Composites in SolidWorks Simulation by Brian Zias
Have you ever considered a composite laminate as a design option? With the ever-increasing power of
SolidWorks, we now support composite laminate materials inside
SolidWorks Simulation to help create and test optimum designs. While we've had this capability inside COSMOS for awhile, this new module makes this tool accessible directly inside the
SolidWorks window.
Used for decades in the automotive and aerospace industries, composite materials are seeing widespread adoption by other industries concerned with creating optimal designs, lowering manufacturing and shipping costs, and providing increased quality to customers. Moving forward you can expect structures technology to adopt composite materials even more. They offer tremendous benefits, specifically in weight to stiffness cost, fatigue and corrosion resistance, and geometric flexibility. Not to mention the capability to embed secondary systems inside of primary structure (e.g. smart structures with embedded strain sensors/accelerometers).
With SolidWorks Simulation 2009, engineers and designers have the ability to immediately explore composite laminates as a material choice. The initial viability testing of such a material choice can be accomplished in a matter of minutes. It just might be the key to saving weight on your next design or expanding into composites as a material choice.
Traditionally, the setup of such composite simulation has been painful. Setup of ply orientation, local coordinate systems, and materials has been reserved for composite analysis specialists. In SolidWorks Simulation, the composite structure is based on a surface body. All the user needs is a surface body that represents the midplane of the laminate. Simulation can use that body to completely define the local coordinate systems.
As an example, below is a case study of a snow ski. Modern skis and snowboards are what we refer to as "sandwich" structures (I am getting hungry already). There is a ‘face' on both the top and bottom, respectively, and a middle core. The faces typically provide planar stiffness, while the core reacts out of plane bending. In this example, typical of modern design, the faces are made from composite laminate, and the core is wood (Balsa).
Figure 1 - SolidWorks model of snow ski
The ski is modeled in SolidWorks as three bodies: one solid to represent the wood, and one surface for each top and bottom laminate. Note that each surface body can represent many layers of laminate.
Figure 2 - Snow ski close up, with Simulation Interface
Figure 3 - definition of the layup
The angle is the ply orientation, and represents the direction of the fibers on a particular layer. These orientations can be arranged to create the optimal stiffness and strength for a given application. The complete visual feedback and automatic element orientation makes this software unique in the industry. Here a designer will easily be able to iterate layer choices: how many, what material, and what orientation. This is done until performance goals are met. Each layer can have a unique material and thickness.
Figure 4 - Displacement, 300 lbf static load
Figure 5 - Factor of safety, 300lbf static load
The results of a static test are displayed above. Besides the usual displacement and stress results, we also implement the Tsai-Hill, Tsai-Wu, and Max. Normal Stress failure criteria for plotting factor of safety. These are industry standards. Keep in mind that the mechanisms of failure for composites are many-fold. While this may predict stress failure, many factors ultimately contribute to composite material failures in the field: environment, damage, complex loading, etc. Our results indicate to the designer that the second play is the critical ply, with a minimum FOS of 2.4.
I encourage any designer who is concerned with weight, or interested in jumping into the next generation of structures, to explore composites. This functionality is included in the Simulation Premium package only.
Also remember that to fully exploit the capabilities of composites, you have to think outside the box. It's not about replacing every aluminum sheet with a composite sheet, it's more about rethinking the way you can manage your loads and join your structures together. And as always, remember that FEA is used to validate a concept, and physical testing should always be an integral part of any development process.
Brian Zias
Application Engineer
Alignex, Inc.
bzia@alignex.com