Evaluation of high-tensile steel using nonlinear analysis: Experiment-FE materials benchmarking of LNG carrier structures under low-temperature conditions

Abstract

Natural gas is the cleanest energy source compared to other fossil fuels. When the temperature is between −160 ºC to −164 ºC at atmospheric pressure, natural gas will be in liquid form, commonly called Liquefied Natural Gas (LNG). Currently, the demand for the availability of natural gas is increasing rapidly. However, not all countries have natural gas reserves. In this case, ships transport Liquefied Natural Gas (LNG) between continents and oceans to meet global needs. Since the Northern Sea Route (NSR) was opened, the route has become an alternative route where ships can save fuel because the distance is closer than the standard route (through the Suez Canal). However, because this route is in the Arctic region, which has a harsh environment, the ship may experience a structural failure, resulting in an accident and possibly causing material, human or other casualties. This paper employed the finite element method to observe the materials used as raw materials for the structure of natural gas shipping vessels. High tensile steel grade AH 32 was tested for tensile using numerical analysis. The temperature varied from room to shallow temperature (−160 ºC). Besides that, the mesh sizes used were 1 mm, 2 mm, 4 mm, 6 mm, 8 mm, and 10 mm to produce outcomes that are most similar to earlier research assessed via experimental testing. The result obtained was that the mechanical properties of AH 32 steel will change significantly at shallow temperatures, which can be observed from the engineering stress–strain graph. High tensile steel grade AH 32 becomes very brittle at −160 ºC. Besides that, the necking phenomenon, as in the experimental test, can also be observed through numerical analysis.

Keywords

• Natural gas
• Liquefied natural gas
• Tensile test
• Numerical analysis
• Necking phenomenon