Learning Forum

[ahm.eltaweel]

Hello,nI have strain gauges installed on the irregular surfaces in some experiments and I am simulating the same setup in Ansys workbench.nHow could I simulate strain gauges on irregular curved surfaces to request normal strain in the direction of the strain gauge?nI found a solution for flat surfaces by creating surface elements of the strain gauge area at the location of interest and by defining local coordinates system at the location of interest then request the normal strain at the strain gauge direction by averaging over the predefined surface element area, but is there a similar solution in case of curved irregular surfaces?nRequesting the normal strain at a certain node isn't reliable in terms of results accuracy. It's dependant on the predefined local coordinates which alter the results significantly. n

[1shan]

,nYou could try out a few things. First, you could create a surface element on the curved surface. You could do this in spaceclaim (by using project option) or any other modelling software and then follow the same procedure which you mentioned for the flat surface. Secondly, you could directly mesh the area where your strain gauge is attached with a very fine mesh (this would result in a lot of nodes in the strain gauge area and hence less/acceptable error). You could add a local refinement by using a sphere of influence in the local mesh size setting. Next you could create element or nodal named selections in this area and scope strain results to this named selections.nRegards,nIshan.n

[ahm.eltaweel]

Thank you for your reply.nI have a question concerning both options, how could I request the normal stress knowing that it is coordinates dependant, and in the case of a curved strain gauge it has a curved direction and not straight anymore? how to define the direction of the requested normal strain in the case of a curved strain gauge? n

[1shan]

,nYou could define a user defined local coordinate system (right click on coordinate systems>insert) aligned with the strain gauge axis and define a normal strain result in this new coordinate system.nRegards,nIshan.n

[ahm.eltaweel]

I know what you just explained, this is applicable for a straight strain gauge on a flat straight surface.nWhat about a strain gauge on a curved surface of irregular shape?n

[1shan]

,nCheck this https://forum.ansys.com/discussion/1839/stress-component-perpendicular-to-a-surface. You could orient the element coordinate system to follow a surface and a edge(right click geometry>element orientation). Once you do this you could request the result in this element coordinate system.nRegards,nIshan.n