PSI - Issue 33

Muhammad Sabiqulkhair Akbar et al. / Procedia Structural Integrity 33 (2021) 67–74 Akbar et al. / Structural Integrity Procedia 00 (2019) 000–000

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1. Introduction As we know oceans are the largest part of the earth. Genda (2016) has been mentioned that around 71% of the earth’s surface is covered by oceans. So, water transportation such as vessels is the most important transportation as a means of connecting between islands even between countries. According to Mathai et al. (2013) ships are classified as cargo carriers, passenger carriers, industrial ships, service vessels, container ships, and others. Approximately almost 90% of global trade is mobilized by shipping (Elkafas et al., 2019). As the demand for ship transportation increased, the loads on the hull structure are also increased. The structural design should achieve two main objectives: the ship should be designed to withstand the applied load on it (it may be environmental load, impact load, and working load – see Prabowo et al., 2016a,b; and Prabowo et al., 2017a,b), and the other is the structure should be designed at considerable cost (Prakash and Smitha, 2018). The strength of the ship's structure is very important to withstand the load of the ship, one of which is the environmental load caused by the environmental influence of the type of ocean that the ship will pass through. Hull testing of hydrostatic loads and hydrodynamic loads can be performed to determine the hull's strength against environmental loads (Muttaqie et al., 2019). By using software to test the strength of the hull with specified loads and boundary conditions to find out how strong the hull is. This paper discusses the numerical study using finite element analysis (FEA) of midship structure with different outcomes for each ELT ratio referring to benchmarking papers. According to Kharmanda (2016), FEA is a commonly used method for evaluating the output of any model that has been developed. Researchers need to conduct a mesh convergence analysis before constructing a model to obtain the necessary meshing scale, as this can result in huge variations in the output (Ahmad et al., 2013). It is important to perform a convergence study, as Carlson and Herdman (2012) mentioned that the magnitudes and interpretability of research results would be affected by poor convergent validity at any stage. The study aims to perform an ELT ratios convergence study for benchmarking of midship structure. The results obtained are displacement, strain, and stress from simulation and will be compared to benchmarking journals with variations on the parameters such as displacement ratio, strain ratio, and stress ratio. The error value can be calculated from the parameters to show that the ELT ratio affects simulation results.

Nomenclature ELT

Element-length-to-thickness

Young’s modulus Yield Strength

E σ δ

Density

Poisson’s ratio Displacement

v

Δ x

ε

Strain

Stress von-Mises

σ v-M

2. Finite Element Setting and Configuration For Finite Element Analysis, it is important to do setting and configuration before we do simulation. Titanium alloy was used as a material for the midship structure in this simulation, nowadays titanium has been used in shipbuilding (Oryshchenko et al., 2020). This material is also used in benchmarking studies that we will compare in this paper to look for convergence results from the pioneer study. Mechanical properties are shown in Table 1 with input for analysis using SolidWorks simulation.

Table 1. Material properties of the midship structure. Material E (N/m 2 )

σ (N/m 2 )

δ (kg/m 3 )

v (-) 0.33

Titanium Alloy

1.15×10 11

792897.09

4730