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  1. mastroit2002

    LINK AND BEAM Connection

    >How about Link and Shell in 3D (2D whatever)????? I'm not sure to get correctly what You mean: let's assume You do want to connect a 2D element shell like element with a 3D Lagrangian element (h-element not p-like element [Lagrangian vs Hermitian one] so only displacements are the unknowns)...
  2. mastroit2002

    LINK AND BEAM Connection

    The problem you mentioned could be solved using a foot like end at Your beam element end. Since only the displacements, not rotations, are the unknows on the general description of "normal" 3D element, one has to simulate generalized ratations via a differential displacements. The beam end...
  3. mastroit2002

    Nonlinear response of a cantilever beam

    >You were a bit off in the calculation of the fundamental >mode. There is a factor of 3.52 after you take the square >root for omega in your formula. Probably you are right: that was only for my by hand calculation (that is interesting that simply using all beam stiffness and mass reported to...
  4. mastroit2002

    Nonlinear response of a cantilever beam

    I agree with GregLocock: the finite element beam solver may be the kernel of the question. I tried to figure out the kind of problem You are solving and the way chosen for solution: I think that You are solving a transient analysis of a cantilever beam whose fixed point undergoes from time 0 a...
  5. mastroit2002

    Using FEA to design a press frame

    I will be glad to help You in this endeavour. From your website I got that the press You are design should enforce a laminate composite giving an appropriate curvature. My simple advice to save some money (I think that the whole structure weights more than one hundred kilos) colud be to design...
  6. mastroit2002

    More on solver speed: ROI of expensive commercial sw?

    Many thanks for Your prompt reply! I still have a question about the case study which really need speed perormances. GregLocock reffers fatigue life prediction and to input data to feed FEM model, while johnhors claims about FEA cost to product cost ratio. I liked the insight and I got clearly...
  7. mastroit2002

    Flowmaster, how good is it?

    We worked on the simulation of a cooling system simulation for design/optimization purposes. We tried the "Kuli" software for the same purpose, but soon it cameout that written in house simulation code was more reasuble, manageble, and simple. It was written in Matlab/Simulink, and from those...
  8. mastroit2002

    More on solver speed: ROI of expensive commercial sw?

    Dear Sirs, I'd like to ask You a new question on this topic which arises from the insight of given aswers. I guess that my opinion about solver speed issue was not far from true: on today computer near all static/modal problems cam be solved quite easly in a proportional to precision ammount...
  9. mastroit2002

    More on solver speed: case study

    Dear Sirs, I'm looking for an advice: is there a list of structural linear case study usable to test commercial FEM packages, like "driven cavity" or "facing step" for CFD codes. Another question: is solver speed cost effective in Your own activity? Is there anyone using a dedicated cluster...
  10. mastroit2002

    Optimisers

    >Reason I ask is that I have written one in matlab... I noticed that, since you were using Matlab and its functions, you were working with a gradient based optimization routine (like bi-conjugate gradient). As known those methods converge to a local stationary point (min/max) since those...
  11. mastroit2002

    torsional vibration problem

    Your problem is really interesting. It seems that you are looking for the time domain simulation of a structure as a response of step increment of load (10 kNm in 0.02 seconds). This behaviour seems due to milling operation starting: this load change could be simulated with an impulsive load...
  12. mastroit2002

    Sanity check of a stiffness matrix

    >The stiffness matrix at element level doesn't necessarily >to be no singular. Rigid body motion is removed after the >assembly. This settence is true but not so common: if one is working with element stiff matrix normally forgets the dof not elastically connected (see CROD element for nodal...
  13. mastroit2002

    Commercial FEM sw: solver improvement

    Now that is quite a long time I'm using FEM code, but there is still an opened question. In a fem job the a big amount of time seems to be used for linear system solution (from 70% to 90% in bigger problems). Now I know that MSC Nastran can solve both directly and iteratevly those linear...
  14. mastroit2002

    routines for nonsymmetric stiffness matrix with skyline storage

    I think that since you are dealing with a non-linear type of equation (as supposed in my previous post) you are looking for a solution that is some steady solution of a transient problem. A suitable way to find the solution is to follow numerically what nature does to find a solution: granting...
  15. mastroit2002

    routines for nonsymmetric stiffness matrix with skyline storage

    I don't know either if you are going to solve this problem in a direct or iteraqtive way, but matrix package could be useful to look for possible bugs even for sparse matrix (the Matlab built in solver for sparse matrix is iterative, I guess to be a Preconditioned Conjugated Gradient method)...
  16. mastroit2002

    simple free 2D CFD for uncompressible fluids ?

    I can give you only a "not so hard" way to solve the problem by yourself. I suggest to define in a easy way the physical zone you are interested in the computation, and solve the fluid via the potential equation with Poisson and finite difference method. This should be suitable to compute Cl...

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