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Just to clarify the process, you cannot duplicate directly a spring property. You cannot also create a spring with the same name (as appearing in Name textbox).
Also, there’s no need to replicate the same spring without NL properties, in linear analyses only linear properties are considered; the NL properties set act only in non-linear analyses.
To conclude, you’re able to create a new spring with a different name by re-setting the properties.
ps.
If your spring don’t have zero length, maybe a local coordinate system (local CS) is suitable for you.For the model: you don’t get 0 stress for the NL model – you’re at time 0, select the last time and you’ll see the results.
ps2
if you’re trying to hang the box by an upper node, maybe you’re looking for a hook spring.Hello,
to correctly use the Spring properties mask, please follow the subsequent steps:
– choose a spring name and then click “Add property”; you created and empty spring
– then, the spring is selected and active on the left box. Change its properties as you wish
– click on “Modify property” to store changes.
By now, removing NL dofs is not supported. We’ll add this to the check list for next updates.For the second issues, please share models to let us check. You may upload them there, or load them at the bottom of the Support page.
Yes, this could be the reason – the option “Shear deformation of beams” is equivalent to assing noShearK=1 to all beams.
Hello,
Pdelta transformation in OpenSees is supported only for elasticBeamColumn and not for ElasticTimoshenkoBeam. Simply add “noShearK” equal to 1 in element properties.
ps.
there’s no change in behaviour of previous versions.It is not a matter of Poisson’s ratio, it will only affects mixed terms of the Jacobian and shear modulus – it’s the same Young modulus valid for stresses in both direction.
To have a numerical proof of what I’m saying, please try releasing x boundary condition on node 2 – you’ll see in results the gradient with a lower sxx around node 2.Hello,
you cannot expect the beam-like behaviour from thermal distorsion in shell elements – the stress is higher since the therma distorsion is applied in both directions and plane directions in shape functions of the shells are tied together, hence you’ll have an additional quota of restrained isotropic stress.ps.
to same the model in the same folder where .py script is, you can use:
# Save the model, including analysis results
dir=os.path.abspath(os.path.dirname(__file__))
print(“Model saved in ” + dir + “\\” + model_name)
nf.saveModel(dir + “\\” + model_name)# Call the app and open the file just created
nf.startDesigner(“\”” + dir + “\\” + model_name + “\””)Dear Luciano,
in shell elements, the uniform thermal distorsion by temperature is applied in both plane directions, hence you cannot expect such value – maybe a monodimensional element is more suitable in this case.It seems you have the command “More stations” active. The display options options is valid only with the standard 5 stations.
Hello,
thanks for pointing it out, this will be corrected in the next patch – you’ll be allowed to select a point out of known addresses.You wrote:
“So, we may conclude that, although the implemented finite element has the advantage of avoiding stress concentrations and peaks (which is the case in many situations, for example concentrated loads on shells), if there is some real peak, we must use a refined mesh, with very small size.”Yes, and this is the desired behaviour. The element is linear (4 nodes); results in the middle of the span are quite good, while at fixed supports you have actually only 1 element to represent the transition from positive to negative moment.
Hello,
it seems that the latest version has been compiled with uncompatible runtime libraries. Please check this version out (https://shorturl.at/loEGI), which has simply been recompiled from the original source code against vc2015 libraries.Dear Luciano,
thanks for your inquiry. Despite the theoretic shell behaviour is well-known, numerical applications with shell elements need a lot of care in implementation, because results can vary on the base of adopted mesh, element formulation, and so on.
In particular, we use MIC4 shells for quad elements, which are integrated also along thickness. They have the advantage of avoiding stress concentrations and peaks, which are very unlikely in reality. You’re comparing a theoretical result (peak values, max and min) with an approximate solution – you get such a difference with 10×10 shell model, if you use a 20×20 you get Mmax=7.58 and Mmin=-15.47 (hence you get closer).
Therefore, the way is to use more shells – unlike beams, their results are strongly mesh-dependent.
ps. other solvers (you can try with OpenSees) gives the same results.
ps2. you can get nodes on sides of the shells (to apply BCs) without counting them with
https://nextfem.it/api/html/M_NextFEMapi_API_getNodesOnSides.htm