船舶英语外文翻译--船舶危险状态下的纵向强度计算-其他专业

1、外文翻译Longitudinal strength of ships with accidentaldamagesGe Wang*, Yongjun Chen, Hanqing Zhang, Hua Peng This paper presents an investigation of the longitudinal strength of ships with damages due to grounding or collision accidents. Analytical equations are derived for the residual hull girder stre

2、ngth and verified with direct calculations of sample commercial ships for a broad spectrum of accidents. Hull girder ultimate strengths of these sample vessels under sagging and hogging conditions are also calculated, based on which correlation equations are proposed. To evaluate a grounded ship, us

3、ing the section modulus to the deck would be optimistic, while using the section modulus to the bottom would be conservative. On the contrary, to evaluate a collided ship, using the section modulus to the deck would be conservative, while using the section modulus to the bottom would be optimistic.

4、The derived analytical formulae are then applied to a fleet of 67 commercial ships, including 21 double hull tankers, 18 bulk carriers, 22 single hull tankers and six container carriers. The mean values, standard deviations and coefficients of variation for the coefficients in these new analytical f

5、ormulae are obtained. The ship length exhibits little influence on these coefficients because they are close to the mean values although ship length spans from 150 to 400 m. The ship type shows some influence on the residual strength. Uniform equations are proposed for commercial ships which do not

6、depend on a ships principal dimensions. These formulae provide very handy tools for predicting the residual strength in seconds, without performing step-by-step detailed calculations, an obvious advantage in cases of emergency or salvage operation. r 2002 Elsevier Science Ltd. All rights reserved.Ke

7、ywords: Residual strength; Hull girder ultimate strength; Section modulus; Damage; Collision;Grounding1. Introduction Traditionally, ships have been designed to resist all loads expected to arise in their seagoing environment. The objective in structural design has been to maintain a ships structura

8、l integrity for normal operating conditions. A combination of the most severe loads is usually selected as the nominal design load. Protection of a ship and the cargo it carries from damages incurred by accidents, though an essential issue in the design of watercraft, has been focused on subdividing

9、 a ship into compartments. National and international standards (Load Line,MARPOL, SOLAS, Classification Societies Rules) have established requirements or watertight bulkheads and subdivision. Structural strength in collision, grounding or internal accidents (such as an explosion) has attracted very

10、 little attention. Public sensation increases each time there is a major loss of ships, cargo and life atsea, or when there is oil pollution from damaged ships. This motivates the development of design procedures and related analysis methods for accidental loads, in particular, the loads due to ship

11、 collision or grounding accidents. A ship may collapse after an accident because of inadequate longitudinal strength.However, the consequences of an accident on a ships strength are seldom investigated.Although there are some papers published on the residual strength of damaged ship hulls 1,2, this

12、field still remains unexplored. This paper reports on an investigation of the longitudinal strength of damaged ship hulls for a broad spectrum of collision and grounding accidents. Both the hull girder section modulus and hull girder ultimate strength are calculated. We aim to obtain simple relation

13、s to assess residual hull girder strength, which may be used ashandy and reliable tools to help make timely decisions in the event of an emergency. Theoretical analyses are presented and analytical formulae are derived. Typical designs of 67 commercial ships, including 21 double hull tankers, 18 bul

14、k carriers, 22 single hull tankers and six container carriers, which have lost portions of bottom shell plating and side shell plating, are analyzed to obtain such simple equations for predicting residual strength of damaged ships.2. Assumptions and analytical methods2.1. Section modulus of hull gir

15、ders It has been a proven practice to use simple beam theory to analyze the global bending of hull girders. Many experiments have confirmed that the bending behavior of ships agrees quite well with the beam theory. The hull girder section modulus indicates the bending strength of the primary hull st

16、ructures. The calculation of a midship section modulus is a very important step in basic ship design. Structural members that are continuous in the longitudinal direction are included in the calculation of the section modulus. Only members that are effective in both tension and compression are assum

17、ed to act as part of the hull girder. The section modulus to the deck or to the bottom is obtained by dividing the moment of inertia by the distance from the neutral axis to the molded deck line at the side or to the base line, respectively. 2.2. Ultimate strength of hull girder The hull girder sect

18、ion modulus is an indicator of initial buckling or initial yielding, which is usually not the state at which the ship achieves its true maximum bending capacity. Plates and longitudinals may experience elastic buckling, plastic buckling, post buckling, yielding, and/or fracture in the process of app

19、roaching hull girder ultimate strength. The so-called ultimate strength of hull girder corresponds to the maximum bending capacity beyond which the ship will break its back due to extensive yielding and buckling. The continuous improvement of knowledge regarding the behavior of hull girders and stru

20、ctural members has led to the development of various methods.ISSC 2000 Special Task Committee VI.2 4 reviews the state-of-the-art technology for predicting hull girder ultimate strength. The committee conducted extensive benchmark calculations and assessed the uncertainties involved in these approac

21、hes. Among all groups of approaches (closed-form formulae, simplified analytical methods and nonlinear FEM simulations), the simplified analytical methods are favored by most analysts. These approaches save modeling time; they generally account for fabrication imperfections and provide reliable resu

22、lts. Extensive related studies have placed simplified methods as the first choice when one tries to calculate ultimate hull girder strength. A program of this kind, ALPS/ISUM3, is used in this investigation.2.3. Extent of damages 2.3. Extent of damages Every accident is different. The resulting dama

23、ge also varies. Accidents require many parameters to describe the damage a ship sustains after an accident. A comprehensive description can easily fill a couple of pages or more, even though not all of the data is necessary for calculating hull girder strength. For simplicity, this paper uses defini

24、tions that are convenient for calculation but retain the main characteristics of accidental damages. For a grounding, it is assumed that the bottom shell and the attached bottom longitudinals are lost. No girders are assumed to be damaged after a grounding. This study investigates a broader range of

25、 bottom loss, up to 80% of ship breadth, to simulate minor to severe grounding damages. For a collision, it is assumed that the side shell and the attached longitudinals are lost. The damage starts from the deck at the side and extends downward. The deck stringer plate and longitudinal bulkhead that

26、 attach to the damaged side are assumed to be intact after an accident. A broad range of side shell loss, ranging from 5% to about 40% of ship depth, is considered. The assumptions mentioned above help to simplify the definition of damages. Only one parameter is used to describe the damage. Introduc

27、tion of additional parameters is avoided. The focus is on shell plating, the first barrier from water flooding. Structures attached to the damaged shell are not considered with the assumption that they may be approximated by smearing as equivalent thickness of shell. There exist other assumptions wi

28、th regard to damage extents. In the ABS Guide for assessing hull-girder residual strength 5, a grounding damage includes bottom girders attached to the damaged bottom shell to a certain depth; collision damage includes deck stringer plate and slope bulkhead plating attached to the damaged side shell

29、 plating for a specified extent. Paik et al. 1 defined collision and grounding damages according to this ABS Guide. For sensitivity studies, they analyzed 0.8 to 1.2 times the specified damage extents described in the ABS Guide. Wang et al. 2 analyzed a broad range of bottom damage, spanning from mi

30、nor to substantial damage. Wang et al. also investigated cases where there is damage in bottom girders in additional to damage to the bottom shell. 2.4. Presentation of results Two means are used to indicate the longitudinal bending strength of a ship hull: hull girder section modulus and ultimate h

31、ull girder strength. Section modulii to thedeck and bottom, and ultimate bending strengths of hull girder under sagging and hogging are calculated and presented in dimensionless format; all are compared with their values at intact condition. Bottom damage is expressed as a percentage of the ships br

32、eadth. Side damage extent is expressed as a percentage of the ships depth.The investigation is focused on midship sections of typical commercial ships. Sections beyond midship are not analyzed in this paper but the same analysis may be performed on those sections readily.3. Simple equations for the

33、residual section modulus Fig. 1 is a sketch of a transverse section, which characterizes the geometry of a ship and ignores many details. This transverse section may be a double hull tanker, a bulk carrier, a container carrier, a single hull tanker or any other type of ship. The shaded area is the a

34、ssumed damage caused by either collision or grounding accident. For an intact hull, the cross-sectional area, height of neutral axis above the base line, distance of the deck at the side to the neutral axis, moment of inertia and section modulus are A; z0; z1; I and eSMT0; respectively. The section

35、modulii to the deck and the bottom, eSMdkT0 and eSMbtmT0; have been used by the industry to indicate the hull girder strength. A is the cross-sectional area of the lost structure. Its center is c from the neutral axis of the intact hull. The c is positive when the center of the damaged area A is abo

36、ve the neutral axis. The shift of neutral axis z0 is Where The neutral axis moves away from the lost area. The moment of inertia of thedamaged hull becomes Substituting Eq. (1) into Eq. (2) gives The section modulus to a location of distance z from the neutral axis when z is abovethe neutral axis be

37、comes Substituting Eq. (1) into Eq. (3) and replacing eSMT0 with I=z into the aboveequation gives An expansion of this equation by neglecting higher order terms of r gives theexpression for dimensionless section modulus for z above the neutral axisThrough a similar process, the following equation is

38、 derived for z below the neutralaxis: Eqs. (1)(8) are applicable to general cases where there is an area loss in a transverse section.中文翻译:船舶危险状态下的纵向强度计算 -Ge Wang*, Yongjun Chen, Hanqing Zhang, Hua Peng摘要此文将提到关于船舶在搁浅和碰撞两种危险状况下的调查报告。给出了破损船体计算方程式和典型商船事故的直接计算方法。船体梁在中垂和中拱下根据所给出的方程式计算极限强度。为了评估搁浅的船，计算时甲板的

39、剖面模数要取得大些，而船底剖面模数要取得小些。相反的，在估算碰撞条件下船时甲板的剖面模数要取得小些，而船底剖面模数要取得大些。导出的方程适用于67系列商船，21型双壳油船，18型散货船，22型单壳油船和6型集装型船。其主要数值、标准差、变动系数将从这些新的分析方程中获得。船长对这些数值的影响是很小的，即使船长从150m长到400m。而船的类型不同将有对船的剩余强度有影响。统一的对于商船的方程式并不是基于船体主尺度的，这些方程将在下次预测剩余强度时很有作用，并不需要再一步步的近似计算，在紧急情况下和补救的情况下。1.简介 一般的，船设计用于承受正常情况下的载重。在船体结构设计方面，它的设计是维持

40、船体结构完整和使船一般状况下的运行。通常以最多载荷的情况作为标准设计载况。 为保存船只和它的货物不遭受损坏是船只设计的必要点，所以已经开始注重分舱设计。我国和国际上已经制定了明确的标准来划分水密舱壁。而对于碰撞后的结构强度，搁浅或者内部受损并不受到关注。公众的关注在逐渐增强关于船舶船舶失事、货船的海上生存能力，或者由于船失事而引起的海上石油污染。这些促使设计和程序上在分析方式上的提升在危险载况下，尤其是船在搁浅和碰撞下的载荷。船可能在事故后断裂，由于纵向强度上的不足，然而船体强度的研究是很少的，虽然有一些关于剩余强度方面的文章，但有待深讨。文章就一个关于纵向强度的调查提出报告，一个关于船体外壳

41、碰撞和搁浅的调查。梁和桁架的剖面模数将考虑在内。我们的目的在于获得一个方便可靠的关系式来评价剩余船体梁的强度，一个可以用在紧急的状况下方便可靠的方法去判定的方法。理论分析并得出解析公式。典型设计的67型商船，21型双壳油船，18型油船。22型单壳油船和6型集装箱船。当船在失去部分船底板和边板，将被分析并以此获得一个简单方程去推测破损船的的剩余强度。2. 假设和分析方法 它已被应用于实际中，以简支梁理论去分析船体的总纵弯曲，很多实验也已证明船体的实际弯曲与简支梁理论分析的结果十分符合。 船体梁的剖面模数反应了船体结构主要的弯曲强度。计算船体中横剖面模数是船体设计过程中相当重要的一个步骤。纵向连续构件参与剖面模数的计算，而将同时影响张力和压力的构件当做船体梁的部分。船底部和上甲板处的剖面模数是通过将剖面对水平中和轴的惯性矩除以两者分别到中和轴的距离得到。 2.2 船体的极限强度 船体的剖面模数只是初步的屈服强度的象征，而通常的并不代表船体受到的最大的弯曲强度。板材和骨材在拉伸逐步接近屈服极限的过程中会经历弹性弯曲、塑性变形、后屈曲、屈服、断裂。 极限强度就是求得刚好让结构发生失稳时的那个应力值临界应力 对于船体梁和船体结构的认识的不断提高，致使