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Recent content by torpen

  1. torpen

    Welding

    Hello, This article can be helpful: www.aws.org/wj/supplement/Weaver/ARTICLE2.pdf For a fillet weld, the required conditions are as follows: 1) equivalent stress < tensile ultimate strength / (beta_w * gama_M2) 2) normal stress prependicular to the weld throat < 0.9 * tensile ultimate...
  2. torpen

    FEA results and correlation

    Hello, In your case (linear static response of an elastic structure), the accuracy of the results obtained by a FE analysis depends mainly of the data (boundary conditions, loading, material properties). That means most of it you have listed as 'correct'. If the data are 'correct', you can...
  3. torpen

    Augmented Lagrange

    Hello, The aim is to introduce kinematic constraints between dofs (contact, rigid body, hing joint, equality, ...). U* = U + 1/2*p*phi^2 + k*lambda*phi where, k is a scale factor and phi is the kinematic constraint. We consider 2 one-dimensional rods. 1 ____ 2 3 ____ 4 Node 4 is fixed...
  4. torpen

    Transition from 3D elements to 2D elements

    Hello, Your FEA code allows to connect shell to solid elements with the constraint relation called RSSCON. Another basic solution is to write the kinematic constraints between the dofs of the facets of the solid elements on both sides of the shells and the rotational dofs of the shells. The...
  5. torpen

    Heat transfer through foam.

    Hello, This AIAA paper seems to be interesting: http://www.box.net/public/qsbegq1b75 Regards, Torpen.
  6. torpen

    Modal Analysis

    Hello Greg, The initial question of this post was to explain the practical usage of mode shapes. That's why I propose the Modal Assurance Criteria which uses mode shapes to compare two models. MAC is an possible and useful (in my experience too) usage of the mode shapes. Regards, Torpen.
  7. torpen

    Thermophysical Props of Polyalphaolephin (PAO)

    Hello, Here : http://www.matweb.com/search/Search_Lubricant_Metric.asp Regards, Torpen.
  8. torpen

    Modal Analysis

    Hello, You can calculate the Modal Assurance Criteria (MAC) between two sets of modes. This can be used to compare the vibration modes of a condensed model (superelement) with those of the original whole model. Regards, Torpen.
  9. torpen

    3D static finite element analysis benchmark?!

    Hello, you can find example solutions of Poisson's equation in 1-d and 2-d at the following link : http://farside.ph.utexas.edu/teaching/329/lectures/node60.html Regards, Torpen
  10. torpen

    choked flow pv=zrt Shouldn't gamma be corrected?

    Hello, We consider a fluid as a mixture of perfect gases. The inputs are Z, Cp, Cv and gamma. These parameters are defined as follows: Cp = Cv+Z*R gamma = Cp/Cv Cp/R = gamma*Z/(gamma-1) gamma = 1/(1-Z*R/Cp) They vary at each point of the flow. The equations of state are written as: p/rho =...
  11. torpen

    choked flow pv=zrt Shouldn't gamma be corrected?

    Hello, The relations you have written hold for a mixture of perfect gases. Z indicates the total number of particules after and before dissociation. For example, Z = 1.2 means that 20 % of the molecules have dissociated. For molecules the internal energy per unit mass is equal to sensible...
  12. torpen

    Damp material conductivity

    Hello, The beginnings of your answer can be found in the following empirical formula : k_wet = k_dry + w * k_wet where, w (kg/m3): water content k_wet (W.m2/kg/K): proportional factor Some values are given below : k_wet w expanded polystyrene...
  13. torpen

    Mechanica thermal problem

    Hello, If you cannot set the initial temperatures of these bodies in Mechanica and then just allow the heat to flow (it seems to me very strange that it is not possible), you can apply (for example) a convective heat flux on the nylon with a very low heat transfer coefficient. And perform your...
  14. torpen

    Thermal stress analysis

    Hello, A 3D structure has 6 rigid body modes whatever the finite element type. You can perform a free-free modal analysis and check the first eigenmodes to verify what cbrn said. Regards, Torpen
  15. torpen

    lumped parameter method, with flux at surface

    Hello, The lumped capacitance method supposes negligible gradients at any instant during time (spatially uniform temperature). With the Fourier’s law this condition is impossible unless the thermal conductivity is infinite. However this condition is approximately satisfied if the resistance to...
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