PSI - Issue 47

M. Iqbal Maulana et al. / Procedia Structural Integrity 47 (2023) 150–158 Maulana et al. / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction Recently, many studies have been carried out on the response of geometrical structures to collision and accidental loads [Muttaqie et al., 2019; Do et al., 2022; Prabowo et al., 2019; 2021; 2022; Widiyanto et al., 2022], including air burst loading [Prabowo et al., 2020; Ansori et al., 2022; Mubarok et al., 2022; Nubli et al., 2020; 2022a,b]. Explosives are materials that are chemically or energetically unstable, or they can produce a sudden expansion of the material followed by the generation of heat and a large change in pressure (and usually also a flash or a big sound) which is known as an explosion. This sudden release of energy occurs in a very short time frame (microsecond scale). Therefore, it takes a subject to restrain this explosion. There is no formally recognized standard for a pressure vessel design that can accommodate explosive or impulsive loads, which may arise from the explosion of highly explosive charges or the ignition of flammable gases [Rushton et al., 2008]. In this paper, research will be carried out to determine the value of plastic tension in an explosion barrier (tubular vessel) using the Conventional Weapon (CONWEP) model with finite element modeling. Findings of this research is projected to obtain reliable finite element methodology in modelling internal blast loading on designed steel pipe. Comparison with pioneer experimental works will be conducted to determine the accuracy of the current nonlinear methodology in terms of structural behaviors, especially structure with the applied API 5l X42 steel. Von Mises stress is defined as the internal resistance per unit area of an object against an externally applied force [Wang et al., 1997]. The value of the Von Mises stress is usually used to determine whether a material will yield or fracture. Failure or yielding of certain structural members when strain energy values are distorted (also called shear strain energy) per unit volume in the material achieves the required limiting distortion energy per unit volume to cause yielding as determined from a simple stress test [Khurmi and Gupta, 2005]. It is widely used for ductile materials, such as metals. The maximum distortion energy for yielding is given by Equation 1. 2 − + 2 = 2 (1) 2.2. Pressure vessel A pressure vessel is a closed leak-tight container (normally cylindrical or spherical) designed to hold fluids (i.e., gases or liquids) at a pressure substantially different (higher or lower) from the ambient pressure. Many applications of pressure vessels in the industrial world today are encountered in various fields. The use also varies depending on the needs and function of the industry. For example, pressure vessels can be used for nuclear reactor vessels, pneumatic reservoirs, and liquid gas storage vessels. There are many types of pressure vessels that we often encounter, but there is one vessel that we most often encounter, namely a conventional pressure vessel. Conventional pressure vessels or often referred to as cylindrical pressure vessels are generally made with a circular cross-section. This is because the circular shape is known as the most efficient structural form, a simple and robust structure. However, conventional pressure vessels also have a weakness, namely low volume efficiency. The volume of conventional pressure vessels has a volume efficiency of 25-50% lower than prismatic pressure vessels depending on the installation space. This problem can be critical, especially in the shipping and offshore industry, due to limited space [Lee et al., 2017]. Many studies have been conducted and discussed this pressure vessel, one of which was done by Duffey and Grieg [1969], where they studied the effects of strain hardening and the sensitivity of strain rate on the transient responses of elastic plastic rings and long cylinders [Duffey and Mitchell, 1973]. The method proposed by Duffy and Mitchell [1973] assumes that the material is rigid- perfectly plastic, the displacement is focused in the center of the cylinder where the explosives are located, the material is not sensitive to strain-hardening or strain-rate effects, and there is no axial deformation during the loading process. The equation of motion for a cylinder under the same impulse is subjected to an ideal triangular pressure pulse with zero rise time and duration ( ), Equation 2, which is solved for certain boundary conditions. For simplification, the membrane hoop stress is equated to the material yield stress. 2. Literature Review 2.1. Von-misses concept