Modeling Tools for the Machining of Ceramic Matrix Composites (CMCs)

ABSTRACT:This Small Business Innovation Research Phase I project, Modeling Tools for the Machining of Ceramic Matrix Composites (CMCs), will develop and demonstrate the feasibility of physics-based modeling tools applied to the machining of ceramic matrix composites (CMC) the Air Force needs to machine critical CMC turbine components faster, more accurately, and with lower cost. At the program conclusion, TWS will demonstrate modeling tools capable of identifying the salient process attributes that will result in a 35-50 percent reduction in machining cycle times while maintaining tool life and improving part quality. This will be achieved through the advancement and application of both a detailed-level finite element modeling (FEM) of the tool-workpiece interaction, as well as a toolpath-level analysis of entire part programs. The outputs of these comprehensive models temperatures, residual stresses, forces, damage and power combined with intelligent process optimization algorithms, will provide the ability to predict and manage cutting forces and tool wear while simultaneously reducing machining cost and cycle time and maintaining acceptable part quality. The validated models will take into account the heterogeneous, orthotropic nature of CMC composites through the use of fracture plane models capable of general representation of material toughness in complex orientations.BENEFIT:Existing CAM software tools generate toolpaths entirely based on the geometric aspects of machining, without consideration for the material properties or the process physics such as forces, deflections, etc. leading to a need for significant input from the manufacturing engineers in order to mitigate the above effects. Manufacturing engineers must rely on their machining knowledge and prior experience from related designs and materials. Where such knowledge is not available, the manufacturing engineer has to undergo significant trial-and-error testing to develop a robust process. These methods are expensive, time consuming, and often lead to suboptimal solutions since only a limited range of process alternatives can be explored. Lack of validated modeling tools necessary to understand the magnitude and nature of the machining forces on the final part, temperature and abrasive wear effects on the tool, or workpiece deflection on the final part geometry are significant factors that limit the ability to improve part quality and reduce costs. Similarly, the inability of current software tools such as CAM or verification systems to consider the workpiece material effects during toolpath generation poses additional barriers to rapid, optimal toolpath programming. The anticipated benefits of proposed CMC machining modeling programs: A 35-50 percent reduction in the machining cycle times for Air Force CMC engine components Development of both detailed-level (FEM) and toolpath-level machining models providing a comprehensive, multi-scale physics-based modeling capability Demonstration of process improvements on a candidate Air Force component Dramatic reduction in machining process set-up times via analysis and optimization off-line, in advance of manufacturing process implementation Maximize capabilities of existing capital equipment through tooling and process improvements Eliminate trial-and-error testing through the use of validated physics-based models Improved tool life resulting from the judicious selection of tooling and process parameters as determined from detailed-level analysis Generic models applicable to a wide variety of materials, machine tools and components throughout the DoD