Re: [Libmesh-users] Integration points through the thickness for shell elements

[Benjamin W. S. <ben...@in...>]

It's pretty standard for shell elements to have multiple integration points through the thickness at every in-plane integration point. Integrating the response through the thickness allows you to represent the variation in the nonlinear constitutive response of the material through the cross-section, and come up with resultant quantities at the locations of the in-plane integration points, which are then integrated using standard procedures.

I haven't really gotten too far into this yet, but I don't think accommodating those extra integration points would involve changing how the integration rules or data structures would work in libMesh. I think you would just evaluate vectors of properties at the standard integration points, with each entry in the vector representing a different point through the thickness. We are just getting started on the path of developing shell elements in  MOOSE, so our group will be looking into how to handle this.

-Ben

On 11/14/18, 8:19 AM, "John Peterson" <jwp...@gm...> wrote:

    On Tue, Nov 13, 2018 at 11:22 PM Yuxiang Wang <yw...@vi...> wrote:
    
    > Dear all,
    >
    > As one usually reads from literature (or commercial software
    > documentation), usually, a shell element would need >= 2 Gaussian
    > quadrature points through the thickness to capture its bending behavior.
    > For example, in the LS-DYNA documentation
    > <https://urldefense.proofpoint.com/v2/url?u=https-3A__www.dynasupport.com_tutorial_ls-2Ddyna-2Dusers-2Dguide_elements&d=DwICAg&c=54IZrppPQZKX9mLzcGdPfFD1hxrcB__aEkJFOKJFd00&r=hn5akMybrkn-1oiQB8nm_y7trT_BOQm9jBgbzQWwxXA&m=d16wjsgwuY6Xejdr47KKgE8srFi-kHjT92yv6KeNbt0&s=XxuqMBzy7V7pzqu5KNGEyqWuMwh-JQEAJerwVZsdQFU&e=> or
    > mentioned in this paper
    > <
    > https://urldefense.proofpoint.com/v2/url?u=http-3A__web.mit.edu_kjb_www_Principal-5FPublications_Performance-5Fof-5Fthe-5FMITC3-2B-5Fand-5FMITC4-2B-5Fshell-5Felements-5Fin-5Fwidely-5Fused-5Fbenchmark-5Fproblems.pdf&d=DwICAg&c=54IZrppPQZKX9mLzcGdPfFD1hxrcB__aEkJFOKJFd00&r=hn5akMybrkn-1oiQB8nm_y7trT_BOQm9jBgbzQWwxXA&m=d16wjsgwuY6Xejdr47KKgE8srFi-kHjT92yv6KeNbt0&s=tSn1-9z_P8T0uME2jwoYDUO7AQEElPc8f3IjxytF-EA&e=
    > >
    > .
    >
    
    I  guess I'm confused about what you mean by "thickness". Our SHELL
    elements are logically two-dimensional (have zero thickness) so IMO it
    doesn't make sense ask about integration in the transverse direction...
    
    -- 
    John
    
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