Mechanical modelling of solid woven fabric composites 83 1-D micro-cell y weft macro-cell t-migro-cell x warp 196t1 wo'ssaudmau'peaupoo/ WV IL:OE LEVEL 2 LEVEL 3 3.7 Schematic of a block cell or macro-cell (level 2)and a micro-cell (level 3). 日 structures can be composed with this library of rectangular macro-cells or I'85I building blocks. It should be pointed out that only the weave construction pattern pro- % vided by the weaving company is sufficient to determine automatically the number of each type of macro-cell present in the unit cell.No extra fabric information,nor any geometric assumptions,nor operator interventions are needed.Therefore,the macro-partition is simple in concept and easy to apply.It provides a theoretical basis for the design of woven fabric composites. The decomposition of the block in micro-cells is called the micro- partition.It is assumed that within each small micro-cell the yarn follows a straight yarn path.The 2-D micro-partition results in a fully 3-D division of the unit cell,so that the variation of properties within the unit cell can be properly analysed.This is essential for understanding the mechanical per- formance of woven fabric composites.For the local stress analysis,it will further be necessary to define the micro-cell also in the 123 local axis system,where 1 corresponds to the longitudinal yarn direction.This is called a combi-cell.Therefore the label micro-cell (xyz)or combi-cell (123)is selected depending on the reference axis system. Then,the multilevel decomposition approach is based on simplifying the geometry within each combi-cell by assuming one matrix layer and onestructures can be composed with this library of rectangular macro-cells or building blocks. It should be pointed out that only the weave construction pattern pro￾vided by the weaving company is sufficient to determine automatically the number of each type of macro-cell present in the unit cell. No extra fabric information, nor any geometric assumptions, nor operator interventions are needed. Therefore, the macro-partition is simple in concept and easy to apply. It provides a theoretical basis for the design of woven fabric composites. The decomposition of the block in micro-cells is called the micro￾partition. It is assumed that within each small micro-cell the yarn follows a straight yarn path. The 2-D micro-partition results in a fully 3-D division of the unit cell, so that the variation of properties within the unit cell can be properly analysed. This is essential for understanding the mechanical per￾formance of woven fabric composites. For the local stress analysis, it will further be necessary to define the micro-cell also in the 123 local axis system, where 1 corresponds to the longitudinal yarn direction.This is called a combi-cell. Therefore the label micro-cell (xyz) or combi-cell (123) is selected depending on the reference axis system. Then, the multilevel decomposition approach is based on simplifying the geometry within each combi-cell by assuming one matrix layer and one Mechanical modelling of solid woven fabric composites 83 3.7 Schematic of a block cell or macro-cell (level 2) and a micro-cell (level 3). RIC3 7/10/99 7:37 PM Page 83 Copyrighted Material downloaded from Woodhead Publishing Online Delivered by http://woodhead.metapress.com Hong Kong Polytechnic University (714-57-975) Saturday, January 22, 2011 12:30:11 AM IP Address: 158.132.122.9