5 Replies Latest reply on Jan 9, 2017 10:06 PM by Ananda Ganesh Madheswaran

    Creep Analysis for thermoplastics

    Richard Obrien
    Richard Obrien Mar 18, 2009 12:13 PM
      Is there a simple way to enter creep data into the material editor? When I choose "Include creep effect", I get a dialogue for (3) Creep constants (1,2 &3). From the help it seems Simulation uses the "Classical Power Law for Creep (Bailey-Norton law) which also has (3) constants (0,1 &2). Are they the same and in the same order? And finally, how do you derive these constants from standard isochronous stress-strain families of curves?
      Thanks
      Rick
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        • Creep Analysis for thermoplastics
          Stephen Endersby
          Stephen Endersby Employee Mar 30, 2009 7:40 PM (in response to Richard Obrien)
          Hi,

          SW Simulation maps the constants as you assumed
          C0 = CreepConst1
          C1 = CreepConst1
          C2 = CreepConst1
          CT = CreepTC

          To calculate these constants you need two sets of time, temperature and stress results to produce a given strain. An example of this for stainless steel can be found here http://www.fanagalo.co.za/tech/tech_grade_310.htm .

          Once you have this data you have to solve the power law eqations as a set of simultaionus equations, so break out your old math books.

          I hope this helps.

          Regards

          Stephen
          • Re: Creep Analysis for thermoplastics
            Jose Eduardo Fernandes de Camargo
            Jose Eduardo Fernandes de Camargo Aug 18, 2009 11:25 AM (in response to Richard Obrien)

            Hello folks,

             

            Is everything ok?

             

            Could you please tell me if there's any source of creep datas?

             

            Best regards,


            Eduardo Camargo

            • Re: Creep Analysis for thermoplastics
              Jack Lynch
              Jack Lynch Sep 13, 2010 4:45 PM (in response to Richard Obrien)

              Bumping this old post.

               

              I have been searching and requesting data from our supplier (custom blender) and have come up empty on finding the proper time, temp, stress data on a 25% glass filled 66 nylon needed to calculate the creep constants.  I have been able to come up with a creep modulus chart (BASF Ultramid materies are one of the few that list this information) for various stress levels at different temperatures over a time period. Is it valid to just solve with the much lower creep modulus and not use "include creep affects" and the C0, C1, C2?

               

              For example the room temp tensile modulus is 1,200,000 psi. From this chart the room temp creep modulus at a 4,300 psi stress level at 10,000 hours is about 51,000 psi.