CompositesWorld
Issue link: https://cw.epubxp.com/i/546021
AUGUST 2015 12 CompositesWorld DESIGN & TESTING ยป Te choice to design with composites is often driven by market demand and cost. Te promise of mass reductions, performance improvements and material and assembly cost reductions is enticing, but realizing a design with fber-reinforced plastic (FRP) remains challenging. As FRP become the material of choice, based on design potential, traditional methods of analysis, design and manufacturing will not sufce. Based purely on the nature of the material itself, a composite design must be optimized not only for fnished part performance but for manufacturability as well. Specifcally, analysis and design must be performed in the context of the manufacturing process. Terefore, composite design requires a serious commitment to what I'll call concurrent engi- neering processes. FRP parts are "inseparable assemblies" made up of tens to hundreds of plies that vary in number, and therefore thickness, across the desired part geometry. A combination of the part geometry, the material form and the manufacturing process afects Designing with composites: Optimizing for performance and manufacturing FIG. 3 A vector fber feld is displayed on the CAD part that represents the variance between the analyst's desired fber orientations and the orientations mapped/defned during the detailed design phase. The vectors are shown in blue, yellow and red, depending on the degrees of variance, where blue is little-to-no variance and red is greater variance. The visualization depends on the desired amount of tolerance. Source (all fgures) / Siemens PLM Software FIG. 1 The image at upper left is the part in CAD with a single ply's fber orientations displayed in white, yellow and red (the colors indicate progres- sively signifcant "deviation from desired") that resulted from the simulated manu- facturing lay-up process. The lower right is the part in CAE displaying the same ply's fber orientations passed from the CAD model after the manufacturing simulations. FIG. 2 The part in CAD can have the manufacturing process defned, refned and simulated to determine the best method with which to produce the part and how best to meet the analyst's desired fber orientations. These two images demonstrate two diferent methods used for hand lay-up and the afect each had on the fber orientations in blue, yellow and red. Yellow and red show deformations, where red indicates actual wrinkling of material. FIG. 4 Consistency in manual lay-up can be assisted by both standard laser projection and with plybooks that display the simulated manufacturing process that was used in CAD to obtain a fat pattern. The plybook features drawings (example shown here) that shows one or more boundary views and a fat pattern view. The boundary views can display the simulated manufacturing process, in orange, that was used to derive the fat pattern generated for lay-up. the fber orientations within the part; therefore, understanding all three characteristics is critical during the design phase. Fibers that deviate from the analyst's defned orientations will afect structural performance due to a signifcant impact on modulus and strength. In addition, in-plane or out-of-plane deformations that occur during production will result in increased manufacturing cost and efort to resolve issues downstream. Preliminary analysis of composite parts is often performed based on idealized geometry and fber orientations that meet loading conditions. However, without the understanding of fber deviation, material knockdown factors are used to reduce the material's mechanical properties. Te result is an overbuilt composite part, which neither achieves the structural perfor- mance nor the desired mass reductions. Virtual visibility into the deviation and deformation of the material during the manu- facturing process can minimize the risk of overdesigning parts. Often referred to as "simulation of manufacturing producibility,"