Determination of void statistics and statistical representative volume elements in carbon fiber-reinforced thermoplastic prepregs. (August 2017)

• Record Type: Journal Article
• Authors: Zhang, Danning; Heider, Dirk; Gillespie, John W
• Is Part Of: Journal of thermoplastic composite materials. Volume 30:Number 8(2017:Sep.)
• Page Start: 1103
• Page End: 1119
• Publication Date: 2017-08
• Subjects: Prepreg -- porosity/voids -- statistical properties/methods -- X-ray microcomputed tomography -- statistical representative volume element; Thermoplastic composites -- Periodicals; 668.423
• DOI: 10.1177/0892705715618002
• Languages: English
• ISSNs: 0892-7057

Abstract

Void consolidation of high-performance thermoplastic composites strongly depends not only on average void content but also on the distributions of void size, shape, and location within the prepreg materials. High-resolution 3-D X-ray microcomputed tomography shows that voids in carbon/poly(ether ether ketone) (AS4/APC2) prepreg are rodlike with major axis along the fiber axial direction. In order to accurately characterize the void microstructure, a detailed study was conducted to quantify the statistical distribution of void content, void length, equivalent void diameter, and void aspect ratio. Resolution of 1.48 μm/pixel provided a balance of measurement accuracy and inspection time. Suitable statistical distribution functions were found to describe the void length, diameter, and aspect ratio. For each void property, a sub-statistical representative volume element (SRVE) was determined. The SRVE of the overall void microstructure is defined as the maximum dimensions of the sub-SRVEs. In case of AS4/APC2 tape, the SRVE was found to be 6.1 mm in length (fiber direction), 27 mm in width (transverse to fiber direction), and 0.18 mm of full prepreg thickness.