The steel structure of a vessel is made up of a complex arrangement of transverse (sideways) and longitudinal (lengthwise) plates and beams with precisely measured cross sections that contribute to the overall “section modulus” of the vessel, a measure of the overall bending strength of a given structure. In the case of the MOL Comfort, the vessel fractured in a transverse fashion because the stress on the structure of the vessel eventually exceeded the fracture point of the sum of the individual steel components.
The steel doesn’t simply snap in pieces like a glass might if you dropped it on a concrete floor. Because the steel itself has elastic properties, the ship itself is elastic. When put under load, the steel flexes and moves elastically, returning to its original shape every time.
The above video shows the elastic flexing of the containership MOL Excellence underway.
In the case of the MOL Comfort, the load put on the steel components exceeded the elastic range of the steel. That is, The stress put on the steel caused it to flex (strain) so much that it did not return to its original shape after the load was removed. At that point, the steel exceeded its yield point.
Plastic deformation was noted by ClassNK when they conducted their evaluations of the sister vessels of the MOL Comfort. They note that “buckling type deformations measuring approximately 20mm in height were observed on the bottom shell plates in the vicinity of center line of midship area.”
Just because the steel exceeded the yield point, does not mean however that the steel began to break. Steel, like many other materials actually becomes stronger as it goes through “plastic deformation.” This is called strain hardening, a process used by metalworkers to make things like sword blades or steel tools harder.
As the stress on the vessel continued to grow, the steel could not deform any further and it fractured.
Hull of the MOL Comfort begins to crack on June 17, 2013.
By Ellen Francis (Reuters) – Interpol has issued red notices for the captain and owner of the ship that carried the chemicals which devastated Beirut in an explosion in August, killing 200...
By Chen Aizhu (Reuters) – China has issued 5 million tonnes of clean marine fuel export quotas in the first release for 2021, to five companies including a private refiner,...
By Andrea Shalal (Reuters) – The United States is urging European allies and private companies to halt work that could help build the Nord Stream 2 natural gas pipeline and...
December 23, 2020
Total Views: 834
Sign Up Now for gCaptain Daily
Just enter your email and get hot news every morning
We use cookies on our website to give you the most relevant experience. By clicking “Accept”, you consent to the use of ALL the cookies.
This website uses cookies to improve your experience while you navigate through the website. Out of these, the cookies that are categorized as necessary are stored on your browser as they are essential for the working of basic functionalities of the website. We also use third-party cookies that help us analyze and understand how you use this website. These cookies will be stored in your browser only with your consent. You also have the option to opt-out of these cookies. But opting out of some of these cookies may affect your browsing experience.
Necessary cookies are absolutely essential for the website to function properly. This category only includes cookies that ensures basic functionalities and security features of the website. These cookies do not store any personal information.
Any cookies that may not be particularly necessary for the website to function and is used specifically to collect user personal data via analytics, ads, other embedded contents are termed as non-necessary cookies. It is mandatory to procure user consent prior to running these cookies on your website.