1、 Guidance Notes on Ship Vibration GUIDANCE NOTES ON SHIP VIBRATION APRIL 2006 (Updated February 2014 see next page) American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 Copyright 2006 American Bureau of Shipping ABS Plaza 16855 Northchase Drive Houston, TX 770
2、60 USA Updates February 2014 consolidation includes: April 2006 version plus Corrigenda/Editorials ABSGUIDANCE NOTES ON SHIP VIBRATION .2006 iii Foreword Foreword The American Bureau of Shipping recognizes the overall ship vibration as an important measure to ensure the habitability, safety and func
3、tionality of the vessels. The ABS Guidance Notes on Ship Vibration have been developed to provide users with specific guidance on the design, analysis, measurement procedures and criteria in order to achieve the goal of limiting the ship vibration to an acceptable level. In the text herein, this doc
4、ument is referred to as “these Guidance Notes”. The design and construction of the hull, superstructure, and deckhouse of a steel vessel are to be based on all applicable requirements of the ABS Rules for Building and Classing Steel Vessels (Steel Vessel Rules 2006). Specifically, for the Container
5、Carriers over 130 meters in length, the ABS Steel Vessel Rules require the consideration of vibratory responses of hull structures, as applicable (5-5-3/13.1). For the LNG Carriers, the ABS Steel Vessel Rules require special attention to the possible collapse of membrane due to hull vibration (5-8-4
6、/4.2). In conjunction with the propulsion shaft alignment, the ABS Steel Vessel Rules require the consideration of propulsion shaft vibrations (4-3-2/7). For the cargo and passenger vessels, ABS provides optional classification notations for crew habitability and passenger comfort (ABS Guide for Pas
7、senger Comfort on Ships and Guide for Crew Habitability on Ships). Also ABS provides Condition Monitoring Program for machinery vibration (7-A-14/5.1.2 ABS Guide for Surveys Based on Preventative Maintenance Techniques). These Guidance Notes provide practical guidelines on the concept design to assi
8、st ship designers to avoid excessive shipboard vibration at an early design stage. These Guidance Notes also assist with the finite element analysis (FEA) based vibration analysis procedure to calculate the vibration response and evaluate the design at detail design stage. The analysis procedure rep
9、resents the current analysis practice in ABS. These Guidance Notes also offer guidelines on the vibration measurement procedure at sea trials and the acceptance criteria on vibration limits based on the international standards and the practice in ABS. These Guidance Notes are issued in 2006. Users o
10、f these Guidance Notes are welcome to contact ABS with questions or comments concerning these Guidance Notes. Users are advised to check periodically with ABS to ensure that this version of these Guidance Notes is current. iv ABSGUIDANCE NOTES ON SHIP VIBRATION .2006 Table of Contents GUIDANCE NOTES
11、 ON SHIP VIBRATION CONTENTS SECTION 1 General 1 1 Introduction . 1 3 Application . 1 5 Scope 1 FIGURE 1 Overall Procedure for Ship Vibration Assessment 2 SECTION 2 Concept Design 3 1 Introduction . 3 3 Design Considerations 3 5 Concept Design Approach 4 FIGURE 1 Items to be Considered During Concept
12、 Design 5 SECTION 3 Excitations 6 1 Introduction . 6 3 Low-speed Main Diesel Engine 6 5 Hull Wake 8 5.1 Hull-Propeller Clearance 11 7 Propeller 13 7.1 Alternating Thrust 13 7.3 Hull Pressure Forces . 17 TABLE 1 . 8 FIGURE 1 External Forces and Moments 6 FIGURE 2 Guide Force Couples 7 FIGURE 3 Nomina
13、l Wake Distribution for a Typical Merchant Ship (DTMB Model 4370, CB= 0.6) 9 FIGURE 4 Alternative Shafting Arrangements: Open Strut Stern (upper); Conventional Skeg Stern (lower) . 10 FIGURE 5 Open Strut Stern Arrangement . 12 FIGURE 6 Conventional Skeg-Stern Arrangement 12 FIGURE 7 Maximum Skew Ang
14、le 13 FIGURE 8 Burrill Cavitation Inception Chart 16 ABSGUIDANCE NOTES ON SHIP VIBRATION .2006 v SECTION 4 Structural Resonances 19 1 Introduction . 19 3 Hull Girder Vertical Vibration Excited by the Main Diesel Engine. 19 5 Main Machinery/Shafting System Longitudinal Vibration Excited by the Propel
15、ler . 22 7 Superstructure Fore-and-Aft Vibration Excited . 26 TABLE 1 Comparison of 2-node Vertical Vibration Natural Frequencies 20 TABLE 2 Flexible Base Correction Factors 27 FIGURE 1 Natural Frequencies of Vertical Hull Vibration 21 FIGURE 2 3-mass Longitudinal Model of Main Propulsion System . 2
16、3 FIGURE 3 Example of Natural Frequencies vs. Foundation Stiffness . 25 FIGURE 4 Deckhouse Types . 27 FIGURE 5 Fixed-base Superstructure Natural Frequencies 27 FIGURE 6 Deckhouse Stiffening 29 SECTION 5 Vibration Analysis 31 1 Introduction . 31 1.1 Scope and Objective . 31 1.3 Procedure Outline of S
17、hip Vibration Analysis 32 3 Finite Element Modeling . 32 3.1 Global Model . 32 3.3 Engine, Propeller Shaft and Stern/Skeg 33 3.5 Lightship Weight Distribution . 35 3.7 Cargo, Water Ballast in Tanks and Fuel Oil in Tanks 35 3.9 Local Models . 35 5 Loading Condition . 35 5.1 Selection of Loading Condi
18、tions and Ship Speed 35 5.3 Added Mass 36 5.5 Buoyancy Springs . 36 5.7 Special Conditions . 36 7 Free Vibration . 36 7.1 Analysis Procedure . 36 7.3 Checking Points 38 9 Propeller Excitation . 38 9.1 Introduction 38 9.3 Propeller Shaft Forces . 38 9.5 Hull Surface Forces Induced by Propeller Cavita
19、tion 39 9.7 Direct Calculation of Bearing and Surface Forces . 43 11 Engine Excitation 44 13 Forced Vibration 44 13.1 General 44 13.3 Critical Areas . 45 13.5 Damping 45 vi ABSGUIDANCE NOTES ON SHIP VIBRATION .2006 TABLE 1 Propeller Bearing Forces and Moments for 20 Real Ship Case Study 39 FIGURE 1
20、Procedure to Perform Ship Vibration Analysis 32 FIGURE 2 Global FE Model Example 33 FIGURE 3 Engine Model Example . 34 FIGURE 4 Turbine Engine and Propeller Shaft Modeling Example . 34 FIGURE 5 Propeller Shaft 35 FIGURE 6 First Two Vertical Mode Shapes . 37 FIGURE 7 First Two Horizontal Mode Shapes
21、. 37 FIGURE 8 Scale Effect due to Propeller Inflow Condition 43 SECTION 6 Measurements 46 1 General . 46 1.1 Scope 46 1.3 Application . 46 1.5 Terminology . 46 3 Instrumentation . 47 3.1 General Requirements . 47 3.3 Calibration . 47 5 Measurement Conditions 48 5.1 Environment Condition 48 5.3 Loadi
22、ng Condition 48 5.5 Course . 48 5.7 Speed and Engine Power 49 7 Measurement Locations 49 7.1 Stern 49 7.3 Superstructure . 49 7.5 Main Engine and Thrust Bearing . 49 7.7 Lateral Shaft Vibration . 50 7.9 Torsional Shaft Vibration . 50 7.11 Local Structures . 50 7.13 Local Deck Transverse 50 7.15 Loca
23、l Machinery and Equipment . 50 7.17 Shell Near Propeller . 50 9 Data Processing Analysis . 50 9.1 Measured Data 50 9.3 Performance of Measurements . 51 9.5 Analysis Methods . 51 11 Measurement Report 54 11.1 Analysis and Reporting of Data . 54 TABLE 1 Typical Frequencies Ranges 51 TABLE 2 Examples o
24、f Alternate Vibration Measurements . 53 ABSGUIDANCE NOTES ON SHIP VIBRATION .2006 vii SECTION 7 Acceptance Criteria 56 1 General . 56 3 Vibration Limits for Crew and Passengers 56 3.1 ABS Criteria for Crew Habitability and Passenger Comfort . 56 3.3 ISO 6954 (1984) Criteria for Crew and Passenger Re
25、lating to Mechanical Vibration . 57 3.5 ISO 6954 (2000) Criteria for Crew and Passenger Relating to Mechanical Vibration . 59 5 Vibration Limits for Local Structures . 59 7 Vibration Limits for Machinery 60 7.1 Main Propulsion Machinery . 60 7.3 Machinery and Equipment . 61 TABLE 1 Maximum Weighted
26、RMS Acceleration Levels for Crew Habitability . 57 TABLE 2 Maximum Weighted RMS Acceleration Levels for Passenger Comfort . 57 TABLE 3 Overall Frequency-Weighted RMS Values (ISO 6954: 2000) . 59 TABLE 4 Vibration Limits for Main Propulsion Machinery 61 FIGURE 1 ISO 6954 (1984) 58 FIGURE 2 Vibration
27、Limits for Local Structures . 60 APPENDIX 1 References 62 1 General References 62 3 Concept Design 62 5 FE Analysis . 63 7 Measurement 63 APPENDIX 2 Corrections . 64 1 Corrective Investigations . 64 3 General Approach . 65 5 Hydrodynamic Modifications . 65 7 Structural Modifications . 67 9 Case Stud
28、y . 67 9.1 Determination of Model Constants 68 9.3 Structural Rectification Analysis 69 9.5 Propeller Change 71 FIGURE 1 Wake Improvement with Special Lines-adapting Stern Devices Conventional Stern Cargo Ship 66 FIGURE 2 Mass-elastic Model of Deckhouse and Support Structure 68 FIGURE 3 Equivalent O
29、ne-mass System . 70 viii ABSGUIDANCE NOTES ON SHIP VIBRATION .2006 APPENDIX 3 Seaway Excitation and Response . 73 1 General . 73 3 Springing . 73 5 Bow Flare Slamming and Whipping 73 7 Bottom Impact Slamming 74 APPENDIX 4 Concept Design Checklist . 75 ABSGUIDANCE NOTES ON SHIP VIBRATION .2006 1 Sect
30、ion 1: General SECTION 1 General 1 Introduction With the increase of ship size and speed, shipboard vibration becomes a great concern in the design and construction of the vessels. Excessive ship vibration is to be avoided for passenger comfort and crew habitability. In addition to undesired effects
31、 on humans, excessive ship vibration may result in the fatigue failure of local structural members or malfunction of machinery and equipment. These Guidance Notes are to provide users, specifically shipyards, naval architects, and ship owners, with practical guidance on the concept design to avoid e
32、xcessive ship vibration at an early design stage. If simple procedures are followed with insight and good judgment in the concept design stage, then the difficult countermeasures and corrections at the subsequent design stages may be avoided in most cases. These Guidance Notes also assist with the f
33、inite element analysis (FEA) based vibration analysis procedure to predict the vibration response and evaluate the design in detail design stage. The vibration analysis procedure represents the most current analysis practice in ABS. These Guidance Notes also offer guidelines on the vibration measure
34、ment procedure during the sea trials and the acceptance criteria on vibration limits based on international standards and practice in ABS. 3 Application These Guidance Notes are applicable to the vessels of all lengths. 5 Scope These Guidance Notes provide overall guidelines on ship vibration excite
35、d by the main engine and propeller. In these Guidance Notes, the following subjects are considered: i) Concept Design ii) Vibration Analysis iii) Measurements iv) Acceptance Criteria The concept design in Sections 2, 3 and 4 provides users with immediate, direct, and concise guidance in effectively
36、dealing with ship vibration in the concept design stage. In attempting to provide a sound and no-nonsense guidelines, these Guidance Notes identify the most serious problem areas that have caused difficulties to the industry, and concentrate on those areas. In the concept design, local vibration is
37、not addressed because detail information is not usually available in the early design stage. Instead, the concept design is focused on those areas that have been known to be of critical importance in avoiding harmful ship vibration. The vibration analysis in Section 5 provides the FE-based vibration
38、 analysis procedure based on first principles direct calculations. The FE-based vibration analysis is recommended to evaluate the design during the detail design stage. If found necessary, the local vibration is to be addressed in the detail vibration analysis. The analysis procedure provides guidel
39、ines on FE modeling, engine and propeller excitation, and free and forced vibration analysis. Section 1 General 2 ABSGUIDANCE NOTES ON SHIP VIBRATION .2006 For the assessment of ship vibration performance, the actual vibration levels at the most critical locations are to be measured and evaluated du
40、ring the sea trials. Section 6 provides guidelines on the vibration measurement procedure on the instrumentation, measurement conditions and locations, data processing and reporting. Section 7 provides acceptance criteria on the vibration limits for human comfort and habitability, local structures a
41、nd machinery based on international standards and practice in ABS. The shaft alignment and torsional vibration are not directly addressed in this document. For the requirements of the shaft alignment and torsional vibratory stress, refer to 4-3-2/7 of the ABS Steel Vessel Rules. The overall procedur
42、e for ship vibration assessment recommended in these Guidance Notes is shown in Section 1, Figure 1. FIGURE 1 Overall Procedure for Ship Vibration Assessment Concept DesignSections 2, 3, 4Vibration AnalysisSection 5CorrectionsAppendix 2Do the vibrationlevels meet the acceptancecriteria?MeasurementsS
43、ection 6Acceptance CriteriaSection 7NoYesAfter ConstructionDetail DesignEarly DesignABSGUIDANCE NOTES ON SHIP VIBRATION .2006 3 Section 2: Concept Design SECTION 2 Concept Design 1 Introduction Concept design is where the vibration avoidance process must begin. It is clear that if the vibration prob
44、lems, repeatedly identified by experience as the most important, are addressed at the earliest design stage, ultimately serious problems, involving great cost in correction efforts, may be avoided. The focus is on planning for vibration early at the Concept Design stage, where there has been no deve
45、lopment of details. If as much as possible can be done in concept design with the simple tools and rules of thumb available at that level, it will help to avoid major vibration problems. The major potential problems may often be present in the crude concept design definition. Just identifying and ad
46、dressing those potential problems in terms of the minimal technology available at the concept design stage is considered very important to the success of ship design. Sections 2 through 4 provide guidelines on the concept design. Some of these guidelines are presented in Principles of Naval Architec
47、ture, Chapter 7 (SNAME, 1988) and the SNAME granted permission to be included in this document. 3 Design Considerations The four elements of importance in ship vibration are: Excitation, Stiffness, Frequency Ratio, and Damping It is noted that any of the following contribute to vibration reduction:
48、i) Reduce exciting force amplitude, F. In propeller-induced ship vibration, the excitation may be reduced by changing the propeller unsteady hydrodynamics. This may involve lines or clearance changes to reduce the non-uniformity of the wake inflow or may involve geometric changes to the propeller it
49、self. Specifics in this regard are addressed in Section 3. ii) Increase stiffness, K. Stiffness is defined as spring force per unit deflection. In general, stiffness is to be increased rather than decreased when variations in natural frequency are to be accomplished by variations in stiffness. It is not a recommended practice to reduce system stiffness in attempts to reduce vibration. iii) Avoid values of frequency ratio near unity; /n= 1 is the resonant condition. At resonance, the excitation is opposed only by damping. Note that /ncan be varied by varying either excitation
