Development on Aegir Reeling Pipeline Analyses by Test Validation

2013 ◽  
Author(s):  
Erwan Karjadi ◽  
Helen Boyd ◽  
Reinout van Rooijen ◽  
Harm Demmink ◽  
Thomas Balder
Keyword(s):  
Cost Effective ◽  
Material Model ◽  
Material Behavior ◽  
Small Scale ◽  
Correct Prediction ◽  
Test Program ◽  
Element Analysis ◽  
Bend Tests ◽  
The Difference ◽  
Cyclic Straining

Heerema Marine Contractors (HMC) is entering a new era of laying pipelines using the reel-lay method in order to be more cost effective for deep and shallow water pipeline installation projects. The new Deep water Construction Vessel (DCV) Aegir is designed to be able to reel/J-lay pipelines for a range of pipe dimension and water depth combinations. The paper describes how the full reeling cycles Finite Element Analysis (FEA) of the Aegir have been developed step by step from the development of the bend rig test, spooling-on to spooling-off FE models which is validated by the bend rig test program. The required material test program is performed to characterize the correct material behavior under plastic cyclic straining. The know-how from the validation of the FEA of bend rig tests by performing the bend tests program is used to setup the full-reeling cycles simulation of spooling-on pipeline on the yard and spooling-off pipeline on board of the Aegir. A series of bend rig tests have been performed at Heriot-Watt University. Ovality measurements from the tests are compared with the predicted results from the bend rig FEA simulation model. Based on small scale specimen tests which are performed to describe the proper material behavior under plastic cyclic straining, a new material model has been proposed and discussed to provide a correct prediction of ovalization against the number of bend cycles. Comparison between the bend rig test measurements and the Aegir full reeling cycles simulation results is made by comparing the deformation of the pipe (ovalization) against a number of bend cycles. Discussion is given to justify the difference in the outcomes as well as the representation of the bend tests program for the qualification test program for reeling with the Aegir.

Hyperelastic Muscle Simulation

2007 ◽  
Vol 345-346 ◽  
pp. 1241-1244 ◽  
Author(s):  
Mohd. Zahid Ansari ◽  
Sang Kyo Lee ◽  
Chong Du Cho
Keyword(s):  
Skeletal Muscle ◽  
Silicone Rubber ◽  
Soft Tissues ◽  
Material Model ◽  
Incompressible Material ◽  
Material Behavior ◽  
Rubber Tube ◽  
Stress Strain ◽  
Element Analysis ◽  
Strain Behavior

Biological soft tissues like muscles and cartilages are anisotropic, inhomogeneous, and nearly incompressible. The incompressible material behavior may lead to some difficulties in numerical simulation, such as volumetric locking and solution divergence. Mixed u-P formulations can be used to overcome incompressible material problems. The hyperelastic materials can be used to describe the biological skeletal muscle behavior. In this study, experiments are conducted to obtain the stress-strain behavior of a solid silicone rubber tube. It is used to emulate the skeletal muscle tensile behavior. The stress-strain behavior of silicone is compared with that of muscles. A commercial finite element analysis package ABAQUS is used to simulate the stress-strain behavior of silicone rubber. Results show that mixed u-P formulations with hyperelastic material model can be used to successfully simulate the muscle material behavior. Such an analysis can be used to simulate and analyze other soft tissues that show similar behavior.

Finite Element Modeling of Biodegradable Stents

2013 ◽  
Author(s):  
Nic Debusschere ◽  
Matthieu De Beule ◽  
Peter Dubruel ◽  
Patrick Segers ◽  
Benedict Verhegghe
Keyword(s):  
Finite Element ◽  
Mechanical Behavior ◽  
Mechanical Performance ◽  
Cost Effective ◽  
Minimal Invasive ◽  
Material Behavior ◽  
Element Analysis ◽  
Design And Optimization ◽  
Stent Restenosis ◽  
Biodegradable Stents

Biodegradable stents, which temporarily support a stenotic blood vessel and afterwards fully disappear, have recently gained a lot of interest. They avoid long-term complications associated with conventional stents such as late stent thrombosis and in-stent restenosis. Moreover, degradable stents allow for a restoration of vasomotion and vessel growth which makes them particularly suitable for pediatric applications [1]. Finite element simulations have proven to be an efficient and cost-effective tool to investigate and optimize the mechanical performance of minimal invasive devices such as stents [2]. Biodegradable stents have however created new challenges in their design and optimization via finite element analysis because of their complex time-varying material behavior. To correctly simulate the mechanical behavior of biodegradable stents, a model should be developed that incorporates the effect of degradation upon all material characteristics. By combining existing constitutive material models based on continuum damage theory we were able to create such a virtual environment in which the transitional mechanical behavior of biodegradable stents can be investigated.

Forming of Al 5182-O in a Servo Press at Room and Elevated Temperatures

2015 ◽  
Vol 137 (5) ◽  
Author(s):  
Long Ju ◽  
Shrinivas Patil ◽  
Jim Dykeman ◽  
Taylan Altan
Keyword(s):  
Finite Element ◽  
Deep Drawing ◽  
Elevated Temperatures ◽  
Cost Effective ◽  
Element Model ◽  
Material Behavior ◽  
Bulge Test ◽  
Element Analysis ◽  
Automotive Manufacturing ◽  
Servo Press

Aluminum alloys are increasingly used in automotive manufacturing to save weight. The drawability of Al 5182-O has been proven at room temperature (RT) and it is also shown that formability is further enhanced at elevated temperatures (ETs) in the range of 250–350 °C. A cost effective application of ET forming of Al alloys can be achieved using heated blank and cold dies (HB–CD). In this study, the material behavior of Al 5182-O is characterized using tensile test and viscous bulge test at RT. The nonisothermal finite element model (FEM) of deep drawing is developed using the commercial software pamstamp. Initially, deep drawing simulations and tests were carried out at RT using a 300 ton servo press, with a hydraulic cushion. The predictions with flow stress curves obtained from tensile and bulge tests were compared with experimental data. The effect of punch speed and temperature rise during forming at RT is investigated. The warm forming simulations were carried out by combining material data at ETs obtained from the literature. The coupled effects of sheet temperatures and punch speeds are investigated through the finite element analysis (FEA) to provide guidelines for ET stamping of Al 5182-O.

scholarly journals A novel length-based empirical estimation method of spawning potential ratio (SPR), and tests of its performance, for small-scale, data-poor fisheries

2014 ◽  
Vol 72 (1) ◽  
pp. 217-231 ◽  
Author(s):  
Adrian Hordyk ◽  
Kotaro Ono ◽  
Sarah Valencia ◽  
Neil Loneragan ◽  
Jeremy Prince
Keyword(s):  
Empirical Test ◽  
Estimation Method ◽  
Size Composition ◽  
Cost Effective ◽  
Small Scale ◽  
Empirical Estimation ◽  
Input Parameters ◽  
Maximum Likelihood Methods ◽  
Spawning Potential Ratio ◽  
The Difference

Abstract The spawning potential ratio (SPR) is a well-established biological reference point, and estimates of SPR could be used to inform management decisions for data-poor fisheries. Simulations were used to investigate the utility of the length-based model (LB-SPR) developed in Hordyk et al. (2015). Some explorations of the life history ratios to describe length composition, spawning-per-recruit, and the spawning potential ratio. ICES Journal of Marine Science, 72: 204–216.) to estimate the SPR of a stock directly from the size composition of the catch. This was done by (i) testing some of the main assumptions of the LB-SPR model, including recruitment variability and dome-shaped selectivity, (ii) examining the sensitivity of the model to error in the input parameters, and (iii) completing an initial empirical test for the LB-SPR model by applying it to data from a well-studied species. The method uses maximum likelihood methods to find the values of relative fishing mortality (F/M) and selectivity-at-length that minimize the difference between the observed and the expected length composition of the catch, and calculates the resulting SPR. When parameterized with the correct input parameters, the LB-SPR model returned accurate estimates of F/M and SPR. With high variability in annual recruitment, the estimates of SPR became increasingly unreliable. The usefulness of the LB-SPR method was tested empirically by comparing the results predicted by the method with those for a well-described species with known length and age composition data. The results from this comparison suggest that the LB-SPR method has potential to provide a tool for the cost-effective assessment of data-poor fisheries. However, the model is sensitive to non-equilibrium dynamics, and requires accurate estimates of the three parameters (M/k, L∞, and CVL∞). Care must be taken to evaluate the validity of the assumptions and the biological parameters when the model is applied to data-poor fisheries.

Material Property Identification and Sensitivity Analysis Using Indentation and FEM

2006 ◽  
Author(s):  
Long Ge ◽  
Nam Ho Kim ◽  
Gerald R. Bourne ◽  
W. Gregory Sawyer
Keyword(s):  
Mechanical Properties ◽  
Numerical Technique ◽  
Response Surfaces ◽  
Small Scale ◽  
Test Statistics ◽  
Element Analysis ◽  
Property Identification ◽  
Indentation Experiment ◽  
Loading And Unloading ◽  
The Difference

Mechanical properties of materials in small-scale applications, such as thin coatings, are often different from those of bulk materials due to the difference in the manufacturing process. Indentation has been a convenient tool to study the mechanical properties in such applications. In this paper, a numerical technique is proposed that can identify the mechanical properties by minimizing the difference between the results from indentation experiments and those from finite element analysis. First, two response surfaces are constructed for loading and unloading curves from the indentation experiment of a gold film on the silicon substrate. Unessential coefficients of the response surface are then removed based on the test statistics. Different from the traditional methods of identification, the tip geometry of the indenter is included because its uncertainty significantly affects the results. In order to validate the accuracy and stability of the method, the sensitivity of the identified material properties with respect to each coefficient is analyzed.

Intensive Validation of Computer Prediction of Welding Residual Stresses in a Multi-Pass Butt Weld

2010 ◽  
Author(s):  
Weijing He ◽  
Liwu Wei ◽  
Simon Smith
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Structural Integrity ◽  
Kinematic Hardening ◽  
Cost Effective ◽  
Material Model ◽  
Element Analysis ◽  
Computer Prediction ◽  
Butt Weld ◽  
Very High

Welding and joining technology is fundamental to offshore engineering. The construction of engineering facilities and pipelines requires the extensive use of welding and associated structural integrity assessments of safety critical or heavily loaded sections. Proof of integrity is based upon the externally applied loads and in service stresses as well as the welding residual stresses. The level and distribution of residual stresses arises from the complex thermo-mechanical history of heat flow and thermal expansion at very high temperatures during welding, so it has not been possible to make very accurate assessments of these in the same way that service stresses can be defined. Conservative assumptions are therefore made and this often means that the as-welded stresses are assumed to be of yield magnitude. The peak values of stress may well be very high, but the shrinkage of the latter passes of multi-pass welds may compress earlier passes giving rise to much lower levels of stress. There is considerable engineering interest in the utilisation of lower levels of residual stress where they exist or of the design of welds with lower residual stresses in sensitive areas such as the weld root. Currently there is no single technique that can claim to provide cost effective, accurate distributions of residual stresses in welds. The current paper provides an important contribution to the understanding of measurement and prediction techniques. It describes an extensive set of measurements taken on a girth butt weld. The weld was made using submerged arc and was made in 18 passes. The pipe was X52 with a 32mm wall thickness and 910mm outside diameter. Temperature, strain and displacement values were measured throughout the production of the weld. The intermediate values between each pass were recorded as well as the time varying history during the production of individual passes. The final through thickness residual stress distribution was measured. Finite Element Analysis (FEA) modelling was undertaken to determine whether modelling could provide a satisfactory prediction of the final residual stresses. Intermediate results were also used to understand the behaviour of the weld and the model more clearly. The modelling used material properties measured on material from a separate specimen. The weld cross section was identified for each pass so that the heat input method could be developed to represent the actual melt pool conditions of the weld. The measured values of hoop residual stress were up to the yield stress magnitude just below the cap, but were 20% of yield in the root of the weld. The axial residual stresses were less than 50% of yield. Linear kinematic hardening provided the most accurate prediction of residual stress. The hoop stresses were predicted to an accuracy of 10% with this material model. Other hardening models were less accurate, but all models were conservative. The results provide a basis for the adoption of more accurate distributions of residual stresses in Engineering Critical Assessments (ECAs) and assessments of weld performance under fatigue and corrosive conditions.

Concrete Material Models in LS-DYNA for Impact Analysis of Reinforced Concrete Structures

2014 ◽  
Vol 566 ◽  
pp. 173-178
Author(s):  
M.A.K.M. Madurapperuma ◽  
Kazukuni Niwa
Keyword(s):  
Reinforced Concrete ◽  
High Speed ◽  
Impact Analysis ◽  
Material Model ◽  
Material Behavior ◽  
Single Element ◽  
Element Analysis ◽  
Material Models ◽  
Concrete Material ◽  
Rc Structures

Performance of three widely used concrete material models available in LS-DYNA is compared using experimental results of drop-weight impact on a reinforced concrete (RC) beam and high speed aircraft engine missile impact on an RC wall. An overview of these material models and typical concrete material behavior shown by these models using single element analysis are also presented. The study is useful for users who have limited experience on the selection of an appropriate material model for concrete in impact simulation of RC structures.

Mesoscale Models Characterizing Material Property Fields Used As a Basis for Predicting Fracture Patterns in Quasi-Brittle Materials

2017 ◽  
Author(s):  
Katherine A. Acton ◽  
Sarah C. Baxter ◽  
Bahador Bahmani ◽  
Philip L. Clarke ◽  
Reza Abedi
Keyword(s):  
Crack Propagation ◽  
Material Property ◽  
Mesoscale Model ◽  
Voronoi Tessellation ◽  
Brittle Materials ◽  
Material Behavior ◽  
Small Scale ◽  
Element Analysis ◽  
Stress Criterion ◽  
Fracture Patterns

To accurately predict fracture patterns in quasi-brittle materials, it is necessary to accurately characterize heterogeneity in the properties of a material microstructure. This heterogeneity influences crack propagation at weaker points. Also, inherent randomness in localized material properties creates variability in crack propagation in a population of nominally identical material samples. In order to account for heterogeneity in the strength properties of a material at a small scale (or “microscale”), a mesoscale model is developed at an intermediate scale, smaller than the size of the overall structure. A central challenge of characterizing material behavior at a scale below the representative volume element (RVE), is that the stress/strain relationship is dependent upon boundary conditions imposed. To mitigate error associated with boundary condition effects, statistical volume elements (SVE) are characterized using a Voronoi tessellation based partitioning method. A moving window approach is used in which partitioned Voronoi SVE are analysed using finite element analysis (FEA) to determine a limiting stress criterion for each window. Results are obtained for hydrostatic, pure and simple shear uniform strain conditions. A method is developed to use superposition of results obtained to approximate SVE behavior under other loading conditions. These results are used to determine a set of strength parameters for mesoscale material property fields. These random fields are then used as a basis for input in to a fracture model to predict fracture patterns in quasi-brittle materials.

scholarly journals Combined Application of Ozone and Hydrogen Peroxide to Degrade Diesel Contaminants in Soil and Groundwater

Water ◽  
2021 ◽  
Vol 13 (23) ◽  
pp. 3404
Author(s):  
Wen-Yu Chen ◽  
Prakash Pokhrel ◽  
Ying-Shun Wang ◽  
Sheng-Lung Lin ◽  
Min-Hsin Liu
Keyword(s):  
Hydrogen Peroxide ◽  
Contaminated Soil ◽  
Cost Effective ◽  
Chemical Oxidation ◽  
Injection System ◽  
Small Scale ◽  
Vapor Extraction ◽  
Combined Application ◽  
Order Of Magnitude ◽  
The Difference

Environmental pollution has been a major concern in recent times, and soil and groundwater pollution are areas which have received particular focus. This has led to the development of various remediation techniques such as excavation, soil vapor extraction, bioremediation, chemical oxidation, and so on. Among all remediation techniques, chemical oxidation has been proven to be the most effective and feasible technique around the world. In this study, various combinations of ozone and hydrogen peroxide were used to treat diesel-contaminated soil and groundwater in an experimental setup. Experimental soil and groundwater were prepared with properties similar to the contaminated soil. An ozone generator and a pump injection system were deployed for combining ozone and hydrogen peroxide. Five different experiment batches were prepared based on the hydrogen peroxide concentration and its ratio to the soil. The diesel concentration in the water dropped from 300 mg/L to 7 mg/L in the first hour of treatment, which dropped below the detection limit (0.01 mg/L) thereafter. Similarly, 63.9% degradation was achieved with the combined sparging of ozone and hydrogen peroxide in the soil. Ozone combined with 7% hydrogen peroxide was the most promising combination for removing the contaminants. In addition, this research explored the hydroxyl radical conversion rate of ozone and the perozone, the difference in order of magnitude is greater than one which shows that the perozone has better oxidation capacity than ozone only. The findings of this study show that combining ozone with hydrogen peroxide is a competent and feasible onsite remediation method for diesel contaminants in soil and groundwater. Thus, this method can be applied in local gas stations, accidental spillage sites, and small-scale refineries for onsite treatment in a cost-effective and technically sound way within a short time span.

Lifetime Prediction of Tires with Regard to Oxidative Aging5

2008 ◽  
Vol 36 (1) ◽  
pp. 63-79 ◽  
Author(s):  
L. Nasdala ◽  
Y. Wei ◽  
H. Rothert ◽  
M. Kaliske
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Temperature Distribution ◽  
Superposition Principle ◽  
Accelerated Aging ◽  
Material Model ◽  
Aging Behavior ◽  
Element Analysis ◽  
Material Parameters ◽  
Reaction Processes

Abstract It is a challenging task in the design of automobile tires to predict lifetime and performance on the basis of numerical simulations. Several factors have to be taken into account to correctly estimate the aging behavior. This paper focuses on oxygen reaction processes which, apart from mechanical and thermal aspects, effect the tire durability. The material parameters needed to describe the temperature-dependent oxygen diffusion and reaction processes are derived by means of the time–temperature–superposition principle from modulus profiling tests. These experiments are designed to examine the diffusion-limited oxidation (DLO) effect which occurs when accelerated aging tests are performed. For the cord-reinforced rubber composites, homogenization techniques are adopted to obtain effective material parameters (diffusivities and reaction constants). The selection and arrangement of rubber components influence the temperature distribution and the oxygen penetration depth which impact tire durability. The goal of this paper is to establish a finite element analysis based criterion to predict lifetime with respect to oxidative aging. The finite element analysis is carried out in three stages. First the heat generation rate distribution is calculated using a viscoelastic material model. Then the temperature distribution can be determined. In the third step we evaluate the oxygen distribution or rather the oxygen consumption rate, which is a measure for the tire lifetime. Thus, the aging behavior of different kinds of tires can be compared. Numerical examples show how diffusivities, reaction coefficients, and temperature influence the durability of different tire parts. It is found that due to the DLO effect, some interior parts may age slower even if the temperature is increased.

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