12 Replies Latest reply on Jun 26, 2014 12:08 AM by Jared Conway

    the difference

    Sinta Fajrian

      dear,
      i want to know what is the differences between linear dynamic analysis and nonlinear analysis. also i want to know the difference between isotropic and anisotropic material. thanks

        • Re: the difference
          Shaun Densberger

          Well, there is nonlinear static and nonlinear dynamic; which do you mean?

           

          Static/Dynamic means Time Independent/Dependent. For example, imagine you have a mass-spring-dampener system at rest and then you set another mass on top of it. A static analysis will give you the new conditions when the system is at rest; a dynamic analysis will give you the conditions going from the initial state to the final state.

           

          Linear/Nonlinear relates to the physics being simulated. Everything in the real-world is pretty much nonlinear, but under the right conditions, a linear model will provide a (very) good approximation. Common nonlinear conditions are material (elastoplastic, hyperelastic, viscoelastic, etc), path dependent solutions (contact and friction), geometric (large displacements and strains, follower forces, etc.), and coupled systems (fluid-structure interaction for example).

           

          You can have any combination between the two sets, giving four types:

           

          1. Linear Static
          2. Linear Dynamic
          3. Nonlinear Static
          4. Nonlinear Dynamic

           

          Which one you'd use depends on what you need to capture in your system from a solution standpoint.

           

          Isotropic materials are those who's properties are direction-independent. In a cube of homogenous A-36 steel, the Young's Modulus, Poisson's Ratio, density, etc. is completely independent of the direction. If there was a XYZ coordinate system at the center of the cube, then the material properties will be the same whether I move along the x-axis, the y-axis, the z-axis, or some combination of the three.

           

          Anisotropic materials are the opposite of isotropic materials; the material properties are direction-dependent. A good example of an anisotropic material is wood.

          • Re: the difference
            Jared Conway

            just to add to this, the defintiions used in solidworks simulation are the standard defintiions for both

             

            it might help if you give us the context of your question so that we can answer in context rather than just defininig the definitions

            • Re: the difference
              Sinta Fajrian

              thank you Shaun Densberger and Jared Conway.

               

              I’m so glad that you respond my question. Usually, I just use CAD of Solidwork. But now, I have to validate my design using SolidWork simulation. So, I’m a beginner. Thank you ... for explaining me what i’ve asked. But, i still don’t understand how they are work for simulation.

               

              Here is the description about the design project that will validate by CAE in solidwork.

              There’s a building which has a front yard. The yard will be covered by canopy, so it will be protected from sun or rain. But the canopy planned can be opened using sliding mechanism.

              The concept:

              1.jpg

              The canopy us planned to be divided into 7 segments. There’re 3 segment which fix, and 2 segments (for each left and right) which sliding. Slide mechanism helped with wheel and rail. And the actuator used for automation is motor and for pulling the sliding canopy, i use wire rope.

               

              Here is the free body diagram for the sliding canopy

              2.jpg

               

              The motor constructed to has 2 direction (clockwise and counterclockwise). When the motor turn counterclockwise, the sliding segments will make the canopy close and if the motor turn counterclockwise, the sliding segments will open.

              The Question:

              1. If we ignore the resistance that caused  by the wire rope, can we simulate the movement caused by the weight of the 2 segments of canopy (W1), slope 10 degree, and the gravity?
              2. If we ignore the wire rope, the acceleration (a) tends to move to the right. But if we expect the acceleration (aa) to move to the left (caused by wire rope), and the aa is slower than a, can we still simulate the movement and make sure the canopy will open when we stalling the wire rope?
              3. If you look the concept, what kind of validation that i can use?

              here is the modelling that i've done:

              4.png

              here is the joint

              5.png

              here is the building

              3.png