1、 Guidance Notes on Ship Vibration GUIDANCE NOTES ON SHIP VIBRATION FEBRUARY 2018 American Bureau of Shipping Incorporated by Act of Legislature of the State of New York 1862 Copyright 2018 American Bureau of Shipping ABS Plaza 16855 Northchase Drive Houston, TX 77060 USA ii ABSGUIDANCE NOTES ON SHIP
2、 VIBRATION .2018 Foreword Foreword (1 February 2018) The American Bureau of Shipping recognizes the overall ship vibration as an important measure to ensure the habitability, safety and functionality of the vessels. The ABS Guidance Notes on Ship Vibration have been developed to provide users with s
3、pecific 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 document is referred to as “these Guidance Notes”. The design and construction of the hull, superstructure, and d
4、eckhouse 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 Carriers over 130 meters in length, the ABS Steel Vessel Rules require the consideration of vibratory response
5、s 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 (5-8-4/4.2). In conjunction with the propulsion shaft alignment, the ABS Steel Vessel Rules require the consideratio
6、n 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 Passenger Comfort on Ships and Guide for Crew Habitability on Ships). Also ABS provides Condition Monitoring Prog
7、ram for machinery vibration (7-A-14/5.1.2 of the ABS Rules for Survey After Construction (Part 7). These Guidance Notes provide practical guidelines on the concept design to assist ship designers to avoid excessive shipboard vibration at an early design stage. These Guidance Notes also assist with t
8、he finite element analysis (FEA) based vibration analysis procedure to calculate the vibration response and evaluate the design at detail design stage. The analysis procedure represents the current analysis practice in ABS. These Guidance Notes also offer guidelines on the vibration measurement proc
9、edure at sea trials and the acceptance criteria on vibration limits based on the international standards and the practice in ABS. The 2018 edition provides guidance on quick local vibration analysis methods for ships. These Guidance Notes become effective on the first day of the month of publication
10、. Users are advised to check periodically on the ABS website www.eagle.org to verify that this version of these Guidance Notes is the most current. Comments or suggestions can be sent electronically to rsdeagle.org Terms of Use The information presented herein is intended solely to assist the reader
11、 in the methodologies and/or techniques discussed. These Guidance Notes do not and cannot replace the analysis and/or advice of a qualified professional. It is the responsibility of the reader to perform their own assessment and obtain professional advice. Information contained herein is considered
12、to be pertinent at the time of publication, but may be invalidated as a result of subsequent legislations, regulations, standards, methods, and/or more updated information and the reader assumes full responsibility for compliance. This publication may not be copied or redistributed in part or in who
13、le without prior written consent from ABS. Table of Contents GUIDANCE NOTES 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
14、 Concept Design Approach 4 FIGURE 1 Items to be Considered During Concept 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 E
15、xternal Forces and Moments 6 FIGURE 2 Guide Force Couples 7 FIGURE 3 Nominal 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 . 1
16、2 FIGURE 6 Conventional Skeg-Stern Arrangement 12 FIGURE 7 Maximum Skew Angle 13 FIGURE 8 Burrill Cavitation Inception Chart 16 ABSGUIDANCE NOTES ON SHIP VIBRATION .2018 iii SECTION 4 Structural Resonances 19 1 Introduction . 19 3 Hull Girder Vertical Vibration Excited by the Main Diesel Engine . 19
17、 5 Main Machinery/Shafting System Longitudinal Vibration Excited by the Propeller . 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
18、 Vibration 21 FIGURE 2 3-mass Longitudinal Model of Main Propulsion System . 23 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
19、31 1 Introduction . 31 1.1 Scope and Objective 31 1.3 Procedure Outline of Ship Vibration Analysis 32 3 Finite Element Modeling . 33 3.1 Global Model . 33 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 36 3
20、.8 Local Structural Component Models 36 3.9 Local Structural Panel Models . 36 5 Loading Condition . 36 5.1 Selection of Loading Conditions and Ship Speed 36 5.3 Added Mass . 36 5.5 Buoyancy Springs 37 5.7 Special Conditions . 37 7 Free Vibration . 37 7.1 Analysis Procedure 37 7.3 Checking Points .
21、39 9 Propeller Excitation . 39 9.1 Introduction 39 9.3 Propeller Shaft Forces . 39 9.5 Hull Surface Forces Induced by Propeller Cavitation . 40 9.7 Direct Calculation of Bearing and Surface Forces . 44 11 Engine Excitation 45 13 Forced Vibration 45 13.1 General 45 13.3 Critical Areas . 46 13.5 Dampi
22、ng 46 iv ABSGUIDANCE NOTES ON SHIP VIBRATION .2018 TABLE 1 Propeller Bearing Forces and Moments for 20 Real Ship Case Study 40 FIGURE 1 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 M
23、odeling Example . 35 FIGURE 5 Propeller Shaft 35 FIGURE 6 First Two Vertical Mode Shapes . 38 FIGURE 7 First Two Horizontal Mode Shapes . 38 FIGURE 8 Scale Effect due to Propeller Inflow Condition 44 SECTION 6 Measurements 47 1 General . 47 1.1 Scope 47 1.3 Application . 47 1.5 Terminology . 47 3 In
24、strumentation . 48 3.1 General Requirements 48 3.3 Calibration . 48 5 Measurement Conditions 49 5.1 Environment Condition 49 5.3 Loading Condition . 49 5.5 Course . 49 5.7 Speed and Engine Power 50 7 Measurement Locations 50 7.1 Stern 50 7.3 Superstructure . 50 7.5 Main Engine and Thrust Bearing . 5
25、0 7.7 Lateral Shaft Vibration . 51 7.9 Torsional Shaft Vibration . 51 7.11 Local Structures 51 7.13 Local Deck Transverse 51 7.15 Local Machinery and Equipment . 51 7.17 Shell Near Propeller 51 9 Data Processing Analysis . 51 9.1 Measured Data 51 9.3 Performance of Measurements . 52 9.5 Analysis Met
26、hods 52 11 Measurement Report 55 11.1 Analysis and Reporting of Data . 55 TABLE 1 Typical Frequencies Ranges 52 TABLE 2 Examples of Alternate Vibration Measurements . 54 ABSGUIDANCE NOTES ON SHIP VIBRATION .2018 v SECTION 7 Acceptance Criteria 57 1 General . 57 3 Vibration Limits for Crew and Passen
27、gers 57 3.1 ABS Criteria for Crew Habitability and Passenger Comfort . 57 3.3 ISO 6954 (1984) Criteria for Crew and Passenger Relating to Mechanical Vibration . 58 3.5 ISO 6954 (2000) Criteria for Crew and Passenger Relating to Mechanical Vibration . 60 5 Vibration Limits for Local Structures . 60 7
28、 Vibration Limits for Machinery. 61 7.1 Main Propulsion Machinery . 61 7.3 Machinery and Equipment . 62 TABLE 1 Maximum Weighted RMS Acceleration Levels for Crew Habitability . 58 TABLE 2 Maximum Weighted RMS Acceleration Levels for Passenger Comfort . 58 TABLE 3 Overall Frequency-Weighted RMS Value
29、s (ISO 6954: 2000) 60 TABLE 4 Vibration Limits for Main Propulsion Machinery 62 FIGURE 1 ISO 6954 (1984) 59 FIGURE 2 Vibration Limits for Local Structures . 61 APPENDIX 1 References 63 1 General References 63 3 Concept Design 63 5 FE Analysis . 64 7 Measurement 64 APPENDIX 2 Corrections . 65 1 Corre
30、ctive Investigations . 65 3 General Approach . 66 5 Hydrodynamic Modifications . 66 7 Structural Modifications . 68 9 Case Study 68 9.1 Determination of Model Constants. 69 9.3 Structural Rectification Analysis. 70 9.5 Propeller Change . 72 FIGURE 1 Wake Improvement with Special Lines-adapting Stern
31、 Devices Conventional Stern Cargo Ship 67 FIGURE 2 Mass-elastic Model of Deckhouse and Support Structure 69 FIGURE 3 Equivalent One-mass System . 71 vi ABSGUIDANCE NOTES ON SHIP VIBRATION .2018 APPENDIX 3 Seaway Excitation and Response 74 1 General . 74 3 Springing . 74 5 Bow Flare Slamming and Whip
32、ping 74 7 Bottom Impact Slamming 75 APPENDIX 4 Concept Design Checklist . 76 ABSGUIDANCE NOTES ON SHIP VIBRATION .2018 vii This Page Intentionally Left Blank Section 1: General SECTION 1 General 1 Introduction With the increase of ship size and speed, shipboard vibration becomes a great concern in t
33、he design and construction of the vessels. Excessive ship vibration is to be avoided for passenger comfort and crew habitability. In addition to undesired effects on humans, excessive ship vibration may result in the fatigue failure of local structural members or malfunction of machinery and equipme
34、nt. These Guidance Notes are to provide users, specifically shipyards, naval architects, and ship owners, with practical guidance on the concept design to avoid excessive ship vibration at an early design stage. If simple procedures are followed with insight and good judgment in the concept design s
35、tage, then the difficult countermeasures and corrections at the subsequent design stages may be avoided in most cases. These Guidance Notes also assist with the finite element analysis (FEA) based vibration analysis procedure to predict the vibration response and evaluate the design in detail design
36、 stage. The vibration analysis procedure represents the most current analysis practice in ABS. These Guidance Notes also offer guidelines on the vibration measurement procedure during the sea trials and the acceptance criteria on vibration limits based on international standards and practice in ABS.
37、 3 Application These Guidance Notes are applicable to the vessels of all lengths. 5 Scope These Guidance Notes provide overall guidelines on ship vibration excited by the main engine and propeller. In these Guidance Notes, the following subjects are considered: i) Concept Design ii) Vibration Analys
38、is iii) Measurements iv) Acceptance Criteria The concept design in Sections 2, 3 and 4 provides users with immediate, direct, and concise guidance in effectively dealing with ship vibration in the concept design stage. In attempting to provide a sound and no-nonsense guidelines, these Guidance Notes
39、 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 not addressed because detail information is not usually available in the early design stage. Instead, the concept design is focused on tho
40、se 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 analysis procedure based on first principles direct calculations. The FE-based vibration analysis is recommended to evaluate the design d
41、uring the detail design stage. If found necessary, the local vibration is to be addressed in the detail vibration analysis. The analysis procedure provides guidelines on FE modeling, engine and propeller excitation, and free and forced vibration analysis. ABSGUIDANCE NOTES ON SHIP VIBRATION .2018 1
42、Section 1 General For the assessment of ship vibration performance, the actual vibration levels at the most critical locations are to be measured and evaluated during the sea trials. Section 6 provides guidelines on the vibration measurement procedure on the instrumentation, measurement conditions a
43、nd locations, data processing and reporting. Section 7 provides acceptance criteria on the vibration limits for human comfort and habitability, local structures and machinery based on international standards and practice in ABS. The shaft alignment and torsional vibration are not directly addressed
44、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 procedure for ship vibration assessment recommended in these Guidance Notes is shown in Section 1, Figure 1. FIGURE 1 Overall Procedure for Ship V
45、ibration Assessment Concept DesignSections 2, 3, 4Vibration AnalysisSection 5CorrectionsAppendix 2Do the vibrationlevels meet the acceptancecriteria?MeasurementsSection 6Acceptance CriteriaSection 7NoYesAfter ConstructionDetail DesignEarly Design2 ABSGUIDANCE NOTES ON SHIP VIBRATION .2018 Section 2:
46、 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 problems, repeatedly identified by experience as the most important, are addressed at the earliest design stage, ultimately serious problems,
47、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 development 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,
48、 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 addressing those potential problems in terms of the minimal technology available at the concept design stage is considered very important to
49、 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 Architecture, 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: i) Reduce exciting force amplitude, F. In propeller-induced ship vibration, the excitation may be reduced by changing the prop
