{"id":98,"date":"2018-08-10T13:49:46","date_gmt":"2018-08-10T13:49:46","guid":{"rendered":"http:\/\/commons.princeton.edu\/63-tiger-cub\/?p=98"},"modified":"2019-04-01T20:36:07","modified_gmt":"2019-04-01T20:36:07","slug":"27-march-2018","status":"publish","type":"post","link":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/2018\/08\/10\/27-march-2018\/","title":{"rendered":"27 March 2018"},"content":{"rendered":"<div class=\"picture-component\">\n<h4>notes by Alex K.<\/h4>\n<div class=\"left\">\n<div class=\"row\">\n<div class=\"cell\"><\/div>\n<\/div>\n<div class=\"row\">\n<div class=\"cell\"><\/div>\n<\/div>\n<\/div>\n<div class=\"body\">\n<p>Today\u2019s agenda: Lecture with Bill Becker on Wheels<\/p>\n<p class=\"p2\">\u00a0Bill Becker biography:<span class=\"Apple-converted-space\">\u00a0<\/span><\/p>\n<ul class=\"ul1\">\n<li class=\"li1\">Retired architect, architecture undergraduate at Case Western and Masters from Penn<\/li>\n<li class=\"li1\">Retired as a motorcycle designer and builder<\/li>\n<li class=\"li1\">Favorite thing about motorcycles: amazing and functional pieces of design, where aesthetics and engineering work together flawlessly<\/li>\n<li class=\"li1\">Likes working with vintage machine and upgrading them to a higher standard than when they were new<\/li>\n<\/ul>\n<p class=\"p2\">\u00a0Lecture:<\/p>\n<p class=\"p2\">Why can\u2019t bicycles or motorcycles stand by themselves? \u201cBecause they\u2019re too (two) tired!\u201d<\/p>\n<p class=\"p2\">\u00a0Wheel from a French moped: has a hub and brake in the middle, essentially analogous to motorcycle wheel<\/p>\n<p class=\"p2\">\u00a0History of wheels:<\/p>\n<ul class=\"ul1\">\n<li class=\"li1\">The wheel is a form, as long as it is circular with a pivot it is consistent<\/li>\n<li class=\"li1\">Spokes: an innovation to make wheels lighter and springier<\/li>\n<li class=\"li1\">First motorcycle has two different wheels\n<ul class=\"ul2\">\n<li class=\"li1\">front wheel: spoked, moves freely through space, only pressure is force of gravity<\/li>\n<li class=\"li1\">back wheel: solid wheel, applying pressure from drive chain onto the ground to move the bike<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p class=\"p1\">Three subjects: physics, engineering, and material science<\/p>\n<p class=\"p2\">\u00a0Physics<\/p>\n<ul class=\"ul1\">\n<li class=\"li1\">Mass: defines how a matter in one object relates to matter in another object (on earth, define by weight: relation of mass of earth to mass of object)<\/li>\n<li class=\"li1\">Objects are subject to\u00a0<b>gravity<\/b>\u00a0and\u00a0<b>motion<\/b>\u00a0\u2013 inertia or acceleration<\/li>\n<li class=\"li1\">\u201cweight is not a friend of the wheel\u201d\n<ul class=\"ul2\">\n<li class=\"li1\">on a railroad car, heavy wheels are OK<\/li>\n<li class=\"li1\">but on a racecourse\/motorcycle, you want wheels to be light so that less work is required to accelerate them \u2013\u2013&gt; spokes; thin rim; aluminum hub<\/li>\n<\/ul>\n<\/li>\n<li class=\"li1\">Vectors: ways to describe the direction and magnitude of forces we are talking about<\/li>\n<\/ul>\n<p class=\"p2\">\u00a0Material science<\/p>\n<ul class=\"ul1\">\n<li class=\"li1\">Athletes look for certain things in different classes, e.g.\n<ul class=\"ul2\">\n<li class=\"li1\">Wrestlers want a high strength to weight ratio<\/li>\n<li class=\"li1\">Gymnasts want flexibility, strength, and small mass<\/li>\n<li class=\"li1\">Basketball players want strength, flexibility, and height<\/li>\n<\/ul>\n<\/li>\n<li class=\"li1\">Materials of a motorcycle also look for different qualities for different needs:\n<ul class=\"ul2\">\n<li class=\"li1\"><b>Aluminum<\/b>: strong, flexible, low weight, corrosion resistant, machinable, malleable, inexpensive; it can be\u00a0<i>cast<\/i>\u00a0into unusual shapes (like in engine case)<\/li>\n<li class=\"li1\"><b>Cast iron<\/b>: strong, porous (can absorb oil), reduces friction, dissipates heat well\u00a0<b>but<\/b>\u00a0brittle<\/li>\n<li class=\"li1\"><b>Steel<\/b>: can be hard, soft, corrosion resistant (hardened steel: ball bearings; woodrift keys) (softened steel: fender, needs to be bent into shape)<\/li>\n<li class=\"li1\"><b>Rubber<\/b>: flexible, not very compressible but high tensile strength, corrosion-resistant, lightweight<\/li>\n<li class=\"li1\">More: polyester, brass, chromium, asbestos, plastic, air<\/li>\n<li class=\"li1\">Material scientists will select from these to do different jobs in the wheel<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p class=\"p2\">\u00a0Engineering<\/p>\n<ul class=\"ul1\">\n<li class=\"li1\">Terms:\n<ul class=\"ul2\">\n<li class=\"li1\"><b>Deadload<\/b>\u00a0&#8211; the weight of the thing itself, i.e. motorcycle with fluids in it<\/li>\n<li class=\"li1\"><b>Liveload<\/b>\u00a0&#8211; weight of it with a rider on it<\/li>\n<li class=\"li1\"><b>Static loading<\/b>: object is stationary, just applying gravitation forces<\/li>\n<li class=\"li1\"><b>Dynamic loading<\/b>: object is moving through space, loading due to contours of the road, turning, impact, acceleration\/deceleration<\/li>\n<\/ul>\n<\/li>\n<li class=\"li1\">Forces acting on a materials:<span class=\"Apple-converted-space\">\u00a0<\/span>\n<ul class=\"ul2\">\n<li class=\"li1\"><b>Compression\u00a0<\/b>&#8211; some materials (e.g. brick) are very good in compression, others (e.g. rubber\/sand) are very compressible<\/li>\n<li class=\"li1\"><b>Tension<\/b>\u00a0&#8211; another structural force that is just \u201cpulling\u201d on things &#8211; aluminum, steel are good; glass is bad<\/li>\n<li class=\"li1\"><b>Bending<\/b>\u00a0&#8211; just a combination of compression and tension<\/li>\n<li class=\"li1\"><b>Shear<\/b>\u00a0&#8211; forces are opposed off-axis to create a \u201ctearing\u201d effect<\/li>\n<\/ul>\n<\/li>\n<li class=\"li1\">Thomas Young: physician, material scientist\n<ul class=\"ul2\">\n<li class=\"li1\">relationship between\u00a0<b>stress<\/b>\u00a0and\u00a0<b>strain<\/b><\/li>\n<li class=\"li1\">Force on an object in compression: expect straining (i.e. getting fatter\/shorter)<\/li>\n<li class=\"li1\">Force on an object in tension: expect stretching<\/li>\n<\/ul>\n<\/li>\n<li class=\"li1\">Young\u2019s models:\n<ul class=\"ul2\">\n<li class=\"li1\">Increasing strain increases stress, up to plastic deformation<\/li>\n<li class=\"li1\">Linear relationship btw. stress and strain during elastic deformation<\/li>\n<li class=\"li1\">concave-down parabolic relationship between stress and strain during plastic deformation<\/li>\n<li class=\"li1\">Fractures at the end of plastic deformation phase<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p class=\"p1\">Wheels:<\/p>\n<ul class=\"ul1\">\n<li class=\"li1\">Patterns of four spokes at a time (36 spokes in total on most bikes; 40 on British)<\/li>\n<li class=\"li1\">Spokes evenly spaced around the rim<\/li>\n<li class=\"li1\">On a motorcycle wheel, spokes are\u00a0<b>not<\/b>\u00a0arranged to intersect the axis of the wheel because of a\u00a0<i>differential between forces on the hub and forces on the wheel<\/i><\/li>\n<li class=\"li1\">Spokes are off-angle to make a\u00a0<b>rigid geometry<\/b>\u00a0by translating forces between hub and rim<\/li>\n<li class=\"li1\">Triangulation both in the plane of the wheel and laterally (i.e. coming out of the plane of the wheel)<\/li>\n<li class=\"li1\">Spokes are in pairs of four to resist opposing and proposing rotation; out of plane bending<\/li>\n<\/ul>\n<p class=\"p2\">\u00a0Loading of the wheel and tension of the spokes:<\/p>\n<ul class=\"ul1\">\n<li class=\"li1\">Spokes are\u00a0<b>great in tension<\/b>\u00a0and\u00a0<b>bad in compression<\/b>\u00a0because of their slender shape and size + how they are connected to the rim<\/li>\n<li class=\"li1\"><b>Static<\/b>\u00a0loading of gravity of the rider \u2013\u00a0top spokes are doing the work to hold the hub up<\/li>\n<li class=\"li1\"><b>Impact<\/b>\u00a0loading \u2013\u00a0all the spokes that are opposite to the point of impact go into tension<\/li>\n<li class=\"li1\"><b>Acceleration<\/b>\u00a0\u2013\u00a0half of the spokes (the ones that point in the direction of acceleration along the hub) go into tension<\/li>\n<li class=\"li1\"><b>Turning<\/b>\u00a0\u2013\u00a0rigidity out of the plane of the wheel go into tension<\/li>\n<\/ul>\n<p class=\"p2\">\u00a0Nowadays, many wheels are cast instead of spoked because of the cost of labour; 88 parts in our spoked wheel but only 1 in a cast wheel. There is some debate as to which is more aerodynamic.<\/p>\n<p class=\"p2\">\u00a0The size of a spoke is determined by its material strength, trying to be maximally aerodynamic while still supporting the weight of the bike. Bicycle spokes are very thin because they are lightweight and very little torque is transmitted by the rider.<\/p>\n<p class=\"p2\">\u00a0This singular spoke brought to demo can hold about 800 lbs! All the spokes in tension at any moment can hold up to 8,000lbs.<\/p>\n<\/div>\n<div class=\"clear\"><\/div>\n<\/div>\n","protected":false},"excerpt":{"rendered":"<p>notes by Alex K. Today\u2019s agenda: Lecture with Bill Becker on Wheels \u00a0Bill Becker biography:\u00a0 Retired architect, architecture undergraduate at Case Western and Masters from Penn Retired as a motorcycle designer and builder Favorite thing about motorcycles: amazing and functional pieces of design, where aesthetics and engineering work together flawlessly Likes working with vintage machine &hellip; <a href=\"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/2018\/08\/10\/27-march-2018\/\" class=\"more-link\">Continue reading<span class=\"screen-reader-text\"> &#8220;27 March 2018&#8221;<\/span><\/a><\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[3],"tags":[],"class_list":["post-98","post","type-post","status-publish","format-standard","hentry","category-diary"],"_links":{"self":[{"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/posts\/98","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/comments?post=98"}],"version-history":[{"count":1,"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/posts\/98\/revisions"}],"predecessor-version":[{"id":99,"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/posts\/98\/revisions\/99"}],"wp:attachment":[{"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/media?parent=98"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/categories?post=98"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/commons.princeton.edu\/63-2-tiger-cub\/wp-json\/wp\/v2\/tags?post=98"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}