Believe it or not, at one point in my life I was trained as a civil engineer; I'm still a registered Professional Engineer in the State of Colorado. Some of my favorite classes at the university revolved around the design of structures. Regardless of the material being used -- steel, concrete, wood or combinations thereof -- the designer still needed to have an intuitive feel for how the structure would react when loads were placed upon it. Those who didn't have that intuition often failed miserably at design problems.
Those poor students would have welcomed TrussMe!, a fun iPad game by Scientific Monkey that teaches engineers of all ages to design strong, yet lightweight trusses. This won't make you a structural engineer, however -- this is a simulation game and should not be considered a design tool at all.
Upon launching TrussMe!, a user is greeted with a series of problems in which they need to design a truss structure to support a load. The game has two modes, freestyle and challenge. In freestyle mode, you can create trusses from slender bars connected by joints and connected to the ground or another surface through pins (fixed supports) or rollers (supports that can move horizontally, but not vertically). Your goal is keep the structure from collapsing while making it as lightweight as possible. A bar with a smaller cross section will be lighter, but more susceptible to buckling under compression or failure under tension.
Once you've created your truss structure, you tap a "play" button and the structure either continues to stand, or collapses in a very realistic manner. You can see exactly where a bar fails and whether it fails under compression or tension. Usually, you can fix the collapsing structure by increasing the size of a bar... but you may not get a very good "rating" for your structure as it becomes heavier.
This, of course, is exactly what a structural engineer needs to do when designing any structure. The structure must be as light as possible while still being able to handle the loads. Fortunately, TrussMe! is only concerned with static loads, as dynamic loading (moving trucks on a bridge, for example) adds a whole new level of complexity for the engineer.
I found that the best way to master TrussMe! was to use the included challenges. These are preset cases with specific loads and supports; your job is to add bars and joints to achieve the highest possible score. You're also awarded one to three "golden nuts" depending on the design you create. At this time, there are only 15 challenges, but you'll find that trying to get the golden nuts will definitely keep you playing for quite a while.
If I have any complaint with TrussMe!, it's that the challenges don't provide an "optimum" solution -- in other words, you may find that you can't achieve more than one golden nut. The implication is that you can get three of the nuts in every challenge, but I found it impossible to do so.
Whether you're an engineering student, a STEM educator or just interested in the mechanics behind the common truss, TrussMe! is an enjoyable and educational way pass the time. TrussMe! is available for the iPad and can be downloaded for US$1.99.