Thin-Walled Cylindrical Shell Storage Tank under Blast Impacts: Finite Element Analysis

Thin-walled cylindrical shell storage tanks are pressure vessels in which the walls of the vessel have a thickness that is much smaller than the overall size of the vessel. These types of structures have global applications in various industries, including oil refineries and petrochemical plants. However, these storage tanks are vulnerable to fire and explosions. Therefore, a parametric study using numerical simulation was carried out, considering the internal liquid level, wall thickness, material yield strength, constraint conditions, and blast intensity, with a diameter of 100 m and height of 22.5 m under different blast loads using the finite element analysis method. The thickness of the tank wall is varied as 10 mm, 20 mm, 30 mm, and 40 mm, while the fill level of internal fluid is varied as 25, 50, 75, and 100%. The blast simulation was conducted using LS-DYNA software. The numerical results are then compared with analytical results. The effects of blast intensity, standoff distance, wall thickness, and fill level of internal fluid on the structural behaviour of the storage tank were investigated and discussed.publishedVersio

Finite Element Analysis of Steel Plates with Rectangular Openings Subjected to Axial Stress

Steel plates with openings are among the important ship structural components used in the ship’s hull to withstand the hydrostatic forces of the ocean, which cause sagging and hogging moments at the ship’s bottom. The existence of openings on plates can cause structural rupture, stress concentration and a decrease in ultimate strength. This research is aimed at investigating the influence of selected parameters on the ultimate capacity of steel plates with rectangular holes subjected to axial stress, using ANSYS finite element analysis (FEA) under its non-linear static structural programme. The main parameters investigated in this paper are the plate thickness, opening aspect ratio, number of openings, position of openings, and the boundary condition of the plate. The influence of these parameters on the stress of plates and their deformation was evaluated. The comparison of the numerical simulation with the well-established analytical method using the Navier solution and Roark’s Formulas showed a good agreement.Finite Element Analysis of Steel Plates with Rectangular Openings Subjected to Axial StresspublishedVersio

DETERMINATION OF HYDRODYNAMIC COEFFICIENTS AND VORTEX INDUCED VIBRATIONS FOR TUBULAR CYLINDERS USING EXPERIMENTAL AND NUMERICAL MODELLING

The present thesis addresses the estimation of hydrodynamic coeflicients for tubular cylinders subjected to oscillatory !lows using wave tank model tests, and presents mathematical models for prediction of hydrodynamic drag and inertia coefficients for Malaysian offshore locations based on linear regression analysis

THE EFFECTS OF SOLAR REFLECTANCE INDEX OF ROOF TILES AND OTHER DESIGN FEATURES ON INDOOR THERMAL COMFORT FOR HOUSING IN TROPICAL CLIAMA TE

Residential buildings in hot humid climate zone are experiencing overheating of living spaces below the roof as a result of inappropriate selection of roofing systems and construction materials. Hence, occupants tend to use air conditioning systems that increase the overall electricity consumption and greenhouse gases emissions i.e. C02. Therefore, this thesis is mainly intended to develop a cool house for hot humid climate zone by simply introducing roofing materials with higher Solar Reflectance Index (SRI). The research methodology adopted in this study consists of experimental investigations and survey data collection methods and is mainly designed· in three phases. The first phase consists of a qualitative survey that aims to investigate and determine the actual condition of roof colors in the existing buildings:·. obtain a perception of home buyers on implementation of light colored roof tiles, and determine the understating level, awareness and barriers facing utilizationof light colored roof tiles with higher SRI in the local construction industry. The second phase of this research is an experimental investigation conducted on an experimental house which was constructed within UTP campus. The experimental study is mainly intended to determine and establish the most important parameters that i~fluence the SRI values, namely, (I) Roof tile's color, (2) material composition, and (3) the roof slope and orientation. While the third phase of this study consists of value engineering, with stress on cost saving and C02 reduction associated with implementation of light colored roof tiles with emphasize on Putrajaya as a case study for a green and sustainable city in Malaysia. The questionnaires data were analyzed using statistical techniques, whilst the analysis of experimental results was based on the theory of heat transfer and thermodynamic in buildings (i.e. building physics). The survey analysis results suggest that 78.5% of the existing buildings in Malaysia have dark colored roof tiles. In addition, 73.6% of Malaysians are depending on air conditioning systems to improve indoor thermal comfort for housing. The survey has determined that (I) lack of knowledge, (2) maintenance issues and (3) cultural and religious background are the main challenges facing implementation of light colored roof tiles especially "white roof' in Malaysia. Further, the experimental study suggested that "white" color roof tile is the best in terms of solar reflectivity, flowed by "orange" and "red" color respectively. Furthermore, regarding the material composition, clay tiles were found to be cooler than concrete roof tiles, whilst the roof configuration with 32° sloping in both sides was much better in terms of achieving cooler and healthier indoor thermal comfort. The overall findings of this research strongly support the need for implementation of roofing materials with higher SRI values in order to improve the indoor thermal comfort, reduce electricity consumption in buildings and, consequently, mitigate greenhouse gases emissions and global warming

A Numerical Study on the Effects of Perforated and Imperforate Baffles on the Sloshing Pressure of a Rectangular Tank

Sloshing has many industry applications, namely in offshore engineering, aerospace, ship building, and manufacturing. Sloshing simulation is essential to better understand the sloshing pattern and consequently to improve the tank design to reduce noise levels, stresses on the structure, and optimize the baffle configurations and arrangements. Thus, the aim of this study is to determine the effects of perforated (porous) and imperforate (solid) baffles on the sloshing pressure using ANSYS FLUENT software based on Volume of Fluid (VOF) method where a rectangular tank with 25% and 60% filling ratios was considered. In the first case, an unbaffled rectangular tank with 60% filling ratio was used for the validation purpose, while in the second case, a 25% filling ratio was investigated considering two scenarios, namely a unbaffled tank and a baffled tank case with perforated and imperforate baffles. The outcomes of the results indicate that perforated baffle can significantly reduce the sloshing pressure in the tank. The validation of the results also shows a good agreement with the published experimental results

Vortex-Induced Vibration Tests of a Marine Growth Wrapped Cylinder at Subcritical Reynolds Number

Vortex Induced Vibrations (VIV) may cause great damage to deep water risers. Estimation of accurate hydrodynamic coefficients and response amplitudes for fouled tubular cylinders subjected to VIVs is a complex task. This paper presents the results of an extensive experimental investigation on in-line and cross-flow forces acting on cylinders wrapped with marine growth, subjected to current at Subcritical Reynolds Number. The drag and lift force coefficients have been determined through the use of the Fast Fourier Analysis methods. The different tests were conducted in the offshore engineering laboratory at Universiti Teknologi PETRONAS (UTP), Malaysia. In this study, a cylinder with outer diameter Do = 27 mm, fixed at top as cantilever beam was used. The in-line and cross-flow forces were measured using VIV Force Totaller (VIVFT). VIVFT is a two degree of freedom (2DOF) forces sensor developed by UTP to measure the VIV forces. The tests were conducted for current velocity varied between 0.118 to 0.59 m/s. The test results suggest that the cylinder wrapped with marine growth has shown an overall increase in drag and inertia coefficients as well as on response amplitudes

Prediction of dynamic responses of floating structures using NARX with mirroring technique

Displacements, velocities and accelerations of Six Degree of freedom of a single floating structure was predicted using Time Series NARX feedback neural Networks. The nonlinear autoregressive network with exogenous inputs (NARX) is a recurrent dynamic network, with feedback connections enclosing several layers of the network is based on the linear ARX model, which is commonly used in time-series modelling is used in this study. Time series data of displacements of a single floating structure was used for training and testing the ANN model. In the training stage, this time series data of environment parameters was used as input and dynamic responses was used as target. Benchmarking result and error prediction was compared between two techniques of Neural Network training. The prediction result of the model responses can be concluded that NARX with mirroring technique increase the accuracy and can be used to predict time series of dynamic responses of floating structures

Downtime Cost Analysis of Offloading Operations Considering Vessel Motions and Mooring Responses in Malaysian Waters

© 2019 IEEE. A real time motion of moored FPSO in side-by-side configuration for regular wave is simulated in ANSYS AQWA to evaluate the structure motion responses and cable forces under criteria and operational wave conditions for two sea-state. The mooring failure is simulated wherein whole cable tensile forces are calculated. Downtime occurs when the vessel motion and cable responses in operating wave conditions exceed the safe limiting values. With the help of a real time wave scatter diagram of three different locations in Malaysian waters, the probability occurrences are obtained and finally a novel study on the downtime cost analysis for offloading operations is performed considering structure responses and mooring failure conditions. In this paper, a successful attempt has been made to connect vessel motion responses to cost. This paper evaluates the possible downtime cost and economical risks involved in the different locations of Malaysian waters for offloading operations