According to the builders of the Titanic, even in the worst possible accident at EAI, the ship should have stayed afloat for two to three days yet it sank in less than three hours. Current theories indicate that the ship sank quickly due to material failures (brittle fracture) and design flaws (non-watertight compartments within the hull). Table of Contents Introduction 2. Overview of Events 3. Causes of the Rapid Sinking 3. 1 Material Failures 3. 1. 1 steel Hull 3. 2 Design Failures 4. Conclusion List of References 1. Introduction 53. 2 Rivets -8 11 The Titanic was a White Star Line steamship built in the early nineteen hundreds by Harlan and Wolff of Belfast, Ireland. With a weight of more Han 46,000 tons, a length of nearly 900 feet and a height of more than 25 stories, she was the largest of three sister ships owned by the company (Division, 1997). At the time of her construction, the Titanic Was the largest ship ever built. The Titanic was deemed an unsinkable ship with turn-of-the-century design and technology, including sixteen major watertight compartments in her lower section that could easily be sealed off in the event of a punctured hull.
According to her builders, even in the event of two ships colliding at sea, the Titanic would stay afloat for two to three days, which would provide enough mime for nearby ships to help (Cannon, 1995). Figure 1 shows how the Titanic was equipped with lifeboats (at left). Figure 1 – The deck of the Titanic Source: Refrigerator (1998). On April 14 191 2, the Titanic sideswiped a massive iceberg and sank in less than three hours. Damaging nearly 300 feet of the ship’s hull, the collision allowed water to flood six of her sixteen major watertight compartments (Cannon, 1995).
She was on her maiden voyage to the United States, carrying more than 2200 passengers and crew. Only 705 survived (Hill, 1996). After what seemed like a minor collision with an iceberg, the largest ship ever built ann. in a fraction of the time estimated for her worst possible accident at sea. The purpose of this report is to explain the material failures and design flaws that contributed to the rapid sinking of the Titanic. Human factors that contributed to the sinking will not be reviewed. On April 10, 1912, the Titanic commenced her maiden voyage from Southampton, England, to New York, with 2227 passengers and crew aboard (Division, 1997).
The passengers included some of the wealthiest and most prestigious people at that time. Captain Edward John Smith, one of the most experienced shipmates on the Atlantic, was navigating the Titanic (Rogers ND others, 1998). On the night of April 1 4, although the wireless operators had received several ice warnings from others ships in the area, the Titanic continued to rush through the darkness at nearly full steam. A time line of the events that followed is shown in Table 1 below. At 1 1 :35 p. M. , the lookouts spotted a massive iceberg less than a quarter of a mile Off the bow of the ship.
Immediately, the engines were thrown into reverse and the rudder turned hard left. Because of the tremendous mass of the ship, slowing and turning took a great distance, more than that available. At 1 1 p. M. Without enough distance to alter her course, the Titanic sideswiped the iceberg, damaging nearly 300 feet of the right side of the hull above and below the waterline (Cannon, 1995). Table 1 -Timeline of the Sinking of the Titanic 11 p. M. Lookouts spot the iceberg 1/4 mile ahead. 11:40 p. M. The Titanic sideswipes the iceberg, damaging nearly 300 feet of the hull.
Midnight Watertight compartments are filling water begins to spill over the tops of the transverse bulkheads. 1:20 a. M. The bow pitches; water floods through anchor-chain holes. 2:00 a. M. The bow continues to submerge; propellers lift out of the water. 2:10 a. . The Titanic tilts 45 degrees or more; the upper structure steel disintegrates. 2:12 a. M. The stern rises up out of the water; the bow, filling with water, grows heavier. 2:18 a. M. Weighing 1 6,000 tons, the bow rips loose; the stern rises to almost vertical. 2:20 a. M. The stern slips beneath the surface. 229 a. M. Coasting at about 13 MPH, the bow strikes the ocean floor. :56 a. M. Falling at about 4 MPH, the stern strikes the ocean floor. Source: Cannon (1995) The damage caused by the collision allowed water to flood six of the sixteen major watertight compartments. As water rushed into the starboard side of he ship’s bow, the ship began to tilt down in front and slightly to the right. By midnight, water in the damaged compartments began to spill over into others compartments. This was because the compartments were only watertight horizontally, and the walls extended just a few feet above the waterline. By 1 a. M. , water began flooding through anchor-chain holes.
Around 2:00 a. M. , as the bow continued submerging, the propellers in the stern were lifted Out of the Water. Flooding progressed until, at about 2:10, the bow of the ship was under water and the stern was lifted above water at almost 45 degrees. Because of the tremendous weight of the three large propellers in the stern of the ship, the stresses in the ship’s midsection increased immensely as the stern was lifted out of the water. At an angle of 45 degrees or more, the stresses in the midsection exceeded the ultimate stresses of the steel, causing it to fail (Garage et al, 1994).
Stresses at failure were estimated at nearly 15 tones per square inch (Cannon, 1995). What survivors of the disaster then described was a loud noise that sounded like breaking china or falling equipment (Hill, 1996). This noise can be attributed to the tearing and consideration of the Titanic’s upper structure. By 2:12, with the bow and stern attached by only the inner bottom structure, the stern angled high out of the water. The bow, dangling beneath, continued to fill with water. At 2: 18, when the bow reached a weight of about 1 6,000 tons, it ripped loose from the stern.
Free from the weight of the bow, the stern rose again sharply to an almost vertical position. Slowly filling with water, the stern began to sink into the water. At 2:20, the stern slid beneath the surface. Meanwhile, the bow had been coasting down at about 13 miles per hour (MPH). At 2:29, the bow struck the bottom of the ocean. Falling nearly vertical at about 4 MPH, the stern crashed into the ocean floor 27 minutes later. On an expedition in 1 991 to the Titanic wreck, scientists discovered a chunk 01 metal lying on the ocean floor that once was a part of the Titanic’s hull.
The Frisbee-sized piece of steel was an inch thick with three rivet holes, each 1. 25 inches in diameter (Cannon, 1995). Since the retrieval of this piece of steel, extensive research has been done to uncover additional clues as to the cause of the rapid sinking of the Titanic. The following is a discussion of the material allures and design flaws that contributed to the disaster. When the Titanic collided with the iceberg, the hull steel and the wrought iron rivets failed because of brittle fracture. A type of catastrophic failure in structural materials, brittle fractures occur without prior plastic deformation and at extremely high speeds.
The causes of brittle fracture include low temperature, high impact loading and high sulfur content. On the night of the Titanic disaster, each of these three factors was present. The water temperature was below freezing, the Titanic was traveling at a high speed on impact with the iceberg, and the hull steel contained high levels of sulfur. The first clue that brittle fracturing of the hull steel had occurred came from a piece of the wrecker’s steel. After cleaning it, scientists noted the condition of the edges. Jagged and sharp, the edges appeared almost shattered, like broken china.
Also, the metal showed no valence of bending or deformation. Typical high-quality ship steel is more ductile and deforms rather than breaks (Cannon, 1995). Similar behavior was found in the damaged hull steel of the Titanic’s sister ship, Olympic, after a collision while leaving harbor on September 20, 1911. A 36-foot high opening was torn into the starboard side of the hull of Olympic when a British cruiser broadsided her. Plate tears exhibited little plastic deformation and the edges were unusually sharp, having the appearance of brittle fractures (Garage et a’, 1994).
Further evidence of the brittle fracture of the hull steel was found when a cigarette-sized coupon of the steel taken from the Titanic wreck was subjected to a Chirpy test. Used to measure the brittleness of material, the Chirpy test is run by holding the coupon against a steel backing and striking the coupon with a 67 pound pendulum on a 2. -foot-long arm. The pendulum’s point of contact is instrumented, with a read-out of forces electronically recorded in millisecond detail. A piece of modern high-quality steel was tested along with the coupon from the hull steel.
Both coupons were placed in a bath of alcohol at -1 co to simulate the conditions on the night of the Titanic disaster. When the coupon of the modern steel was tested, the pendulum swung down and halted with a thud; the test piece had bent into a However, when the coupon of the Titanic steel was tested, the pendulum struck the coupon with a sharp “ping,” barely slowed, and intended up on its swing. The Titanic sample, broken into two pieces, flew across the room (Cannon, 1995). Pictures of the two coupons following the Char pay test are shown in Figure 2.
What the test showed, and the readout confirmed, is the brittleness of the Titanic’s hull steel. When the Titanic struck the iceberg, the hull plates did not deform. They fractured. Figure 2 – Results of the Chirpy test for modern steel and Titanic steel Note: When a pendulum struck the modern steel, on the left, with a large force, the sample bent without breaking into pieces; it was ductile. Under the name impact loading, the Titanic steel, on the right, was extremely brittle; it broke in two pieces with little deformation. Source: Cannon (1995).
A micro-structural analysis of the Titanic steel also showed the plausibility of brittle fracture of the hull steel. The test showed high levels of both oxygen and sulfur, which implies that the steel was semi-kilned low carbon steel. High oxygen content leads to an increased ductile-to-brittle transition temperature, which was determined as ICC to CEQ for the Titanic steel. Most modern steels would need to be chilled below minus ICC before they exhibited similar behavior. High sulfur content increases the brittleness of steel by disrupting the grain structure.
Sulfur combines with magnesium in the steel to form stringers of magnesium sulfide, which act as ‘highways’ for crack propagation. Although most Of the steel used for shipbuilding in the early asses had a relatively high sulfur content, the Titanic’s steel was high even for those times (Hill, 1996). 3. 1. 2 Rivets The wrought iron rivets that fastened the hull plates to the Titanic’s main structure also failed because of brittle fracture. This was due to the high impact loading of the collision with the iceberg and the low temperature of the water during the disaster.
Figure 3 shows the Titanic during her construction, with the riveted hull plates of her stern visible. With the ship traveling at nearly 25 MPH, the contact with the iceberg was probably a series of impacts that caused the rivets to fail either in shear or by elongation (Garage and others, 1994). As the iceberg scraped along sections Of the Titanic’s hull, the rivets were sheared off, which opened up riveted seams. Also, because of the tremendous forces created on impact with the iceberg, he rivet heads in the areas of contact were simply popped off, which caused more seams to open.
Normally, the rivets would have deformed before failing because of their ductility, but with water temperatures below freezing, the rivets had become extremely brittle. Figure 1 – The Titanic in the shipyard during her construction Note the hull plates, fastened on all sides to the ship’s main structure by thousands of rivets. Source: Refrigerator (1998). Along with material failures, poor design of the watertight compartments in the Titanic’s lower section was a factor in the disaster.
The lower section of the Titanic was divided into sixteen major watertight compartments that could easily be sealed off if part of the hull were punctured and leaking water. After the collision with the iceberg, the hull portion of six of these sixteen compartments was damaged, as shown in Figure 3. Sealing off the compartments was completed immediately after the damage was realized, but as the bow of the ship began to pitch forward from the weight of the water in that area of the ship, the water in some of the compartments began to spill over into adjacent compartments.
Although the compartments were called ‘watertight’, they were actually only watertight horizontally. Their tops were open and the walls extended only a few feet above the waterline (Hill, 1996). If the transverse bulkheads (the walls of the watertight compartments that are positioned across the width of the ship) had been a few feet taller, the water would have been better contained within the damaged compartments. Consequently, the sinking would have been slowed, possibly allowing enough time for nearby ships to help.
Figure 2 – A layout of the watertight compartments and the damage from the illusion Note: The thick black lines below the waterline indicate the approximate locations of the damage to the hull. Source: Refrigerator (1998). The watertight compartments were useless to countering the damage done by the collision with the iceberg. Some Of the scientists studying the disaster have even concluded that the watertight compartments contributed to the disaster by keeping the flood waters in the bow of the ship.
If there had been no compartments at all, the incoming water would have spread out, and the Titanic would have remained horizontal. The ship would have sunk, but she loud have remained afloat for another six hours before foundering (Cannon, 1995). This amount of time would have been sufficient for nearby ships to reach the Titanic’s location so all of her passengers and crew could have been saved. Because of the terrible loss of life and the demise of what was believed to be an ‘unsinkable’ ship, people are interested to know what caused the rapid sinking of the infamous Titanic.
This report has presented the most probable theory, which has become dominant as a result of evidence acquired during expeditions to the Titanic site. The failure of the hull steel resulted from brittle fractures. These fractures Were caused by (a) the high sulfur content of the steel, (b) low temperature water on the night, and (c) the high impact loading of the collision. The low water temperature and high impact loading also caused the brittle failure of the rivets, which were used to fasten the hull plates to the ship’s main structure.
On impact, the rivets were either sheared off or the heads popped off because of excessive loading which opened up riveted seams. Also, the rivets around the perimeter of the plates became elongated due to the stresses applied by the water, which broke the caulking and provided another inlet for the water. The rapid sinking of the Titanic was worsened by the poor design Of the transverse bulkheads of the watertight compartments. As water flooded the damaged compartments of the hull, the ship began to pitch forward, and water in the damaged compartments was able to spill over into adjacent compartments.