# Normal and shear stress on liner - struct.liner.normal.stress(p,inode<,i>)

Dear All, I am looking for clarifications on the fish function “struct.liner.normal.stress(p,inode<,i>)”. Since this fish funciton is on the nodes and the nodes are share by a few liner elements, Is the normal stress obtained on node, “inode”, is only for one liner element, “p”? In another word, Is it correct to assume that the total normal stress on the node will be sum of those contributed by each liner elements which share the same node? I found it would be more useful if the normal (and shear) stress can be for each element at the center of the element, instead of on the nodes.

Our engineers have advised that the function you are referring to returns the normal stress value in the coupling spring at the node. This is given at the node because the coupling springs are defined at the nodes and not at the centre of the element. This is detailed in the manual. For further reference, the full HTML FLAC3D documentation set is accessible online via the following link - http://docs.itascacg.com

Thanks Karen! Could you please confirm the unit is kPa (it just feels odd to have stress on nodes instead of force)? Also Is it correct that the average of the stresses on the three nodes of the same element will be equal to the stress at the centre of the element?

If you refer to structure element internal stress, yes, we can plot them or output them by FISH. The FISH intrinsic “struct.shell.stress” and “struct.shell.resultant” do the job, which are for all available 2D structure elements since geogrid and liner are shell as well.

If you refer to liner normal stress, which is the interaction stress between liner the surrounding, they are through links, and thus at nodes.

The unit is stress unit (depending on which unit you choose in the model, e.g., Pa, kPa). You can plot link force as well. They are related by an area, which is generally the contributed element area around the node.

2 Likes

Thanks, Cheng!
I am looking for the liner normal stress. It is a good reminder that I can use link to plot or extract force. I guess there are two ways and should achieve the same results: (a) struct.link.model.force(p,3) (b) struct.liner.normal.stress() * struct.link.model.area(p,3), though some attention is required to find the same nodes.

Hello, Mr. cheng. I have some question about liner links in 3dec. how to understand ’ There are two types of links: (1) node-to-zone , which connect nodes to zones (not simply to gridpoints) '? for example, blocks in jointed blocks connect surrounding blocks by contacts and subcontacts. And how do links connect nodes to zones ? by what means? what is the object on zones connected by links? For liner, nodes on liner are connected by links, what about zones?