9 Replies Latest reply on Aug 31, 2018 2:26 PM by James Riddell

    Material Properties for Plywood Simulation

    Grant Devries

      Does anyone know where there is a good data base for plywood properties? I am trying to do a simulation on a plywood sofa frame and I need stress/strain properties in the x,y,z coordinates. The plywood I am using is 5 ply, 23/32 inches thick, southern yellow pine, and CC face grade.

        • Re: Material Properties for Plywood Simulation
          Chris Saller

          You would not be able to download a material properties for plywood. It's an assembly.

          As Bill mentioned, look up the wood in a handbook, model it's layer and assign properties to each one.

            • Re: Material Properties for Plywood Simulation
              Bill McEachern

              While I realize your comment was well intentioned modeling plywood as an assembly is probably not a good call. You can model it as an orthotropic material for many cases just as a single body. There are calculators that could provide the stiffness of a laminate based on the constituent ply properties. If you are interested in the failure of plywood you could model it as a laminated shell element in the sim premium product (still a linear analysis but that is where they have that functionality). For a very detailed analysis you could model plywood using continuum shell elements is say Abaqus or other programs that have that type of element. Either way it is not likely to be done as an assembly but I suppose you could do it in swx sim but it would not be very efficient.

            • Re: Material Properties for Plywood Simulation
              James Riddell

              I disagree with Bill McEachern, the wood handbook isn't what would apply here.  I'd suggest the standards from APA - https://www.apawood.org/publication-search?q=&f=Plywood as a start.

               

              As has been mentioned previously, you are looking into a composite material which is a very difficult topic to master and I have my doubts that SWX can even help.

                • Re: Material Properties for Plywood Simulation
                  Grant Devries

                  I agree that trying to simulate the plywood in SWX as a composite may result in unfavorable results. I would prefer to have data from a physical test. APA has data on material that is closely related to the material I use, but the modulus of elasticity is calculated using a static bending test and is listed as a single value. How does the MOE for static bending relate to an orthotropic material that requires material properties in the X, Y, Z coordinates? APA also does not include Poisson's ratio.

                  • Re: Material Properties for Plywood Simulation
                    Bill McEachern

                    My copy of the Wood Handbook has the APA numbers for stiffness and strength on pg 218, table 10-6. It states that the numbers are not to be used for design allowables. The fundamental theoretical basis for the analysis of composite materials came from the methods developed for plywood by the US Forest Products Laboratory in the 1930' and 40's. The whole theory of laminated composites from the rule of mixtures  on up derives its heritage from this work. So the simulation of plywood as a composite is exactly how its done for high fidelity. Further, the wood handbook has directional properties for various species. For example, table 4-1 will give you the ratio of the various direction moduli and Poisson's ratio's of various species.  Values for the the actual properties for various hardwood and softwood species are provided in table 4-3 a & b. As I mentioned previously, there are levels of approximation that can be used. If you type in "composite laminate calculator" into google various option appear (some are free) that will take the properties of the lamina and compute the laminate properties so that isotropic properties can be obtained for a well approximated stiffness based calc. FEA is a stiffness based method and hence deflections would be well approximated. You could up the sophistication of the calc by using the laminated shell element so that failure theories could be used to enable the proximity to failure to be evaluated.

                    The above discussion does not preclude that simplified methods to enable approximate solutions are promoted and used by specific industries. The exist even in aerospace level first pass analysis. These methods are based on an understanding of the theory and practice of laminated composite analysis.

                  • Re: Material Properties for Plywood Simulation
                    James Riddell

                    Grant Devries, two free downloads at the APA website - D510 & Y510, Everything You Wanted To Know About Plywood But Were Afraid To Ask.  (JK, that is not really the title but those are the two standards you would likely need.)

                     

                    You will have to register (for free) to download the documents.