Today is Louis Henry Sullivan’s birthday. Sullivan’s wiki-page lists him as a famous American Architect widely considered the “Father of the Skyscraper.” In an 1896 essay Sullivan wrote:
Whether it be the sweeping eagle in his flight, or the open apple-blossom, the toiling workhorse, the blithe swan, the branching oak, the winding stream at its base, the drifting clouds, over all the coursing sun, form ever follows function, and this is the law. Where function does not change form does not change. The granite rocks, the ever-brooding hills, remain for ages;the lightning lives, comes into shape, and dies in a twinkling.
Sullivan’s famous statement, form follows function, has defined engineering design for over a century. In many ways this is an early incarnation of the Constructal Law, i.e. the Design Law of thermodynamics that I alluded to earlier. Said plainly, you should not envision the form of your design until you fully understand how the design must function. To understand how the design must function you must fully understand: 1) what is flowing in the system, 2) the necessary steps required to accomplish this flow, and 3) how your customers will assess and quantify the performance of your design. Hopefully all 3 coalesce. We know our system is flowing hydrogen, have started the process of identified key sub-systems required to accomplish this flow, and are beginning to consider how our customers will assess design performance.
Last class each of the teams created conceptual system diagrams for the entire fueling station concept. The votes are in and the vortex tube team’s diagram was a landslide winner. What’s fascinating is that almost everyone, more or less, had similar essential steps in the process, but almost all of the the diagrams are organized differently. The PLC and Sensor team’s diagram is particularly interesting and shows that their head’s are in the right place. Only minor re-alignment of the initial team sub-assemblies will be required to conform to this new diagram.
Let’s take our sub-system diagrams one step further by drawing a diagram with the essential steps required for our specific sub-systems.
Now that you’ve presented and discussed. How does this spatial diagram relate to the MUSTS and SHOULDS that you drafted before class? Now take the time to merge the two. It really is an interesting point of Conway’s Law when you see how these two very different approaches to organizing information about a design’s function can lead to differing results. The reality is that our design won’t be set in stone until it has to be. It’s a highly iterative process.
One of the factors that will influence the design that we need to begin thinking about is how our customers will assess performance. We’re taking an interesting approach to our customers with this design. Ag Energy Solutions is our local client with very similar needs to the H2-Refuel competition at the national level. The H2-Refuel competition has devised a very rigorous scoring criterion to assess design performance for the competition. That takes care of a major, and difficult, part of the design process for us. Our task is to develop a system for determining how our design quantitatively addresses the performance criterion. Anybody can simply say one design is better than another. Engineers our valuable because we quantify why a design is superior.
The leading tool for quantifying the performance for complex systems is the House of Quality (HOQ). A free house of quality template is available here. Here’s an unlocked Turn Table HOQ.
We’ve already mapped the competition criterion into a Global HOQ for H2 Refuel. Over the weekend your task is to draft an initial HOQ for your sub-assembly and upload to your team’s Slack thread before class on Tuesday. We’ll begin integrating these sub-assembly HOQ’s into the Global HOQ on Wednesday.