scholarly journals Considerations regarding ice accretion on board ships and the influence on intact stability

2018 ◽  
Vol 27 (2018) ◽  
pp. 17-20
Author(s):  
Cristian Andrei
Keyword(s):  
Loading Condition ◽  
Ice Accretion ◽  
Intact Stability ◽  
The Impact

The main goal of the present paper is to highlight the main aspects of the ice accretion phenomenon and to illustrate the impact on the ship's intact stability based on a simulation carried out for a ship in a real loading condition.

scholarly journals 3D Physical Modelling Study of Shield-Strata Interaction under Roof Dynamic Loading Condition

2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Shengli Yang ◽  
Hao Yue ◽  
Gaofeng Song ◽  
Junjie Wang ◽  
Yanyao Ma ◽  
...  
Keyword(s):  
Impact Loading ◽  
Loading Condition ◽  
Impact Load ◽  
Physical Modelling ◽  
Coal Face ◽  
Dynamic Impact ◽  
Immediate Roof ◽  
Cutting Height ◽  
The Impact ◽  
Dynamic Impact Loading

The dynamic hazards in the open face area caused by the impact load of the massive strong roof become increasingly severe with the increase in the cutting height of the longwall face and its depth of cover. Understanding the strata-shield interaction under the dynamic impact loading condition may relieve the dynamic hazards. In this paper, a 3D physical modelling platform is developed to study the interaction between the roof strata and the longwall shield under the dynamic impact load conditions. A steel plate is dropped to the coal face wall at a certain height above the immediate roof to simulate the free fall of the main roof and the dynamic impact loading environment. The occurrence of major roof falls is modelled at different height above the model and at different positions relative to the longwall faceline. The large-cutting-height and top-coal-caving mining methods are modelled in the study to include the nature of the immediate roof. The results show that the level of face and roof failures depends on the magnitude of the dynamic impact load. The position and height of the roof fall have an important influence to the stability of the roof and face. The pressures on the shield and the solid coal face are relieved for the top-coal-caving face as compared to the large-cutting-height face.

Vortex Dynamics in Sidewall Aneurysms: Hemodynamic Transition During Growth and Clinical Implications

2017 ◽  
Author(s):  
Trung Bao Le ◽  
Fotis Sotiropoulos
Keyword(s):  
Numerical Simulation ◽  
Shear Stress ◽  
Vortex Dynamics ◽  
Loading Condition ◽  
Aneurysm Rupture ◽  
Clinical Implications ◽  
Aneurysmal Wall ◽  
Flow Pulsatility ◽  
The Impact

Recent works have suggested that aneurysm size and shape might not be the only indicators to predict aneurysm rupture. Rather, the long-term interaction between hemodynamics and aneurysmal wall via the loading condition (i.e shear stress and pressure) may also be important. In this work, we investigate the impact of flow pulsatility on the hemodynamic patterns on aneurysmal dome during its growth using numerical simulation.

Sea spray icing: The physical process, and review of prediction models and winterization techniques

2021 ◽  
pp. 1-26
Author(s):  
Sujay Deshpande ◽  
Ane Sæterdal ◽  
Per-Arne Sundsbø
Keyword(s):  
Prediction Models ◽  
Offshore Structures ◽  
Cold Climate ◽  
Working Environment ◽  
The Arctic ◽  
Design Stage ◽  
Sea Spray ◽  
Ice Accretion ◽  
Sea Wind ◽  
The Impact

Abstract Ice accretion on marine vessels and offshore structures is a severe hazard in the Polar Regions. There is increasing activities related to oil and gas exploration, tourism, cargo transport, and fishing in the Arctic. Ice accretion can cause vessel instability, excess load on marine structures and represents a safety risk for outdoor working environment and operations. Freezing sea spray is the main contributor to marine icing. For safe operations in cold climate, it is essential to have verified models for prediction of icing. Sea spray icing forecast models have improved. Empirical and theoretical models providing icing rates based may be useful as guidelines. For predicting the distribution of icing on a surface at the design stage, Computational Fluid Dynamics has to be applied along with a freezing module. State-of-the-art models for numerical simulation of sea spray icing are still not fully capable of modelling complex ship-sea-wind interactions with spray generation and impact of shipped water. Existing models include good understanding of spray flow effects and freezing. Further development should focus on developing models for dynamic ship-sea-wind interactions, in particular including spray generation, effects of shipped water and distribution of icing on the vessel surface. More experimental and full-scale data is needed for development and verification of new and improved models. Models that estimate ice distribution may improve the winterization design process and reduce effort required for de-icing. Improved methods for de-icing and anti-icing will reduce the impact of sea spray icing and increase safety for marine operations in cold waters.

Impact Loading Analysis of Light Sport Aircraft Landing Gear

2014 ◽  
Vol 518 ◽  
pp. 252-257 ◽  
Author(s):  
Pu Woei Chen ◽  
Shu Han Chang ◽  
Chan Ming Chen
Keyword(s):  
Simulation Model ◽  
Impact Loading ◽  
Loading Condition ◽  
Element Model ◽  
Landing Gear ◽  
Market Demand ◽  
Critical Loading ◽  
Aircraft Landing ◽  
Aluminum Plates ◽  
The Impact

This paper examined the critical loading condition of a light sport aircrafts main landing gear during the impact loading condition. The new category airplane was established by the FAA in 2004. The light sport aircraft has great market demand for personnel entertainment purpose and regional transportation. The main object of this research was to establish a static and dynamic loading simulation model for the aluminum alloy landing gear of a light sport aircraft. This work also examined the critical loading parameters of the main landing gear, including the maximum take-off weight and maximum stall speed. The analysis was performed using ANSYS and LS-DYNA to establish the finite element model after simplifying the geometric characteristics and verifying the results by energy conservation, hourglass energy, and sliding energy. The study tested aluminum plates with a thickness from 15~25 mm. The results showed all the samples could sustain the required loading condition, except for the thickness of 15mm that failed under impact loading. The simulation model provides a cost-saving process compared to a real crashworthiness drop test to test the main landing gears compliance with regulations.

Investigation on the Effect of Liquid Hammer Geometry to the Pressure Distribution of Innovative Hybrid Impact Hydroforming

2014 ◽  
Vol 941-944 ◽  
pp. 1843-1849 ◽  
Author(s):  
Murhaf Marai ◽  
Li Hui Lang ◽  
Shao Hua Wang ◽  
Li Jin Lin ◽  
Chun Lei Yang ◽  
...  
Keyword(s):  
Loading Condition ◽  
Experimental Approach ◽  
High Energy ◽  
Geometrical Shape ◽  
Wave Loading ◽  
Forming Process ◽  
Short Time ◽  
The Impact ◽  
Complex Parts

The innovative hybrid impact hydroforming (IHF) technology is a kind of high energy forming technique which can be used for forming complex parts with small features, such as convex tables, bars etc. which are widely employed in automotive and aircraft industries. The impact hydroforming technology means the most features are formed by hydroforming and the small features are rapidly reshaped by high intensity impact energy in a very short time after the traditional hydroforming. The impact pressure rises to the peak in 10ms which belongs to dynamic loading. The present work investigates IHF using a numerical /experimental approach. Finite element simulations using MSC.Patran were carried out changing the geometrical shape of liquid hammer.. Using this shock wave loading condition we did forming experiments. During forming process, stress distribution in the blank is comparatively better as compared with traditional methods so possibility of fracture is reduced. Inertia is also an important factor which affects control quality. Therefore, the research is very useful for improving forming quality of complicated products. It will be widely applied in automotive and aircraft industries.

scholarly journals LCTC Ships Concept Design in the North Europe- Mediterranean Transport Scenario Focusing on Intact Stability Issues

2021 ◽  
Vol 9 (3) ◽  
pp. 278
Author(s):  
Germano Degan ◽  
Luca Braidotti ◽  
Alberto Marinò ◽  
Vittorio Bucci
Keyword(s):  
Design Stage ◽  
Strong Impact ◽  
Large Set ◽  
Concept Design ◽  
The North ◽  
Design Alternatives ◽  
Intact Stability ◽  
Multi Attribute Decision Making ◽  
Stability Issues ◽  
The Impact

In late years, the size of RoRo cargo ships has continuously increased, leading to the so-called Large Car Truck Carriers (LCTC). The design of these vessels introduced new challenges that shall be considered during the ship design since the conceptual stage, which has a very strong impact on the technical and economic performances of the vessel during all its life-cycle. In this work, the concept design of an LCTC is presented based on Multi-Attribute Decision Making (MADM). A large set of design alternatives have been generated and compared in order to find out the most promising feasible designs. The proposed approach is based on a Mathematical Design Model (MDM) capable to assess all the main technical and economic characteristics for each design. Among the others, here focus has been done on the ship stability to assure the compliance with statutory rules within the MDM. A new stability metamodel has been developed capable to define the cross curves of stability at the concept design stage. The proposed MADM methodology has been applied to North Europe-Mediterranean transport scenario highlighting the impact of main particulars describing hull geometry on the technical and economic performances of an LCTC ship.

scholarly journals Study on Striking Ship with Loading Impact on the Performance of the Double Hull Oil Tanker Collision

2018 ◽  
Vol 25 (s2) ◽  
pp. 42-48
Author(s):  
Wenfeng Wu ◽  
Yubin Yang ◽  
Jianwei Zhang ◽  
Jinshu Lu
Keyword(s):  
Loading Condition ◽  
Damage Mechanism ◽  
Impact Performance ◽  
Finite Element Software ◽  
Force Impact ◽  
Collision Force ◽  
Oil Tankers ◽  
Double Hull ◽  
The Impact ◽  
Oil Tanker

Abstract Due to the great danger of the collision of oil tankers, lots of research on the collision of oil tankers has been carried out. But, at present, the research on the collision of oil tankers mainly focuses on the loading condition of the struck ship, ignores the impact on the loading condition of the striking ship. However, during the actual oil tanker collision, the striking ship is generally in the state of loading. Therefore, it is necessary to carry out the analysis of the impact of the loading condition of the striking ship on the collision damage of the oil tanker. In this paper, the effect of striking ship with loading on the impact performance of the side structure during the collision of the cargo double hull oil tanker has been investigated. The ship collision model was established by using the finite element software ANSYS/LS-DYNA which is based on 7000 tons of double hull oil tankers. Based on the analysis of the collision force, impact of striking speed changes, impact of striking deep changes and structural energy absorption during the collision process, the influence of the striking ship with loading on the damage mechanism and the impact performance of the double shell oil ship side structure was expounded. The results show that the influence of the striking ship with loading can be great to the damage to side hull during the research of the collision performance of the oil tanker.

scholarly journals Sensitivity of Mesoscale Model Forecasts of Icing Conditions to Land Use: Dynamic and Diabatic Impacts

2020 ◽  
Author(s):  
Erik Janzon ◽  
Heiner Körnich ◽  
Johan Arnqvist ◽  
Anna Rutgersson
Keyword(s):  
Surface Roughness ◽  
Cloud Water ◽  
Ice Accretion ◽  
Single Column ◽  
Wind Response ◽  
Primary Driver ◽  
Water Response ◽  
Cloud Ice ◽  
The Impact ◽  
Surface Vegetation

In-cloud ice mass accretion on wind turbines is a common challenge faced by energy companies operating in cold climates. On-shore wind farms in Scandinavia are often located in regions near patches of forest, the heterogeneity length scales of which are often less than the resolution of many numerical weather prediction (NWP) models. The representation of these forests--including the cloud water response to surface roughness and albedo effects related to them--must therefore be parameterized in NWP models used as meteorological input in ice prediction systems, resulting in an uncertainty that is poorly understood and to present date not quantified. The sensitivity of ice accretion forecasts to the subgrid representation of forests is examined in this study. A single column version of the HARMONIE-AROME 3D NWP model is used to determine the sensitivity of the forecast of ice accretion on wind turbines to the subgrid forest fraction. Single column simulations of a variety of icing cases at a location in northern Sweden were examined in order to investigate the impact of vegetation cover on ice accretion in varying levels of solar insulation and wind magnitudes. In mid-winter cases, the wind speed response to surface roughness was the primary driver of the vegetation effect on ice accretion. In early season cases, the cloud water response to surface albedo effects plays a secondary role in the impact of in-cloud ice accretion, with the wind response to surface roughness remaining the primary driver for the surface vegetation impact on icing. Two different surface boundary layer (SBL) forest canopy subgrid parameterizations were tested in this study that feature different methods for calculating near-surface profiles of wind, temperature, and moisture, with the ice mass accretion again following the wind response to surface vegetation between both of these schemes.

scholarly journals Single Column Model Simulations of Icing Conditions in Northern Sweden: Sensitivity to Surface Model Land Use Representation

Energies ◽  
2020 ◽  
Vol 13 (16) ◽  
pp. 4258
Author(s):  
Erik Janzon ◽  
Heiner Körnich ◽  
Johan Arnqvist ◽  
Anna Rutgersson
Keyword(s):  
Surface Roughness ◽  
Ice Accretion ◽  
Northern Sweden ◽  
Single Column ◽  
Wind Response ◽  
Primary Driver ◽  
Water Response ◽  
Cloud Ice ◽  
The Impact ◽  
Surface Vegetation

In-cloud ice mass accretion on wind turbines is a common challenge that is faced by energy companies operating in cold climates. On-shore wind farms in Scandinavia are often located in regions near patches of forest, the heterogeneity length scales of which are often less than the resolution of many numerical weather prediction (NWP) models. The representation of these forests—including the cloud water response to surface roughness and albedo effects that are related to them—must therefore be parameterized in NWP models used as meteorological input in ice prediction systems, resulting in an uncertainty that is poorly understood and, to the present date, not quantified. The sensitivity of ice accretion forecasts to the subgrid representation of forests is examined in this study. A single column version of the HARMONIE-AROME three-dimensional (3D) NWP model is used to determine the sensitivity of the forecast of ice accretion on wind turbines to the subgrid forest fraction. Single column simulations of a variety of icing cases at a location in northern Sweden were examined in order to investigate the impact of vegetation cover on ice accretion in varying levels of solar insolation and wind magnitudes. In mid-winter cases, the wind speed response to surface roughness was the primary driver of the vegetation effect on ice accretion. In autumn cases, the cloud water response to surface albedo effects plays a secondary role in the impact of in-cloud ice accretion, with the wind response to surface roughness remaining the primary driver for the surface vegetation impact on icing. Two different surface boundary layer (SBL) forest canopy subgrid parameterizations were tested in this study that feature different methods for calculating near-surface profiles of wind, temperature, and moisture, with the ice mass accretion again following the wind response to surface vegetation between both of these schemes.

Sign in / Sign up

Export Citation Format

Share Document