Why America's Fastest-Built Ships Kept Cracking in Half скачать в хорошем качестве

Why America's Fastest-Built Ships Kept Cracking in Half

On January 16, 1943, a brand-new tanker sitting in calm water at a Portland, Oregon dock cracked almost completely in two. No torpedo. No storm. The SS Schenectady was sixteen days old and had never carried cargo. The sound was heard more than a mile away. She was not a fluke. Over the next three years, more than a thousand American-built ships would develop serious cracks — and somewhere between three and nineteen of them would literally snap in half, depending on who is counting and what they count. The Liberty ship program was building three ocean-going cargo vessels per day, faster than anyone had built ships before or has since. But something in the steel, the welds, and the design was catastrophically wrong — and for months, nobody could explain it. The Liberty ship was America's answer to the U-boat crisis: a simple British cargo design scaled up for mass production. At 441 feet long, powered by a 2,500-horsepower triple-expansion steam engine, these ships were built from prefabricated sections welded together on the slipway. The critical decision — replacing rivets with welds — made it possible to build 2,708 ships between 1941 and 1945. It also removed the one thing that had always stopped cracks from spreading through a steel hull. When the SS John P. Gaines broke in two near the Aleutian Islands on November 24, 1943, eleven people died. She was four months old. Post-war investigation revealed the terrifying truth: the steel in these ships could turn as brittle as glass at temperatures well above freezing. A metallurgist at Cambridge named Constance Tipper proved it — and her work changed how every ship, bridge, and pipeline on Earth is built. 📍 TIMESTAMPS: 0:00 — A Brand-New Ship Cracks in Half at the Dock 2:37 — The U-Boat Crisis: Why America Built Ships Faster Than Ever 4:19 — Designed to Be Disposable: The Five-Year Expendable Hull 5:16 — Rivets vs. Welds: The Decision That Changed Everything 6:06 — Why Welded Steel Gives a Crack a Highway 8:28 — The First Fractures Nobody Talked About 11:24 — SS John P. Gaines: Eleven Dead on a Four-Month-Old Ship 12:41 — Blaming the Welders — And Why That Was Wrong 14:02 — Constance Tipper: The Woman Who Solved It 16:38 — The Charpy Impact Test: Making the Invisible Visible 20:51 — Three Conditions for Catastrophe 22:28 — The Fixes That Saved Lives 25:41 — The Final Count: 1,031 Ships Cracked, 200+ Lost 29:54 — How the Liberty Ship Crisis Changed Engineering Forever 📚 SOURCES: https://econwpa.ub.uni-muenchen.de/ec... https://danotes.mech.uwa.edu.au/fract... https://www.mastermariners.org.au/sto... https://www-mdp.eng.cam.ac.uk/web/lib... https://books.google.hu/books/about/F... https://en.wikipedia.org/wiki/SS_John... https://www.usdeadlyevents.com/1943-n... 📋 ABOUT THIS VIDEO: This video covers the Liberty ship brittle fracture crisis of 1942-1946, beginning with the catastrophic cracking of the T2 tanker SS Schenectady on January 16, 1943, at Kaiser's Swan Island yard in Portland, Oregon. It examines the US Maritime Commission's emergency Liberty ship program, which produced approximately 2,708 vessels at sixteen shipyards including California Shipbuilding Corporation (Calship) at Terminal Island, Oregon Shipbuilding Corporation, Bethlehem-Fairfield in Baltimore, and North Carolina Shipbuilding. The program employed 700,000 workers building prefabricated welded hulls from the original J.L. Thompson and Sons British Ocean-class design. The SS John P. Gaines broke in two near Chirikof Island in the Aleutian Islands on November 24, 1943, killing eleven crew and passengers. By April 1946, 1,031 Liberty ships had suffered fracture damage, with 103 Class I fractures and 291 Class II fractures recorded. Cambridge metallurgist Constance Tipper's Charpy impact testing research identified the ductile-to-brittle transition temperature phenomenon in wartime ship steels, with origin plates showing transition temperatures averaging 40°C (104°F). Ship Structure Committee report SSC-80 established the three-condition model for brittle fracture: high stress exceeding 10,000 psi, sharp stress concentrators at square hatch corners, and low notch toughness at operating temperature. Design fixes including rounded hatch corners, riveted crack-arresting seams, and stop-hole drilling reduced serious cracking from 195 per 1,000 ship-years to 35 per 1,000 ship-years. The economic cost exceeded $100 million in 1940s dollars. #WW2 #WWII #LibertyShips #WorldWar2 #MilitaryHistory #BrittleFracture #WW2History #ShipBuilding #ConstanceTipper #NavalHistory #WW2Documentary #EngineeringDisaster