Who can guide me through a Fourier Transformation in Patran/Nastran? To run a modal transient analysis I need to know which modes are dominantly participating.
Thank you.
I am doing an impact simulation on an electronic housing. The material is an injection molding ASA grade with enhanced toughness and heat resistance.
Any recommendations regarding material properties required for this analysis?
Additional to the usual, Young’s Modulus, Poisson’s Ratio...
MLoew,
How does this capability in MECHANICA work?
I fully agree, I would not trust comparing results from models that had unknown or different convergences either. But we are still talking linear and convergence in respect to mesh discretization – regardless h- or p-elements and assuming a...
Yes, as we know the output of a finite element analysis is always as good as the input and the input is a lot of guesstimate especially when it comes to boundary conditions, loads, connections or lovely homogeneous material. Results are always to be seen relative. And regarding the issue of...
Hi all,
I recently read in the MSC.Dytran users guide:
Euler with shear strength used to model
- Solids with large deformation
- Viscous fluids
- Viscous gases
Ok, a gas can exert a tangential (shearing) force on a surface, which acts like friction between solid surfaces. This "sticky"...
Hi all,
Can someone explain to me why ones would build a finite element solid model with a shell skin? Is it for more accurate answers on the surface? How does one determine the shell thickness to get the most accurate answer bearing in mind not to add too much material or additional stiffness...
feajob,
back to your original question:
I agree with gelu (check for coincident nodes, boundaries: free edges, duplicate elements, elements distortion: taper, skew, warp …, degenerated elements, check association of elements and nodes, element normals, connectivity, shade FEM) and with...
I recently had a NASTRAN model with CQUAD8 shell elements. The model was perfectly correct, but I still got the FATAL MESSAGE 9050. I then changed the CQUAD8 to CQUAD4 and the model ran through. A possible explanation for this as follows:
... boundary consists of p-element edges along an...
feaude
You are right. Von Mises stresses - always a positive number - convenient and commonly used, works well especially for ductile material. But depending on the material and problem you wouldn’t always rely on the von Mises stresses. Think of a concrete or other composite structure where it...
Nastran calculates the stresses at the top and the botton of the shell at the fiber distances for stress calculations Z1 and Z2 which are t/2 if not differently specified by the user. The definition of top and bottom obviously depends on the element definition (element normal, face 1 and face2)...
Thin shell elements (ie. Bending stiffness included but shear stiffness infinite): thickness < 5% of other dimensions
Thick shell elements (ie. Bending and shear stiffness included): Thickness between 5% and 10% of the other dimensions.
Using the shear stiffness on elements < 5% thick will not...
