Dynamic Analysis of Offshore Pile Launch

2009 ◽  
Author(s):  
F. Yiu ◽  
N. Liu ◽  
J. Wang ◽  
D. Litton
Keyword(s):  
Time Domain ◽  
New Technologies ◽  
Dynamic Simulations ◽  
Element Analysis ◽  
Dynamic Finite Element Analysis ◽  
Software Packages ◽  
New Ideas ◽  
Cable Wire ◽  
Good Agreement ◽  
Nonlinear Time Domain

Successful installation of offshore piles is often challenged by the constraints of cost, technical feasibility, availability of suitable installation vessels and the environment. A practical installation procedure is defined as one that utilizes the capacity of available equipment to operate in a wide allowable environmental window. To find such procedures there is a continuing need for research, use of new technologies, and the adoption of new ideas. This paper presents a feasibility study for side launching piles from a conventional cargo barge. Sophisticated nonlinear time domain dynamic simulations formed the basis of the evaluation. Two noted software packages with nonlinear time domain dynamic finite element analysis capabilities were used to predict the trajectory of the launched pile and the resulting impulsive load on the restraining cable/wire. Analytical results from the software programs were compared to provide a first level of validation. The numerical results were in good agreement. Cable/wire properties (size, length, and material) and tug vessel velocity were varied in an effort to minimize the cable loads during the highly dynamic launch event. The study concluded that side launch was feasible and design recommendations are provided.

scholarly journals Finite Element Analysis and Full-Scale Testing of Locomotive Crashworthy Components

2013 ◽  
Author(s):  
Patricia Llana ◽  
Richard Stringfellow ◽  
Ronald Mayville
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
New Technologies ◽  
Element Model ◽  
Full Scale ◽  
Element Analysis ◽  
Design Concepts ◽  
Dynamic Finite Element Analysis ◽  
Full Scale Tests ◽  
Force Displacement

The Office of Research and Development of the Federal Railroad Administration (FRA) and the Volpe Center are continuing to evaluate new technologies for increasing the safety of passengers and operators in rail equipment. In recognition of the importance of override prevention in train-to-train collisions in which one of the vehicles is a locomotive, and in light of the success of crash energy management technologies in cab car-led passenger trains, the Volpe Center seeks to evaluate the effectiveness of components that could be integrated into the end structure of a locomotive that are specifically designed to mitigate the effects of a collision and, in particular, to prevent override of one of the lead vehicles onto the other. A research program has been conducted to develop, fabricate and test two crashworthy components for the forward end of a locomotive: (1) a deformable anti-climber, and (2) a push-back coupler. Detailed designs for these components were developed, and the performance of each design was evaluated through large deformation dynamic finite element analysis (FEA). Designs for two test articles that could be used to verify the performance of the component designs in full-scale tests were also developed. The two test articles were fabricated and dynamically tested by means of rail car impact in order to verify certain performance characteristics of the two components relative to specific requirements. The tests were successful in demonstrating the effectiveness of the two design concepts. Test results were consistent with finite element model predictions in terms of energy absorption capability, force-displacement behavior and modes of deformation.

Calculation of Dynamic Stress Intensity Factors for Pipes During Crack Propagation by Dynamic Finite Element Analysis

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Masaki Mitsuya ◽  
Hiroyuki Motohashi ◽  
Noritake Oguchi ◽  
Shuji Aihara
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Velocity ◽  
Dynamic Stress ◽  
Intensity Factors ◽  
Dynamic Stress Intensity Factors ◽  
Element Analysis ◽  
Dynamic Finite Element Analysis ◽  
High Crack ◽  
Good Agreement

A dynamic finite element analysis method was proposed for calculating the dynamic stress intensity factors for pipes during crack propagation. The proposed method can directly calculate the stress intensity factors without the simplification used in theoretical analyses, and it can consider the effects of the crack velocity and gas decompression. It was found that the stress intensity factors of long propagating cracks in pipes saturated at a certain value in the case of a high crack velocity. However, the stress intensity factors for pipes were in good agreement with those of band plates in the case of a high crack velocity, the stress intensity factors for pipes were different from those of band plates in the case of a low crack velocity. This result could be explained by the effect of bulging on the stress distribution around a crack tip. The effect of bulging was more prominent for pipes with smaller diameters. In contrast, the dynamic stress intensity factors for band plates were in good agreement with the theoretical values that consider the dynamic effects and tended to decrease monotonically with increasing crack velocity. Additionally, the effects of gas decompression, caused by leakage from opened cracks, on the stress intensity factors for pipes were investigated. An explanation of the change in crack direction, reflecting a change from an axial crack to a circumferential crack, which is observed in actual pipeline fractures, was given by analyzing the ratio of the longitudinal stress to lateral stress.

Dynamic Finite Element Analysis of Cracked Bodies

1980 ◽  
Vol 102 (1) ◽  
pp. 2-7 ◽  
Author(s):  
J. L. Glazik
Keyword(s):  
Finite Element ◽  
Vibrational Modes ◽  
The Finite Element Method ◽  
Singular Element ◽  
Element Analysis ◽  
Element Mesh ◽  
Dynamic Finite Element Analysis ◽  
Mass Matrices ◽  
Maximum Amplification ◽  
Good Agreement

Application of the finite element method to problems involving finite cracked bodies subjected to impact loadings is discussed. Mass matrices for a particularly simple, well-established singular element have been developed and applied to the problem of a centrally cracked strip whose ends are loaded by a step tensile stress. The results agree extremely well with those obtained by using a higher order singular element. Results are also presented for this problem employing an equally coarse finite element mesh with no singular element at all, and again good agreement is demonstrated. The problems of an edge cracked strip suddenly pulled at its ends and of a cracked cylinder subjected to sudden internal pressure are also analyzed using these two approaches. The response of these examples, like the majority of cracked finite bodies, are dominated by their vibrational modes. Results indicate that for the purpose of determining the maximum amplification of the stress intensity factor due to dynamic loading, the use of a singular element is unnecessary.

Calculation of Dynamic Stress Intensity Factors for Pipes During Crack Propagation by Dynamic Finite Element Analysis

2012 ◽  
Author(s):  
Masaki Mitsuya ◽  
Hiroyuki Motohashi ◽  
Noritake Oguchi ◽  
Shuji Aihara
Keyword(s):  
Stress Intensity ◽  
Stress Intensity Factors ◽  
Crack Velocity ◽  
Dynamic Stress ◽  
Intensity Factors ◽  
Dynamic Stress Intensity Factors ◽  
Element Analysis ◽  
Dynamic Finite Element Analysis ◽  
High Crack ◽  
Good Agreement

A dynamic finite element analysis method was proposed for calculating the dynamic stress intensity factors for pipes during crack propagation. The proposed method can directly calculate the stress intensity factors without the simplification used in theoretical analyses, and it can consider the effects of the crack velocity and gas decompression. It was found that the stress intensity factors of long propagating cracks in pipes saturated at a certain value in the case of a high crack velocity. However, although the stress intensity factors for pipes were in good agreement with those of band plates in the case of a high crack velocity, the stress intensity factors for pipes were different from those of band plates in the case of a low crack velocity. This result could be explained by the effect of bulging on the stress distribution around a crack tip. The effect of bulging was more prominent for pipes with smaller diameters. In contrast, the dynamic stress intensity factors for band plates were in good agreement with the theoretical values that consider the dynamic effects and tended to decrease monotonically with increasing crack velocity. Additionally, the effects of gas decompression, caused by leakage from opened cracks, on the stress intensity factors for pipes were investigated. An explanation of crack deviation, which is observed in actual pipeline fractures, was provided by analyzing the ratio of the longitudinal stress to lateral stress.

Implementation and Application of Modal Analysis During Time Domain Dynamic Simulation of Floating Offshore Systems

2006 ◽  
Author(s):  
Fabri´cio Nogueira Correˆa ◽  
Breno Pinheiro Jacob
Keyword(s):  
Modal Analysis ◽  
Dynamic Simulation ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Jacobi Method ◽  
Hydrodynamic Behavior ◽  
Mooring Lines ◽  
Dynamic Simulations ◽  
Floating System ◽  
Nonlinear Time Domain

This paper presents the implementation and application of modal analysis during nonlinear time-domain dynamic simulations of floating offshore systems. The simulations are performed by a fully coupled nonlinear time-domain analysis methodology, which considers the interaction between the hydrodynamic behavior of the hull and the structural/hydrodynamic behavior of the mooring lines and risers. Considering the nonlinear variation of the stiffness and added mass of the floating system with time, the objective is to assess the variation of the natural periods of vibration for the 6-DOF of the floating system (surge, sway, heave, roll, pitch and yaw). To accomplish this goal, the generalized eigenvalue problem associated to the system is assembled, and the Generalized Jacobi Method is employed to solve this problem and determine natural periods of the system, at selected time intervals during the dynamic simulation. Case studies are selected to assess the variation with time of the natural periods, considering two different types of floating systems: the ITTC semi-submersible platform, for which experimental results are available; and a CALM monobuoy system. The results obtained stresses the importance of the calculation of natural periods in different positions of the system: due to the marked nonlinear behavior of the mooring lines and risers, the natural periods can show considerable variations, for instance, from the neutral design position to an equilibrium position under action of current.

Computer Modeling of a Tire under Cornering Loads

1989 ◽  
Vol 17 (2) ◽  
pp. 86-99 ◽  
Author(s):  
I. Gardner ◽  
M. Theves
Keyword(s):  
Finite Element Analysis ◽  
Geometric Approach ◽  
Lateral Force ◽  
Slip Angle ◽  
Element Analysis ◽  
Pressure Distributions ◽  
Slip Effects ◽  
Improved Accuracy ◽  
Nonlinear Geometric ◽  
Good Agreement

Abstract During a cornering maneuver by a vehicle, high forces are exerted on the tire's footprint and in the contact zone between the tire and the rim. To optimize the design of these components, a method is presented whereby the forces at the tire-rim interface and between the tire and roadway may be predicted using finite element analysis. The cornering tire is modeled quasi-statically using a nonlinear geometric approach, with a lateral force and a slip angle applied to the spindle of the wheel to simulate the cornering loads. These values were obtained experimentally from a force and moment machine. This procedure avoids the need for a costly dynamic analysis. Good agreement was obtained with experimental results for self-aligning torque, giving confidence in the results obtained in the tire footprint and at the rim. The model allows prediction of the geometry and of the pressure distributions in the footprint, since friction and slip effects in this area were considered. The model lends itself to further refinement for improved accuracy and additional applications.

Application of Computational Mechanics to Tire Design—Yesterday, Today, and Tomorrow

2011 ◽  
Vol 39 (4) ◽  
pp. 223-244 ◽  
Author(s):  
Y. Nakajima
Keyword(s):  
Finite Element ◽  
New Technologies ◽  
Computational Mechanics ◽  
Design Procedure ◽  
Side Wall ◽  
Rolling Resistance ◽  
Optimization Techniques ◽  
Stress Strain ◽  
Element Analysis ◽  
Crown Shape

Abstract The tire technology related with the computational mechanics is reviewed from the standpoint of yesterday, today, and tomorrow. Yesterday: A finite element method was developed in the 1950s as a tool of computational mechanics. In the tire manufacturers, finite element analysis (FEA) was started applying to a tire analysis in the beginning of 1970s and this was much earlier than the vehicle industry, electric industry, and others. The main reason was that construction and configurations of a tire were so complicated that analytical approach could not solve many problems related with tire mechanics. Since commercial software was not so popular in 1970s, in-house axisymmetric codes were developed for three kinds of application such as stress/strain, heat conduction, and modal analysis. Since FEA could make the stress/strain visible in a tire, the application area was mainly tire durability. Today: combining FEA with optimization techniques, the tire design procedure is drastically changed in side wall shape, tire crown shape, pitch variation, tire pattern, etc. So the computational mechanics becomes an indispensable tool for tire industry. Furthermore, an insight to improve tire performance is obtained from the optimized solution and the new technologies were created from the insight. Then, FEA is applied to various areas such as hydroplaning and snow traction based on the formulation of fluid–tire interaction. Since the computational mechanics enables us to see what we could not see, new tire patterns were developed by seeing the streamline in tire contact area and shear stress in snow in traction.Tomorrow: The computational mechanics will be applied in multidisciplinary areas and nano-scale areas to create new technologies. The environmental subjects will be more important such as rolling resistance, noise and wear.

Prediction of Tire Tread Wear with FEM Steady State Rolling Contact Simulation

2003 ◽  
Vol 31 (3) ◽  
pp. 189-202 ◽  
Author(s):  
D. Zheng
Keyword(s):  
Weight Loss ◽  
Steady State ◽  
Cross Section ◽  
Rolling Contact ◽  
Dynamic Simulations ◽  
Element Analysis ◽  
Vehicle Acceleration ◽  
Steady State Rolling ◽  
Driving Conditions ◽  
Rate Profile

Abstract A procedure based on steady state rolling contact Finite Element Analysis (FEM) has been developed to predict tire cross section tread wear profile under specified vehicle driving conditions. This procedure not only considers the tire construction effects, it also includes the effects of materials, vehicle setup, test course, and driver's driving style. In this algorithm, the vehicle driving conditions are represented by the vehicle acceleration histogram. Vehicle dynamic simulations are done to transform the acceleration histogram into tire loading condition distributions for each tire position. Tire weight loss rates for different vehicle accelerations are generated based on a steady state rolling contact simulation algorithm. Combining the weight loss rate and the vehicle acceleration histogram, nine typical tire loading conditions are chosen with different weight factors to represent tire usage conditions. It is discovered that the tire tread wear rate profile is changing continuously as the tire is worn. Simulation of a new tire alone cannot be used to predict the tire cross-section tread wear profile. For this reason, an incremental tread wear simulation procedure is performed to predict the tire cross section tread wear profile. Compared with actual tire cross-section tread wear profiles, good results are obtained from the simulations.

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