MODSIM 3DXCONFERENCE Lightweight Engineering
I am pleased to invite you to Carlos Cimini and Naresh Sharma's presentation on the Global 3DEXPERIENCE Modeling and Simulation Virtual Conference on November 17th & 18th. Please register now!
https://events.3ds.com/global-3dexperience-modeling-simulation-virtual-conference
The presentation
In every single simulation, analysts face the necessity to input the material elastic constants into their models. It may not be difficult for some people to determine 3D stress and strain fields for laminated composite materials. However, with so many elastic constants to input, it is difficult to know their values. It turns out that the Tsai's modulus in 2D [4] can be extended to 3D in a straightforward fashion. As a result, there exists a master ply from which one solution is sufficient for all materials by scaling with Tsai's modulus [1-4]. This modulus is the trace of the elastic stiffness in C that is modified to take into account the use of engineering shear moduli; thus, Tsai’s modulus = C11 + C22 + C33 + 2C44 + 2C55 + 2C66. In Figure 1, comparison of 3D universal stiffness C* and 2D universal stiffness A* for laminate [02/±45] shows the invariance of their components as function of the trace for 11 different CFRP material systems. Both were normalized by Tsai’s modulus. It can be seen the marginal increment of universal stiffness for the 3D case and also that the master ply concept can be applied to both ply stiffness C* and laminate stiffness A*.The 3D laminate stiffness A* can be also partitioned to a fraction of its components. It turned out that the in-plane stiffness components correspond to 86% and the remaining out-of-plane, 14%. Figure 2 shows these 2D vs. 3D proportions of 3D stiffness A* for 15 different CFRP material systems considering several layups. The accuracy is less than 2%. Experimentally it is only necessary to measure one constant, i.e., the Tsai's modulus, from which all diagonal components of the 3D stiffness can be scaled, with 2% accuracy. There are other invariants that can used to determine the off-diagonal components with the same degree of accuracy. The bottom line is, with the recognition of the existence of the Tsai's modulus for 3D stiffness, confidence in the stress analysis is increased and solution based on one material can be scaled for all other CFRP. There is no need for recalculation. Moreover, master ply concept relies on one-parameter input: the unidirectional ply longitudinal modulus (Ex), which defines the Tsai’s modulus and, therefore, the particular CFRP material system.
Presentation Replay
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