Design of Ship Weight Reduction Based on Reliability Analysis of Longitudinal Bending Strength

2015 ◽  
Author(s):  
Huilong Ren ◽  
Qingyue Zhang ◽  
Xueyun Jiang ◽  
Yumeng Hu
Keyword(s):  
Reliability Analysis ◽  
Optimization Model ◽  
Bending Strength ◽  
Structural Strength ◽  
Safety Margin ◽  
General Characteristic ◽  
Wave Loads ◽  
Strength Assessment ◽  
Component Size ◽  
Longitudinal Bending

As the focus of the structural design, the form and dimension of components in the mid-ship section reflect the general characteristic of the whole ship, thus playing a significant role in the weight and structural strength of the whole ship. However, traditional deterministic methods of structural strength assessment will bring excessive safety margin, which will lead to excessive weight of ship structure. In this paper, the optimization model was built in view of ship longitudinal bending strength reliability analysis by MATLAB software. With the information of wave loads forecast and that of the section bending strength, the failure probability was obtained. Objective function was the weight of mid-ship section, and optimization variables were the size of sectional components, and the constraints were reliability index and component size limits were required by relevant norms. Combined with the optimization model, genetic algorithm toolbox integrated in MATLAB was applied to study mid-ship section optimization. Results of the examples showed that in the case that the limiting conditions were satisfied, the weight of mid-ship section was reduced to a certain extent, which meant that this method was effective for mid-ship section optimization.

The Research of Statistic Prediction for Wave Loads Based on Three Dimensional Method

2013 ◽  
Author(s):  
Yihan Zhang ◽  
Huilong Ren ◽  
Hui Li ◽  
Xiaoyu Li
Keyword(s):  
Structural Strength ◽  
Wave Spectrum ◽  
Three Dimensional ◽  
Frequency Interval ◽  
Wave Loads ◽  
Short Term ◽  
Empirical Formulas ◽  
Strength Assessment ◽  
Term Prediction

The exact prediction of wave loads for ship or other marine structure is the key to its design and the assessment of structural strength, reliability and security. The short-term and long-term prediction of wave loads are always used in direct calculation for structural strength, fatigue strength assessment and so on based on spectral analysis method. In this paper, the numerical calculation method for statistic prediction is discussed firstly, including the Weibull distribution fitted method and the stack method. Further more, it is necessary to find a quick solution in order to improve the efficiency to compute the nonlinear equation in the second method. Then, some main factors that may influence the long-term or short-term prediction are discussed, such as wave spectrum, wave scatter diagram, incident wave angle interval and frequency interval. Finally, the wave loads prediction for a series of typical bulk carriers and oil tankers are calculated by the uniform predict method discussed above base on three dimensional wave loads calculation theory. The results showed that the method used in this paper can predict the statistic value of wave loads induced by irregular incident waves conveniently and efficiently. A rule to choose a series of uniform factors is confirmed for statistic prediction and some empirical formulas for long-term value of wave bending moment are concluded which are very useful in marine engineering.

Structural Safety Assessment of a 1100 TEU Container Ship, Based on a Enhanced Long Term Fatigue Analysis

2014 ◽  
Vol 1036 ◽  
pp. 935-940
Author(s):  
Leonard Domnisoru ◽  
Ionica Rubanenco ◽  
Mihaela Amoraritei
Keyword(s):  
Safety Assessment ◽  
Safety Evaluation ◽  
Irregular Waves ◽  
Structural Safety ◽  
Random Wave ◽  
Wave Loads ◽  
Strength Assessment ◽  
Integrated Method ◽  
Hydroelastic Response

This paper is focused on an enhanced integrated method for structural safety assessment of maritime ships under extreme random wave loads. In this study is considered an 1100 TEU container test ship, with speed range 0 to 18 knots. The most comprehensive criteria for ships structural safety evaluation over the whole exploitation life is based on the long term ship structures analysis, that includes: stress hot-spots evaluation by 3D/1D-FEM hull models, computation of short term ship dynamic response induced by irregular waves, long term fatigue structure assessment. The analysis is enhanced by taking into account the ships speed influence on hydroelastic response. The study includes a comparative analysis on two scenarios for the correlation between the ships speed and waves intensity. The standard constant ship speed scenario and CENTEC scenario, with total speed loss at extreme waves condition, are considered. Instead of 20 years ship exploitation life estimated by classification societies rules from the long term structural safety criteria, the enhanced method has predicted more restrictive values of 14.4-15.7 years. The numerical analyses are based on own software and user subroutines. The study made possible to have a more realistic approach of ships structural strength assessment, for elastic and faster ships as container carriers, in compare to the standard one based only on naval rules, delivering a method with higher confidence in the designed structural safety.

Materials Selection for Sandwich Pipes Under the Combined Effect of Pressure, Bending and Temperature

2007 ◽  
Author(s):  
Allan R. de Souza ◽  
Theodoro A. Netto ◽  
Ilson P. Pasqualino
Keyword(s):  
Structural Strength ◽  
Material Selection ◽  
Low Cost ◽  
Polymeric Materials ◽  
External Pressure ◽  
Core Material ◽  
Annular Layer ◽  
Oil And Natural Gas ◽  
Longitudinal Bending ◽  
Logic Approach

Recent researches point to the great potential of the sandwich pipe conception for ultra deepwater exploitation and production of oil and natural gas. Its configuration is very simple and comprises two concentric metallic pipes with a core material, polymeric or ceramic, in the annulus. The main functions of the annular layer are: to provide satisfactory thermal insulation so as to avoid the formation of wax and hydrates along the pipeline during production shutdown; to improve the overall structural strength of the system. Polypropylene and cement have been recently proposed for these applications. The reason for the choice of these materials was the low cost and the extensive availability in industry. Here a systematic material selection approach is employed in order to assess the applicability of other polymeric materials. The attributes of materials needed to meet the design specification are thoroughly studied. The list of possible materials was enlarged and the modified digital logic approach is used with the purpose to define a top group of materials for further numerical comparative study. Finite element analyses are carried out to assess the structural strength of the sandwich pipe under pure external pressure or longitudinal bending and combined external pressure and bending. Additionally, the effect of thermal gradient is included to the numerical analyses to evaluate each pre-selected material of the top group. Results indicate that other potential materials such as PEEK and polycarbonate can improve the structural performance of the sandwich pipe conception and yet meet other several design criteria.

scholarly journals Safety Standard for Special Class Damslopes Based on Reliability Analysis

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Lingzhi Huang ◽  
Zheng Si ◽  
Xiaoqi Du ◽  
Lifeng Wen ◽  
Bin Li
Keyword(s):  
High Risk ◽  
Reliability Analysis ◽  
Special Class ◽  
Slope Failure ◽  
Safety Margin ◽  
Class Ii ◽  
Class I ◽  
Safety Factors ◽  
Safety Standard ◽  
Risk Levels

The risk of slope failure is determined by the degree of damage caused by the slope slide. For the special-high slope of some high-risk water conservancy and hydropower projects, the standard should be appropriately raised. Thus, the safety standard for these slopes is explored on the basis of reliability analysis. The slopes with high risk of failure are divided into special class I and special class II slopes depending on the risk levels and acceptable risk standards. The concept of reliability theory-based relative ratio of the safety margin is utilized to establish the relationship between annual failure probability and safety factor, thereby obtaining the reasonable safety factors for different slopes. Results show that the values of safety factors for special class I and special class II are 1.40 and 1.35, respectively. These results can provide a reference for exploring the safety standards of dams with a height of more than 200 m.

scholarly journals The Key Construction Technology Research on the Intercontinental Shanghai Wonderland

2020 ◽  
Vol 2020 ◽  
pp. 1-16
Author(s):  
Peng Jiang ◽  
Shaole Yu ◽  
Wei Luan ◽  
Xinxi Chen ◽  
Yang Qin ◽  
...  
Keyword(s):  
Finite Element ◽  
Dynamic Response ◽  
Safety Margin ◽  
Time History ◽  
Construction Technology ◽  
Construction Process ◽  
Component Size ◽  
Finite Element Software ◽  
Deep Pit ◽  
The Stability

The Intercontinental Shanghai Wonderland is the first natural ecological hotel built in an abandoned mine in the world, which faces many difficulties in the construction process. To solve the difficult problems in the construction process, the study was carried out from the stability analysis of the deep pit cliff, the mechanical performance of the structure, and the construction technology. The Intercontinental Shanghai Wonderland is built around the abandoned deep pit cliffs, and the stability of the deep pit cliffs directly affects the safety of the building. The dynamic response characteristics and the instability characteristics of the mine slope under the dynamic response were analyzed by a three-dimensional dynamic finite element method. The calculation results showed that with effective anchoring support measures, the stability coefficient of slope under static load and small earthquakes was large, which had a certain safety margin. Under the action of large earthquakes, the slope could still meet the stability requirements. The structure of the Intercontinental Shanghai Wonderland is a unique two-point support structure system. It shows the deformation and stress characteristics of one fixed end and one simply supported end under horizontal load. The elastic-plastic time history response of structures under actions of rare earthquakes was analyzed through the finite element analysis software. The analysis results show that the current structural system along with the design of component size and strength can meet the seismic performance of the structure under actions of rare earthquakes. The Intercontinental Shanghai Wonderland was built in a stone pit 88 m below the surface. Therefore, the transportation of materials was a difficulty in the construction process. A set of ultradeep concrete downward conveying equipment was invented to solve the difficulty. The construction process of the whole structure was simulated by finite element software, which provided a safety guarantee for the construction of the whole structure.

Study on the Wave Loads and Strength Assessment Method on Semi-Submersible Platform

2009 ◽  
Author(s):  
Hui Li ◽  
Huilong Ren ◽  
Tao Wei ◽  
Guoqing Feng
Keyword(s):  
Fatigue Strength ◽  
Assessment Method ◽  
Wave Method ◽  
Wave Loads ◽  
Strength Assessment ◽  
Buckling Strength ◽  
Comprehensive Comparison ◽  
Comparison Of The Results ◽  
Classification Society

In this paper, the wave loads of a semi-submersible platform is calculated by the deterministic design wave method and the stochastic design wave method based on the rules established by ABS and DNV classification society respectively. Then, the yielding strength, buckling strength and fatigue strength of important members are assessed according to these different rules. Through the comprehensive comparison of the results of wave loads and strength assessment, the differences between these rules are summarized. Then some significant suggestions are given.

Optimization Design of Front Suspension Spring Cover

2012 ◽  
Vol 590 ◽  
pp. 492-495
Author(s):  
Qin Man Fan
Keyword(s):  
Topology Optimization ◽  
Shape Optimization ◽  
Optimization Model ◽  
Optimization Design ◽  
Structural Strength ◽  
Suspension Spring ◽  
Front Suspension ◽  
Original Proposal ◽  
Stiffness Properties ◽  
Strength And Stiffness

Taking the front suspension spring cover of a tractor as the research object, the ANSYS as topology optimization design platform, the minimum value of the volume of spring cover as the objective function, the strength and stiffness of the spring cover does not exceed the set value as the constraint conditions conduct topology optimization and obtained spring cover topology shape optimization model. The results showed that the optimized spring cover, while maintaining the original structural strength and stiffness properties, the new spring cover materials than the original proposal to reduce by 12.9%.

Longitudinal bending strength of corrugated steel pipe

1980 ◽  
Vol 7 (3) ◽  
pp. 547-551
Author(s):  
C. D. Smith
Keyword(s):  
Bending Strength ◽  
Steel Pipe ◽  
Buried Pipe ◽  
Highway Engineering ◽  
The Earth ◽  
Large Numbers ◽  
Wall Stiffness ◽  
Cantilever Length ◽  
Strength Tests ◽  
Longitudinal Bending

Corrugated steel pipe (CSP) is used in large numbers for drainage structures, particularly in highway engineering. The corrugations increase the wall stiffness of the pipe by a factor of about 100, so relatively light-gauge material can be used to resist the earth loading on the buried pipe. These same corrugations, however, result in a decrease in longitudinal bending strength. This can be an important consideration in situations where the culvert may be undermined at the outlet, or is deliberately cantilevered beyond its imbedment. Strength tests were carried out on three sizes of standard 16 gauge (0.001676 m) rivetted CSP. From this it was determined that the safe cantilever length for a flowing full culvert is about 2 m for pipes of 0.61 m diameter and larger.

scholarly journals Reliability Analysis Approach For Intersection Sight Distance Of A Symmetrical Single-Lane Roundabout

2021 ◽  
Author(s):  
Paria Sarshar
Keyword(s):  
Reliability Analysis ◽  
Safety Margin ◽  
Random Variables ◽  
Analysis Approach ◽  
Deterministic Models ◽  
Second Moment ◽  
First Order ◽  
Sight Distance ◽  
Design Variables ◽  
First Order Second Moment

The current intersection sight distance values on a roundabout provided by ASSHTO and other worldwide guidelines are based on deterministic methods considering only single variables as the design inputs. However, most of the input design variables such as entering speed and the deceleration rate are random variables which are stochastic in nature. Therefore, this study proposes a reliability analysis approach to add uncertainty to the current deterministic models. Two different reliability approaches; the first order second moment and advanced first order second moment are presented in this paper. These approaches rely on the normal distribution of the random variables using the mean, variance and the covariance of the probability distribution of each variable rather than the single deterministic values. Results show that the AFOSM reliability methodology provides a more conservative outcome which ensures a greater safety margin comparing to FOSM which appears to be a more efficient and robust methodology.

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