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Tham khảo tài liệu 'woven fabric engineering part 2', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Anisotropy in Woven Fabric Stress and Elongation at Break 17 0.5 it depends on fibers length staple friction coefficients yarn twist etc. b In fabric at break in principal directions Cfup is similar or slightly higher it depends on fabric packing density and on other parameters. c In fabric at break in diagonal directions Cfud is maximal due to jamming. Extremely it can be near to 1. From these reasons final parameters Cfui 2 as a function of p0 will be predicted as parabolic relation without derivation . z J p p fa Cfud -Cfup - p I Cfup 34 4 Fabric strip strength from broken yarns with implementation of jamming Fj1 2b is from 33 and 34 fj1 2b Cfu1 2 fa1 2b Cfu1 2 S1 2 b0 cos P1 20 y1 2b 35 Correction for cut yarn ends With the exception of p0 0 and p0 90 there are yarns bearing fabric load having one or two free ends Kovar Dolatabadi 2007 . Near cut yarn end axial stress is zero and gradually increases linear increase is assumed due to friction till it reaches yarn strength in length 1 see Fig. 14 a. In this area fabric jamming is not as important as in sample inner parts and shear angle is smaller. This length l is hardly predictable and depends on many parameters setts yarn properties including frictional fabric finishing shear deformation angle of load jamming etc. . It can be evaluated experimentally by testing yarn pullout force from the fabric Pan Yoon 1993 or testing the samples of variable widths. By this effect some width on each side of fabric bin l sin P1 20 is inefficient this is important mainly for broken yarns. This strip bin can bear only about 50 of full load. It results in reduction of original sample width to effective one bef bb0 -1 sin p 20. Fig. 14. Free ends of yarns in fabric at bias load. 18 Woven Fabric Engineering Total effective force from broken yarns with reduced fabric width Ff1 2b is then from 35 Ff1 2b Cfu1 2 S1 2 bef cos2 A 20 Fy1 2b Cfu1 2 S1 2 bb0 - I sin A 20 cos2 A 20 Fy1 2b 36 Correction for critical angles In our theory .
