Coupled Fluid-Structural Modelling to Predict Wave Impact Loads on High-Speed Planing Craft

2001 ◽  
Author(s):  
Simon Rees ◽  
◽  
David Reed ◽  
Colin Cain ◽  
Bob Cripps ◽  
...  
Keyword(s):  
High Speed ◽  
Impact Loads ◽  
Structural Modelling ◽  
Wave Impact ◽  
Planing Craft

A Method to Quantify Mitigation Characteristics of Shock Isolation Seats Before Installation in a High-Speed Planing Craft

2015 ◽  
Author(s):  
Michael R. Riley ◽  
Timothy W. Coats ◽  
Heidi P. Murphy ◽  
Neil Ganey
Keyword(s):  
High Speed ◽  
Historical Perspective ◽  
Lessons Learned ◽  
Computational Method ◽  
Impact Loads ◽  
Wave Impact ◽  
New Approach ◽  
Planing Craft ◽  
Acceleration Data ◽  
Shock Isolation

This paper presents a new approach for quantifying the mitigation achieved by a passive marine shock isolation seat. A brief historical perspective is summarized to explain why common myths have evolved that has led to seats being integrated into craft only to find out during subsequent seakeeping trials that the seats provide little to no mitigation or that they actually amplify wave impact loads. Acceleration data is presented to demonstrate use of the new computational method and the lessons learned are explained in terms that support development of a standard for laboratory seat testing.

scholarly journals An Experimental Investigation of Ride Control Algorithms for High-Speed Catamarans Part 2: Mitigation of Wave Impact Loads

2017 ◽  
Vol 61 (2) ◽  
pp. 51-63 ◽  
Author(s):  
Javad AlaviMehr ◽  
Jason Lavroff ◽  
Michael R. Davis ◽  
Damien S. Holloway ◽  
Giles A. Thomas
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Control Algorithms ◽  
Impact Loads ◽  
Wave Impact ◽  
Ride Control

Impact Loads From Drop Test of a Circular Section With 42 Force Transducers

2015 ◽  
Author(s):  
Gunnar Lian ◽  
Ole David Økland ◽  
Tone M. Vestbøstad
Keyword(s):  
Model Test ◽  
Large Volume ◽  
High Speed ◽  
Limit State ◽  
Ultimate Limit State ◽  
Impact Loads ◽  
Wave Impact ◽  
Circular Section ◽  
Force Transducers ◽  
Drop Tests

Results from previous model test campaigns of various large-volume platforms indicate that wave impact loads on vertical platform columns can become high in extreme sea states. Moreover, column slamming is a highly non-linear and complex problem and reliable estimation of Ultimate Limit State (ULS) and Accidental Limit State (ALS) design loads is a challenge. A model test campaign dedicated to investigate column slamming has been performed on a large volume platform at Marintek. Special effort was put into designing a model and instrumentation package that could capture the complex phenomenon of slamming due to breaking or near breaking waves as accurately as possible. As part of the validation of the instrumentation for this test, drop tests were performed on a circular section with 42 force transducers. In the model test, this section was mounted on one of the platform columns for measuring wave impacts. In the present drop tests, the same section was dropped in still water in a small basin. Different impact velocities and impact angles were investigated. High-speed video recordings were also used to document the tests. This paper presents the setup used in the drop tests. The results from the drop tests are discussed and compared to theoretical solutions.

A Dynamic Simulation of Wave Impact Loads on Offshore Floating Platforms

1976 ◽  
Vol 98 (2) ◽  
pp. 550-557
Author(s):  
J. G. Giannotti
Keyword(s):  
Structural Analysis ◽  
High Speed ◽  
Degrees Of Freedom ◽  
Impulsive Loading ◽  
Impact Loads ◽  
Offshore Platforms ◽  
Wave Impact ◽  
Six Degrees Of Freedom ◽  
Marine Vehicles ◽  
Floating Platforms

Some of the most critical loads to consider in developing design criteria for offshore platforms are those caused by wave hydrodynamic impact. The effect of these loads can be of a local nature in the form of plating damage as a result of impulsive loading, or it can be felt on the overall structure in the form of induced vibration, and increased bending moments and shears. Traditionally, the prediction of these loads has been highly empirical and designers have had to rely heavily on conservative factors of safety in order to account for the lack of confidence in these predictions. The current degree of sophistication of advanced techniques of structural analysis such as the finite element method has not been matched by equally sophisticated loads prediction methods. Consequently, the advantages offered by the computerized structural analysis schemes are considerably reduced due to the unacceptable load inputs. This paper fills part of this void by presenting an analytical model for predicting wave impact loads for the design of offshore platforms. The method is based on the Payne Impact Program which has been used before for predicting impact pressures and loads acting on high speed marine vehicles. The model simulates six-degrees-of-freedom and allows impacts at any wave heading. As inputs it requires geometric information, sea state definition, and a description of the relative motion of platform and wave. It is particularly suited to allow analysis of the results in probabilistic form, so that the severity and frequency of occurrence of impacts can be predicted.

scholarly journals An Experimental Investigation of Ride Control Algorithms for High-Speed Catamarans Part 2: Mitigation of Wave Impact Loads

2017 ◽  
Vol 61 (02) ◽  
pp. 51-63
Author(s):  
Javad AlaviMehr ◽  
Jason Lavroff ◽  
Michael R. Davis ◽  
Damien S. Holloway ◽  
Giles A. Thomas
Keyword(s):  
Control System ◽  
High Speed ◽  
Control Algorithms ◽  
Impact Loads ◽  
Wave Impact ◽  
Pitch Control ◽  
Model Scale ◽  
Ride Control ◽  
Control Feedback ◽  
Ride Control System

High-speed craft frequently experience large wave impact loads due to their large motions and accelerations. One solution to reduce the severity of motion and impact loadings is the installation of ride control systems. Part 1 of this study investigates the influence of control algorithms on the motions of a 112-m highspeed catamaran using a 2.5-m model fitted with a ride control system. The present study extends this to investigate the influence of control algorithms on the loads and internal forces acting on a hydroelastic segmented catamaran model. As in Part 1, the model active control system consisted of a center bow T-Foil and two stern tabs. Six motion control feedback algorithms were used to activate the model-scale ride control system and surfaces in a closed loop system: local motion, heave, and pitch control, each in a linear and nonlinear application. The loads were further determined with a passive ride control system and without control surfaces fitted for direct comparison. The model was segmented into seven parts, connected by flexible links that replicate the first two natural frequencies and mode shapes of the 112-m INCAT vessel, enabling isolation and measurement of a center bow force and bending moments at two cross sections along the demi-hulls. The model was tested in regular head seas at different wave heights and frequencies. From these tests, it was found that the pitch control mode was most effective and in 60-mm model-scale waves it significantly reduced the peak slam force by 90% and the average slam induced bending moment by 75% when compared with a bare hull without ride controls fitted. This clearly demonstrates the effectiveness of a ride control system in reducing wave impact loads acting on high-speed catamaran vessels.

Liquid Behavior in Containers with a Liquid-Packing Bag for Liquid Products Subjected to Drop Impact

2006 ◽  
Vol 321-323 ◽  
pp. 1280-1283 ◽  
Author(s):  
Eisaku Umezaki ◽  
Yuuma Shinoda ◽  
Katsunori Futase
Keyword(s):  
High Speed ◽  
Free Fall ◽  
The Other ◽  
Impact Loads ◽  
Visualization Technique ◽  
Transparent Plastic ◽  
Plastic Films ◽  
Liquid Behavior ◽  
Liquid Products ◽  
Polyethylene Particles

The behavior of liquid in containers subjected to impact loads due to free fall was investigated using a visualization technique. Two types of containers were used. One consisted of a case made of transparent plastic plates and a liquid-packing bag made of transparent plastic films. The bag contained about 1,000 ml of liquid. The other was a case made only of transparent plastic plates. The case contained about 1,000 ml of water. The liquid consisted of water and ethanol. Polyethylene particles of about 3 mm in diameter were included in the liquid to visualize the movement of liquid in the containers. The containers were subjected to impact due to free fall, and photographs of the containers were taken using a high-speed camera. Results indicated that the behavior of liquid in the container with a liquid-packing bag is different from that of the container without a liquid-packing bag.

Wave Impact Loads on the Bottom of Flat Decks

2021 ◽  
Author(s):  
Daniel de Oliveira Costa ◽  
Julia Araújo Perim ◽  
Bruno Guedes Camargo ◽  
Joel Sena Sales Junior ◽  
Antonio Carlos Fernandes ◽  
...  
Keyword(s):  
Scale Effects ◽  
Offshore Structures ◽  
Model Tests ◽  
Analytical Models ◽  
Navier Stokes ◽  
Impact Loads ◽  
Wave Impact ◽  
Wave Channel ◽  
Waves And Currents ◽  
The Impact

Abstract Slamming events due to wave impact on the underside of decks might lead to severe and potentially harmful local and/or global loads in offshore structures. The strong nonlinearities during the impact require a robust method for accessing the loads and hinder the use of analytical models. The use of computation fluid dynamics (CFD) is an interesting alternative to estimate the impact loads, but validation through experimental data is still essential. The present work focuses on a flat-bottomed model fixed over the mean free surface level submitted to regular incoming waves. The proposal is to reproduce previous studies through CFD and model tests in a different reduced scale to provide extra validation and to identify possible non-potential scale effects such as air compressibility. Numerical simulations are performed in both experiments’ scales. The numerical analysis is performed with a marine dedicated flow solver, FINE™/Marine from NUMECA, which features an unsteady Reynolds-averaged Navier-Stokes (URANS) solver and a finite volume method to build spatial discretization. The multiphase flow is represented through the Volume of Fluid (VOF) method for incompressible and nonmiscible fluids. The new model tests were performed at the wave channel of the Laboratory of Waves and Currents (LOC/COPPE – UFRJ), at the Federal University of Rio de Janeiro.

Adequate Strength for Small High-Speed Vessels

1968 ◽  
Vol 5 (01) ◽  
pp. 63-71
Author(s):  
Philip J. Danahy
Keyword(s):  
Stress Analysis ◽  
High Speed ◽  
Structural Strength ◽  
Integrated Approach ◽  
Suggested Method ◽  
Impact Loads ◽  
Analysis Method ◽  
Safety Factors ◽  
Recreational Vessels

The paper presents a method for the determination of the critical minimum scantlings for small high-speed vessels. Particular attention is given to the shell plating strength for hydrodynamic impact loads. The suggested method uses an integrated approach involving assumed loads, suggested safety factors, and preferred stress-analysis method. The stress analysis uses plastic theory based partly on the works of J. Clarkson and Thein Wah. Included in the paper is a comparison of the relative structural strength of several commercial, military, and experimental hydrofoil vessels along with a few planing boats and a seaplane hull. This shows the variation of existing vessel structures and compares them to the results obtained by the suggested method. Most commercial, military, and recreational vessels exceed the minimum scantlings of the suggested method. The most significant deviation is the hull of the seaplane:

Distribution of Wave Impact Forces From Breaking and Non-Breaking Waves

2009 ◽  
Author(s):  
Anne M. Fullerton ◽  
Thomas C. Fu ◽  
Edward S. Ammeen
Keyword(s):  
Free Surface ◽  
Wave Height ◽  
Breaking Waves ◽  
Qualitative Assessment ◽  
Total Force ◽  
Impact Loads ◽  
Wave Impact ◽  
Data Set ◽  
Wave Characteristics ◽  
Wide Range

Impact loads from waves on vessels and coastal structures are highly complex and may involve wave breaking, making these changes difficult to estimate numerically or empirically. Results from previous experiments have shown a wide range of forces and pressures measured from breaking and non-breaking waves, with no clear trend between wave characteristics and the localized forces and pressures that they generate. In 2008, a canonical breaking wave impact data set was obtained at the Naval Surface Warfare Center, Carderock Division, by measuring the distribution of impact pressures of incident non-breaking and breaking waves on one face of a cube. The effects of wave height, wavelength, face orientation, face angle, and submergence depth were investigated. A limited number of runs were made at low forward speeds, ranging from about 0.5 to 2 knots (0.26 to 1.03 m/s). The measurement cube was outfitted with a removable instrumented plate measuring 1 ft2 (0.09 m2), and the wave heights tested ranged from 8–14 inches (20.3 to 35.6 cm). The instrumented plate had 9 slam panels of varying sizes made from polyvinyl chloride (PVC) and 11 pressure gages; this data was collected at 5 kHz to capture the dynamic response of the gages and panels and fully resolve the shapes of the impacts. A Kistler gage was used to measure the total force averaged over the cube face. A bottom mounted acoustic Doppler current profiler (ADCP) was used to obtain measurements of velocity through the water column to provide incoming velocity boundary conditions. A Light Detecting and Ranging (LiDAR) system was also used above the basin to obtain a surface mapping of the free surface over a distance of approximately 15 feet (4.6 m). Additional point measurements of the free surface were made using acoustic distance sensors. Standard and high-speed video cameras were used to capture a qualitative assessment of the impacts. Impact loads on the plate tend to increase with wave height, as well as with plate inclination toward incoming waves. Further trends of the pressures and forces with wave characteristics, cube orientation, draft and face angle are investigated and presented in this paper, and are also compared with previous test results.

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