Effects of Voids on Mechanical Properties of Graphite Fiber Composites

Lenoe, E. M.

doi:10.21236/ad0727236

Cited by 5 publications

(8 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This is believed to be a result of the high fiber volume fractions and fairly low amount of voids present in the tested specimens. It is also well known that the elastic modulus is primarily dependent on the fiber property [19,[26][27][28].…”

Section: Resultsmentioning

confidence: 99%

Properties of Composite Cylinders Fabricated by Bladder Assisted Composite Manufacturing

Anderson¹,

Altan

2012

Journal of Engineering Materials and Technology

View full text Add to dashboard Cite

An innovative manufacturing method, bladder assisted composite manufacturing (BACM), to fabricate geometrically complex, hollow parts made of polymeric composite materials is presented. Unlike the conventional bladder or diaphragm assisted curing processes, BACM uses an internally heated bladder to provide the consolidation pressure at the required cure temperature. The feasibility of this manufacturing method is demonstrated by fabricating laminated composite cylinders using multiple cure pressures and number of plies. The elastic moduli, failure strength, fiber volume fraction, and void contents of the cylinders were found to be comparable to the values obtained fi-om fiat laminates produced by hot plate molding of the same material. Compared to conventional bladder manufacturing methods, the BACM process reduced the energy required to cure the cylinders by almost 50% due to internal heating and insulatedmold.

show abstract

Section: Resultsmentioning

confidence: 99%

Properties of Composite Cylinders Fabricated by Bladder Assisted Composite Manufacturing

Anderson¹,

Altan

2012

Journal of Engineering Materials and Technology

View full text Add to dashboard Cite

show abstract

“…e.g., for pultrusion or RTM processes ϕ f e.g., for filament winding (1) With the adjusted fiber volume content, the resulting properties are calculated assuming transversely isotropic behavior of the composite domain. For the Young's modulus in fiber direction the mixing rule is used, where index " f , ij" stands for fiber stiffness tensor components in "i, j" and "m" denotes the matrix properties:…”

Section: Two-step Homogenization Schemementioning

confidence: 99%

“…In recent decades, numerous researchers investigated on the influence of voids on the resulting properties of composite materials. Early experimental investigations by Lenoe focused on the effects of voids on the mechanical properties for unidirectional and quasi-isotropic laminates for carbon fiber epoxy composites [1]. Void contents were estimated between 1% and 5%.…”

Section: Introductionmentioning

confidence: 99%

Stiffness Estimates for Composites with Elliptic Cylindrical Voids

Becker

Hopmann

2020

Materials

View full text Add to dashboard Cite

A two-step homogenization procedure is presented to investigate the stiffness of a unidirectional continuous fiber-reinforced composite material containing voids of different shapes and volume contents. Since the Mori–Tanaka scheme is limited to moderate volume contents of the inhomogeneity phase, fiber and matrix are homogenized with semi-empirical relations with use of the adjusted fiber volume content in a first step. In the second step, the Mori–Tanaka scheme is applied to obtain the homogenized stiffness tensor of a transversely isotropic material containing voids aligned with the fiber direction. The voids are modelled with infinite length, but an elliptic base characterized by the aspect ratio. The tensor components of the Eshelby tensor for this case are presented in closed form for a transversely isotropic material depending on the aspect ratio and matrix material properties. The scheme is solved directly for easy implementation and the use of fast calculations of the effective engineering constants of a composite material containing voids. Experimental results from literature for different void contents and shapes are compared to the predicted moduli with cylindrical voids. From the results it is further concluded that the aspect ratio of the void and the manufacturing process of the composite should be considered.

show abstract

“…The presence of porosity in a structural material generally has a detrimental effect on the strength and mechanical properties of the component [1]. Excessive porosity is especially undesirable in laminated composites such as graphite-epoxy as it substantially degrades the interlaminar shear strength, the compressive strength and the transverse flexural strength.…”

Section: Introduction David K Hsu and Kevin M Uhlmentioning

confidence: 99%

“…The presence of porosity in composite laminates can be due to many causes [1,2]. Both the material constituents and the fabrication process may be contributing sources of voids.…”

Section: Introduction David K Hsu and Kevin M Uhlmentioning

confidence: 99%