Homogenization and Stress Analysis of Multilayered Composite Offshore Production Risers

2013 ◽  
Vol 81 (3) ◽  
Author(s):  
X. S. Sun ◽  
Y. Chen ◽  
V. B. C. Tan ◽  
R. K. Jaiman ◽  
T. E. Tay
Keyword(s):  
Stress Analysis ◽  
Elastic Constants ◽  
Material Properties ◽  
Axial Loading ◽  
Stress And Strain ◽  
Multilayered Composite ◽  
External Pressures ◽  
Complex Models ◽  
Composite Cylinders ◽  
Stress Analyses

An approach for stress analysis of multilayered composite cylinders is proposed for the analysis of new composite risers used in deep-water oil production of offshore petroleum industries. Risers essentially comprise long cylindrical sections connected end-to-end. In the formulation, only stresses and strains that are continuous through the thickness of the multilayered composite risers are taken to be equal to reported solutions for homogenous orthotropic hollow cylinders using homogenized material properties. These stress and strain solutions are then used to calculate the remaining discontinuous stresses and strains from the material properties of individual layers of materials. The homogenized elastic constants of cylindrically orthotropic composite risers are derived from force-deformation equivalence, taking into account the stress and strain distributions in each layer. Four typical loading conditions are considered in the stress analysis, namely, internal and external pressures, axial loading, bending, and torsion. Examples of homogenized elastic constants and stress analyses of composite cylindrical structures with different layups and materials are presented to demonstrate the application of the proposed method. The results compared very favorably with those from other solutions. This method provides practical benefits for the design and analysis of composite risers. Because there is no requirement to explicitly enforce interfacial continuity in this method, stress analyses of composite cylinders with many layers of different fiber angles or materials can be carried out efficiently. The homogenized elastic constants can greatly expedite the analysis of entire composite riser systems by replacing complex models of riser sections with homogenized riser sections.

An Analytical Model for the Unbonded Flexible Pipe Stress Analysis With Consideration of Nonlinear Material Properties for Metal Layers

2010 ◽  
Author(s):  
Jian Liu ◽  
Zhimin Tan ◽  
Terry Sheldrake
Keyword(s):  
Stress Analysis ◽  
Analytical Model ◽  
Material Properties ◽  
Failure Modes ◽  
Nonlinear Material ◽  
Von Mises Stress ◽  
Stress And Strain ◽  
Flexible Pipe ◽  
Metal Layers ◽  
Plastic Stress

This paper presents an improved analytical model for the unbonded flexible pipe stress analysis with consideration of nonlinear material properties for metal layers. Analytical methods have often been used to analyse the stress and strain of flexible pipe systems because of their low cost and efficiency compared with detailed finite element modeling. Most of these kinds of models only consider the deformation of pipes within the elastic region. Such linear models can not be used directly to assess pipe failure modes such as the pipe burst strength, where the nonlinearity of the metallic material plays an important role in governing the pipe deformation and pipe structural capacity. The improved analytical model presented in this paper has fully considered the nonlinearity of metal layers such as the pressure armour and tensile armour layers because of their importance in resisting internal pressure and tension loads. Non-associative elasto-plastic stress strain curves obtained from experiments are used to simulate the metal layers. Von Mises stress is adopted in the model as the yield criterion of the metal layers. Radial return method (Simo and Taylor 1985 [1], Simo and Hughes 1998 [2]) is used to solve the plastic stress and strain of metal layers beyond the yield point. Due to its high nonlinearity from both system equations and material properties, Newton-Raphson method is adopted in the model as the solving method. The proposed study here considers tension, torque and pressure loads only for a straight pipe. The model predictions have been compared against measurements from Wellstream burst tests and failure tension tests performed over the full scale pipe samples. The prediction and experiment results agree.

The Elastic Characterization of Composite Based on Ultrasonic Waves

2021 ◽  
Author(s):  
Y. H. Park ◽  
J. Dana
Keyword(s):  
Composite Materials ◽  
Fatigue Failure ◽  
Elastic Constants ◽  
Material Properties ◽  
Weight Ratio ◽  
Transversely Isotropic ◽  
Ultrasonic Waves ◽  
Material Strength ◽  
Isotropic Composite

Abstract Anisotropic composite materials have been extensively utilized in mechanical, automotive, aerospace and other engineering areas due to high strength-to-weight ratio, superb corrosion resistance, and exceptional thermal performance. As the use of composite materials increases, determination of material properties, mechanical analysis and failure of the structure become important for the design of composite structure. In particular, the fatigue failure is important to ensure that structures can survive in harsh environmental conditions. Despite technical advances, fatigue failure and the monitoring and prediction of component life remain major problems. In general, cyclic loadings cause the accumulation of micro-damage in the structure and material properties degrade as the number of loading cycles increases. Repeated subfailure loading cycles cause eventual fatigue failure as the material strength and stiffness fall below the applied stress level. Hence, the stiffness degradation measurement can be a good indication for damage evaluation. The elastic characterization of composite material using mechanical testing, however, is complex, destructive, and not all the elastic constants can be determined. In this work, an in-situ method to non-destructively determine the elastic constants will be studied based on the time of flight measurement of ultrasonic waves. This method will be validated on an isotropic metal sheet and a transversely isotropic composite plate.

scholarly journals Infarcted Left Ventricles Have Stiffer Material Properties and Lower Stiffness Variation: Three-Dimensional Echo-Based Modeling to Quantify In Vivo Ventricle Material Properties

2015 ◽  
Vol 137 (8) ◽  
Author(s):  
Longling Fan ◽  
Jing Yao ◽  
Chun Yang ◽  
Dalin Tang ◽  
Di Xu
Keyword(s):  
Wall Thickness ◽  
Material Properties ◽  
Strain Curve ◽  
Stress And Strain ◽  
Stress Strain ◽  
Material Stiffness ◽  
The Mean ◽  
Lv Volume ◽  
Parameter Values

Methods to quantify ventricle material properties noninvasively using in vivo data are of great important in clinical applications. An ultrasound echo-based computational modeling approach was proposed to quantify left ventricle (LV) material properties, curvature, and stress/strain conditions and find differences between normal LV and LV with infarct. Echo image data were acquired from five patients with myocardial infarction (I-Group) and five healthy volunteers as control (H-Group). Finite element models were constructed to obtain ventricle stress and strain conditions. Material stiffening and softening were used to model ventricle active contraction and relaxation. Systolic and diastolic material parameter values were obtained by adjusting the models to match echo volume data. Young's modulus (YM) value was obtained for each material stress–strain curve for easy comparison. LV wall thickness, circumferential and longitudinal curvatures (C- and L-curvature), material parameter values, and stress/strain values were recorded for analysis. Using the mean value of H-Group as the base value, at end-diastole, I-Group mean YM value for the fiber direction stress–strain curve was 54% stiffer than that of H-Group (136.24 kPa versus 88.68 kPa). At end-systole, the mean YM values from the two groups were similar (175.84 kPa versus 200.2 kPa). More interestingly, H-Group end-systole mean YM was 126% higher that its end-diastole value, while I-Group end-systole mean YM was only 29% higher that its end-diastole value. This indicated that H-Group had much greater systole–diastole material stiffness variations. At beginning-of-ejection (BE), LV ejection fraction (LVEF) showed positive correlation with C-curvature, stress, and strain, and negative correlation with LV volume, respectively. At beginning-of-filling (BF), LVEF showed positive correlation with C-curvature and strain, but negative correlation with stress and LV volume, respectively. Using averaged values of two groups at BE, I-Group stress, strain, and wall thickness were 32%, 29%, and 18% lower (thinner), respectively, compared to those of H-Group. L-curvature from I-Group was 61% higher than that from H-Group. Difference in C-curvature between the two groups was not statistically significant. Our results indicated that our modeling approach has the potential to determine in vivo ventricle material properties, which in turn could lead to methods to infer presence of infarct from LV contractibility and material stiffness variations. Quantitative differences in LV volume, curvatures, stress, strain, and wall thickness between the two groups were provided.

scholarly journals Stress analysis of multi-layered composite cylinders subjected to various loadings

2021 ◽  
Vol 1172 (1) ◽  
pp. 012005
Author(s):  
M H Elgohary ◽  
M I El-Geuchy ◽  
H M Abdallah ◽  
S S Sayed
Keyword(s):  
Stress Analysis ◽  
Layered Composite ◽  
Composite Cylinders

Use of Finite-Element Stress Analysis in the Design of a Tank-Cannon-Launched Training Projectile

1994 ◽  
Author(s):  
Michael S. L. Hollis
Keyword(s):  
Finite Element ◽  
Stress Analysis ◽  
Structural Integrity ◽  
Compressive Loading ◽  
Structural Failure ◽  
Finite Element Stress Analysis ◽  
Von Mises ◽  
Current Kinetic ◽  
A Current ◽  
Stress Analyses

Abstract The U.S. Army Armament Research. Development, and Engineering Center (ARDEC) recently expressed a need for a tank-cannon-launched training projectile with reduced penetration capability. The expressed primary design goals for this projectile were to minimize the probability of personnel injury and materiel loss in the event of an accidental impact during a training exercise. In order to meet these design goals, the solid-steel flight body of a current kinetic energy (KE) training projectile, the M865IP, was replaced with a hollow aluminum configuration. Because of the incorporation of aluminum, the structural integrity of the entire projectile during launch was put in question. Thus, a thorough stress analysis of the new design was conducted to alleviate concerns about its structural integrity. Two-dimensional, axisymmetric, quasi-static stress analyses were performed on two new KE training projectile designs. The first analysis indicated that structural failure was possible in the aft portion of the projectile due to compressive loading by the gun gases. Structural failure in this case would be circumferential yielding of the hollow flight body. The aft portion of the round was redesigned, and subsequent stress analysis showed the possibility of structural failure to be resolved. The finite-element modeling approach, the applied boundary conditions, and the results of the stress analyses conducted, based on use of the von Mises failure criterion, will be discussed in detail.

Simulation of stress and strain analysis on a delimbing knife with replaceable cutting edge

BioResources ◽  
2020 ◽  
Vol 15 (2) ◽  
pp. 3799-3808
Author(s):  
Ján Melicherčík ◽  
Jozef Krilek ◽  
Pavol Harvánek
Keyword(s):  
Finite Element Method ◽  
Stress Analysis ◽  
Cutting Force ◽  
Woody Plants ◽  
Strain Analysis ◽  
Cutting Edge ◽  
Stress And Strain ◽  
Cutting Knife ◽  
Basic Parameters

This study focused on stress and strain analysis of the cutting force of a branch knife with a replaceable cutting edge. The replaceable edge forms part of the delimbing head, which is applied to the arms of a mechanical harvester working in forestry. Basic parameters of the knife and head of the harvester with the basic calculations necessary to determine the number of knives based on input parameters, such as wood diameter, woody plants, and determination of the cutting force acting on the cutting knife, were examined. Based on the cutting force and the design of the special cutting knife, a stress analysis and a finite element method (FEM) was performed. This study confirmed the correctness of the selected material to produce the delimbing knife, which was designed using a replaceable cutting edge. The output of the stress analysis is reported.

Thermo-viscoelastic residual stress analysis of metal liner-inserted composite cylinders

2003 ◽  
Vol 17 (2) ◽  
pp. 171-180 ◽  
Author(s):  
Ho Yon Hwang ◽  
Yeong Kook Kim ◽  
Cheol Rim ◽  
Young Doo Kwon ◽  
Woong Choi
Keyword(s):  
Residual Stress ◽  
Stress Analysis ◽  
Residual Stress Analysis ◽  
Metal Liner ◽  
Composite Cylinders

Effect of Temperature on the Material Properties and the Results of Thermal Stress Analysis

2017 ◽  
Vol 729 ◽  
pp. 8-12
Author(s):  
Tae Kyung Kim ◽  
Dong Kwon Oh ◽  
Kwang Ju Lee
Keyword(s):  
Thermal Stress ◽  
Elastic Modulus ◽  
Stress Analysis ◽  
Material Properties ◽  
Room Temperature ◽  
Test System ◽  
Effect Of Temperature ◽  
Air Conditioning System ◽  
Thermal Stress Analysis ◽  
Different Levels

Use of correct values of material properties is important in structural analysis. When incorrect values are used in the analysis, engineers may end up with misleading conclusions. The magnitudes of elastic modulus and strength are usually measured from experiments at room temperature. When these values are used in the thermal stress analysis of structures, the results may not be reliable because the magnitudes of elastic modulus and strength depend on temperature. The temperature distribution of HVAC (Heating, Ventilation and Air Conditioning) system was analyzed. The material properties were measured using MTS810 material test system and MTS 651 environmental chamber at different levels of temperature. They were used in the thermal stress analysis of HVAC system. It was found that the results of thermal stress analysis were significantly different from the results using material properties which were measured from experiments at room temperature.

Structural, phase transition, mechanical and thermodynamic properties of TMNs under external pressures: A first-principles study

2018 ◽  
Vol 32 (15) ◽  
pp. 1850181 ◽  
Author(s):  
Xin Tan ◽  
Yinan Dong ◽  
Yuan Ren ◽  
Xuan Li ◽  
Hui Qi ◽  
...  
Keyword(s):  
Phase Transition ◽  
Elastic Constants ◽  
Density Functional ◽  
Mechanical Stability ◽  
Structural Phase ◽  
Potential Method ◽  
External Pressure ◽  
Nanocomposite Films ◽  
External Pressures ◽  
Energy Relations

The plane-wave pseudo-potential method, which is based on density functional theory, is used to determine the structure, elastic constants and phase transition properties of transition metal nitride (TMN; TM = Ti, Zr, Hf, V, Nb and Ta) nanocomposite films under external pressures. Enthalpy–pressure and volume–energy relations of TMNs with different structures are calculated, and their relative stability is discussed. Mechanical stability of external pressure is calculated, and changes in elastic constants with external pressure are analyzed. The present study obtains influence of external pressure on the mechanical properties of material. By analyzing total energy–volume relation, enthalpy–pressure relation and mechanical stability, phase transition law of TMNs under external pressure is obtained.

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