scholarly journals METODOLOGI PENGEMBANGAN MODEL SIMULASI UNTUK EVALUASI KESELAMATAN PENUMPANG FREEFALL LIFEBOAT

2012 ◽  
Vol 16 (2) ◽  
pp. 75
Author(s):  
Aulia Windyandari
Keyword(s):  
Simulation Model ◽  
Water Surface ◽  
Impact Load ◽  
Free Fall ◽  
Response Prediction ◽  
Offshore Structures ◽  
Shock Acceleration ◽  
Occupant Injury ◽  
Serious Injury ◽  
The Impact

Aulia Windyandari, in paper simulation model of development method for passenger savety evaluation of freefaal lifeboat explain that since the launching procedure of Freefall Lifeboat (FFL) may have an impact with the water surface, the occupant injury is possible be occured in the evacuation process of the offshore structures.  The FFL shock acceleration has been conducted by the impact force when the lifeboat entry the water surface. If the shock acceleration over the human conciousness allowance, the serious injury will be happened during the FFL launching.According to the conditions, the IMO regulations have standard for the acceptance criteria of FFL shock acceleration induced by water entry impact load. The results measurement of Combined Acceleration Ratio Index (CAR) or Combined Dynamic Response Ratio Index (CDRR) should be comply with the IMO index criteria.In this paper, the methodology of FFL acceleration response prediction by the simulation model analysis will be proposed. The simulation model will be developed by using LS-Dyna code. The Simplified Arbitratry Lagrangian Eulerian Coupling will be used to define the coupling analysis between the Lifeboats (Lagrangian elements) with Water Fluids (the Eulerian Elements)Keywords: Free Fall Lifeboat, Response Acceleration, Impact Load

Practical Structural Assessment of Offshore Structures for Wave Slap

2012 ◽  
Author(s):  
Joong Soo Moon ◽  
Tae Hyun Park ◽  
Woo Seung Sim ◽  
Hyun Soo Shin
Keyword(s):  
Static Pressure ◽  
Impact Load ◽  
Offshore Structures ◽  
Model Tests ◽  
Design Stage ◽  
Load Prediction ◽  
Structural Assessment ◽  
Pressure Impulse ◽  
The Impact ◽  
Design Pressure

By the combination of theoretical and empirical approach, the methodology for practical structural assessment of offshore structures for wave slap is proposed. It is developed for engineers in the sense that the precise design pressure is easily obtainable and quickly applicable in early and detail design stage. For impact load prediction, the Pressure-Impulse theory that was well developed and validated in coastal engineering field is applied. The impact pressures are classified into three types (traditional, sharp, and immersed slap) according to model tests and BP Schiehallion FPSO’s bow monitoring. The time histories of impact pressures for the classified impact types are generated with the pressure impulse predicted by the Pressure-Impulse theory. Nonlinear transient structural analyses are performed using the time series of impact pressures to obtain equivalent static pressure factors. Finally, the design pressure is determined by multiplying the maximum peak pressure by the equivalent static pressure factor. The results are validated through the comparison with model tests and dedicated reports.

Experimental Investigation of Ice Mass Hydrodynamic Interaction With Offshore Structure in Close Proximity

2015 ◽  
Author(s):  
Tanvir Mehedi Sayeed ◽  
Bruce Colbourne ◽  
Heather Peng ◽  
Benjamin Colbourne ◽  
Don Spencer
Keyword(s):  
Hydrodynamic Interaction ◽  
Impact Load ◽  
Numerical Study ◽  
Numerical Models ◽  
Offshore Structures ◽  
Ocean Engineering ◽  
Offshore Structure ◽  
Area Of Interest ◽  
Close Proximity ◽  
The Impact

Iceberg/bergy bit impact load with fixed and floating offshore structures and supply ships is an important design consideration in ice-prone regions. Studies tend to divide the iceberg impact problem into phases from far field to contact. This results in a tendency to over simplify the final crucial stage where the structure is impacted. The authors have identified knowledge gaps and their influence on the analysis and prediction of iceberg impact velocities and loads (Sayeed et. al (2014)). The experimental and numerical study of viscous dominated very near field region is the main area of interest. This paper reports preliminary results of physical model tests conducted at Ocean Engineering Research Center (OERC) to investigate hydrodynamic interaction between ice masses and fixed offshore structure in close proximity. The objective was to perform a systematic study from simple to complex phenomena which will be a support base for the development of subsequent numerical models. The results demonstrated that hydrodynamic proximity and wave reflection effects do significantly influence the impact velocities at which ice masses approach to large structures. The effect is more pronounced for smaller ice masses.

An Experimental Investigation of Wave Impact Loads on a Slender Horizontal Cylinder

2014 ◽  
Author(s):  
Joseph F. Haley ◽  
Chris Swan ◽  
Richard Gibson
Keyword(s):  
Water Surface ◽  
Impact Load ◽  
Horizontal Cylinder ◽  
The Body ◽  
Impact Loads ◽  
Wave Impact ◽  
Wide Range ◽  
Wave Event ◽  
Vector Sum ◽  
The Impact

This paper concerns the difficulties arising in the prediction of the impact loads associated with an extreme wave event. A new set of experimental observations are presented. These concern the impact loads arising on a slender horizontal cylinder located at varying elevations above the still water level. The experimental observations incorporate a wide range of wave forms. In each case, data is provided describing (i) the incident water surface profiles, (ii) the incident fluid velocities and (iii) the load components acting on the cylinder. Comparisons between the measured data and the classical impact load solutions confirm a number of important departures. In particular, it is shown that as the wave becomes very steep (approaching the breaking limit) the vector sum of the horizontal and vertical velocity components at the water surface may deviate significantly from the normal to the local water surface. In such cases it becomes unclear exactly what direction the impact force acts. The present data suggests that this is, in part, dependent on the rate of inundation of the body. Furthermore, the present results also show that if the direction of the force is correct modelled, the variations in the predicted loading (or slamming) coefficient are much reduced.

Iceberg Impact Simulation on Offshore Structures

2017 ◽  
Author(s):  
Marc Cahay ◽  
Brian A. Roberts ◽  
Kenton Pike ◽  
Pierre-Antoine Béal ◽  
Cyril Septseault ◽  
...  
Keyword(s):  
Impact Load ◽  
Development Program ◽  
Offshore Structures ◽  
Separation Distance ◽  
Offshore Structure ◽  
Pressure Area ◽  
Common Framework ◽  
Multi Agent ◽  
Crushing Behavior ◽  
The Impact

In 2012 TechnipFMC, Cervval and Bureau Veritas initiated a common development program to offer a new tool for the design of offshore structures interacting with ice combining a variety of models and approaches. This numerical tool called Ice-MAS (www.ice-mas.com) is using a multi-agent technology and has the possibility to combine in a common framework multiple phenomena from various natures and heterogeneous scales (i.e. drag, friction, ice-sheet bending failure, local crushing and rubble stack up). The current development phase consists of the determination of the forces generated by an iceberg during an impact on an offshore structure. This paper will provide an overview of the latest Ice-MAS development. It will introduce the main functionalities of the simulation tool and the different options for modelling an offshore structure. It will then focus on the modelling approach used for an iceberg, the calculation of the different hydrodynamic coefficients and their variability according to the separation distance from the structure. The model used to compute the impact load will be detailed, including the local crushing behavior which is simulated by a pressure-area correlation.

On the Distribution of Wave Impact Loads on Offshore Structures

2017 ◽  
Author(s):  
Thomas B. Johannessen ◽  
Øystein Lande ◽  
Øistein Hagen
Keyword(s):  
Model Test ◽  
Load Distribution ◽  
Impact Load ◽  
Peak Load ◽  
Offshore Structures ◽  
Impact Loads ◽  
Test Results ◽  
Wave Impact ◽  
The Impact ◽  
Crest Height

For offshore structures in harsh environments, horizontal wave impact loads should be taken into account in design. Shafts on GBS structures, and columns on semisubmersibles and TLPs are exposed to impact loads. Furthermore, if the crest height exceeds the available freeboard, the deck may also be exposed to wave impact loads. Horizontal loads due to waves impacting on the structure are difficult to quantify. The loads are highly intermittent, difficult to reproduce in model tests, have a very short duration and can be very large. It is difficult to calculate these loads accurately and the statistical challenges associated with estimating a value with a prescribed annual probability of occurrence are formidable. Although the accurate calculation of crest elevation in front of the structure is a significant challenge, industry has considerable experience in handling this problem and the analysis results are usually in good agreement with model test results. The present paper presents a statistical model for the distribution of horizontal slamming pressures conditional on the incident crest height upwave of the structure. The impact load distribution is found empirically from a large database of model test results where the wave impact load was measured simultaneously at a large number of panels together with the incident crest elevation. The model test was carried out on a circular surface piercing column using long simulations of longcrested, irregular waves with a variety of seastate parameters. By analyzing the physics of the process and using the measured crest elevation and the seastate parameters, the impact load distribution model is made seastate independent. The impact model separates the wave impact problem in three parts: – Given an incident crest in a specified seastate, calculate the probability of the crest giving a wave impact load above a threshold. – Given a wave impact event above a threshold, calculate the distribution of the resulting peak load. – Given a peak load, calculate the distribution of slamming pressures at one spatial location. The development of the statistical model is described and it is shown that the model is appropriate for fixed and floating structures and for wave impact with both columns and the deck box.

Simulation Based Reduction of the Impact Load Occurring in the Moment of Cutting Edge Entrance in Order to Prolong Tool-Life

2016 ◽  
Vol 1140 ◽  
pp. 173-180
Author(s):  
Boris Matuschka ◽  
Nikolay Boev ◽  
Frederik Zanger ◽  
Volker Schulze
Keyword(s):  
Simulation Model ◽  
Tool Life ◽  
Cutting Tool ◽  
Impact Load ◽  
Cutting Edge ◽  
Machining Processes ◽  
Impact Forces ◽  
Simulation Based ◽  
The Moment ◽  
The Impact

High mechanical impact loads in interrupted or inhomogeneous machining processes frequently lead to spontaneous fracture of the cutting edge. Even modern cutting materials cannot provide a combination of high enough hardness and toughness that is capable of preventing this sort of tool failure. Such machining conditions therefore remain difficult and further investigations, aiming to reduce the impact load of the cutting tool in order to enhance tool-life, are necessary. A simulation model of the impact situation, that serves to optimize a force conducting structure with regard to elasticity, damping properties and resulting force peaks, was developed and is presented in this paper. Furthermore measurement devices were composed that are needed for high-resolution recording of impact forces without repercussions and for verification of the elaborated simulation model. It could be shown that mechanical damping of the cutting tool can lead to reduced impact forces on the cutting edge, which in turn should lead to longer tool life.

Study on the Effect of Impact Load Generated From Pile Driving on Adjacent Berthing Structure

2019 ◽  
Author(s):  
Jeena Mary John ◽  
Nilanjan Saha ◽  
R. Sundaravadivelu
Keyword(s):  
Impact Load ◽  
Damping Ratio ◽  
Offshore Structures ◽  
Pile Driving ◽  
Soil Medium ◽  
Existing Structures ◽  
Adjacent Structure ◽  
Prime Concern ◽  
The Impact ◽  
Plaxis 3D

Abstract The extension of ports and offshore structures has increased due to feasible marine transportation with more cargoes pouring into the ports across the world. In many ports, there is limited availability of favourable conditions to berth and lack of space for an extension. This leads to the construction of new berthing structures at very close vicinity to existing structures which are aged but significant. One prime concern in such berths is the vibration that will be transmitted to the existing old structure during the construction of the new one. Therefore there is a requirement to keep vibration effects under control to ensure that existing structures remain serviceable. One of the scenarios that determine the intensity of vibration that will be transmitted to soil and adjacent structure is the impact load applied on the pile. In the paper, the study is chosen at a specific port which needs reconstruction and extension due to the change in nature of the cargo to be handled and its requirements and also due to deterioration of aged berthing structure. Therefore, this study aims to find out the effect of impact load that is applied on pile casing during the pile driving process, so that the adjacent structure and machinery can be kept serviceable. The structure, soil medium and pile driving process are modelled in PLAXIS 3D. A damping ratio of 5 percent is assumed for both structure and soil throughout the modelling. A parametric study is done by varying the load on the pile casing while pile driving. The study gives the response of the structure to dynamic loading and influence of load on peak particle velocity during pile driving that gives economical piling and also ensures the safety of the adjacent berthing structure.

Impact Load Buffering Method Based on Stress Wave Attenuation Principle

2019 ◽  
Vol 11 (02) ◽  
pp. 1950019 ◽  
Author(s):  
Lin Gan ◽  
He Zhang ◽  
Cheng Zhou ◽  
Lin Liu
Keyword(s):  
Stress Wave ◽  
Wave Attenuation ◽  
Impact Load ◽  
Dynamics Simulation ◽  
Scanning System ◽  
Isolation Method ◽  
Element Analysis ◽  
System A ◽  
High Emission ◽  
The Impact

Rotating scanning motor is the important component of synchronous scanning laser fuze. High emission overload environment in the conventional ammunition has a serious impact on the reliability of the motor. Based on the theory that the buffer pad can attenuate the impact stress wave, a new motor buffering Isolation Method is proposed. The dynamical model of the new buffering isolation structure is established by ANSYS infinite element analysis software to do the nonlinear impact dynamics simulation of rotating scanning motor. The effectiveness of Buffering Isolation using different materials is comparatively analyzed. Finally, the Macht hammer impact experiment is done, the results show that in the experience of the 70,000[Formula: see text]g impact acceleration, the new buffering Isolation method can reduce the impact load about 15 times, which can effectively alleviate the plastic deformation of rotational scanning motor and improve the reliability of synchronization scanning system. A new method and theoretical basis of anti-high overload research for Laser Fuze is presented.

Stochastic simulation for determining the design flood of cascade reservoir systems

2012 ◽  
Vol 43 (1-2) ◽  
pp. 54-63 ◽  
Author(s):  
Baohong Lu ◽  
Huanghe Gu ◽  
Ziyin Xie ◽  
Jiufu Liu ◽  
Lejun Ma ◽  
...  
Keyword(s):  
Simulation Model ◽  
Stochastic Simulation ◽  
Southern China ◽  
Flow Simulation ◽  
Simulation Method ◽  
Simulation Approach ◽  
Design Flood ◽  
Design Values ◽  
Stochastic Simulation Model ◽  
The Impact

Stochastic simulation is widely applied for estimating the design flood of various hydrosystems. The design flood at a reservoir site should consider the impact of upstream reservoirs, along with any development of hydropower. This paper investigates and applies a stochastic simulation approach for determining the design flood of a complex cascade of reservoirs in the Longtan watershed, southern China. The magnitude of the design flood when the impact of the upstream reservoirs is considered is less than that without considering them. In particular, the stochastic simulation model takes into account both systematic and historical flood records. As the reliability of the frequency analysis increases with more representative samples, it is desirable to incorporate historical flood records, if available, into the stochastic simulation model. This study shows that the design values from the stochastic simulation method with historical flood records are higher than those without historical flood records. The paper demonstrates the advantages of adopting a stochastic flow simulation approach to address design-flood-related issues for a complex cascade reservoir system.

scholarly journals A Rational Numerical Method for Simulation of Drop-Impact Dynamics of Oleo-Pneumatic Landing Gear

2021 ◽  
Vol 11 (9) ◽  
pp. 4136
Author(s):  
Rosario Pecora
Keyword(s):  
Numerical Method ◽  
Initial Conditions ◽  
Impact Load ◽  
Numerical Models ◽  
Landing Gear ◽  
Design Stage ◽  
Impact Dynamics ◽  
State Variables ◽  
Adopted Model ◽  
The Impact

Oleo-pneumatic landing gear is a complex mechanical system conceived to efficiently absorb and dissipate an aircraft’s kinetic energy at touchdown, thus reducing the impact load and acceleration transmitted to the airframe. Due to its significant influence on ground loads, this system is generally designed in parallel with the main structural components of the aircraft, such as the fuselage and wings. Robust numerical models for simulating landing gear impact dynamics are essential from the preliminary design stage in order to properly assess aircraft configuration and structural arrangements. Finite element (FE) analysis is a viable solution for supporting the design. However, regarding the oleo-pneumatic struts, FE-based simulation may become unpractical, since detailed models are required to obtain reliable results. Moreover, FE models could not be very versatile for accommodating the many design updates that usually occur at the beginning of the landing gear project or during the layout optimization process. In this work, a numerical method for simulating oleo-pneumatic landing gear drop dynamics is presented. To effectively support both the preliminary and advanced design of landing gear units, the proposed simulation approach rationally balances the level of sophistication of the adopted model with the need for accurate results. Although based on a formulation assuming only four state variables for the description of landing gear dynamics, the approach successfully accounts for all the relevant forces that arise during the drop and their influence on landing gear motion. A set of intercommunicating routines was implemented in MATLAB® environment to integrate the dynamic impact equations, starting from user-defined initial conditions and general parameters related to the geometric and structural configuration of the landing gear. The tool was then used to simulate a drop test of a reference landing gear, and the obtained results were successfully validated against available experimental data.

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