Uncorrelated volume element for stochastic modeling of microstructures based on local fiber volume fraction variation

2015 ◽  
Vol 117 ◽  
pp. 191-198 ◽  
Author(s):  
Seyed Hamid Reza Sanei ◽  
Ray S. Fertig
Keyword(s):  
Stochastic Modeling ◽  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Volume Element ◽  
Fiber Volume ◽  
Local Fiber

Automated reconstruction and conformal discretization of 3D woven composite CT scans with local fiber volume fraction control

2020 ◽  
Vol 248 ◽  
pp. 112438
Author(s):  
Badadjida Wintiba ◽  
Dmytro Vasiukov ◽  
Stéphane Panier ◽  
Stepan V. Lomov ◽  
Karim Ehab Moustafa Kamel ◽  
...  
Keyword(s):  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Ct Scans ◽  
Woven Composite ◽  
Fiber Volume ◽  
Local Fiber

Property Prediction of Composites with Different Fiber Volume Fractions by Representative Volume Element Method

2013 ◽  
Vol 275-277 ◽  
pp. 1605-1609
Author(s):  
Nan Zhang ◽  
Cheng Hong Duan
Keyword(s):  
Elastic Properties ◽  
Representative Volume Element ◽  
Fiber Volume Fraction ◽  
Empirical Equation ◽  
Volume Fraction ◽  
Volume Element ◽  
Fiber Volume ◽  
Finite Element Software ◽  
Representative Volume ◽  
Properties Of Composites

In this paper, a representative volume element (RVE) model of composites with different fiber volume fraction is established by ANSYS finite element software. The stiffness matrix of the RVE model can be calculated by studying its stress field, and then the elastic properties of composites could be obtained. By comparing with the results from NASA empirical equation, the reliability of the method can be proved. This is a new way to predict the elastic properties of composites.

Simulation of the Influence of Embedded Inserts on the RTM Filling Behavior Considering Local Fiber Structure

2017 ◽  
Vol 742 ◽  
pp. 681-688 ◽  
Author(s):  
Julian Seuffert ◽  
Luise Kärger ◽  
Frank Henning
Keyword(s):  
Fiber Volume Fraction ◽  
Volume Fraction ◽  
Front Propagation ◽  
Mold Filling ◽  
Fiber Structure ◽  
Flow Front ◽  
Fiber Volume ◽  
Two Phase ◽  
Local Flow ◽  
Local Fiber

Resin Transfer Molding (RTM) enables an intrinsic manufacturing of fiber reinforced composite parts containing integrated metallic inserts. The inserts are embedded into the fiber layers in the preforming stage of the process and therefore influence the following mold filling. The fiber structure around the embedded insert is strongly influenced by the insert resulting in high local variations of fiber volume fraction which changes the local permeability. This leads to an inhomogenic flow front and can even result in dry spots of the cured part. To predict the formation of air bubbles, a two-phase mold filling simulation is used under consideration of local fiber volume fraction. Local fiber structure is determined using CT-scans of manufactured parts with different orientations of the insert in relation to the preform and to the filling direction. The mold filling simulations allow the evaluation of different filling strategies and show a strong influence of the insert on the local flow front propagation.

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.

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