高等結(jié)構(gòu)動力學(xué)

1、高等結(jié)構(gòu)動力學(xué)1第一章 緒論一、現(xiàn)代結(jié)構(gòu)動力學(xué)的研究內(nèi)容1、外載荷分析確定性、周期性、瞬態(tài)：動力機械，旋轉(zhuǎn)機械產(chǎn)生的激勵碰撞、爆炸、沖擊等瞬態(tài)荷載隨機性：風(fēng)荷載、波浪荷載、地震荷載、車輛等路面行駛引起的荷載2、結(jié)構(gòu)系統(tǒng)的動力響應(yīng)時域：載荷可以是非線性的，系統(tǒng)也可以是非線性的，解析解法，數(shù)值解法頻域：目前僅能處理線性化系統(tǒng)，譜分析方法，優(yōu)點：計算效率高時頻混合分析方法：將時域解法與頻域解法的優(yōu)點結(jié)合，提高計算效率和求解精度解析法：數(shù)學(xué)上直接求解，許多實際結(jié)構(gòu)難以采用該方法數(shù)值解法：工程上可以應(yīng)用的近似解法，有限元法、邊界元法、隨機樣條法、有限條法23、結(jié)構(gòu)系統(tǒng)的辨識和參數(shù)估計動力學(xué)的擬問題（1）

2、已知input 和output，識別結(jié)構(gòu)參數(shù)（2）已知input滿足一定假設(shè)，output可測，識別結(jié)構(gòu)參數(shù)（3）Health mornitoring:a、有無結(jié)構(gòu)失效 b、損傷位置 c、損傷程度SystemInputLoadsoutputResponse？InputLoadsoutputResponse34、容許標(biāo)準和可靠性分析評估結(jié)構(gòu)系統(tǒng)在某種載荷激勵下的可靠性，系統(tǒng)壽命評估，系統(tǒng)疲勞分析等。5、結(jié)構(gòu)振動控制大型結(jié)構(gòu)如高層、潛艇、海洋平臺等，環(huán)境荷載比較惡劣，在使用過程中會出現(xiàn)幅度比較大的振動。這些振動會誘發(fā)（1）疲勞破壞（2）降低系統(tǒng)的可靠度（3）給居住會作業(yè)人員帶來身體不適措施：在結(jié)構(gòu)

3、上安裝控制設(shè)備（裝置），使結(jié)構(gòu)具有自動調(diào)節(jié)的能力，從而使其振動減小，避免破壞。在建筑結(jié)構(gòu)中主要是抵抗風(fēng)、地震載荷、橋梁的振動上海電視塔、楊浦大橋等都安裝了減振裝置，日本的200多個高層建筑海洋結(jié)構(gòu)主要抵抗波浪、風(fēng)荷載控制方法主要有：被動式控制：調(diào)諧質(zhì)量阻尼器，調(diào)諧液體阻尼器，粘彈性阻尼器等主動控制：主動質(zhì)量驅(qū)動器等半主動控制：主動變剛度，主動變阻尼，磁流變阻尼器，電流變阻尼器混合式控制6、結(jié)構(gòu)動力優(yōu)化設(shè)計按照設(shè)計要求確定可控變量或設(shè)計變量使結(jié)構(gòu)系統(tǒng)達到預(yù)期的狀態(tài)，或者達到最優(yōu)設(shè)計目標(biāo)最優(yōu)綜合或最優(yōu)設(shè)計4Special topic I:Dynamic response 動態(tài)響應(yīng)5678不同方法計

4、算whipping響應(yīng)的比較9Springing analysis激勵頻率固有頻率10In whipping and springing there are 111213通過分析結(jié)構(gòu)能量傳遞途徑，采用改變結(jié)構(gòu)參數(shù)實現(xiàn)抑制振動向目標(biāo)區(qū)域傳遞1415結(jié)構(gòu)破壞指數(shù)16冰載測量17181920212223n結(jié)構(gòu)動力學(xué)的前沿和熱點問題主動控制技術(shù)海洋工程動力學(xué)海上陸色能源開發(fā)的動力學(xué)問題24IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)25IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(

5、V.7)Damaged structure due to Bow Slamming艏艏部砰部砰擊擊下的下的結(jié)構(gòu)損傷結(jié)構(gòu)損傷Damaged plate外板外板損傷損傷Damaged stiffener骨材骨材損傷損傷26IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Damaged structure due to Stern Slamming艉艉部砰部砰擊擊下的下的結(jié)構(gòu)損傷結(jié)構(gòu)損傷Damaged plate外板外板損傷損傷Damaged stiffener骨材損傷骨材損傷27IMPULSIVE PRESSURE LOADING AN

6、D RESPONSE ASSESSMENT(V.7)Damaged structure due to Sloshing晃晃蕩蕩引起的引起的結(jié)構(gòu)損傷結(jié)構(gòu)損傷Damaged corrugationImpacted Area28IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Damaged structure due to Green Water上浪引起的上浪引起的結(jié)構(gòu)損傷結(jié)構(gòu)損傷Damaged water breaker Damaged stiffener29IMPULSIVE PRESSURE LOADING AND RESPONSE

7、 ASSESSMENT(V.7)nStructural design against impulsive pressure loadings from slamming, sloshing and green water has always been a difficult task. Many ships have still reported experiencing structural damage due to impulsive pressure loadings. This indicates that the relevant rules of classification

8、societies needs to be improved regarding impulsive pressure loadings. 受脈沖壓力載荷（砰擊、晃蕩、上浪等）作用的船體結(jié)構(gòu)的設(shè)計總是一件棘手的事情。到目前為止，脈沖載荷引起的結(jié)構(gòu)損壞還是時有發(fā)生，表明船級社現(xiàn)行的相關(guān)規(guī)范需要進一步改進。nWhen the duration of an impulsive pressure loading is much shorter than the natural period of the impacted structure, the impulse may represent the

9、 loading. However, if the duration is long enough as compared to the natural period, the amplitude of pressure may play an important role. 當(dāng)脈沖壓力載荷的持續(xù)時間遠遠小于結(jié)構(gòu)的固有周期時，可以用脈沖特性來描述載荷；當(dāng)脈沖壓力載荷的持續(xù)時間遠遠大于結(jié)構(gòu)的固有周期時，可以用壓力峰值來描述載荷。nIn extreme cases, the structural design against impulsive pressure loadings may be t

10、reated as an ultimate limit state or an accident limit state problem. However, for more probable situations, this can be solved as a serviceability limit state problem especially from the impacts of slamming whereby the tolerable extent of damage needs to be provided.在極端情況下，脈沖壓力載荷作用下的結(jié)構(gòu)設(shè)計可以用極限強度或事故強

11、度問題處理。但在更多的情況下，可以將該問題當(dāng)作服務(wù)強度來處理。30nModel and full-scale test 模型和實船試驗技術(shù)Model test :模型試驗- drop test on containership stern section (Yang, et al, 2007)集裝箱船尾部剖面落體試驗- drop test on rigid and deformable cone-shaped samples (Peseux, et al, 2005) 剛性和彈性錐形體落體試驗- drop test on flat plate (Higo and Yamada, 2006)平板

12、落體試驗- planning craft model in oblique waves (Rosen and Garme, 2004)滑行艇模型斜浪中試驗Full scale test:實船試驗- deep-V pleasure craft (Carrera and Rizzo, 2005)深V型游艇- containership in the North Pacific Ocean (Lee, et al, 2007)北太平洋集裝箱船試驗IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)31nNumerical simulation

13、 數(shù)值模擬- VOF(Volume of Fluid) and SPH(Smoothed Particle Hydrodynamics) - explicit FEM analysis for 2D rigid wedge (Stenius, et al, 2005)二維剛體顯式有限元法- direct coupling of FEM and Wagner representation for elastic body of small dead-rise angle (Korobkin, et al, 2006a)小斜升角問題的有限元與Wagner砰擊壓力直接耦合法- numerical s

14、imulation of trapped air effects (Dobashi, 2006; 2007)氣墊效應(yīng)數(shù)值模擬nAnalytical prediction 解析計算- publication about analytical methods has been rare in recent years.很少- analytical solution for 2D wedge (Yettou, et al., 2007)Yettou提出了一種新的解析算法IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)32nPractica

15、l procedures in determining design slamming pressure確定設(shè)計砰擊壓力的實用過程- computational procedure for the analysis of a ships motions in waves and spatial mean slamming pressures (Ould, et al., 2005)波浪中船舶運動以及平均砰擊壓力空間分布的計算流程- numerical procedure to predict slamming loads on offshore supply vessel (Schellin,

16、 2006) car carrier (Hermundstad and Moan, 2005) cruise ship (Hermundstad and Moan, 2007)海洋工程供應(yīng)船、滾裝船、游船的砰擊載荷預(yù)報流程- feed-forward neural network to predict horizontal force (Fullerton, et al., 2007) peak value of slamming pressure (Chen and Xiao, 2005)利用神經(jīng)網(wǎng)絡(luò)技術(shù)預(yù)報橫向力和砰擊壓力峰值IMPULSIVE PRESSURE LOADING AND R

17、ESPONSE ASSESSMENT(V.7)33IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Pressure coefficients obtained using a commercial package (Yang, et al., 2007)經(jīng)經(jīng)典理典理論論、經(jīng)經(jīng)典模型典模型試驗試驗、新模型、新模型試驗試驗、CFD計計算的比算的比較較34nBackground背景- In general, the global slamming response needs to be combined with the simulta

18、neously obtained global and local steady state load effects, in terms of extreme values for ultimate limit state checks and cyclic load histories for fatigue design checks.總體砰擊載荷響應(yīng)一般與穩(wěn)態(tài)波浪載荷相疊加，用于極限強度和疲勞強度校核- Generally, 3D effects can reduce the 2D slamming pressure force by approximately 30%. Fully

19、3D slamming prediction methods are not ready for use in a global response analysis. Correction factors on 2D estimates may be applied to yield reasonable values for design.計入三維效應(yīng)可以減小30%的砰擊力，但三維砰擊理論尚不成熟。IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Measured and calculated plamming pressure35

20、nGlobal Structural Modeling總體結(jié)構(gòu)模型- The hull may be modelled by the beam theory or FE shell models. While vertical bending is relatively well represented by beam elements, modelling of torsional behaviour of open ships such as container vessels as well as catamarans is more challenging. 船體結(jié)構(gòu)可用梁理論或有限元

21、模型進行分析；垂向彎曲問題可用梁理論較好的表示，但大開口船的扭轉(zhuǎn)問題和雙體船則比較麻煩- Quite accurate results are obtained if the beam model is based on an advanced thin-walled girder theory. A more detailed FE model will be necessary if the 1D beam is to be applied in the dynamic analysis, to obtain response values especially for fatigue d

22、esign.利用先進的薄壁梁理論可以較準確的結(jié)果；對于疲勞等問題，有限元方法比一維梁理論更好- No publications seem to have been published on slamming induced torsional response of ships.砰擊引起的扭轉(zhuǎn)振動問題目前未見有文章發(fā)表。IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)36nWhipping Analysis: Extreme values for ultimate strength design顫振分析：極限強度設(shè)計- experi

23、ment on the short-term probability distribution of the midships vertical hogging bending moment (Drummen and Moan, 2007) 通過模型試驗確定載荷的短期概率分布- numerical and experimental study to measure ship responses to extreme wave impact. 數(shù)值和試驗研究極限砰擊下的船體響應(yīng)(Minami et al., 2006) - hybrid method for calculating wave-i

24、nduced linear and nonlinear global load effects in ships with hull flexibility (Wu and Moan, 2005) 線性與非線性混合法- experimental and numerical investigation of the effect of bow flare and stern slamming induced whipping in large passenger vessels (Cusano et al, 2007) 大型游船艏艉砰擊下顫振響應(yīng)的模型與數(shù)值研究- experiment on t

25、he VBM response to stern slamming loads on a large modern passenger ship (Dessi et al., 2007) 大型豪華游船艉砰擊- long-term analysis of extreme sloshing and whipping-induced pressures and structural response of the Mark III containment system for LNG(Graczyk et al, 2007) Mark III型大型LNG船圍護系統(tǒng)極端晃蕩和顫振壓力長期預(yù)報和結(jié)構(gòu)響應(yīng)

26、IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)37nWhipping Analysis: Cyclic stress history for fatigue analysis顫振響應(yīng)，疲勞分析中的循環(huán)載荷- Full scale measurements:實船試驗Capesize iron ore carriers (Moe et al (2005) and Storhaug et al (2006)礦砂船4000TEU container ship (Drummen et al, 2006, 2007)集裝箱船10 000 dw

27、t. general cargo ship (Aalberts and Nieuwenhuijs , 2006) 一般貨船6800TEU container ship (Toyoda et al ., 2006) - For container ships, the predicted total fatigue damage for the midships section was approximately 50% higher than the damage determined experimentally.對集裝箱船，理論預(yù)報的疲勞損傷比試驗值大50%左右- High frequen

28、cy damage can be significantly reduced by including the steady wave for the relevant ship.當(dāng)包含穩(wěn)態(tài)載荷引起的破壞時，高頻疲勞損傷的程度相對明顯減輕。IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)38IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7) Sloshing test equipments試驗試驗裝置裝置Model and full-scale tests模型和模型和實實船

29、船試驗試驗for quasi full scale model準準實實船船for “intermediate” scale model中模型中模型for small scale model小模型小模型39nModel and full-scale tests模型和實船試驗- Small scale model tests give a reasonable overview of the overall sloshing motions inside the tank but the local pressures measurements are still difficult to obt

30、ain due to the highly localized (in time and space) pressures which occur during impact. The problem of transferring these pressures to a full scale represents a big challenge. 小模型可獲得晃蕩運動整體特征，但由于砰擊壓力在時間和空間上的特征，測量困難，轉(zhuǎn)換成實船更難- Important databases of the quasi full scale measurements were realized using

31、 these tests in various research projects, but many problems were reported with respect to the repeatability of the measurement that makes the proper interpretation and use of the results very difficult. 在不同的項目中，準實船試驗積累了很多數(shù)據(jù)，但結(jié)果離散性問題使利用和解釋這些結(jié)果變得困難- “Intermediate” model tests will allow for the detai

32、led validation of the simplified semi analytical and more sophisticated numerical models. Indeed, all the important impact parameters can be measured with very good precision and this allows for proper validation of all the intermediate modelling steps.中模型試驗可以為簡化的半解析預(yù)報方法和復(fù)雜的數(shù)值計算模型提供詳細的驗證IMPULSIVE PR

33、ESSURE LOADING AND RESPONSE ASSESSMENT(V.7)40nNumerical modelling of hydro-structure interactions during impacts砰擊中流固耦合的數(shù)值模擬- Even if some attempts were made to solve the 3D impact problems, the 2D modelling of fluid flow is used most often. On the structural side the 3D effects of the response can

34、be treated by the standard FEM codes 二維流動模型比三維模型更常用，結(jié)構(gòu)的三維效應(yīng)用有限元模擬nCFD Numerical simulationsCFD數(shù)值模擬- the most popular methods belong to the family of the VOF (Volume of Fluid) technique and to the so called SPH (Smoothed Particle Hydrodynamics) method. However, all CFD methods suffer from various num

35、erical problems when it comes to the evaluation of highly localized pressures. VOF和SPH法最常用，但當(dāng)涉及到砰擊壓力時，所有的數(shù)值方法都存在問題IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Typical sloshing motions simulated41IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Comparison of the quasi-static and hydro

36、elastic structural responses準準靜態(tài)靜態(tài)和水和水彈彈性性結(jié)構(gòu)響應(yīng)結(jié)構(gòu)響應(yīng)42nCombined semi analytical (fluid flow) and finite element (structure) models半解析（流體）和有限元方法的組合- Semi analytical impact models represent another type of method for sloshing impact problems. The idea is to identify the most typical impact situations an

37、d then simplify them in order to be able to describe them with simple geometry including the few most important physical parameters. 半解析砰擊模型是晃蕩砰擊的另一類解法，找出最典型的砰擊，通過簡化，以幾個簡單但重要的物理參數(shù)去描述砰擊IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Aerated impact and corresponding simplification(left-real sit

38、uation, middle-geometrical simplification, right-mathematical model43nExperimental investigations試驗研究 - A nonintrusive quantitative velocity measurement technique, PIV (Particle Image Velocimetry) and BIV (Bubble Impact Velocimerty), highlighted turbulence intensity throughout the different phases o

39、f the impingement-run up-overtopping sequence. This scenario suggested the application of Ritters dam-breaking flow solution to green water problem. PIV 測量上浪瞬態(tài)速度場， BIV測量平均速度場，潰壩理論的實用性IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7). Instantaneous velocity field using PIV and measured mean vel

40、ocity field using BIV (Ryu et al, 2007a)44nExperimental investigations試驗研究 - The model test to simulate the green water scenarios for a fixed FPSO indicated that the plunging wave plus the dam-breaking type event as the most common water-on deck scenario, whereas the so-called hammer-fist type was f

41、ound to be the most dangerous one.IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Hammer-fist type event: evolution of the shipped water (Greco et al, 2007)45nNumerical simulations數(shù)值模擬 - Impacting flow features: Domain decomposition technique (Navier-Stokes solver with a level set (LS0 techni

42、que and BEM solver ) (Greco et al, 2007) - Dam breaking problem: Volume-of-fluid (VOF) scheme (Kleefsman et al, 2005), VOF technique with a finite volume method (Zhang et al, 2005) and Edge-based stabilized finite element solver using VOF extensions (Elias and Coutinho, 2007) - Two-layer flow overto

43、pping a fixed body with a vertical wall: Modified marker abd cell (MAC) method (Yamasaki et al, 2005) - Free surface over fixed deck with a round profile: moving particle method (Shibata and Koshizuka, 2007) - Water shipping problem: smoothed particle hydrodynamics (SPH) method (Violeau and Issa, 20

44、07)IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Two-layer flow overtopping a fixed body with a vertical wall: Modified marker and cell (MAC) method (Yamasaki et al, 2005)46nLoad alleviation - Pham and Varyani (2006) compared the performances of V-shape and vane type breakwaters for differe

45、nt values of the geometrical parameters. They concluded that the confronting angle has less influence in both cases for load alleviation and that the V-shape breakwater is more effective in sustaining part of the water flow otherwise fully directed toward containers and structures placed behind. 擋浪板

46、的效果IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)47nExperimental and numerical simulation試驗和數(shù)值模擬- The energy of the explosive is consumed by the shockwaves and a gas bubble and approximately, 60% into shockwave and 40% to the gas bubbles. 爆炸能量的60%轉(zhuǎn)換成沖擊波，40%為氣泡- Sturtevant (2007) described t

47、he full ship shock trials (FSST) done by US Navy. The current FSST practice consists of three UNDEX shots of 10,000 pound HBX explosive charge weight detonated in series at large stand-off distances abeam of the ship. The costs associated with the test can exceed $50 million per trial. 美國海軍實船試驗，每個試驗

48、花費5000萬美元 - Bubble collapse under a submerged flat plate: RANSE (Reynolds-averaged Navier-Stokes equations) based finite difference Equation Independent Transient Analysis Computer Code (Kan et al, 2005) 浸沒平板下的氣泡潰滅數(shù)值計算- Shock transparency: basic linear method (Iakovlev, 2006; 2007) 沖擊波透射：基本線性法IMPULS

49、IVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Full ship shock trial (FSST) (Sturtevant, 2007)48nExperimental and numerical simulation數(shù)值與模型試驗- Effect of bulk cavitation and attenuation of floating structures response: Explicit finite element approach with BEM (Gong, 2006)- Near contact calculation

50、s: The chinook solver with the large deformation fluid-structure interaction (Gregson, 2006)- Hull whipping response: The source-sink method (Noma, 2006)- Ultimate strength of hull girder: Explicit FEM for bending moment, BEM for local pressure from bubble jet and FEM for local structural damage (Ya

51、suda, 2006;2005)- Explosion bubble: BEM coupled with structural FE code (Klaseboer, 2005) Classification society rules船級社規(guī)范- Lloyds Register Rules and Regulations (2008) describe how a ships structure is designed by taking UNDEX into account. It also gives general information about shock waves, bubb

52、le pulses, bubble jets and their effects to structural response. Lloyds defines three levels of shock notations for the effects of an initial shock wave. In addition to the shock notations, it defines design levels for whipping induced by explosion bubble effects and another notations for residual s

53、trength assessment. 英國勞氏規(guī)范（2008）有水下爆炸問題的較多規(guī)定和方法IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)49IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7) Cumulative effect of multiple impacts 多次沖多次沖擊變擊變形累形累積積Deformed shape of stiffened plate 加筋板加筋板變變形形 Effects of multiple impacts and Tripping

54、of stiffener (a) P = 0.631 MPa (b) P = 1.656 MPa (c) P = 2.070 MPa 50nShip Type ; OIL TANKER with D.W. 39,000Ton nLBP ; 172.mnBreadth(mld.) ; 31.40mnDraft(Scantling, mld.) ;10.95mnBlock Coefficient ; 0.785nDesign Speed ; 14.5knot油船底部砰擊壓力下板厚沿船長分布要求（四個規(guī)范）IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSM

55、ENT(V.7)Required thickness of the bottom plate by the bottom slamming pressure51nShip Type ; OIL TANKER with D.W. 39,000Ton nLBP ; 172.mnBreadth(mld.) ; 31.40mnDraft(Scantling, mld.) ;10.95mnBlock Coefficient ; 0.785nDesign Speed ; 14.5knot油船艏外飄砰擊壓力下板厚沿高度分布要求（四個規(guī)范）IMPULSIVE PRESSURE LOADING AND RESP

56、ONSE ASSESSMENT(V.7)Required thickness of side shell plate by bow flare slamming pressure52IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)nH(Tank Height) = 15.1mnLc (Longitudinal distance of the tank) = 17.40mnbc (Transverse distance of the tank) = 24.94mnh(Filling Height) = 10.57m(0.7H)nCal

57、culated point = 10.57m(0.7H)油船晃蕩砰擊壓力下的板厚比較（橫艙壁，縱艙壁）Calculated pointClass AClass B Class C CSR Transverse Bulkhead9.50 8.93 6.51 6.35 Longitudinal Bulkhead 9.50 10.95 8.60 8.60 Required plate thickness by sloshing pressure (mm)53IMPULSIVE PRESSURE LOADING AND RESPONSE ASSESSMENT(V.7)Required thicknes

58、s of the deck plate by green water loads上浪砰上浪砰擊擊下的甲板厚度要求下的甲板厚度要求0.00 2.00 4.00 6.00 8.00 10.00 12.00 0.750.800.850.900.951.001.05Required Plate Thickness(mm)Longitudinal Calculation Point / Ship LengthClass AClass BClass CCSR54nImpulsive pressure loads generalEven though significant progress has bee

59、n made over the last decade, the proper determination of relative impact geometry, relative velocity and amount of entrapped air still remains extremely challenging, since the overall sea-keeping problem of ship sailing with arbitrary forward speed in waves is still an open problem. 由于船舶航行條件的復(fù)雜性，砰擊過

60、程中的相對砰擊面、速度、氣墊等的確定仍然存在困難nLocal slamming Numerical predictions of slamming pressures accounting for viscous flow separation, entrapped air, compression of fluids and elasticity of structures need to enhance their accuracy, stability and efficiency. More validations with tests results are needed for t