Dynamic Compression of Rigid and Flexible Risers: Experimental and Numerical Results

2005 ◽  
Vol 128 (3) ◽  
pp. 233-240 ◽  
Author(s):  
Alexandre N. Simos ◽  
André L. C. Fujarra
Keyword(s):  
Finite Element ◽  
Numerical Models ◽  
Dynamic Compression ◽  
Flexible Structures ◽  
Experimental Results ◽  
Small Scale ◽  
Element Analysis ◽  
Steel Catenary Riser ◽  
Compression Load ◽  
Flexible Risers

Dynamic compression and buckling are critical issues in the viability analysis of rigid and flexible risers developed for offshore applications, especially concerning deep-water operations. Those subjects have been addressed both numerically and analytically. However, few experimental data for validation purposes is found in literature. This paper presents a set of experimental results on the dynamic compression of rigid and flexible risers in catenary configurations, obtained by means of towing-tank tests. Two small-scale models have been built, the first one emulating the dynamic behavior of a steel catenary riser (SCR) and the other representing a much more flexible line. Uniform circular motion has been applied to the top of the models, emulating the floating system first-order oscillations. Different amplitudes of top motion have been considered, each one of them imposed with different frequencies of oscillation. Tension has been measured at the top of the models. The influence of current velocity has also been evaluated. Dynamic tension estimations obtained through finite element analysis are compared to the experimental results. Tension amplitude and critical compression load values are evaluated and compared for both, the steel catenary (SCR) and the flexible models. Comparisons show, in general, a fair agreement between simulations and experiments, reassuring the reliability of numerical models. Results also demonstrate that finite element code provides good predictions of maximum tension loads even when the risers are subjected to high levels of dynamic compression and buckle. Nevertheless, it is clearly noted that difficulties arise in the treatment of flexible structures under severe buckling and torsion. The accuracy of analytical methods proposed for the estimation of critical compression loads is also discussed, based on the experimental results.

Dynamic Compression of Rigid and Flexible Risers: Part II — Comparison of Theoretical and Experimental Results

2003 ◽  
Author(s):  
Alexandre N. Simos ◽  
Andre´ L. C. Fujarra ◽  
Karime H. Alves
Keyword(s):  
Numerical Models ◽  
Dynamic Compression ◽  
Experimental Results ◽  
Dynamic Tension ◽  
Element Analysis ◽  
Analytical Formulation ◽  
Compression Load ◽  
Flexible Risers ◽  
Flexible Models ◽  
Theory And Experiments

In a previous paper, experimental results on the dynamic compression of rigid (steel catenary) and flexible risers were presented. Tests considered different combinations of amplitude and frequencies of top motion and distinct current velocities. In this paper, dynamic tension estimations obtained through finite element analysis and analytical formulation are compared to the experimental results. Tension amplitude and critical compression load values are evaluated and compared both for the steel catenary (SCR) and flexible models. Comparisons have shown, in general, a fair agreement between theory and experiments, reassuring the reliability of numerical models. The results also demonstrate that the analytical formulation applied provides reasonable predictions of maximum tension loads and is able to cope well with the variation of critical load with the frequency of motion.

Dynamic Compression of Rigid and Flexible Risers: Part I — Experimental Results

2003 ◽  
Author(s):  
Andre´ L. C. Fujarra ◽  
Alexandre N. Simos ◽  
Newton Y. Yamamoto
Keyword(s):  
Dynamic Compression ◽  
Critical Issue ◽  
Companion Paper ◽  
Experimental Results ◽  
Small Scale ◽  
Steel Catenary Riser ◽  
Scale Models ◽  
Floating System ◽  
The Subject ◽  
Flexible Risers

Dynamic compression is a critical issue for the viability of submerged lines used in offshore applications, especially for deepwater operations. The subject has been addressed both numerically and analytically. However, few experimental data exist in literature for validation purposes. The aim of this first paper is to present experimental results on the dynamic compression of rigid and flexible risers, obtained in towing-tank tests. Two small-scale models have been built, one emulating the dynamic behavior of a steel catenary riser (SCR) and the other corresponding to a much more flexible case. Uniform circular motion has been applied to the top of the line, representing the floating system oscillation. Four different amplitudes have been considered, each one of them with five different frequencies. The influence of current velocity has also been evaluated. Tension has been measured at the top. In this work the small-scale models and experimental setup are described and some comprehensive results are presented and discussed. In a companion paper, comparisons between theoretical (numerical and analytical) and experimental results are presented.

Experimental and Numerical Analysis of a Pristine and a Nano-Modified Thermoplastic Adhesive

2018 ◽  
Author(s):  
Carlo Boursier Niutta ◽  
Raffaele Ciardiello ◽  
Giovanni Belingardi ◽  
Alessandro Scattina
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Numerical Analysis ◽  
Mechanical Behavior ◽  
Numerical Models ◽  
Surface Preparation ◽  
Experimental Results ◽  
Element Analysis ◽  
Piping Systems ◽  
Set Up

In this work, the mechanical properties of two different adhesives compositions have been investigated both experimentally and numerically. The studied thermoplastic adhesives are Hot-Melt Adhesive (HMA). In particular, a pristine and a nanomodified adhesive with 10% in weight of iron oxide have been considered. The adhesives have been subjected to a series of single lap joint (SLJ) tests using adherends made of polypropylene copolymer. As it is well-known, the structural-mechanical behavior of adhesive joints is mostly influenced by the bonding process: thickness of adhesive as well as its application procedures and the surface preparation of adherends are among the most influencing factors. In addition, the mechanical behavior of SLJ test is particularly influenced by the correct alignment of adherends and applied load. These aspects have been investigated, analyzing the experimental results. Moreover, the experimental results have been used to develop a numerical model of the two adhesives. The numerical analysis has been carried out using the commercial software LS-DYNA. Transient nonlinear finite element analysis has been performed to simulate the mechanical behavior of the thermoplastic adhesives. In particular, the cohesive formulations of the elements have been taken into consideration after a careful literature review. In order to set-up and to validate the mechanical properties of the adhesives, the experimental SLJ tests have been simulated. The developed finite element models enable to investigate more complex joint structures where these types of adhesives are used, such as plastic piping systems and automotive applications. Further, the numerical models allow to investigate with higher accuracy and lower time different aspects such as manufacturing and non-linear effects.

Periodic and Fixed Boundary Conditions for Multi-Scale Finite Element Analysis of Flexible Risers

2016 ◽  
Author(s):  
M. T. Rahmati ◽  
G. Alfano ◽  
H. Bahai
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Boundary Conditions ◽  
Three Dimensional ◽  
Element Model ◽  
Small Scale ◽  
Flexible Pipe ◽  
Element Analysis ◽  
Time Saving ◽  
Flexible Risers

In this paper the implementation of two types of boundaries, periodic and fixed in-plane boundaries, for a detailed finite-element model of flexible risers is discussed. By using three-dimensional elements, all layer components are individually modelled and a surface-to-surface frictional contact model is used to simulate their interaction. The approach is applied on several riser models with various lengths and layers. It is shown that the model with periodic boundaries can be effectively employed in a fully-nested (FE2) multiscale analysis based on computational homogenization. In fact, in this model only a small fraction of a flexible pipe is needed for a detailed nonlinear finite-element analysis at the small scale. The advantage of applying periodic boundary conditions in capturing the detailed nonlinear effects and the efficiencies in terms of significant CPU time saving are demonstrated.

Tire Cornering Simulation Using an Explicit Finite Element Analysis Code

1998 ◽  
Vol 26 (2) ◽  
pp. 109-119 ◽  
Author(s):  
M. Koishi ◽  
K. Kabe ◽  
M. Shiratori
Keyword(s):  
Finite Element Method ◽  
Finite Element Analysis ◽  
Finite Element ◽  
Test System ◽  
Experimental Results ◽  
The Finite Element Method ◽  
Element Analysis ◽  
Explicit Finite Element ◽  
Explicit Finite Element Analysis ◽  
Element Method

Abstract The finite element method has been used widely in tire engineering. Most tire simulations using the finite element method are static analyses, because tires are very complex nonlinear structures. Recently, transient phenomena have been studied with explicit finite element analysis codes. In this paper, the authors demonstrate the feasibility of tire cornering simulation using an explicit finite element code, PAM-SHOCK. First, we propose the cornering simulation using the explicit finite element analysis code. To demonstrate the efficiency of the proposed simulation, computed cornering forces for a 175SR14 tire are compared with experimental results from an MTS Flat-Trac Tire Test System. The computed cornering forces agree well with experimental results. After that, parametric studies are conducted by using the proposed simulation.

Accuracy of Failure Criteria Commonly Used for Ship Collision Simulations

2018 ◽  
Author(s):  
R. Villavicencio ◽  
Bin Liu ◽  
Kun Liu
Keyword(s):  
Finite Element ◽  
Failure Criteria ◽  
Small Scale ◽  
Finite Element Models ◽  
Impact Loads ◽  
Large Scatter ◽  
Element Analysis ◽  
Advantages And Disadvantages ◽  
Ship Collision ◽  
Double Hull

The paper summarises observations of the fracture response of small-scale double hull specimens subjected to quasi-static impact loads by means of simulations of the respective experiments. The collision scenarios are used to evaluate the discretisation of the finite element models, and the energy-responses given by various failure criteria commonly selected for collision assessments. Nine double hull specimens are considered in the analysis so that to discuss the advantages and disadvantages of the different failure criterion selected for the comparison. Since a large scatter is observed from the numerical results, a discussion on the reliability of finite element analysis is also provided based on the present study and other research works found in the literature.

scholarly journals An Improved Analytical Solution for Process-Induced Residual Stresses and Deformations in Flat Composite Laminates Considering Thermo-Viscoelastic Effects

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2506 ◽  
Author(s):  
Chao Liu ◽  
Yaoyao Shi
Keyword(s):  
Differential Equation ◽  
Finite Element ◽  
Analytical Solution ◽  
Residual Stresses ◽  
Composite Laminates ◽  
Composite Structures ◽  
Numerical Models ◽  
Element Analysis ◽  
Current Time ◽  
Viscoelastic Effects

Dimensional control can be a major concern in the processing of composite structures. Compared to numerical models based on finite element methods, the analytical method can provide a faster prediction of process-induced residual stresses and deformations with a certain level of accuracy. It can explain the underlying mechanisms. In this paper, an improved analytical solution is proposed to consider thermo-viscoelastic effects on residual stresses and deformations of flat composite laminates during curing. First, an incremental differential equation is derived to describe the viscoelastic behavior of composite materials during curing. Afterward, the analytical solution is developed to solve the differential equation by assuming the solution at the current time, which is a linear combination of the corresponding Laplace equation solutions of all time. Moreover, the analytical solution is extended to investigate cure behavior of multilayer composite laminates during manufacturing. Good agreement between the analytical solution results and the experimental and finite element analysis (FEA) results validates the accuracy and effectiveness of the proposed method. Furthermore, the mechanism generating residual stresses and deformations for unsymmetrical composite laminates is investigated based on the proposed analytical solution.

scholarly journals Finite Element Analysis of Artificially Frozen C-Phi soil

2019 ◽  
Vol 8 (4) ◽  
pp. 12722-12728
Keyword(s):  
Finite Element ◽  
Numerical Analysis ◽  
Frozen Soil ◽  
Experimental Results ◽  
Soil Freezing ◽  
Strength Parameter ◽  
Frozen Ground ◽  
Element Analysis ◽  
Test Setup ◽  
Geological Conditions

Artificial Ground Freezing techniques eliminate the need for structural supports during the course of an excavation, as frozen ground is solid and waterproof. At present, it is adopted as an effective way to deal with various construction ground control challenges such as the mitigation of seepage infiltration into tunnels and shaft excavations; or ground strengthening for excavation. In-depth knowledge of the frozen soil characteristics through experiments and the development of suitable constitutive models that suit the geological conditions of our country are necessary to predict the strength and behavior of the frozen soils. Numerical analysis of frozen soil can be used for mass works like tunneling which cannot be experimentally verified. This paper presents a validation of experimental results obtained from laboratory setup and soil freezing system for C-Phi soil. The main aim is to compare numerical and experimental results and hence obtaining the shear strength parameter of the soil, similar to the conventional triaxial test setup. To perform numerical analysis Finite element tool ANSYS 19 is used. Soil model is made in ANSYS 19 and required loads are inputted to performed the analysis similar to the experimental method. The result obtained from experimental test setup and numerical analysis was verified and compared and it was found that values of numerical results lies closer to experimental results

Sign in / Sign up

Export Citation Format

Share Document