fiber reinforced epoxy composites over a period of 12 months after manufacturing. The composites were prepared using three different fiber volume fractions 25%, 30%, and 40%. The results of mechanical testing showed that the prestressed composites acquired an initial increase up to 29% in the tensile properties and up to 32% in the flexural properties compared to the non-prestressed counterparts. Throughout the 12 months of study, the initial increase in both tensile and flexural strength showed a progressive reduction. The loss ratio of the initial increase was observed to be inversely proportional to the fiber volume fraction. For the prestressed composites fabricated with 25%, 30%, and 40% fiber volume fraction, the initial increase in tensile and flexural strength dropped by 29%, 25%, and 17%, respectively and by 34%, 26%, and 21%, respectively at the end of the study. Approximately 50% of the total loss took place over the first month after the manufacture, while after the sixth month, the reduction in mechanical properties became insignificant. Tensile modulus started to show a very slight reduction after the fourth/sixth month, while the flexural modulus reduction was observed from the beginning. Although the prestressed composites displayed time-dependent losses, their long-term mechanical properties still outperformed the non-prestressed counterparts.

scholarly journals Effect of Fiber Volume Fraction on Behavior of Concrete Beams Made with Recycled Concrete Aggregates

2019 ◽  
Vol 253 ◽  
pp. 02004
Author(s):  
Wael Alnahhal ◽  
Omar Aljidda
Keyword(s):  
Fiber Volume Fraction ◽  
Concrete Beams ◽  
Volume Fraction ◽  
Recycled Concrete ◽  
Flexural Behavior ◽  
Beam Specimen ◽  
Rc Beam ◽  
Fiber Volume ◽  
Concrete Aggregates ◽  
Recycled Concrete Aggregates

This study investigates the effect of using different volume fractions of basalt macro fibers (BMF) on the flexural behavior of concrete beams made with 100% recycled concrete aggregates (RCA) experimentally. A total of 4 reinforced concrete (RC) beam specimens were flexural tested until failure. The parameter investigated included the BMF volume fraction (0%, 0.5%, 1%, and 1.5%). The testing results of the specimens were compared to control beam specimen made with no added fibers. The experimental results showed that adding BMF improves the flexural capacity of the tested beams.

The Effects of Fiber Volume Fraction on the Experiment Modal Behavior of 45°/-45° Carbon Fiber Plain Woven Fabric/Epoxy Resin Composites

2012 ◽  
Vol 583 ◽  
pp. 150-153
Author(s):  
Qian Liu ◽  
Xiao Yuan Pei ◽  
Jia Lu Li
Keyword(s):  
Carbon Fiber ◽  
Epoxy Resin ◽  
Natural Frequency ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Laminated Composites ◽  
Woven Fabric ◽  
Resin Composites ◽  
Fiber Volume ◽  
Epoxy Resin Composites

The modal properties of carbon fiber woven fabric (with fiber orientation of 45°/-45°) / epoxy resin composites with different fiber volume fraction were studied by using single input and single output free vibration of cantilever beam hammering modal analysis method. The effect of different fiber volume fraction on the modal parameters of laminated composites was analyzed. The experimental results show that with the fiber volume fraction increasing, the natural frequency of laminated composites becomes larger and damping ratio becomes smaller. The fiber volume fraction smaller, the peak value of natural frequency becomes lower and the attenuating degree of acceleration amplitude becomes faster.

Determination of fiber volume fraction in a cured laminate

2021 ◽  
pp. 002199832110112
Author(s):  
Qing Yang Steve Wu ◽  
Nan Zhang ◽  
Weng Heng Liew ◽  
Vincent Lim ◽  
Xiping Ni ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Fiber Volume Fraction ◽  
Evaluation Method ◽  
Volume Fraction ◽  
Matrix Material ◽  
Volume Ratio ◽  
Gravimetric Analysis ◽  
Fiber Volume ◽  
Laser Ultrasonic ◽  
The Matrix

Propagation of ultrasonic wave in Carbon Fiber Reinforced Polymer (CFRP) is greatly influenced by the material’s matrix, resins and fiber volume ratio. Laser ultrasonic broadband spectral technique has been demonstrated for porosity and fiber volume ratio extraction on unidirection aligned CFRP laminates. Porosity in the matrix materials can be calculated by longitudinal wave attenuation and accurate fiber volume ratio can be derived by combined velocity through the high strength carbon fiber and the matrix material with further consideration of porosity effects. The results have been benchmarked by pulse-echo ultrasonic tests, gas pycnometer and thermal gravimetric analysis (TGA). The potentials and advantages of the laser ultrasonic technique as a non-destructive evaluation method for CFRP carbon fiber volume fraction evaluation were demonstrated.

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