Designing any product — from complex car parts to wrenches — is a balancing act with conflicting performance tradeoffs. Making something lightweight, for instance, may compromise its durability.
To navigate these tradeoffs, engineers use computer-aided design (CAD) programs to iteratively modify design parameters — such as height, length, and radius of a product — and simulate the results for performance objectives to meet specific needs such as weight, balance, and durability. But these programs require users to modify designs and simulate the results for only one performance objective at a time. As products usually must meet multiple, conflicting performance objectives, this process becomes very time-consuming.
A visualization tool for CAD was developed that, for the first time, lets users instead interactively explore all designs that best fit multiple, often-conflicting performance tradeoffs in real time. The tool first calculates optimal designs for three performance objectives in a precomputation step. It then maps all those designs as color-coded patches on a triangular graph. Users can move a cursor in and around the patches to prioritize one performance objective or another. As the cursor moves, 3D designs appear that are optimized for that exact spot on the graph.
The work builds off InstantCAD software that lets users interactively modify product designs and get real-time information on performance. The tool reduced the time of some steps in designing complex products to seconds or minutes instead of hours; however, a user still had to explore all designs to find one that satisfied all performance tradeoffs, which was time-consuming. The new tool provides real-time feedback on the designs that give the best performance. A product may have 100 design parameters, but the important one is how it behaves in the physical world.
A critical aspect of performance, called the “Pareto front,” is a set of designs optimized for all given performance objectives, where any design change that improves one objective worsens another objective. This front is usually represented in CAD and other software as a point cloud (dozens or hundreds of dots in a multidimensional graph), where each point is a separate design; for example, one point may represent a wrench optimized for greater torque and less mass, while a nearby point will represent a design with slightly less torque but more mass. Engineers modify designs in CAD to find these Pareto-optimized designs using a fair amount of guesswork. Then they use the front’s visual representation as a guideline to find a product that meets a specific performance, considering the various compromises.
The new tool, instead, rapidly finds the entire Pareto front and turns it into an interactive map. Inputted into the model is a product with design parameters, and information about how those parameters correspond to specific performance objectives.