tailieunhanh - Advances in Modern Woven Fabrics Technology Part 5

Tham khảo tài liệu 'advances in modern woven fabrics technology part 5', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Finite Element Modeling of Woven Fabric Composites at Meso-Level Under Combined Loading Modes 69 Fig. 4. The X-ray image from cross section of fibrous yarns top before loading bottom after loading Badel et al. 2008 to arrive at strain-dependant relationships for the yarns transverse stiffness parameters Gasser et al. 2000 Badel et al. 2008 . The general form of material properties in the current model are adapted from Komeili and Milani 2010 which were extracted by matching the numerical simulations to the experimental measurements by Buet-Gautier and Boisse 2001 under axial tension and by Cao et al. 2008 under shear loading. The properties used for a simultaneous extensionshear are summarized in the following stiffness matrix E11 11 C E11 0 0 0 0 0 0 E 22 0 0 0 0 0 0 E 33 0 0 0 0 0 0 G 0 0 100 MPa 5 GPa 50 GPa sa X10-3 X10-3 su X10-3 X10-3 u 6 7 0 0 0 0 G 0 0 0 0 0 0 G Ett X105 sff 4 MPa 8 C is the stiffness matrix E11 and S11 are the axial stiffness and strains Ett stt tt 22 33 are the transverse stiffness and strains respectively. G is the shear modulus of the yarns which for dry fabrics should be small compared to the axial and transverse stiffness values. Here G 60 MPa as been selected merely for numerical stability purposes Gasser et al. 2000 although the shear modulus is at the same order of magnitude as the other two stiffness values in the beginning of loading it becomes less significant as E11 and E22 increases with the loading magnitude. The material model of Eqs 6 - 8 was implemented in the Abaqus finite element software via a UMAT implicit user-defined subroutine. In doing so however it was noted that the 70 Advances in Modern Woven Fabrics Technology large difference between the stiffness in the yarn axial direction compared to the transverse and shear stiffness values highlights the extreme importance of applying proper material orientation updates during loading steps. The point is that the material properties should be .