1 Reply Latest reply on Mar 22, 2012 10:02 PM by Max P

    Min FOS: 1.$ problem with composites

    Max P

      I'm a student and I'm just beginning to get to grips with SolidWorks, but I've hit a bit of a snag that I can't find any reference for.

       

      Let me provide a really simple example of a 1.2m dia x 2m long cylinder, made of a simple revolved surface.   In the simulation it is specificed as 6 layers of carbon fiber/resin, each 0.253mm thick and layed-up in different directions (1deg, 89deg, 75deg, -89deg, -75deg, -1deg).

       

      The bottom of the cylinder is fixed and a pressure of 10psi is applied to the inside of the cylinder. The cylinder should be plenty strong enough for this.

       

      I run the simulation and everything looks good until I add a Factor of Safety result. This is what I then see:Part1-Study 1-Results-Factor of Safety1.jpg

      Does anyone know why the "Min FOS" is reading a very unhelpful "1.$" and why the scale is showing numbers so ridiculously large?   Surely the structure isn't *that* strong...

       

      Thanks for any guidance you can offer.

       

      -MP.

        • Re: Min FOS: 1.$ problem with composites
          Max P

          Okay, silly me, I was using an isotropic material definition, not an orthotropic. Changing that seems to have fixed the "1.$" prolem, but I am still getting incredibly high FOS values that are just hard to believe.

           

          I'm guessing that the custom material definition I'm using has some bugs in it... So I'm changing my request for assistance:

           

          Is there anyone on the forum here who is using IM7/8552 who would be willing to check and correct my material definition?

           

          Elastic Modulus in X: 1.587e+011 N/m^2

          Elastic Modulus in Y: 8780000000 N/m^2

          Elastic Modulus in Z: 8780000000 N/m^2

          Poisson's Ratio in XY: 0.322

          Poisson's Ratio in YZ: 0.322

          Poisson's Ratio in XZ: 0.322

          Shear Modulus in XY: 4570000000 N/m^2

          Shear Modulus in YZ: <Blank> N/m^2

          Shear Modulus in XZ: <Blank> N/m^2

          Mass Density 1530: kg/m^3

          Tensile Strength in X: 2528000000 N/m^2

          Tensile Strength in Y: 70100000 N/m^2

          Compressive Strength in X: 1529000000 N/m^2

          Compressive Strength in Y: 1529000000 N/m^2

          Shear Strength in XY: 88400000 N/m^2

          Yield Strength: 2528000000 N/m^2

          Thermal Expansion Coefficient in X: -0.3 /K

          Thermal Expansion Coefficient in Y: -0.3 /K

          Thermal Expansion Coefficient in Z: -0.3 /K

          Thermal Conductivity in X: 0.061 W/(m·K)

          Thermal Conductivity in Y: 0.061 W/(m·K)

          Thermal Conductivity in Z: 0.061 W/(m·K)

          Specific Heat: 1850.57 J/(kg·K)

          Material Damping Ratio: <Blank> N/A

           

          No tables/curves defined.

           

          Thanks.

           

          -MP.