scholarly journals A Numerical Ice Load Prediction Model Based on Ice-Hull Collision Mechanism

2020 ◽  
Vol 10 (2) ◽  
pp. 692
Author(s):  
Meng Zhang ◽  
Karl Garme ◽  
Magnus Burman ◽  
Li Zhou
Keyword(s):  
Failure Modes ◽  
Impact Load ◽  
Infinite Plate ◽  
Design Parameters ◽  
Load Prediction ◽  
Impact Location ◽  
Crushing Force ◽  
Broken Ice ◽  
Level Ice ◽  
Ice Failure

A simplified numerical model is introduced to predict ice impact force acting on the ship hull in level ice condition. The model is based on ice-hull collision mechanisms and the essential ice breaking characteristics. The two critical ice failure modes, localized crushing and bending breaking, are addressed. An energy method is used to estimate the crushing force and the indentation displacement for different geometry schemes of ice-ship interaction. Ice bending breaking scenario is taken as a semi-infinite plate under a distributed load resting on an elastic foundation. An integrated complete ice-hull impact event is introduced with ice failure modes and breaking patterns. Impact location randomness and number of broken ice wedges are considered in order to establish a stochastic model. The analysis is validated by comparison with the model ice test of a shuttle passenger ferry performed in May 2017 for SSPA Sweden AB at Aker Arctic Technology Inc. Good agreement is achieved with appropriate parameter selection assumed from the model test and when ice bending failure is dominant. This model can be used to predict the ice impact load and creates a bridge between design parameters (ice properties and ship geometry) and structure loads.

Impact Response and Failure Mode for Single-Layer Geodesic Spherical Domes under Impact Load

2013 ◽  
Vol 351-352 ◽  
pp. 80-84
Author(s):  
Duo Zhi Wang ◽  
Feng Fan ◽  
Xu Dong Zhi ◽  
Jun Wu Dai
Keyword(s):  
Dynamic Response ◽  
Failure Mode ◽  
Failure Modes ◽  
Impact Load ◽  
Single Layer ◽  
Impact Response ◽  
Impact Location ◽  
Parametric Analyses ◽  
The Impact ◽  
Local Dent

Based on the ANSYS/LS-DYNA software, the analysis for the 40m span geodesic spherical domes under impact load is carried out. By changing the mass of impact object, impact velocity and impact location, the parametric analyses on the dynamic response of the structures under the impact loading are carried out. The three failure modes of the spherical domes are summed up: local dent of structure and global collapse of structure, Punch failure of structure. Then the characteristics of the dynamic response of the structure with different failure mode, such as the impact course, impact load, speed of nodes, displacement of nodes, and stress of bars, are investigated. It is further improvement of failure mode for single-layer reticulated dome under impact.

Vulnerability-Based Design of Sliding Concave Bearings for the Seismic Isolation of Steel Storage Tanks

2016 ◽  
Author(s):  
Hoang Nam Phan ◽  
Fabrizio Paolacci ◽  
Silvia Alessandri ◽  
Phuong Hoa Hoang
Keyword(s):  
Liquid Steel ◽  
Seismic Isolation ◽  
Failure Modes ◽  
Fragility Curves ◽  
Time History ◽  
Probability Of Failure ◽  
Design Parameters ◽  
Economic Losses ◽  
Storage Tanks ◽  
Isolation System

Liquid steel storage tanks are strategic structures for industrial facilities and have been widely used both in nuclear and non-nuclear power plants. Typical damage to tanks occurred during past earthquakes such as cracking at the bottom plate, elastic or elastoplastic buckling of the tank wall, failure of the ground anchorage system, and sloshing damage around the roof, etc. Due to their potential and substantial economic losses as well as environmental hazards, implementations of seismic isolation and energy dissipation systems have been recently extended to liquid storage tanks. Although the benefits of seismic isolation systems have been well known in reducing seismic demands of tanks; however, these benefits have been rarely investigated in literature in terms of reduction in the probability of failure. In this paper, A vulnerability-based design approach of a sliding concave bearing system for an existing elevated liquid steel storage tank is presented by evaluating the probability of exceeding specific limit states. Firstly, nonlinear time history analyses of a three-dimensional stick model for the examined case study are performed using a set of ground motion records. Fragility curves of different failure modes of the tank are then obtained by the well-known cloud method. In the following, a seismic isolation system based on concave sliding bearings is proposed. The effectiveness of the isolation system in mitigating the seismic response of the tank is investigated by means of fragility curves. Finally, an optimization of design parameters for sliding concave bearings is determined based on the reduction of the tank vulnerability or the probability of failure.

OPTIMIZATION DESIGN OF ALU FOAM-FILLED S-SHAPE SQUARE TUBE UNDER AXIAL DYNAMIC LOADING

2020 ◽  
Vol 40 (04) ◽  
Author(s):  
NGUYEN VAN SY ◽  
NGUYEN THANH TAM
Keyword(s):  
Energy Absorption ◽  
Optimization Design ◽  
Optimal Designs ◽  
Design Parameters ◽  
Aluminum Foams ◽  
Response Surface Models ◽  
Element Simulation ◽  
Crushing Force ◽  
Surface Models ◽  
Foam Filled

This paper presents finite element simulation of the crash behavior and the energy absorption characteristics of S-shape square tubes which were fully or partially filled with aluminum foams. Base on the numerical results, it is found that, the density, the length of the filled foam and the thickness of tube directly affect the specific energy absorption (SEA) and peak crushing force (PCF) of the S-shape tubes. In this paper, the multi-objective particle swarm optimization (MOPSO) algorithm is employed to seek for optimal designs for the partial foam-filled S-shape tubes (PFSTs) and the full foam-filled S-shape tubes (FFSTs) with various design parameters such as the density, the length of filled foam and the thickness of tube, where response surface models are established to formulation SEA and PCF. The optimization results showed the energy absorption capability per unit mass of the PFSTs is more powerful than that of the FFSTs while the PCF constrained under the same level.

The Icebreaking Problem in Two Dimensions: Experiments and Theory

1992 ◽  
Vol 36 (04) ◽  
pp. 299-316
Author(s):  
Petri Valanto
Keyword(s):  
Transient Response ◽  
Ice Sheet ◽  
Two Dimensions ◽  
Flexural Failure ◽  
Theoretical Assumptions ◽  
Broken Ice ◽  
Fluid Boundary ◽  
Level Ice ◽  
Physical Phenomena ◽  
Made In

Model experiments on the transient response of a floating ice sheet to an advancing icebreaker were carried out in two dimensions in order to provide information on the actual icebreaking phenomenon associated with ships advancing in level ice. The response consists of two parts:the dynamic bending of the ice sheet to flexural failure; andthe rotation of the broken ice slab until the slab is parallel to the bow plate of the advancing vessel. A theoretical approach to calculate the transient response of the floating ice sheet is presented. The theory is based on the assumption of potential flow with a relatively complicated boundary condition on the ice sheet-fluid surface. The numerical solution is based on an initial-value approach. The kinematic and dynamic boundary conditions on the ice sheet-fluid boundary are used to advance the solution in time. The predicted results are compared to the experimental ones to evaluate the validity of the theoretical assumptions made. In most cases close agreement between experiments and theory is demonstrated. Together with the experiments, the numerical model developed is able to clarify several physical phenomena contributing to icebreaking resistance at the waterline of a vessel advancing in level ice.

Evaluation of Impulse Attenuation by Football Helmets in the Frequency Domain

2020 ◽  
Vol 142 (6) ◽  
Author(s):  
Nicolas Leiva-Molano ◽  
Robert J. Rolley ◽  
Taylor Lee ◽  
Kevin G. McIver ◽  
Goutham Sankaran ◽  
...  
Keyword(s):  
Frequency Domain ◽  
Head Injuries ◽  
Mechanical Impedance ◽  
Design Parameters ◽  
Impact Loads ◽  
Design Standards ◽  
Impact Location ◽  
Dynamic Impedance ◽  
Grading Systems ◽  
Football Helmets

Abstract Design of helmets used in contact sports has been driven by the necessity of preventing severe head injuries. Manufacturing standards and pass or fail grading systems ensure protective headgear built to withstand large impacts, but design standards do no account for impacts resulting in subconcussive episodes and the effects of cumulative impacts on its user. Thus, it is important to explore new design parameters, such as the frequency-domain measures of transmissibility and mechanical impedance that are based on energy absorption from a range of impact loads. Within the experimentally determined frequency range of interest (FROI), transmissibilities above unity were found in the 0–40 Hz range with the magnitude characteristics varying considerably with impact location. A similar variability with location was observed for the mechanical impedance, which ranged from 9 N/m to 50 N/m. Additional research is required to further understand how changes in the components or materials of the components will affect the performance of helmets, and how they may be used to reduce both transmissibility and dynamic impedance.

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.

scholarly journals Reliability analysis of built concrete dam

2019 ◽  
Vol 12 (3) ◽  
pp. 551-579
Author(s):  
K. O. PIRES ◽  
A. T. BECK ◽  
T. N. BITTENCOURT ◽  
M. M. FUTAI
Keyword(s):  
Structural Reliability ◽  
Failure Modes ◽  
Design Parameters ◽  
Concrete Gravity Dam ◽  
Gravity Dams ◽  
Deterministic Method ◽  
Concrete Dam ◽  
Case Study Analysis ◽  
Concrete Gravity Dams

Abstract The conventional design of concrete gravity dams still follows the deterministic method, which does not directly quantify the effect of uncertainties on the safety of the structure. The theory of structural reliability allows the quantification of safety of these structures, from the quantification of the inherent uncertainties in resistance and loading parameters. This article illustrates application of structural reliability theory to the case study analysis of a built concrete gravity dam. Results show that reliability of the built structure is greater than that of the designed structure. The study compares reliability for design conditions, with the corresponding safety coefficients, illustrating a lack of linearity between safety coefficients and reliability. Furthermore, the study shows which are the failure modes and the design parameters with greater influence on dam safety.

Dynamic Ice Force Analysis on a Conical Structure Based on Direct Observation and Measurement

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Ning Xu ◽  
Qianjin Yue
Keyword(s):  
Video Camera ◽  
Temporal Variations ◽  
Qualitative Description ◽  
Basic Model ◽  
Broken Ice ◽  
Conical Structure ◽  
Ice Failure ◽  
Ice Force ◽  
Bending Failure ◽  
Ice Forces

In order to study dynamic ice force induced by ice-structure interaction, we adopted the most reliable method to directly measure ice force on full-scale structure. This paper mainly demonstrates the qualitative description on the basic model for dynamic ice forces based on direct measurement on the jackets with ice-breaking cone in the Bohai Sea. Temporal variations of ice force are recorded by the ice load panels, and corresponding ice failure processes on conical structures are recorded by video camera. It is found that, when an ice sheet acts on the upward narrow cone, bending failure occurs and broken ice pieces are completely cleared up by the side of the cone. The basic form of dynamic ice force in time domain is a series of impulse signals with minimum load of zero.

Ice Model Testing of Structures With a Downward Breaking Cone at the Waterline JIP: Presentation, Set-Up and Objectives

2011 ◽  
Author(s):  
Per Kristian Bruun ◽  
Sveinung Lo̸set ◽  
Arne Gu¨rtner ◽  
Guido Kuiper ◽  
Ted Kokkinis ◽  
...  
Keyword(s):  
First Year ◽  
Test Set ◽  
Ice Load ◽  
Fixed Model ◽  
Ice Conditions ◽  
Level Ice ◽  
Ice Model Test ◽  
Set Up ◽  
Ice Failure ◽  
Ice Model

Two large ice model test campaigns were performed in the period 2007–2010 as a part of a Joint Industry Project. The objectives of the project were to investigate different floater geometries and ice model test set-ups (model fixed to a carriage and pushed through the ice vs. ice pushed towards a floating model moored to the basin bottom) and their influence on the ice failure mode and structure responses in the various tested ice conditions. This paper presents the objectives and motivations for the project, the models tested, the target test set-up for the various tested configurations and the test matrix. Initial results from a fixed model tested in three first-year ice ridges with similar target ice properties are also presented and compared. Fixed models of both deep and shallow water platforms were tested in various ice conditions. All models except one had a downward breaking cone at the waterline. The influences of the waterline diameter, the angle of the downward breaking cone and the vertical cone height on the ice failure mode and the resulting ice load were investigated. Tests were conducted in level ice with a thickness ranging from 2 to 3 m and variable ice drift speeds ranging from 0.1 to 1.0 m/s in full scale values. The models were subjected to tests in managed level ice with varying speeds, ice concentrations and ice floe sizes. Fixed structures were also subjected to testing in typical first-year design ice ridge conditions with ridges of different depths and widths, as well as one multi-year ice ridge. One fixed model was also utilised for testing of the repeatability of scaled ice model testing. Moored models with the same waterline geometry as the fixed models were also tested. The moored models were tested in ice conditions similar to those of the fixed models with the objective of comparing their influences on the ice load due to structural responses.

Fundamental Design Issues of Brush Seals for Industrial Applications

2002 ◽  
Vol 124 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Saim Dinc ◽  
Mehmet Demiroglu ◽  
Norman Turnquist ◽  
Jason Mortzheim ◽  
Gayle Goetze ◽  
...  
Keyword(s):  
High Speed ◽  
Failure Modes ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Design Parameters ◽  
Design Criteria ◽  
Seal Design ◽  
Brush Seal ◽  
Brush Seals ◽  
As Stress

Advanced seals have been applied to numerous turbine machines over the last decade to improve the performance and output. Industrial experiences have shown that significant benefits can be attained if the seals are designed and applied properly. On the other hand, penalties can be expected if brush seals are not designed correctly. In recent years, attempts have been made to apply brush seals to more challenging locations with high speed (>400 m/s), high temperature (>650 °C), and discontinuous contact surfaces, such as blade tips in a turbine. Various failure modes of a brush seal can be activated under these conditions. It becomes crucial to understand the physical behavior of a brush seal under the operating conditions, and to be capable of quantifying seal life and performance as functions of both operating parameters and seal design parameters. Design criteria are required for different failure modes such as stress, fatigue, creep, wear, oxidation etc. This paper illustrates some of the most important brush seal design criteria and the trade-off of different design approaches.

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