Experimental and Numerical Analyses of Dented Stiffened Panels

2015 ◽  
Vol 137 (3) ◽  
Author(s):  
Diogo do Amaral M. Amante ◽  
John Alex Chujutalli ◽  
Segen F. Estefen
Keyword(s):  
Numerical Models ◽  
Strength Loss ◽  
Correlation Study ◽  
Numerical Analyses ◽  
Small Scale ◽  
Geometric Imperfection ◽  
Stiffened Panels ◽  
Shell Elements ◽  
Before And After ◽  
Parametric Studies

Numerical–experimental correlation study for small scale damaged stiffened panels was performed. Six small scale models were fabricated. Two of them were employed for the correlation of intact panels and the remaining four for the correlation of dented panels. Ultimate strength analyses were carried out in order to adjust the numerical model for further use in parametric studies. The damage was imposed by a local indentation of the panels. Measurements of geometric imperfection distributions and damage shapes have been performed before and after the damage using a laser tracker equipment. The numerical models were represented by shell elements assuming finite membrane strains and large rotations, considering both geometric and material nonlinearities. Results obtained showed very good agreement between experimental and numerical analyses for both intact and dented panels. Additionally, numerical simulations of damaged stiffened panels were performed. The aim of the parametric study was to evaluate the behavior up to and beyond buckling, to observe the strength loss due to the presence of the damage on the panel. The explicit nonlinear finite element code from abaqus program was employed to simulate the dent damage. Therefore, distortions and the residual stresses due to the damage were both considered in subsequent numerical compression analyses.

Buckling Strength of Damaged Stiffened Panels

2011 ◽  
Author(s):  
Diogo do Amaral Amante ◽  
Segen F. Estefen
Keyword(s):  
Numerical Models ◽  
Strength Loss ◽  
Correlation Study ◽  
Small Scale ◽  
Failure Behavior ◽  
Geometric Imperfection ◽  
Stiffened Panels ◽  
Shell Elements ◽  
Buckling Strength ◽  
Parametric Studies

Numerical and experimental simulations for small scale damaged stiffened panels are performed. Six small scale stiffened panels were fabricated following special techniques to keep them in accordance with usual tolerances related to initial geometric imperfections due to fabrication. Ultimate buckling strength analyses were carried out in order to perform a correlation study to adjust the numerical model for further use in parametric studies. The damage was imposed with a local indentation on the panels. Measurements of the geometric imperfection distributions and damage shapes were accomplished using the equipment laser tracker. It is a portable contact measurement equipment that uses laser technology with sub-millimeter accuracy. The numerical models are represented by shell elements assuming finite membrane strains and large rotations, considering both geometric and material nonlinearities. The aim of the work is to study the failure behavior up to and beyond buckling to evaluate the strength loss due to the damage imposed to the panel. Additionally, some numerical simulations of damaged stiffened panels were performed. In these analyses the damage was done with explicit nonlinear finite element code from ABAQUS program. Therefore the distortions and the residual stresses due to the damage are both considered in subsequent compression analysis.

Influence of the Geometric Imperfection on the Buckling Behavior of Floating Platform Column Under Axial Load

2007 ◽  
Author(s):  
Tiago P. Estefen ◽  
Daniel S. Werneck ◽  
Segen F. Estefen
Keyword(s):  
Progressive Failure ◽  
Correlation Study ◽  
Gas Production ◽  
Small Scale ◽  
Failure Behavior ◽  
Floating Platform ◽  
Cross Sectional ◽  
Geometric Imperfection ◽  
Stiffened Panels ◽  
Buckling Behavior

The present work focuses on the design of the new generation of semi-submersible platforms for oil&gas production offshore that is based on column square cross-sectional area. The platform column is based on an arrangement of stiffened flat panels having their ultimate strength characterized by buckling under in-plane compressive loading. Distortions induced by fabrication have considerable influence on the buckling behavior and are discussed in order to provide design recommendations. The aim of the paper is to study a segment of the column structural arrangement between robust transverse frames to analyze the failure behavior of the stiffened panels. Previous research demonstrated the strong influence of both mode and magnitude of the geometric imperfection distribution, as well as the boundary conditions. Numerical and experimental simulations for small scale isolated panels are carried out in order to perform a correlation study to adjust the numerical model for further use in more complex numerical simulations of the structural failure of the column arrangement. The stiffened panels are analyzed to identify the buckling initiation on a particular panel and then the interaction between plates, longitudinal stiffeners and the robust transverse frames during the progressive failure of the whole column.

Residual Strength of Dented Stiffened Panels

2013 ◽  
Author(s):  
Diogo do Amaral Amante ◽  
John Alex Chujutalli ◽  
Segen F. Estefen
Keyword(s):  
Compressive Strength ◽  
Numerical Models ◽  
Compressive Load ◽  
Strength Loss ◽  
Failure Behavior ◽  
Stiffened Panels ◽  
Shell Elements ◽  
Residual Compressive Strength ◽  
Large Rotations ◽  
Indentation Damage

The residual compressive strength of dented stiffened panels is investigated. Numerical simulations were performed using the finite elements program ABAQUS. The analysis is carried out in two steps. First the panel indentation damage is imposed using the ABAQUS explicit code program. After the indentation, a compressive load is applied and then the panel residual compressive strength is verified. Local damage was simulated by a dynamic collision due to an object fall. Therefore the distortions and the residual stresses due to the damage are both considered in the subsequent compression analysis. The aim of the work is to study the failure behavior up to and beyond buckling to evaluate the strength loss due to the damage imposed to the panel. The numerical models are represented by shell elements assuming finite membrane strains and large rotations, considering both geometric and material nonlinearities.

Hull Girder Ultimate Strength of Intact and Damaged Double Hull Tankers

2016 ◽  
Author(s):  
Diogo do Amaral M. Amante ◽  
John Alex Chujutalli ◽  
Segen F. Estefen
Keyword(s):  
Numerical Model ◽  
Ultimate Strength ◽  
Numerical Models ◽  
Experimental Tests ◽  
Small Scale ◽  
Box Girders ◽  
Shell Elements ◽  
Hull Girder ◽  
Damage Scenarios ◽  
Double Hull

The aim of this work is to accomplish an assessment of the hull girder ultimate strength of intact and damaged double hull tankers. First, the paper presents the validation of the numerical model through comparisons with experimental tests of small-scale box girders. The numerical models are represented by shell elements assuming finite membrane strains and large rotations, considering both geometric and material nonlinearities. Simulation results show very good agreement with experimental tests. Then, a numerical model of a double hull tanker was developed and analyzed in the intact and damaged conditions. Several damage scenarios were investigated.

Study of Diabetic Mellitus and Knowledge of Lotion Foot Care on the Community

2018 ◽  
Vol 9 (3) ◽  
Author(s):  
Hariyadi DM ◽  
Athiyah U ◽  
Hendradi E ◽  
Rosita N ◽  
Erawati T ◽  
...  
Keyword(s):  
Blood Glucose ◽  
T Test ◽  
Small Scale ◽  
Scale Production ◽  
Foot Care ◽  
Diabetic Mellitus ◽  
Glucose Levels ◽  
Blood Glucose Levels ◽  
Before And After ◽  
History Of

The prevention of Diabetic Mellitus (DM) and its complications is the main aim of this study, in addition to the training of lotion foot care application and the development of small scale industry. The research team delivered knowledge in the form of training on Diabetic Mellitus, healthy food, treatment and prevention of complications, and small-scale production of cosmetic products. The aim of this study was to determine the correlation between training on diabetic and lotion foot care application as preventive measures against diabetic complications on the patient's blood glucose levels in the community of residents in Banyuurip Jaya, Surabaya. It was expected from this training that the knowledge of the residents increases and people living with diabetic undergo lifestyle changes and therefore blood sugar levels can be controlled. The parameters measured in this research were blood glucose levels, the anti diabetic drug types consumed, and compliance on diabetics. This study used the data taken from 60 patients with DM over a period of one month. Questionnaires and log books was used to retrieve data and changes in blood glucose levels in diabetic patients. The results showed the demographic data of patients with type 2 diabetic of 85% female and 15% male, with the range of patients aged of 61-70 years of 46.67% and had history of diabetic (90%). The history of drugs consumed by respondents was anti diabetic drugs such as metformin (40%), glimepiride (33.37%) and insulin (6.67%). In addition, the increased knowledge of DM patients after being given the training compared to before training was shown in several questions in the questionnaire. A statistical analysis using t-test analyzed a correlation between training provided in order to enhance understanding of the patient, as well as correlation with blood glucose levels. A paired T-test showed that there was a relationship between the knowledge of trainees before and after training (p less than 0.05). An interesting result was that there was no relationship between blood glucose levels before and after training provided (p> 0.05).

scholarly journals A Computational Approach to Solve a System of Transcendental Equations with Multi-Functions and Multi-Variables

Mathematics ◽  
2021 ◽  
Vol 9 (9) ◽  
pp. 920
Author(s):  
Chukwuma Ogbonnaya ◽  
Chamil Abeykoon ◽  
Adel Nasser ◽  
Ali Turan
Keyword(s):  
Numerical Models ◽  
Problem Formulation ◽  
Science And Engineering ◽  
Physical Systems ◽  
Engineering Problems ◽  
Parametric Studies ◽  
Independent Variable ◽  
Transcendental Equations ◽  
The Waves ◽  
Modelling Approach

A system of transcendental equations (SoTE) is a set of simultaneous equations containing at least a transcendental function. Solutions involving transcendental equations are often problematic, particularly in the form of a system of equations. This challenge has limited the number of equations, with inter-related multi-functions and multi-variables, often included in the mathematical modelling of physical systems during problem formulation. Here, we presented detailed steps for using a code-based modelling approach for solving SoTEs that may be encountered in science and engineering problems. A SoTE comprising six functions, including Sine-Gordon wave functions, was used to illustrate the steps. Parametric studies were performed to visualize how a change in the variables affected the superposition of the waves as the independent variable varies from x1 = 1:0.0005:100 to x1 = 1:5:100. The application of the proposed approach in modelling and simulation of photovoltaic and thermophotovoltaic systems were also highlighted. Overall, solutions to SoTEs present new opportunities for including more functions and variables in numerical models of systems, which will ultimately lead to a more robust representation of physical systems.

scholarly journals The Effectiveness of Ensemble-Neural Network Techniques to Predict Peak Uplift Resistance of Buried Pipes in Reinforced Sand

2021 ◽  
Vol 11 (3) ◽  
pp. 908
Author(s):  
Jie Zeng ◽  
Panagiotis G. Asteris ◽  
Anna P. Mamou ◽  
Ahmed Salih Mohammed ◽  
Emmanuil A. Golias ◽  
...  
Keyword(s):  
Neural Network ◽  
Numerical Models ◽  
Correlation Coefficients ◽  
Network Models ◽  
Small Scale ◽  
Offshore Platforms ◽  
Neural Network Models ◽  
Buried Pipes ◽  
Ensemble Techniques ◽  
Uplift Resistance

Buried pipes are extensively used for oil transportation from offshore platforms. Under unfavorable loading combinations, the pipe’s uplift resistance may be exceeded, which may result in excessive deformations and significant disruptions. This paper presents findings from a series of small-scale tests performed on pipes buried in geogrid-reinforced sands, with the measured peak uplift resistance being used to calibrate advanced numerical models employing neural networks. Multilayer perceptron (MLP) and Radial Basis Function (RBF) primary structure types have been used to train two neural network models, which were then further developed using bagging and boosting ensemble techniques. Correlation coefficients in excess of 0.954 between the measured and predicted peak uplift resistance have been achieved. The results show that the design of pipelines can be significantly improved using the proposed novel, reliable and robust soft computing models.

scholarly journals Species and characteristics of volatile organic compounds emitted from an auto-repair painting workshop

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
M. Y. Song ◽  
H. Chun
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Large Scale ◽  
Butyl Acetate ◽  
Small Scale ◽  
Indoor Environments ◽  
Voc Emissions ◽  
Volatile Organic ◽  
Before And After ◽  
Adsorption Systems

AbstractVolatile organic compounds (VOCs) are secondary pollutant precursors having adverse impacts on the environment and human health. Although VOC emissions, their sources, and impacts have been investigated, the focus has been on large-scale industrial sources or indoor environments; studies on relatively small-scale enterprises (e.g., auto-repair workshops) are lacking. Here, we performed field VOC measurements for an auto-repair painting facility in Korea and analyzed the characteristics of VOCs emitted from the main painting workshop (top coat). The total VOC concentration was 5069–8058 ppb, and 24–35 species were detected. The VOCs were mainly identified as butyl acetate, toluene, ethylbenzene, and xylene compounds. VOC characteristics differed depending on the paint type. Butyl acetate had the highest concentration in both water- and oil-based paints; however, its concentration and proportion were higher in the former (3256 ppb, 65.5%) than in the latter (2449 ppb, 31.1%). Comparing VOC concentration before and after passing through adsorption systems, concentrations of most VOCs were lower at the outlets than the inlets of the adsorption systems, but were found to be high at the outlets in some workshops. These results provide a theoretical basis for developing effective VOC control systems and managing VOC emissions from auto-repair painting workshops.

Effect of Full- and Small-Scale Reeling Simulation on Mechanical Properties of Weldable 13Cr Seamless Line Pipe

2013 ◽  
Author(s):  
Hidenori Shitamoto ◽  
Nobuyuki Hisamune
Keyword(s):  
Mechanical Properties ◽  
Plastic Deformation ◽  
Oil And Gas ◽  
Small Scale ◽  
Line Pipe ◽  
Offshore Pipeline ◽  
Oil And Gas Pipelines ◽  
Before And After ◽  
Offshore Oil And Gas ◽  
Offshore Oil

There are several methods currently being used to install offshore oil and gas pipelines. The reel-lay process is fast and one of the most effective offshore pipeline installation methods for seamless, ERW, and UOE line pipes with outside diameters of 18 inches or less. In the case of the reel-laying method, line pipes are subjected to plastic deformation multiplication during reel-laying. It is thus important to understand the change of the mechanical properties of line pipes before and after reel-laying. Therefore, full-scale reeling (FSR) simulations and small-scale reeling (SSR) simulations are applied as evaluation tests for reel-laying. In this study, FSR simulations were performed to investigate the effect of cyclic deformation on the mechanical properties of weldable 13Cr seamless line pipes. Furthermore, SSR simulations were performed to compare the results obtained by FSR simulations.

scholarly journals Observational aspects of prominence oscillations

2007 ◽  
Vol 3 (S247) ◽  
pp. 152-157 ◽  
Author(s):  
Oddbjørn Engvold
Keyword(s):  
Magnetic Structure ◽  
Numerical Models ◽  
Small Scale ◽  
Solar Prominences ◽  
Scale Structures ◽  
Oscillations And Waves ◽  
Available Information ◽  
Small Scale Structures

AbstractSeismology has become a powerful tool in studies of the magnetic structure of solar prominences and filaments. Reversely, analytical and numerical models are guided by available information about the spatial and thermodynamical structure of these enigmatic structures. The present invited paper reviews recent observational results on oscillations and waves as well as details about small-scale structures and dynamics of prominences and filaments.

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