翻译

On-line Diagnosis OF Marine Diesel Crankshaft Crack

对船舶柴油机曲轴裂纹线诊断

BASED ON Magnetic Memory[ This research is supported by Nature Science Funding Project of Fujian Province A0410022.]

基于磁记忆[这项研究是由福建省自然科学基金资助项目a0410022。]

LI Han-lin, LIN Jin-biao, CAI Zhen-xiong, LU Yong

李涵林，林彪，蔡镇熊，陆永

(Marine Engineering Institute, Jimei University, Xiamen, Fujian 361021)

（海军工程学院，集美大学，厦门，福建，361021）

Abstract: This paper summarized recent diagnosis methods of marine diesel crankshaft crack and introduced the fundamental principle, development and application of metal magnetic memory testing (MMMT) diagnosis technology. Compared with other methods, a scheme developed from MMMT combined with torsional signal to make on-line diagnosis of crankshaft crack was proposed, and the on-line diagnosis experimental platform of diesel was designed. Finally, comments were also made on the on-line MMMT method.

摘要：本文总结了船舶柴油机曲轴裂纹的诊断方法，并介绍了最近的基本原理，以及金属磁记忆检测技术的应用开发（MMMT）诊断技术。与其他方法相比，一个方案从技术结合扭振信号使曲轴裂纹的在线诊断算法，以及柴油机在线故障诊断实验平台的设计。最后，评论也做了在线检测方法。

Keywords: marine diesel; crankshaft; crack; metal magnetic memory

关键词：柴油机；曲轴；裂纹；金属磁记忆

1Introduction

导论

Most of the crankshaft cracks on ocean marine diesel are deeply latent and difficult to detect artificially. In general, while the crack develops to a certain extent it will rupture and cause destructive breakage1. If inchoate stress concentration and tiny crack of crankshaft are detected on-line by Non-Destructive Testing (NDT) methods, the diesel can be stopped before the full development of the crack and thus rupture can be avoided. A new NDT method, MMMT developed rapidly recent years with advantages in such areas as cheap and simple sensors, measuring without impacting diesel operation and long-term on-line detection. Therefore, there will be a great foreground to use MMMT in crankshaft crack detection.

海洋船舶柴油机曲轴裂纹的最深的潜在的和难以检测的人为。在一般情况下，在裂纹发展到一定程度就会破裂，造成破坏性的breakage1。如果早期的应力集中和曲轴小裂纹检测的无损检测（NDT）方法，在线柴油可在裂纹的充分发展，从而可以避免停破裂。一种新的无损检测方法，检测迅速发展，近年来随着便宜和简单的传感器测量等领域的优势，而不影响柴油运行和长期在线检测。因此，将曲轴裂纹检测技术中使用的伟大前景。

2Dynamic Diagnosis of Crankshaft Crack

2dynamic诊断曲轴裂纹

2.1 Static Diagnosis of Crankshaft Crack

2.1静态诊断曲轴裂纹

Crankshaft crack is one of the fatal faults in diesels. There are some static NDT methods to diagnose crankshaft crack2 such as Ultrasonic Testing, Radiographic Testing, Magnetic Particle Testing, Penetrate Testing, Eddy Current Testing, Optical Holography, and Microwave Testing. These methods have taken an important part in crankshaft quality control and accident prevention. However, on the other hand there are several disadvantages of these methods. Firstly, all of them must find cracks already formed and can not detect unexpected ones. Secondly, they are unable to make on-line detection and fault diagnosis. Thirdly, most of them need surface pretreatment of the facilities before inspection. Finally, the accuracy of detection is affected by crankshaft configuration and personal skill.

曲轴裂纹是在柴油机的致命的错误。有一些静态的无损检测方法诊断曲轴crack2如超声波探伤，射线探伤，磁粉检测，渗透检测，涡流检测，光学全息，和微波测试。这些方法都有一个重要的组成部分，在曲轴的质量控制和事故预防。然而，另一方面也有这些方法的一些缺点。首先，他们必须找到裂纹已经形成并不能检测到意外的。其次，他们无法进行在线检测和故障诊断。第三，他们中的大多数需要的设施检查前表面预处理。最后，检测精度是由曲轴配置和个人能力的影响。

2.2 Dynamic Diagnosis of Crankshaft Crack

2.2动曲轴裂纹的诊断

At present there are some methods to diagnose shaft cracks on-line: rotor engine vibration displacement method, train wheel shaft temperature testing, acoustic emission and tortional vibration signal testing. However, vibration displacement method is unfit for diesel crankshaft crack diagnosis due to the strong vibration from reciprocating movement which makes it difficult to survey displacement and acceleration. Although there is local high temperature on the cracks, it is hard to inspect the change of the crankshaft temperature due to the high temperature of the lube oil in the diesels. Acoustic emission method is still in developing as great noise from diesel operation makes it difficult to measure high frequency acoustic wave emitted by crack. Therefore at present it is feasible to diagnose crankshaft crack on-line by using torsional vibration signal.

目前有一些方法：在线诊断轴裂纹转子发动机的振动位移的方法，火车轮轴温度检测，声发射和扭转振动信号测试。然而，振动位移的方法是不适合柴油机曲轴裂纹诊断由于强烈振动的往复运动，这使得它很难测量位移和加速度。虽然是局部高温对裂缝，很难检查由于在柴油机润滑油的高温曲轴温度的变化。声发射方法仍在发展从柴油机运行噪音使得它很难测量高频声波发射的裂缝。因此，目前它是诊断曲轴裂纹的利用扭振信号在线可行。

2.3 Crankshaft Crack Diagnosis Using Torsional Vibration Signal

利用扭振信号2.3曲轴裂纹故障诊断

Literature 3 brought forward a method using torsional vibration signal detected real-time from diesel to diagnose crankshaft fault. It studied crack fault diagnosis though measuring the characteristics of the torsional vibration of the shafting flywheel system, and presented that model frequency and damp were sensitive parameters of cracks. The torsional vibration measuring system of the diesel had several advantages such as: easy measuring, no direct contact, cheap sensor and longevity. It was a long-term reliable alarm method for diesel shafting crack. Research group in Marine Engine Institute of Jimei University has done the research of internal-combustion engine score fault with intelligent torsional vibration diagnosis system4, and it was a successful case of on-line fault diagnosis based on torsional vibration signal.

文献3提出利用扭振信号的实时检测柴油机曲轴故障诊断方法。研究了裂纹故障诊断通过对轴系飞轮系统扭振特性的测量，提出了模型的频率和阻尼进行裂纹敏感参数。柴油机的扭振测量系统有如几个优点：容易测量，没有直接接触，廉价的传感器和长寿。这是柴油轴系裂纹长期可靠的报警方法。在集美大学的海洋发动机研究所集团已与智能诊断系统的扭转振动进行了评分的内燃机故障的研究，它是一个成功的基于扭振信号在线故障诊断案例。3Metal Magnetic Memory Testing Technique

3metal磁记忆检测技术

In the year 1997, Russian professor A. A. Dubov brought forward correlative theory of metal magnetic memory on the World Conference on NDT, developed MMM instruments and formed MMM NDT technique5.

在1997年，俄罗斯教授A.杜波夫对无损检测的世界会议，金属磁记忆提出了相关的理论，开发了MMM仪器和形成MMM检测technique5。

3.1 Theory of Metal Magnetic Memory Testing

3.1金属磁记忆检测理论

Under the condition of the existence of the outside magnetic field, usually the magnetic field of the earth, there will appear a phenomenon in the stress concentration zone of ferromagnetic components with load that permeability of material besides the zone reduces and surface leak magnetic field increases, which is called magnetostriction. It will makes the surface magnetic field of the ferromagnetic accessory increase, and the magnetic field can remember the location of disfigurement and stress concentration zone, thus it is named metal magnetic memory.

的外部磁场存在的情况下，通常的地球磁场，将出现在负载，除了带降低表面漏磁场增加材料的磁导率铁磁构件的应力集中区的现象，称为磁致伸缩。这将使铁附件增加表面的磁场，和磁场能记得的缺陷和应力集中区的位置，从而为金属磁记忆。

At present, one of the most popular explanation to the magnetic memory is that, loaded by alternating stresses, unsymmetrical elasto-plastic strain will take place in the magnetic domain formed by spontaneous magnetization in ferromagnetic material, and then unequal magnetic flux density will be induced by tensile and compressive stress6. Within the magnetic field of the earth, disfigurement and stress concentration zone of ferromagnetic components will produce maximum leak magnetic field, and there will be maximum tangential component HpX of the magnetic field intensity and zero normal component HpY.

目前，对一个磁记忆最流行的解释是，非对称加载的交变应力，弹塑性应变发生在磁畴的铁磁材料中形成的自发磁化，然后不等磁通密度会被拉伸和压缩stress6诱导。地球的磁场内，缺陷和铁磁性构件的应力集中区将产生最大的漏磁场，将有最大切向分量HPX的磁场强度和零的正常成分HPY。

3.2 Metal Magnetic Memory Testing Instruments and Their Practical Use

3.2金属磁记忆检测仪器及其实际应用

Research on magnetic memory testing instruments in foreign is in pace with the technological development. Foremost of all were TSC-1M (see Fig. 1), TSCM-2FM and TSC-IM-4 stress concentration magnetic testing instrument developed by Energodiagnostika Ltd. of Russia. These instruments were associated with different types of sensor for various requirements. Software of these instruments for signal analysis and data processing was also developed in Russia. For example, MM-System data processing software produced by Energodiagnostika Ltd. was able to analyze MMM signal and display the signal in three models: 2-D, 3-D and polar coordinates model (see Fig. 2).

国外对磁记忆检测仪器的研究与技术发展的步伐。首先是tsc-1m（见图1），tscm-2fm和tsc-im-4应力集中的磁性测试仪由俄罗斯energodiagnostika公司开发。这些仪器和各种不同类型的传感器的相关要求。信号分析与数据处理也在俄罗斯开发这些工具软件。例如，MM系统数据处理软件的energodiagnostika公司生产能够分析磁信号和三模型显示信号：二维，三维坐标和极坐标模型（见图2）。

Internal MMM testing instruments were mainly developed by Eddysun (Xiamen) Electronic CO., LTD. In the year 2000, EMS-2000 metal magnetic memory diagnosis instrument (see Fig. 3) with different types of sensor was produced by the company for ferromagnetic components disfigurement diagnosis. At the same time, M3DPS (see Fig. 4) software for signal analysis and data processing was developed to locate early fatigue damage7.

内部磁记忆的检测仪器是由爱德森主要发达国家（厦门）电子有限公司，公司在2000年度，EMS-2000金属磁记忆诊断仪（见图3）与不同类型的传感器是由本公司生产的铁磁元件的缺陷诊断。同时，m3dps（见图4）的信号分析和数据处理的开发定位早期疲劳damage7软件。

Applications of MMM testing in China has developed rapidly focusing on crack testing of steel welding line, pressure vessel, aeronautical structure, thermal power plant and so on. Firstly, in the field of steel material weld testing, it was mainly used for dissimilar steel welding, hull structure steel plate welding8, early diagnosis of welding disfigurement, welding line quality examination, power plant EH oil pipe fillet welding joint, high pressure boiler pipe seat fillet welding joint and so on. Secondly, it was applied in pressure vessel testing for high pressure bottle, vessel welding residual stress measurement and so on. Thirdly, it was applied in aeronautical structure testing for earlier disfigurement and plane undercarriage inspection. Fourthly, it was applied in thermal power plant testing for steam turbines component, blades crack, throttle valve and reheat tube crack diagnosis.

MMM测试在中国的应用迅速发展，针对钢焊缝，裂纹检测压力容器，航空结构，火电厂等。首先，在钢铁材料焊接测试领域，它主要用于异种钢焊接，船体结构钢的焊接缺陷welding8，早期诊断，焊缝质量检查，电厂EH油管的角焊缝接头，高压锅炉管座角焊缝的焊接等。其次，它被应用在压力容器检测高压瓶，容器的焊接残余应力测量等。第三，它被应用在航空结构测试的早期缺陷和飞机起落架检查。第四，它是应用在火电厂测试汽轮机部件，叶片裂纹，节流阀和再热管裂纹诊断。

4On-line Diagnosis of Crankshaft Crack Using Metal Magnetic Memory Testing

曲轴裂纹的金属磁记忆检测4线诊断

4.1 Crankshaft Crack Metal Magnetic Memory Testing

4.1曲轴裂纹的金属磁记忆检测

Marine diesel engine crankshafts are mainly made up from ferromagnetic material. According to MMM theory, stress concentration zone on crankshaft will produce maximum tangential component HpX of the magnetic field intensity and zero normal component HpY with alternation of symbol. With scanning inspection of the surface magnetic field of crankshaft by MMM testing sensor and instrument, the stress concentration zone will be found out according to the zero normal component of the field intensity, and then the existence of crack on the crankshaft can be estimated indirectly. With this method, the location of cracks can be found out without interrupting normal operation of the diesel, and give an alarm in time to remind engineers of operation condition of the diesel.

船用柴油机曲轴主要是由铁磁材料。根据我的理论，应力集中区对曲轴将产生最大的切向分量的HPX的磁场强度和零的正常成分HPY交替的符号。通过MMM检测传感器和仪器扫描的曲轴表面磁场检测，应力集中区将被发现，根据磁场强度为零的正常组成部分，然后对曲轴裂纹的存在可以间接地估计。用这种方法，裂纹的位置可以发现不中断正常运转的柴油，并及时报警，提醒的柴油机运行工况的工程师。

In the design, the sensor of the instrument will be placed into the body of the diesel through the guide door of the diesel, and it can directly scan zones with the most probable existence of stress concentration, such as locations near oil bore and fillet. In case the normal component of magnetic field intensity of the location shows a change from positive to negative or from negative to positive, it means that there may be tiny crack or stress concentration taking place, and at the same time, the instrument will record in a log and give an alarm. The method is simple, effective and feasible to on-line testing on operating diesel on ships.

在设计中，仪器的传感器将被放置到柴油机机体通过柴油导门，它可以直接与应力集中最可能存在的扫描区域，如近油孔和角位置。在案件的位置的磁场强度的正常成分表现出改变从正到负的或从负到正的，这意味着可能会出现细小的裂纹或应力集中的地方，并在同一时间，仪器将记录在日志和报警。该方法简单，有效，对船舶操作柴油机在线检测是可行的。

4.2 Design for Crankshaft Crack Testing Simulation Experiment

4.2曲轴裂纹检测仿真实验设计

In order to put MMM crankshaft crack testing method into practical application to ships, simulation experiment should be done, and the model experiment platform is built from a two cylinders diesel. The platform takes shaft accessory as the research object, and uses standard ball bearings to support shaft. By means of replacing shaft and bearings, the platform is able to do simulate experiment for shafts in different sharp or length such as roll shaft and crankshaft. The shaft is connected to electromotor by adapting flange, and the motor controlled by transducer can drive the shaft with different rotate speed to simulate running of uniform velocity and accelerated velocity. The bearings are fixed on steel foundation by two bearing seats, and the shell on the steel foundation is made up from organic glass to make the observation and the installation of the MMM sensor easy. There is lube oil deposited in the steel foundation and heated up by electro thermal coil. Heated lube oil is pumped to the top of the shell by a small gear oil pump and injected to shaft and bearings to lubricate them and simulate high temperature in diesel. Then the oil flows into oil sump forming a cycle. The MMM sensor is installed in the sides of the platform body through a probe hole, and its installation angle, depth and horizontal location can be adjusted to scan the magnetic field intension of the whole shaft to find the stress concentration zone.

为了把MMM曲轴裂纹测试方法为船舶的实际应用，仿真实验应该做的，和模型实验平台的搭建一二缸柴油。该平台以轴零件为研究对象，并使用标准的球轴承支撑轴。通过更换轴和轴承装置，该平台能够模拟实验在不同长度的轴尖或如辊轴与曲轴。轴采用法兰连接的电机，与电机控制的变频器驱动轴以不同的转速来模拟均匀的速度运行，加快速度。轴承是由两个轴承座固定在钢的基础上，对钢基壳是由有机玻璃制作的观察和MMM传感器易于安装。有润滑油沉积在钢基和加热的电热圈。加热润滑油抽到的小齿轮油泵壳体顶部注入轴和轴承的润滑和模拟柴油机高温。然后，油流入油底壳，形成一个循环。磁传感器通过探测孔安装在平台的身体两侧，其安装角度，深度和水平位置可以调整扫描整个轴的磁场强度发现应力集中区。

At the same time, stress distribution of diesel crankshaft with crack will be analysized by finite element method software ANSYS and the magnetic field intension model varied with time and temperature will also be constructed for calculation. All of these simulations are fundamental to MMM crack testing of crankshaft9.

同时，随着裂纹的柴油机曲轴的应力分布是通过有限元软件ANSYS和磁场强度模型随时间和温度的分析也将被计算。所有这些模拟的裂纹检测的基本crankshaft9嗯。

5Conclusion

5conclusion

MMM crankshaft crack testing method is a new technique used for on-line inspection, and there are some issues to deal with in further study. The first one is quantificational relation between leak magnetic field intension near crack and stress, surrounding magnetic field, and the depth and width of crack10. Secondly, there are several factors having certain impacts to the MMM signal such as temperature, residual magnetic field and surface roughness, therefore, data processing should be done to eliminate these impacts.

嗯曲轴裂纹的测试方法，用于在线检测新技术，并有一些问题与进一步研究解决。第一个是漏磁场强度的裂纹与应力之间的定量关系，周围的磁场，和深度和宽度crack10。其次，将有一定的影响，磁信号如温度的几个因素，剩余磁场和表面粗糙度，因此，数据处理应消除这些影响。

At present, marine diesel crankshaft crack testing is still being done by means of static method in China. MMM testing may solve the problem of early stress concentration inspection. This method has the advantages as cheap and simple sensors, measuring without affecting diesel operation and long-term on-line detection. It may forecast stress concentration zone and avoid hidden trouble of crankshaft rupture accident. Combined with torsional signal, MMM testing on-line diagnosis of crack will be achieved.

目前，船舶柴油机曲轴裂纹的测试仍然是在中国通过静态方法做的。MMM测试可能解决应力集中问题的早期检测。该方法的优点是便宜和简单的传感器，测量不影响柴油机运行和长期在线检测。它可以预测的应力集中区，避免曲轴断裂事故隐患。结合扭振信号，裂纹磁记忆诊断在线诊断会实现的。

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