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.

Experimental Evaluation of Ageing Marine Structures

2015 ◽  
Author(s):  
Yordan Garbatov ◽  
Carlos Guedes Soares
Keyword(s):  
Tensile Strength ◽  
Fatigue Strength ◽  
Ultimate Strength ◽  
Large Scale ◽  
Uniform Elongation ◽  
Bending Moment ◽  
Experimental Tests ◽  
Small Scale ◽  
Box Girders ◽  
Strength Tests

The objective of this work is to present a review of recently performed experimental tests of large and small scale steel corroded specimens. Four types of tests are discussed here: corrosion deterioration, ultimate strength, tensile strength and fatigue strength material properties. Two large scale specimens, in the form of box girders simulating the midship section of tanker ship where corroded in a natural open sea condition. The corrosion degradation and its distribution around the structural components of the box girders are presented and discussed. The effect of the severity of corrosion degradation on the strength of the corroded steel specimens is experimentally evaluated, where the box girders are tested under four-point loading, producing a constant bending moment along the box girder until collapse. The experimental results of fatigue strength tests of small scale corroded steel specimens, cut from the same corroded box girders, are also presented. Finally, the experimental tensile strength tests are performed using small-scale corroded specimens, cut from the corroded box girders after the ultimate strength test was completed. The test identifies the effect of the degree of degradation to the mechanical properties of the specimens, namely modulus of elasticity, yield stress, tensile strength and total uniform elongation are also presented. The results of the experimental tests, presented here, are highly important and need to be accounted for when linear or nonlinear structural analyses are performed to evaluate the structural capacity of ageing marine structure.

scholarly journals The Application of Barnes Filter to Positioning the Center of Landed Tropical Cyclone in Numerical Models

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Haibo Zou ◽  
Shanshan Wu ◽  
Xueting Yi ◽  
Nan Wu
Keyword(s):  
Numerical Model ◽  
Tropical Cyclone ◽  
Sea Level ◽  
Numerical Models ◽  
Small Scale ◽  
Model Output ◽  
Sea Level Pressure ◽  
Level Pressure ◽  
Distance Difference

After a tropical cyclone (TC) making landfall, the numerical model output sea level pressure (SLP) presents many small-scale perturbations which significantly influence the positioning of the TC center. To fix the problem, Barnes filter with weighting parameters C=2500 and G=0.35 is used to remove these perturbations. A case study of TC Fung-Wong which landed China in 2008 shows that Barnes filter not only cleanly removes these perturbations, but also well preserves the TC signals. Meanwhile, the centers (track) obtained from SLP processed with Barnes filter are much closer to the observations than that from SLP without Barnes filter. Based on the distance difference (DD) between the TC center determined by SLP with/without Barnes filter and observation, statistics analysis of 12 TCs which landed China during 2005–2015 shows that in most cases (about 85%) the DDs are small (between −30 km and 30 km), while in a few cases (about 15%) the DDs are large (greater than 30 km even 70 km). This further verifies that the TC centers identified from SLP with Barnes filter are more accurate compared to that directly obtained from model output SLP. Moreover, the TC track identified with Barnes filter is much smoother than that without Barnes filter.

scholarly journals THE WOOD‐FRAMED WITH SHEATHING BUILDINGS ‐ ALTERNATIVE FOR HOUSING CONSTRUCTION

2006 ◽  
Vol 12 (2) ◽  
pp. 143-151 ◽  
Author(s):  
Mikołaj Malesza ◽  
Czesław Miedziałowski
Keyword(s):  
Numerical Model ◽  
Composite Structure ◽  
Three Dimensional ◽  
Experimental Tests ◽  
Beam Element ◽  
Housing Construction ◽  
Residential Housing ◽  
Shell Elements ◽  
Linear Behaviour ◽  
Floor Diaphragms

Numerical model of the wood‐framed with sheathing structure and selected results of experimental tests are presented in the paper. Wall and floor diaphragms as the three‐dimensional composite structure are modeled applying plane shell elements representing framing and sheathing and beam element describing the fasteners. Experimental tests were conducted on typically disposed the wood‐framed wall and floor diaphragms in residential housing in Poland. Associated tests of materials and connections and their results are also included in the paper. Non‐linear behaviour of fasteners is examined in the numerical model. Results obtained from model and experiments are coincident.

Limit States for Deepwater Flowlines and Risers: Review of the Research Activities at the Submarine Technology Laboratory/COPPE

2003 ◽  
Author(s):  
S. F. Estefen ◽  
T. A. Netto ◽  
I. P. Pasqualino
Keyword(s):  
Ultimate Strength ◽  
Large Scale ◽  
Failure Modes ◽  
Numerical Models ◽  
Experimental Tests ◽  
Limit States ◽  
Collapse Pressure ◽  
Research Activities ◽  
Structural Resistance ◽  
Buckle Arrestors

Research activities related to the limit states of flowlines and risers conducted at the Submarine Technology Laboratory / COPPE in cooperation with PETROBRAS are presented. The motivation for most of the research programs is associated with deepwater challenges arising from the rigid pipe installations at Campos Basin. Initially ultimate strength of intact pipes are investigated together with aspects related to residual strength, buckling propagation and buckle arrestors. Based on the experimental results numerical models have been correlated in order to be used to generate results for full scale steel pipes. Ultimate strength curves have been then produced as well as the analytical equation representative of these curves. Experimental tests of buckling propagation for small and large scale pipes have also been performed to obtain the bias factor for different equations proposed in the literature. Based on this study an equation for propagation pressure has been recommended. In addition, ring and cylinder buckle arrestors have been tested in order to propose an expression relating crossing over pressure with the arrestor geometries. An overview of the studies aiming at establishing the influence of the reeling method of installation on the failure modes of flowlines and steel catenary risers is presented. It is emphasized the influence of cross-section ovality and weld defect amplification due to plastic bending on collapse pressure and fatigue life, respectively. Finally, the development of a new concept of sandwich pipe for ultra deepwater, combining structural resistance and thermal insulation is discussed.

Low Cycle Fatigue of Internally Pressurized Corroded Pipes Under Cyclic Bending

2009 ◽  
Author(s):  
Marcos Andre´ Baeta ◽  
Marcelo Igor Lourenc¸o ◽  
Theodoro A. Netto
Keyword(s):  
Cyclic Load ◽  
Low Cycle Fatigue ◽  
Numerical Models ◽  
Experimental Tests ◽  
Small Scale ◽  
Cycle Fatigue ◽  
Cyclic Tests ◽  
Operational Conditions ◽  
Oil Transportation ◽  
Operational Load

Corroded pipes for oil transportation can eventually experience low cycle fatigue failure after some years of operation. The evaluation of the defects caused by corrosion in these pipes is important when deciding for the repair of the line or continuity in operation. Under normal operational conditions, these pipes are subject to constant internal pressure and cyclic load due to bending and/or tension. Under such loading conditions, the region in the pipes with thickness reduction due to corrosion could experience the phenomenon known as ratcheting. The objective of this paper is to present a revision of the available numerical models to treat the ratcheting phenomenon. Experimental tests were developed allowing the evaluation of occurrence of ratcheting in corroded pipes under typical operational load conditions as well as small-scale cyclic tests to obtain the material parameters. Numerical and experimental tests results are compared.

Numerical Analysis of Masonry Confined by FRCM

2017 ◽  
Vol 747 ◽  
pp. 558-566 ◽  
Author(s):  
Francesco Saverio Murgo ◽  
Claudio Mazzotti
Keyword(s):  
Numerical Model ◽  
Numerical Models ◽  
Experimental Tests ◽  
Numerical Approach ◽  
Structural Behaviour ◽  
Confined Masonry ◽  
Axial Forces ◽  
Commercial Code ◽  
The University ◽  
Model Approach

In the present paper, structural behaviour of masonry columns strengthened with fiber reinforced cementitious matrix have been investigated; in particular, numerical 3D simulations calibrated on experimental tests have been presented. T hree-dimensional numerical model, realized by using the commercial code MIDAS FEA, based on a macro-model approach, has been used to simulate the nonlinear structural behavior of masonry columns strengthened with FRCM, and two different models for unreinforced and strengthened columns have been adopted. The 3D numerical approach are presented and results discussed to investigate the interaction between masonry columns and reinforcement. The numerical model has been calibrated on a large number of experimental tests on confined masonry columns carried out at the University of Bologna; in particular, columns have been wrapped by FRP and FRCM and with different arrangements (continuous and discontinuous). The comparison of the numerical models with the experimental outcomes shows a good matching in terms of axial forces-strain curves and strength peak.

Adhesion Effect on the Ultimate Strength of Sandwich Pipes

2006 ◽  
Author(s):  
Xavier Castello ◽  
Segen F. Estefen
Keyword(s):  
Ultimate Strength ◽  
Structural Strength ◽  
Numerical Models ◽  
Maximum Shear Stress ◽  
Experimental Tests ◽  
External Pressure ◽  
Friction Model ◽  
Shear Loads ◽  
Longitudinal Bending ◽  
Contact Models

Sandwich pipes composed of two steel layers separated by a polypropylene annular can be used for deepwater oil&gas transportation. They combine high structural strength to resist external pressure with thermal insulation to prevent blockage by paraffin and hydrate. In this work, experimental tests and numerical models were employed to verify the influence of the inter-layer adhesion on the ultimate strength under external pressure and longitudinal bending of a sandwich pipe prototype. The maximum shear stress obtained from sandwich pipe specimens bonded with a specific adhesive indicated the adhesion levels to be adopted in the numerical simulations. Two contact models were employed to simulate the bonding and slipping conditions between layers, one adopting a friction model and the other including non-linear springs between metal and polymer nodes. The latter is an adapted solution to simulate both tension and shear loads. As expected for a sandwich structure, the structural strength is strongly dependent on the interface stickiness. The analyzed geometry is able to withstand a water depth up to 3,000 meters with a bonding strength corresponding to only 10% of the idealized perfect adhesion condition.

Ratcheting of Corroded Pipes

2012 ◽  
Author(s):  
Marcelo Igor Lourenço ◽  
Theodoro A. Netto
Keyword(s):  
Cyclic Load ◽  
Numerical Models ◽  
Experimental Tests ◽  
Small Scale ◽  
Cyclic Tests ◽  
Operational Conditions ◽  
Material Parameters ◽  
Oil Transportation ◽  
Operational Load ◽  
Practical Tool

Corroded pipes for oil transportation can eventually experience Ratcheting after some years of operation. The evaluation of the defects caused by corrosion in these pipes is important when deciding for the repair of the line or continuity in operation. Under normal operational conditions, these pipes are subject to constant internal pressure and cyclic load due to bending and/or tension. Under such loading conditions, the region in the pipes with thickness reduction due to corrosion could experience the phenomenon known as ratcheting. The objective of this paper is to present a revision of the available numerical models to treat the ratcheting phenomenon. Experimental tests were developed allowing the evaluation of occurrence of ratcheting in corroded pipes under typical operational load conditions as well as small-scale cyclic tests to obtain the material parameters. Numerical and experimental tests results are compared. Shakedown models are also investigated as a practical tool for ratcheting prediction.

An experimental and numerical investigation on active compliant joint made by shape memory alloy actuator

2019 ◽  
Vol 234 (2) ◽  
pp. 156-164 ◽  
Author(s):  
Babak Katanchi ◽  
Alireza Fathi ◽  
Mostafa Baghani ◽  
Hamed Afrasyab
Keyword(s):  
Finite Element ◽  
Numerical Model ◽  
Shape Memory ◽  
Numerical Models ◽  
Niti Alloy ◽  
Experimental Tests ◽  
Finite Element Program ◽  
Heating Source ◽  
Compliant Joint ◽  
Actuator Performance

In this paper, a novel active compliant joint for robotic and microdisplacement applications is investigated numerically and experimentally. The proposed actuator structure is simple and possesses a higher energy density compared to the available actuators. Experimental tests are performed employing the shape memory behavior of NiTi alloy by the electric current as a heating source. To verify the actuator performance, numerical models are simulated in a nonlinear finite element program through employing a user subroutine according to experimental tests. Finite element implementation of the proposed actuator is performed based on the constitutive equations developed in Boyd–Lagoudas phenomenological model. Comparing the test and numerical results revealed that the numerical model is successful in predicting the actuator response. Finally, based on the verified numerical model, the effects of different parameters, e.g. the compression spring stiffness on the actuator performance are studied, and an optimal design for the actuator structure is proposed.

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.

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