## General Mechanical

#### Determination of the volume change of a shell-structure due to an inner load

• Christijaaan
Subscriber
Hi, ndoes anybody know if there is a function which enables the determination of the inner volume change delta_v of a shell structure due to an inner static load (static mechanic case). I was thinking about a function which has an output like displacement of a surface in normal direction - > apply on the surface areas of the inner elements - >This values times the surface area itself gives a volume change. A math integration over the whole area of interest should give the volume change... Is there an area function as described above available? Or is there an easier way to do all this? nThanks in advance to everybody und greetingsn
• HuiLiu
Ansys Employee
There is no direct way of output what you are looking for. If there is no volume (solid element) inside of the shell structure, there is nothing to output. For the workflow that you described, you can check out the ARNODE(N) and NORMNX/Y/Z(N1,N2,N3) get functions, which get the area of node and normal directions defined by 3 nodes. For a full list of get functions, see thislinkfrom APDL user's guide. Hope this can make your calculation easier.n
• Christijaaan
Subscriber
that sounds as to be a nice feature for my problem. Thank you very much. Will try it out. nFurthermore...nDo you have any suggestion for an APDL function which gets the displacement of a node / surface in normal direction? I did it ones for selected nodes by placing user defined coordinate systems within every single node and orientate the z-axis by normal in click-point in the really near surrounding (as near as possible). Last step was to define a solution (one for every single node) which gets the diplacement in local z-direction. That felt like a work around... isn't there any function which makes it easier?n
• Christijaaan
Subscriber
Does nobody alse have an idea? When I first thought about that problem, I was pretty sure that there was a standard solution available ...n
• peteroznewman
Subscriber
nThere is a FLUID221 quadratic tetrahedral element. If your shell mesh was quadratic triangles, you could fill the volume with FLUID221 elements that shared the outer surface nodes with the shell elements.nThe volume of the FLUID221 element is an output result quantity: VOLU.nFor a completely different approach that does not require meshing the volume, read this discussion:nThis approach uses an element called HSFLD242 but you don't mesh the volume, you just need a node on the inside and have a named selection to all the element faces that enclose the volume.n
• Christijaaan
Subscriber
nThank you so much. Both ways seem really worth a try. Really cool!n