thread1234-329957
Hi ALL
Thanks so much for the very helpful contributions on the first thread "Why do you like Femap?" I did not set it up but I did get quite a bit of dialogue going from a post I submitted.
After making my initial comment I was amazed at the responses, although I only got...
Hi Tg
I really appreciate your response.
However, my point is it should not have many ways to do something. It just creates clutter and confusion. Experienced users are never the issue as they can adapt to simplifications very easily. I agree that the model info tree is a very nice addition...
Femap ... Overcomplicated to use!!!
I have been a PATRAN user for many years and while it has limitations in features it is easy to use.
FEMAP has way too many options and redundancies ... many ways to do one thing !!! ... clutter !!!!
There are too many mouse clicks and menu popping required...
I have found smoother stress gradient results from this approach in the past i.e. if you look at un-averaged values.
However, I have also had difficulty at times trying to get this to work in non-linear problems (i.e. surface contact and large displacement) mainly due to the 2D elements away...
The reason to do this is not to help resolve poor solid meshing. A 3D solid element calculates the stress away from the boundary and extrapolation is required, no matter what!
My point is merely an approach to assist in getting stresses calculated on the boundary itself. That's all.
If can also...
I would use membrane elements, if possible, but there may be issues with these in terms of acceptable warp if the solid shape has complex curvature. Otherwise, I would use shell elements because they are more liberal in accepting geometric issues.
Having similar nodal boundaries addresses the...
A clarification on the previous point
I have always used the same material property for the 2D elements as the solid elements but small thicknesses for the geometric properties. If you use a different material property you need to make adjustments to the thicknesses to arrive at the same...
No problem Johnhors ..
A useful approach for interpreting stress levels on the boundaries of 3D solids is to "skin" the boundary with 2D face elements. However, you do need a pre-processor (like PATRAN) to achieve this if it is a complex solid. The idea is to create 2D face elements on the...
Gauss Points or Node Points for stress interpretation ....
In my experience of displacement based elements I find that nodal extrapolation of element stresses give higher stress values for many structural applications. Although the mathematical correctness of stresses and strains at gauss points...
just a few more words on this issue....
stress based elements (actually the assumed field is a force distribution) were initially developed for the aircraft industry and they work very well in that environment because the important parameter across element boundaries is equilibrium of forces...
ABAQUS or MARC ?
I have used both programs in the past for contact problems. In fact we bench marked MARC with ABAQUS and found MARC was not able to handle some of our complex non-linear problems. These included non-linear geometry, material, and contact. In all instances we got answers from...
MSC have really dropped the ball in terms of their core programs (Patran and NASTRAN). Minimal enhancements over the years have cost them dearly. PATRAN is not a native PC product and as such was doomed from any significantr enhancements unless a re-write was carried out (come in Bangladore)...
Modal Analysis - What to look for!
As mentioned previously, fundamental natural frequencies of a structure should differ from those of the forcing function to avoid being excited and causing excessive motion. It is important to distinquish between local and global modes. Modal effective mass...
