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154 results on '"Cox, Brian N."'

3. Characterizing In‐Plane Geometrical Variability in Textile Ceramic Composites

Author

Rossol, Michael N, Fast, Tony, Marshall, David B, Cox, Brian N, and Zok, Frank W

Subjects
Materials Engineering, Mechanical Engineering, Materials
Abstract

We present a methodology for characterizing and reconstructing in-plane weave variability in textile composites. Surface topography of a partially processed C-fiber/SiC matrix composite panel was measured using digital image correlation. The centroids of tow segments that appear periodically on the fabric surface were located by image analysis and used as fiducial markers. Stochastic deviations of the fiducial markers from the ideal periodic weave structure indicate geometrical variance. Fourier analysis shows that spatial wavelengths of the deviations range from the size of one unit cell to the dimensions of the entire panel. Long-range deviations are attributed principally to fabric deformation after manufacture, during handling. Short-range fluctuations, extracted by computing spatial derivatives of the positions of the fiducial markers, are attributed to variations in tow packing density that arises during weaving. A simple set of statistics for these deviations is presented and its use in generating stochastic virtual specimens is demonstrated.

Published
2015

15. Integral Textile Structure for 3-D CMC Turbine Airfoils

Author

Marshall, David B, Cox, Brian N, and Sudre, Olivier H

Subjects
Composite Materials
Abstract

An integral textile structure for 3-D CMC turbine airfoils includes top and bottom walls made from an angle-interlock weave, each of the walls comprising warp and weft fiber tows. The top and bottom walls are merged on a first side parallel to the warp fiber tows into a single wall along a portion of their widths, with the weft fiber tows making up the single wall interlocked through the wall's thickness such that delamination of the wall is inhibited. The single wall suitably forms the trailing edge of an airfoil; the top and bottom walls are preferably joined along a second side opposite the first side and parallel to the radial fiber tows by a continuously curved section in which the weave structure remains continuous with the weave structure in the top and bottom walls, the continuously curved section being the leading edge of the airfoil.

Published
2017

23. Fatigue of advanced materials, part II

Author

Dauskardt, Reinhold H., Ritchie, Robert O., and Cox, Brian N.

Subjects
Fiber-reinforced ceramics -- Research, Ceramics -- Fracture, Fatigue -- Testing
Published
1993

24. Handbook of Analytical Methods for Textile Composites

Author

Cox, Brian N and Flanagan, Gerry

Subjects
Composite Materials
Abstract

The purpose of this handbook is to introduce models and computer codes for predicting the properties of textile composites. The handbook includes several models for predicting the stress-strain response all the way to ultimate failure; methods for assessing work of fracture and notch sensitivity; and design rules for avoiding certain critical mechanisms of failure, such as delamination, by proper textile design. The following textiles received some treatment: 2D woven, braided, and knitted/stitched laminates and 3D interlock weaves, and braids.

Published
1997

25. Modeling the Properties of 3D Woven Composites

Author

Cox, Brian N

Subjects
Composite Materials
Abstract

An extensive study has been completed of the internal geometry, the mechanisms of failure, and the micromechanics of local failure events in graphite/epoxy composites with three dimensional (3D) woven reinforcement. This work has led to the development of models for predicting elastic constants, strength, notch sensitivity, and fatigue life. A summary is presented here.

Published
1995

30. Stochastic modelling of the geometrical variability in textile composites using experimental data

Author

Vanaerschot, Andy, Cox, Brian N, Lomov, Stepan Vladimirovitch, Vandepitte, Dirk, Sas, P, Moens, D, and Denayer, H

Abstract

Realistic descriptions of a carbon-epoxy 2/2 twill woven composite are generated by a stochastic multi-scale modelling approach. First, experimental data are collected on the short- and long-range variations in the reinforcement structure. Statistical information of each tow path parameter is computed in terms of mean, standard deviation and correlation information. Next, virtual reinforcements are constructed as a combination of average trends with zero-mean deviations. Depending on the presence of cross-correlation, either the Monte Carlo Markov Chain algorithm or a cross-correlated Series Expansion is applied to generate the random tow path deviations. The stochastic tow path instances are subsequently used to construct virtual composite specimens in the WiseTex format. Each specimen possesses the statistical data of the experimental samples on average. ispartof: pages:4741-4750 ispartof: Proceedings of the International Conference on Uncertainty in Structural Dynamics pages:4741-4750 ispartof: USD location:Leuven date:15 Sep - 17 Sep 2014 status: published

Published
2014

31. Stochastic multi-scale modelling of short- and long-range effects in textile composites based on experimental data

Author

Vanaerschot, Andy, Cox, Brian N, Lomov, Stepan Vladimirovitch, and Vandepitte, Dirk

Subjects
multi-scale simulation, variability, textile composites
Abstract

Realistic virtual textile composites are generated of a carbon-epoxy 2/2 twill woven composite. Each specimen, spanning ten by ten unit cells, possesses the short- and long-range variability characterised from experimental samples in prior work. A stochastic multi-scale modelling approach is presented to simulate many random reinforcements as combination of average trends with zero-mean deviations. Depending on the presence of cross-correlation, either the Monte Carlo Markov Chain method or Series Expansion technique is applied to generate the tow path deviations. Virtual specimens are acquired in the WiseTex format that reproduce the statistical information of the experimental samples on average. ispartof: pages:1-8 ispartof: Proceedings of the 16th European Conference on Composite Materials pages:1-8 ispartof: ECCM location:Seville, Spain date:22 Jun - 26 Jun 2014 status: published

Published
2014

32. Stochastic multi-scale modelling of composite materials based on experimental data

Author

Vanaerschot, Andy, Cox, Brian N, Lomov, Stepan Vladimirovitch, Vandepitte, Dirk, Cunha, A, Caetano, E, Ribeiro, P, and Muller, G

Subjects
extile composites, Probabilistic methods, Multi-scale modellin g, Non-determinism
Abstract

ariability in textile composites is substantial. A full characterisation of the internal geometry supports material design and increases the reliability of numerical simulations. An approach is presented and tested to obtain a full statistical description of the internal structure of a carbon-epoxy 2/2 twill woven composite, produced using resin transfer moulding. In a first step experimental data are collected using micro-CT to characterise the short range, i.e. within unit cell dimensions, and optical imaging for the long range, spanning several unit cells. The statistical information of the tow reinforcement is quantified per tow type, warp and weft direction, in terms of standard deviation and correlation length. The largest variation is found for the in-plane tow centroid coordinate with a significantly different behaviour in warp and weft direction. Tow cross-sectional properties such as area and aspect ratio vary within the unit cell size with limited scatter. Cross-correlation between neighbouring tows is only observed for the in-plane position. In a second step the statistical data are the input for a multi-scale modelling strategy to generate virtual specimens with random tow reinforcement. While the mean trends of each tow property are directly taken from the experiments, the deviations are generated by two different geometry generators. The properties without cross-correlation are produced using a Markov Chain algorithm, while the cross-correlated in-plane coordinate is generated using the Karhunen-Loève series expansion. Virtual specimens are obtained which possess the same statistical information as present in the experimental samples. ispartof: pages:219-226 ispartof: Proceedings of the IX International Conference on Structural Dynamics vol:2014-January pages:219-226 ispartof: EURODYN 2014 location:Porto, Portugal date:30 Jun - 2 Jul 2014 status: published

Published
2014

37. Stochastic Virtual Tests for High-Temperature Ceramic Matrix Composites

Author

Cox, Brian N., primary, Bale, Hrishikesh A., additional, Begley, Matthew, additional, Blacklock, Matthew, additional, Do, Bao-Chan, additional, Fast, Tony, additional, Naderi, Mehdi, additional, Novak, Mark, additional, Rajan, Varun P., additional, Rinaldi, Renaud G., additional, Ritchie, Robert O., additional, Rossol, Michael N., additional, Shaw, John H., additional, Sudre, Olivier, additional, Yang, Qingda, additional, Zok, Frank W., additional, and Marshall, David B., additional

Published
2014
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43. Dynamic Cracking and Energy Absorption in Laminates Containing Through-Thickness Reinforcement

Author

ROCKWELL SCIENTIFIC CO THOUSAND OAKS CA, Cox, Brian N., Narayanaswamy, Sridhar, ROCKWELL SCIENTIFIC CO THOUSAND OAKS CA, Cox, Brian N., and Narayanaswamy, Sridhar

Abstract

Inertial effects in the mechanism of fiber pullout were examined, with emphasis on how the rate of propagation of stress waves along the fiber, and thence the pullout dynamics, are governed by friction and the propagation of companion waves excited in the matrix. The frictional sliding between the fiber and the matrix is described by a constant interfacial friction stress, the sign of which depends on the relative particle velocity of the fiber and the matrix. The analytical results also were validated by detailed numerical finite element calculations with a cohesive law simulating interfacial friction. In addition to the theoretical work, through a sub-contract to ETech, the authors performed fundamental experiments to investigate the process of dynamic interfacial debonding and fiber push-in, especially in 2D model composite systems. With the use of high-speed diagnostics, a quantitative comparison was made between the experimental observations and the theoretical results, and they show excellent agreement. Steady state crack propagation characteristics in through-thickness reinforced laminate structures was mapped out in terms of controllable loading and material parameters, including the crack velocity and the properties of the through-thickness reinforcement. The paper includes a list of 17 publications prepared under this contract and a list of participating scientific personnel. Six of the publications prepared under this contract are appended: Delamination Dynamics in Through-Thickness Reinforced Laminates with Application to DCB Specimen; Stick, Slip and Reverse Slip Characteristics during Dynamic Fiber Pullout; Inertial Effects in the Pullout Mechanism during Dynamic Loading of a Bridged Crack; Computation of Dynamic Crack Energy Release Rate for Orthotropic Systems; The Physics of Dynamic Fiber Push-In Opposed by Friction; and Modern Topics and Challenges in Dynamic Fracture., The original document contains color images.

Published
2004

49. Magnetically Actuable Scaffolds for Tissue Regeneration

Author

Mack, Julia J., primary, Corrin, Abigail A., additional, dos Santos e Lucato, Sergio L., additional, Cox, Brian N., additional, Andrew, Jennifer S., additional, Clarke, David R., additional, Lam, Mandy, additional, Dunn, James C. Y., additional, and Wu, Benjamin W., additional

Published
2008
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