Engineers love data. We always want more high-speed cameras from more angles to record more prototype scenarios to verify more simulations. This brings us to one of a program manager’s greatest frustrations: usable data. Whether you are designing an autonomous surgical robot, a patient-specific knee implant, or a paperweight for all the new regulations, volumes of data are useless without the proper specification framework to filter and process it. This is the role of the Product Requirement Document (PRD).
The PRD is designed to keep the development team on task and focused on specific product functionality. If the PRD is written at the end or evolves during the development program, truth-seeking engineers will generate ever increasing volumes of data. We do this to provide program decision makers a broad spectrum of options with varying degrees of feasibility. Working without a PRD is absolutely the slowest and most expensive way to develop a product. In a perfect world, every program would start with a detailed PRD backed by historical benchmarking data, but this is not an option for truly innovative technology looking for a production platform. Even without a PRD, the development team will still need critical, effective processes to reach definitive milestones and eventually a market-conquering product. Without hard stops during the process to critically analyze data, you will get stuck in never-ending loops of data gathering and end up creating more variables than answers.
One of the most powerful tools to reduce and accelerate prototyping loops is finite element analysis (FEA). FEA has made giant leaps forward in capability over the past 15 years. Large assemblies are now translated directly from any CAD environment, contact pairs are automatically assigned, and a mesh is created after the click of one button. It is the perfect tool to fail fast in both positive and negative ways. The results are shown plain as a rainbow on the computer screen, but are they fact? The quickest way to further a concept with FEA is through comparative analysis. If option A predicts X stress and option B is 1/2X stress with the exact same setup, you are moving in the right direction. The question then becomes are the physical stress levels at X or 10X.
There are many ways to validate FEA simulations in the real world. With the ever decreasing cost of 3D printers, you can be up and testing concepts in hours. The 3D printing materials will not be exactly representative of production materials (build layers, for example, are ideal crack slip planes), but remember that stress is force/area. Whether a part is printed or machined, both will have the same high-stress location when tested in identical setups just different ultimate loads and displacements. The issue arises when your prototype fails in ways you did not predict or expect. The failure load and location are in essence only one data point in a complex system. Would thinning out a section and increasing flexibility actually be more beneficial than thickening and stiffening a part? Does adding a gusset to support a corner relocate the high stresses to an even more critical location? To fully comprehend the behavior of a part or assembly, you need multiple data points within the system to trend or predict how your concept is performing as a whole.
The desire to compress timeframes through the “intelligent engineering process” has become a reality across multiple industries. Development teams of today have the most incredible physical and virtual tools at their disposal, but they need to know how to most efficiently utilize them. Even without a PRD, data still needs to be gathered, sorted, and acted upon to develop and validate a concept. The right data in the right hands at the right time does make all the difference. Budgets, personnel, and time to market have all been significantly reduced, while at the same time product expectations have never been higher.