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- Bulsara, V.N., et al.
(author)
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Damage initiation under transverse loading of unidirectional composites with arbitrarily distributed fibers
- 1999
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In: Composites Science And Technology. - 0266-3538 .- 1879-1050. ; 59:5, s. 673-682
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Journal article (peer-reviewed)abstract
- A limiting property governing the thermomechanical behavior of composites is the strength transverse to the fibers. The present study investigates the dependence of this property on the distribution of fibers in the cross-section of a unidirectional composite. The approach taken is to consider actual distributions, which are arbitrary and are not necessarily described by random or periodic distributions. A fundamental issue in studying non-uniform distributions is the size of a representative volume element (RVE). By the use of an actual radial distribution function obtained for a ceramic-matrix composite by quantitative stereology in conjunction with a simulation technique developed in this study, the RVE size is investigated with respect to initiation of debonding and radial matrix cracking - two basic mechanisms governing the transverse strength of composites. Tensile loading transverse to the fibers and residual stresses induced by thermal cooldown are considered separately as loading modes for transverse failure. The results provide some useful insight into the importance of non-uniformity of fiber spatial distribution with regard to the transverse failure of composites. A limiting property governing the thermomechanical behavior of composites is the strength transverse to the fibers. The present study investigates the dependence of this property on the distribution of fibers in the cross-section of a unidirectional composite. The approach taken is to consider actual distributions, which are arbitrary and are not necessarily described by random or periodic distributions. A fundamental issue in studying non-uniform distributions is the size of a representative volume element (RVE). By the use of an actual radial distribution function obtained for a ceramic-matrix composite by quantitative stereology in conjunction with a simulation technique developed in this study, the RVE size is investigated with respect to initiation of debonding and radial matrix cracking - two basic mechanisms governing the transverse strength of composites. Tensile loading transverse to the fibers and residual stresses induced by thermal cooldown are considered separately as loading modes for transverse failure. The results provide some useful insight into the importance of non-uniformity of fiber spatial distribution with regard to the transverse failure composites.
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- Bulsara, V.N., et al.
(author)
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Using spatial descriptors to identify damage initiation in NicalonTM/MAS-5
- 2006
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In: Proceedings of the American Society for Composites technical conference. - Lancaster : Technomic Publ. Co. - 1566764882 ; , s. 875-884
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Conference paper (peer-reviewed)abstract
- Quantitative microscopy in conjunction with finite element analysis is used to study the effects of fiber distribution on damage initiation in the transverse direction of a [0]8 NicalonTM/MAS-5 glass-ceramic composite. Fiber centroid locations in a transverse cross-section of the composite are collected and stored and used to evaluate the second order intensity function, K(r), and the radial distribution function g(r). The g(r) yields several representative volume elements (RVEs) of the composite, where each element represents one statistical realization of the actual fiber distribution. Potential damage initiation sites are identified by applying a simple failure criterion to the stress distribution in each RVE
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