How Did the Titanic
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How did the Titanic sink? Recent engineering evidence suggests that the unsinkable ship experienced a hull failure at the surface and Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/120/08/54/6381729/me-1998-aug1.pdf by guest on 30 September 2021 broke into pieces before it went down. By Dan Deitz, Executive Editor HEN OUR BOAT had rowed about half a mile matic-event in their lives, disagreed on one major point, from the vessel, the Titanic-which was illu and it has remained a mystery for more than 80 years: Did W minated from stem to stern-was perfectly the Titanic break apart at the surface or sink intact? stationary, like some fantastic piece of stage scenery," re Although all the officers testified that the ship sank in called Pierre Marechal, a French aviator and a surviving tact, some survivors and crew testified to a hull failure at first-class passenger of the ill-fated liner. "Presently, the the surface. Even during the American and British in gigantic ship began to sink by the bows ... suddenly the quiries into the disaster, few questions focused on the lights went out, and an immense clamor filled the air. structural aspects of the ship. Despite survivors' testi Little by little, the Titanic settled down ... and sank with monies, it was concluded that the ship sank intact. out noise .. In the final spasm the stern of the leviathan stood in the air and then the vessel finally disappeared." EVIDENCE FROM THE DEPTH S Elmer Z . Taylor, who watched from Lifeboat No. 5, The mystery arose again when the wreck .of the Titanic close enough to the Titanic to observe its final demise, was discovered in 1985 and the hull was found in two would later write, "The cracking sound, quite audible pieces. Many theories were developed as to how the ship a quarter of a mile away, was due, in my opinion, to broke apart during the sinking process, and research was tearing of the ship's plates apart, or that part of the hull begun to determine how this could have happened. The below the expansion joints, thus breaking the back at a speculation intensified further when the wreck site was point almost midway the length of the ship." revisited in 1986 and a third 17.4-meter section from the "At that time the band was playing a ragtime tune," re midship region of the ship was found. membered Harold Sydney Bride, the surviving wireless To help solve this mystery, the Discovery Channel, in operator of the TitaniC. "I saw a collapsible boat on deck developing its award-winning " Titanic: Anatomy of a ... I went to help when a big wave swept it off, carrying Disaster" television documentary, approached Gibbs & me with it. The boat was overturned and I was beneath Cox, Inc., one of the oldest naval architecture and ma it, but I managed to get clear. I swam with all my might rine engineering firms in the world. Gibbs & Cox and I suppose I was 150 feet away when the Titanic, with agreed to perform a stress analysis to help determine the her aft quarter sticking straight up, began to settle." possibility of hull fracture at the surface. "The orchestra belonging to the first cabin assembled With funding provided jointly by the Discovery Chan on deck as the liner was going down and played 'Nearer nel and the Society of Naval Architects and Marine En My God to Thee.' By that time," as Miss C. Bounnell, gineers, Gibbs & Cox conducted a basic study of the first-class survivor, relived the night, "most of the breakup of RMS Titanic using linear finite-element lifeboats were some distance away and only a faint sound analysis (FEA) software. This study was done in conjunc of the strains of the hynm could be heard. As we pulled tion with materials testing of the Titanic steel by the Uni away from the ship, we noticed that she was hog-backed, versity of Missouri-Rolla, with advice from Prof. H .P. showing she was already breaking in two." Leighly Jr. , Dr. Timothy Foecke, and Dr. Harold Reem Four survivors with firsthand knowledge, remembering snyder of the Bethlehem Steel Corp.'s Homer Research probably the most important-certainly the most trau- Laboratory in Bethlehem, Pa. 54 AUGUST 1998 M EC H AN ICAL ENG I NEE R.I NG Important to the analysis effort was accurate weight and ry. In the 1960s, engineers started to analyze the stresses buoyancy data for the ship at the time it struck the ice in ship hulls using finite-element modeling (FEM). As a berg, and then later while it was sinking. These data were pioneer of FEA technology, MSC has been in the fore provided via a recent study of the ship's breakup undertak front of dramatically improving this technique to take en for another technical paper, "The 'Titanic and Lusitania, advantage of advances in computer technology. A Final Forensic Analysis," published in a 1996 issue of A full-ship model was graphically constructed, employ Marine Technology. The study provided the loading in ing a modern approach similar to that used for U.S. Navy formation needed to take "snapshots" of the ship's state of destroyers and cruisers today. Loadings for the model stress during the sinking process. Tests conducted on the were developed based on one flooding scenario from the steel recovered from the wreck site were performed at the paper, "The Sinking of the Titanic," by Chris Hackett University of Missouri and the National Institute of Stan and John C. Bedford. dards and Technology in Gaithersburg, Md. The results The corresponding weight and buoyancy curves, devel from these metallurgical tests of Titanic steel and rivets oped by Arthur Sandiford and William H. Garzke, Jr., Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/120/08/54/6381729/me-1998-aug1.pdf by guest on 30 September 2021 were also input as data for the finite element analysis. were used to model the critical flooding conditions be Gibbs & Cox engineers selected MSC/ NASTRAN, lieved to represent the hull loading just prior to hull frac from the MacNeal-Schwendler Corp. in Los Angeles, to ture. Since the flooding process took place over several perform the analysis. FEMAP engineering-analysis hours, a quasi-static analysis was considered appropriate. modeling and visualization software from Enterprise The initial modeling effort focused on the determination Software Products in Exton, Pa. , was used to perform of the location and magnitude of high-stress regions that the pre- and postprocessing of the analyses. Gibbs & Cox developed in the hull while she remained on the surface. had been using MSC/ NASTRAN for approximately Engineers determined that stress levels in the midsec five years. According to David Wood, the firm's struc tion of the ship were at least up to the yield strength of tures department manager, MSC worked closely with his the steel just prior to sinking. When considered alone, team during the development of MSC / NASTRAN stresses at these levels do not indisputably imply cata Version 70 to provide the special program solutions strophic failure. Additional analyses, focusing on proba needed for use in their industry. ble locations of initial hull fracture, are required to indi Engineers analyzed the stresses in the Titanic as the cate that the ship sustained possible catastrophic failure at flooding progressed within the bow region, using mod the surface and began to break apart. ern FEA techniques that simply were not available until Significant stresses were developed in the vicinity of the the 1960s, and certainly were not known to the structur two expansion joints, and in the inner bottom of the ship al designers of the ship in the first decades of the centu- between the forward end of Boiler Room No. 1 and the \ Z 2: < ~ ~ 0:> '" ~ c u :0, " => '"fE '"~ British and U.S. investigations of the Titanic tragedy have resulted in greater lifeboat capacity, improved subdivision of ships, and the creation of an ice patrol. MECHANICAL ENG I NEER.ING AUGUST 1998 55 aft end of the Reciprocating Engine Room. Structural William Garzke, staff naval architect at Gibbs & Cox, discontinuities, such as expansion joints, result in stress points out that, had the liner been elevated at 90 degrees, concentration development. Typically, stress concentra the huge boilers would have been ripped from their tion levels are three to four times that of free-field stress moorings, which was not the case. He suggests that the es. While these structural discontinuities have not yet stern section likely rose from the surface to at least 20 de been thoroughly investigated, it is believed that stresses grees but not more than 35 degrees, as it filled with wa developed at these locations were significantly higher ter or was dragged down by the bow section. than the material yield stress. Chief Baker Charlie Joughin, who was at the ensign staff at the stern end, later testified that it was like rid THE DEATH OF A SHIP ing an elevator down to the water. With the absence of At 2: 17 a.m., according to the various investigations after suction forces, he was able to swim away without even the disaster, the Titanic began to go under, her lights wetting his hair, so swift was the stern's demise. blazing in the cold of the sub-Arctic night and with The failure of the main hull girder of the Titanic was Downloaded from http://asmedigitalcollection.asme.org/memagazineselect/article-pdf/120/08/54/6381729/me-1998-aug1.pdf by guest on 30 September 2021 more than 1,500 people still on board.