8 Replies Latest reply on Mar 22, 2012 10:45 AM by Agnes Uijttewaal

    plastic nonlinear data

      I have been doing some simulations with plastic parts and am wondering if there is a good resource somewhere to get nonlinear stress/strain curves for various materials. Matweb has a lot of material data, but I haven't seen any type of nonlinear information.

      I am sure many others have done simulations with nonlinear materials... does a person always have to get their material tested in a lab?

        • plastic nonlinear data
          I am interested in this as well. We have just started trying to work in this area more.
          • plastic nonlinear data
            Robert Stupplebeen
            In general to get good material data you have to create it yourself. I am sure that some vendors provide reliable data including various nonlinearities however I have found many do not. Most provide only a modulus. I have found experimentally E to be off by 50% relatively often. In short don't trust the data unless your FEA correlates with an experimental test or you have compared the vendor data with some you created your self. I hope this helps.

            Rob Stupplebeen
              • plastic nonlinear data
                laurent klopfenstein
                hi,

                we are doing many nolinear simulation with plastic part, and most of the time we are taking the Von-mises curve from Campus. We have to creat each time the material ! it not the best but after a couple of month we have most of them available.
                Of course ba doing this we are considering the Part as isotropic and have to take some safety coeficient ( about 10% below the limite given in Campus ).

                I did an overview for the limit we are taking depending of the situation and the typ of constraint ( see attachment ).

                regards
                  • Re: plastic nonlinear data
                    Derek Bishop
                    I think if you want accurate properties at a range of temperatures the universities are a good place to start. I've contacted a local university and they've expressed an interest. I noticed that a plastic pipe supplier has highlighted in their discussion on HDPE that Young's Modulus is time dependent. Maybe another thing to test.
                • Re: plastic nonlinear data
                  Derek Bishop

                  Doing some design work with plastics at the moment also and am having the same problems with material properties. And yes the plastics suppliers don't seem to be much help. Matweb has got a lot of rubbish on their site and trying to find the good stuff is tricky when you are looking at anything a bit unusual. Worth a try anyway. So it looks like organising some test work is the order of the day especially if you are going to look at properties at different temperatures. I remember at uni one of the blokes was doing a project on testing plastics. He had a wood box and some pieces of plastic beams simply supported. The box was insulated and could be heated. You hung a load off the centre of the beam and recorded the deflection. This could be used to work out the elastic (or is it flexural) modulus. Its slightly different to a standard usiaxial tensile test but its probably better than a lot of the stuff you get off the net.

                   

                  This is my first post on this new forum. Why are all the letters going wonky? No I haven't had too much to drink.

                  • Re: plastic nonlinear data
                    Joe Galliera

                    CAMPUS: http://www.campusplastics.com/

                    Interactive version is called WebView, but also I recommend downloading and installing their offline version, WebUpdate.

                     

                    Atlas of Stress-Strain Curves (mostly metals), where SWS gets its curves from: http://books.google.com/books?id=up5KS9fd_pkC

                     

                    Aerospace metals, formerly called Mil-HDBK-5: http://tinyurl.com/l5583b (70.4 MB zip)