The stiffness matrix for the workhouse quad shell element in ANSYS (until shell181 came along) SHELL63 consists of a superposition of the stiffness matrices of 4 DKT (triangular) elements. Many commercial codes have shell elements like this..which is what I think he was talking about.
Prost,
The superconvergent-like behavior of stresses at Gauss points for Q4 or Q8 elements is shown to be true in many textbooks..for example look on page 231 of Cook fourth edition. My example gave the reason for this and was actually taken directly from Cook.
The reason that the statement is often made that stresses are more accurate at the Gauss points, even for linear problems, is that for elements like Q4 and Q8 the stresses are superconvergent and their accuracy is comparable to the accuracy of computed displacements.
For example impose on an...
Not sure what you mean by full-blown RANS..the act of averagin g the Navier-Stokes equations introduces unclosed stresses which is why you need turbulence (closure) models. So full-blown in the context of RANS always means some sort of closure approximation. Maybe what you meant was full blown...
How can you explain shear locking without "spraying equations all over the page" ? You need to at least write the expression for strain energy or at the very least the expression for shear strain for the concept to make any sense.
Some of you sound as if you are afraid of mathematics. You...
I think one of the the basic questions here is whether or not the oscillation of the flag is fundamentally a forced oscillation or self-excited instability. If it is the former than the flag should be fluttering with a frequency near one of the fluid frequencies. For example if it is due to...
In FEM for fluids the strong form of the equations (differential equations) are converted to the weak form via the Galerkin method. These are the integral forms you are seeing. Then to get [K] these integrals are numerically integrated using some sort of quadrature scheme. This has to be...
