Adrian Bejan | I beam cross section, from Design in Nature скачать в хорошем качестве

Adrian Bejan | I beam cross section, from Design in Nature

The video examines a family of drawings spread across a space using two simple moves, tapering and hollowing, and demonstrates how the expense decreases as you transition from a solid round rod to a hollow tube, then to a tapered solid beam, and finally to a hollow tapered tube. It then turns the drawing on its side and reads the cross-section. Only the top fiber and bottom fiber are doing the most challenging work, while the material near the neutral plane sits idle. The drawing removes the idle part, retains the two hard workers, and connects them with a thin plate, allowing them to bend as one. This is the idea behind the I profile and the reason the useful material lives far from the neutral plane. The picture builds a map of designs in two directions, one for tapering and one for hollowing, and marks spending steps at twelve, six, four, and two, which invites the thought of going even lower, like sliding down an apron on a slope covered by snow. By examining the hollow tapered tube in cross section, the video identifies equality at the top and bottom fibers, then observes the equator near the neutral plane as being lazy and ready for removal, thereby clearing a path to a leaner shape. Keeping only two free fibers makes the object limp like a wire, since they bend on their own. To address this, the drawing adds a plate that ties them together, ensuring plane cross sections remain plane as they bend. The thin plate is the web that connects the dorsal fiber and the ventral fiber. It is treated as massless in the spending picture, yet it makes the section act as one piece and gives the letter I in profile, with the most rigid working material kept far from the neutral plane. The message is to give the drawing more freedom, take out lazy material around the equator, and keep the work spread where it counts, so the I beam idea lets the design move beyond the valley marked by two while staying honest about where the work is done.