Hello, in a results from fibre orientaion (PA6GF30 BASF B3WG6) shows the maximum E-Modul 10841MPa higher that the materialparameter in Mechanical Properties 10700 MPa.
if Moldflow use the input data 10700 für the halpin-Tsai as the maximum data, why give the Moldflow after the calculation a local E-Moduli higher than the INPUT?
I know that the data in Mechanical Properties are from a tensile specimen, the orientation is not 100 % in the flow direction. But as a input data, Moldflow do not know that.
how can the calculation give a results, that higher than the Input?
You are correct, the E1 and E2 (etc.) in the material database, are derived from an experimental sample, and you are right, will not be fully alligned. Moldflow can however, use these datapoints (including the level of anisotropy) of the composite AND the Fiber mechanical properties, to derive the properties of the matrix.
These calculated matrix properties, the calculated fiber orientaiton and the fiber mechancial properties can then be used to calculate the mechanical properties in the product.
As you indicated the fiber orientation in the product may be substantially higher than that was introduced in the dog bone, and therefore the maximum calculated mechanical properties can be substantially higher than the measured fiber orientationin the dog bone.
Product Manage for Autodesk Simulation Moldflow products
I also have a question regarding micro mechanic modeling. According to the literature (e.g. [Tuc99]), almost all micromechanic models require the following input variables:
- isotropic (or anisotropic, e.g. in the case of Mori Tanaka) stiffness parameters of the fiber
- isotropic stiffness parameters of the matrix
- fiber volume fraction Φ
- the fiber’s aspect ratio (length/diameter)
But i can't find the isotropic stiffness parameters of the matrix in the MF material description ( tab "mechanical properties" in the MF material database). As described by Hanno above, the anisotropic stiffness values determined by tests are used for the halpin Tsai calculation. But accordung to [Tuc99] the Halpin Tsai equations (as well as the equations of Tandon Weng) need an isotropic stiffness value (young modulus) for the matrix. So now I'm a bit confused. Where can I find the isotropic matrix properties in the material database.
best regards from Germany,
[Tuc99] Tucker, C.L., Liang, E.: Stiffness Prediction for Unidirectional Short-Fiber Composites: Review and Evaluation. Comp. Sci. Tech. 59, pp. 655-671 (1999).