MECHATRONICS IN NON DESTRUCTIVE TESTING (NDT) APPLICATIONS

AHMAD SYAZANI BIN JAAFAR AHMAD ZUHDI BIN UZIR1125941 1120799

Mechatronics Engineering Mechatronics Engineering

Supervisor: DR. ALI SOPHIANDepartment of Mechatronics Engineering

International Islamic University MalaysiaJalan Gombak, Selangor Darul Ehsan

ABSTRACT

Non Destructive Testing had been using in many fields because the nature of its applications is to preserve the integrity of materials or components. Non-destructive testing was proven to be the effective way to test the irregularities in materials. While there are many ways to perform the test, some of it requires mechatronics to further the efficiency. Mechatronics is a new way to perform NDT in various places with variety new technology. This paper will discover more on the use of mechatronics in non-destructive testing and discuss on the future technologies for NDT.

1. INTRODUCTION

In today market, materials that are produce need to undergo inspection or perform some testing to grade its quality. This quality covers from ductility, brittleness, toughness and strength. Apart from material, the testing also had been performing on mechanical components or structural. There was many ways to perform the testing and most of it will destroy the material permanently. This kind of test is commonly known as destructive testing.

To preserve the material, Non Destructive Testing (NDT) comes into play and gives huge impact on material, structural and component testing. NDT will ensure the integrity of the structure and mechanical

component and simultaneously preserve the continuity of material, component and parts to perform their function.

When performing NDT, it will locate the pointers and incoherence that may cause systems to fails or shut down. The tests that are performed will not affect the quality of test object or in other word ‘non-destructive’. To avoid deconstruction or damage, NDT will carefully evaluate the material thoroughly. NDT is typically used at different point in component life cycle [1]. Another prior use of NDT is as a quality control and to detect service related conditions that may affect reliability [1].

Today, modern non-destructive tests are used to ensure product integrity and reliability in manufacture, fabrication and operating inspection [2]. When using in construction, NDT will be used to protect the quality of materials and joining processes when undergoes fabrication and erection phases. Apart from that, NDT inspection is common for in-service usage to ensure the product in use to maintain its usefulness and the safety of the public.

A. Different Types of NDT Techniques

Over the past few years, scientists and engineers have produced various test method for NDT applications. These test methods or techniques mostly refer to the type of penetration use (medium) or

different equipment that help to perform specific test. Some of the current NDT methods are: Electromagnetic Testing (ET), Leak Testing (LT), Magnetic Flux Leakage (MFL), Liquid Penetrant Testing (PT), Magnetic Particle Testing (MT), Radiographic Testing (RT), Ultrasonic Testing (UT), Vibration Analysis (VA) and Visual Testing (VT) [2].

These different methods or techniques all have their merits and will be use when the situation need it most but there are six test method that are frequently use, namely Ultrasonic Testing (UT), Radiographic Testing (RT),Magnetic Particle Testing (MT),Electromagnetic Testing (ET),Visual Testing (VT) and Liquid Penetrant Testing (PT). We will describe four of these techniques to provide more insights on NDT test methods.

i) Ultrasonic Testing (UT)

Ultrasonic testing adapts the same principle as in use in fish finder and sonar. This technique uses ultra-high frequency sound waves on the part of inspection and it will detect irregularities by sensing the material using acoustic impedance. When there is change in the material characteristic, the sound will reflect back to the receiver to be presented in visual display. The frequencies that were used in UT were commonly between 1.0 and 10.0 MHz. This frequency is higher to be heard and do not travel through air. Higher frequencies were preferable because it can detect smaller indications.

Some of the UT techniques are Straight Beam, Angle Beam, Immersion Testing, Through Transmission, Phased Array and Time of Flight Diffraction.

ii) Radiographic Testing (RT)

Radiographic testing will expose the material to a radiation that penetrating the body to detect irregularities. On opposite side of the material is a recording medium that receive the radiation that already pass

through the object as an image. The common radiation uses is electrically generated x-radiation or x-ray. X-ray was typically use on material with less density or thinner, example: aluminium. For thicker and denser material, the common radiation is gamma radiation.

The techniques that were used to perform RT were Film Radiography, Computed Radiography, Computed Tomography and Digital Radiography.

iii) Magnetic Particle Testing (MT)

Magnetic Particle Testing was use on ferromagnetic materials to locate discontinuities on the surface or near surface. This testing applies one or more magnetic fields which can be produce using permanent magnet or an electromagnet. These magnetic fields will produce flux leakage when encounter irregularity and will attract magnetic particle to gather at the discontinuity producing a visible indication on the surface.

The techniques that can be used to perform MT were Yokes, Prods, Coils, Heads and Central Conductor.

iv) Electromagnetic Testing (ET)

Magnetic Particle Testing was basically an Electromagnetic Testing but due to its widespread, MT is consider an individual test. As in general use, ET is a popular choice. ET consists of Eddy Current Testing, Alternating Current Field Measurement (ACFM), and Remote Field Testing.

B. NDT Applications

With introduction of non-destructive testing, many fields adapt this kind of testing to preserve the material and mechanical component. Some of the fields benefit greatly from the usage of NDT. NDT was used to protect the integrity of

machine equipment, oil-ducts, gas-pipes, aeronautics and nuclear power equipment [3].

i) Aircraft

During aircraft maintenance NDT is the most economical way of performing inspection and is a way of discovering defects on metallic plates[3].Mainly use Eddy Current testing, it useful to detect cracks caused by fatigue or by stress corrosion. The cause of widely use of eddy current is because it use minimal time to prepare and has a high sensitivity.

ii) Oil and Gas

With the rising of demand on oil and gas, the cost of operating the equipment and maintenance keep rising. NDT help to prevent future complication if the equipment becomes faulty. The most effective methods which guarantee capacity for work of oil & gas equipment and tools are systematic non-destructive testing and technical diagnostics of their working state [4]. NDT will allow detecting any defect on the equipment before putting it into work.

iii) Structure

In Civil Engineering, Non Destructing Testing is widely use in different application. Most of these applications can be recognising as structural but they also consist of site surveying and highways difficulties [5]. Testing may be used during planning and construction periods, but the greater part of applications are apprehensive with troubleshooting, maintenance and repair [5].

C. Mechatronics Systems

Before we discuss further about mechatronic on NDT application, we first must understand the concept of mechatronic system. As in today worlds, mechatronics had been using in many

fields. Mechatronics system helps to ensure safety and increase productivity. Furthermore, mechatronics help to achieve something beyond the human physical limit. One of the definitions of mechatronics is: Mechatronics is the synergistic mixture of mechanical and electrical engineering, computer science, and information technology, which contains control systems along with numerical methods used to design products with integrated intelligence [6].

Vehicles, aircraft, power systems, and fundamentally all design systems rely on the combination of electrical, mechanical, and software technologies to control or replace mechanical operations [7]. Mechatronics helps to combine all this into a simpler and reliable system with much more efficiency.

2. MECHATRONICS IN NON DESTRUCTIVE TESTING APPLICATIONS

Industrial Robot

Non-destructive testing (NDT) play a vital role in many industries to ensure the quality and safety of materials, products and structures. In this topic regarding an industrial robot, we will give a several preview about the use of mechatronic systems in different industries. There are many types of mechatronic systems that have been developed by engineers such as wheeled, climbing or crawling robots to reflects the difficulties and safety issues in major industries. [8]

i. Magnetic Flux Leakage Pipeline Inspection Gauges ( MFL PIG)

MFL PIG has been used since the 1960s for gas pipeline inspection, this tools use permanent powerful magnets to magnetize the pipe’s wall to near saturation flux density. If there are defects present on pipe wall, magnetic flux will leaks from wall

into surrounding air. In this gauge, there is a sensor named Hall-effect sensor that detect leakage flux and will estimating the shape and size of the wall defects. [9][10][11]

Figure 9 Schematic view of a MFL PIG [9]

This tool will be sent down to a pipeline by a launcher and the pressure of product (gas) is used to push it along down the pipe until it reaches the receiving trap at the end of each run. The first MFL PIG tool is designed and build in Iran with collaboration of Segal Pardazesh Part Co. And University of Tehran.[12][13] See the figure below:

Figure 10 First MFL PIG designed for inspection of 30 inch pipelines [12][13]

Its consists of two part : [12][13]

Front body:

Batteries

Data acquisition

Electronics board

Gyroscope sensors

Coil type sensors

Rear body :

Magnets

Brushes

Odometer system

Hall-effect sensors

ii. Other pipeline inspection robot

The “Explorer”. [8]

Being design because of some pipes are not compatible to previous pigging tool as the pigs cannot navigate through narrow region such as Y- and T-joints, 90˚ turns and small diameter pipes.

Design by engineers at Carnegie Mellon University’s (CMU) Robotics Institute (RI) which are funded by Department of Energy (DoE). CMU had develop an advanced remote and robotic inspection system, being able for long-duration travel inside pipeline for in-situ inspection in the 6-8 inch diameter range gas pipelines. [8] [14][15]

Main advantage of Explorer is capability to locomote the robot through different type of pipes including sharp bends, elbows, Ys and Ts, by using its on-board driving arms and steering joints. The system can normally operate in natural gas environment. There are five type of modules in one Explorer which are locomotor (drive), camera, battery, computer and support modules. Each module is connected by an articulated joint. For locomotor modules, it connected to other module by pitch roll joints while

the remaining modules connected by pitch joints. [14][15]

Figure 11 Overall design configuration for X-I and X-II [16]

Explorer modules : [16][17][18]

A. Locomotion module

Design to combine a powered wheel-driven preloadable and adjustable hybrid leg locomotor into a single unit. It has the ability to expand to self center itself in a 6-8 inch diameter pipe. The arm are powered by single motor which drives the three bar linkage arrangement to extend/collapse the arm. The dual sets of wheel at each arm are driven also by single motor through a planatery gear reduction. The different between these two robot (X-I and X-II) is the placement of camera section. For X-I camera was added with driver module, while for X-II, camera and driver separate train with each other.

Figure 12 Drive module between X-I and X-II [9]

B. Camera module

Design as an imaging only add on to the drive module. It integrate the CMOS imager using fish-eyes lens LED lighting plus a protective dome. The nose cone of the camera was designed as an RF-transparent unit, with embedded antennae. It also have a set of recharge points on the nose cone, so the robot can be recharged in situ (external).

C. Support Module

To provide alignment with the pipe’s centerline during climbing and turning to reduce friction. It have same design with drive module and also have same structure and leg-deployment drive design. However it only features an arm with free spinning wheel at the end.

Figure 13 Support module design [16]

D. Battery Module

Based on chemical energy storage, namely batteries. The selection was limited to nickel-metal-hydride (NiMh) for X-I and lithium-polymer (LiP) for X-II.

Figure 14 Comparison between battery chemistry and configuration [16]

“Robotic Pipe Scanner”. [8]

This robot had been develop by Rosen Swiss AG, which move along the outside of the pipe’s surface for fully 360˚ coverage of above-ground. Its used magnetic flux leakage principle to detects flaws on the pipes.

Figure 15 Robotic Pipe Scanner [Source: Rosen Swiss AG]

iii. Other example from different industries

“FlexiRiserTest” - Offshore industries. [8]

Before NDT methods had been used in this industries, all testing and visual inspection have being conducted manually by divers. This a prototype system for the NDT od sub-sea flexible risers. The system consists of a crawling robot with a digital gamma radiography system. Its has the ability to move along the length of a riser and also can rotate about the axis. The detector is attached to an ambedded PC and generate the images that sended to the host PC via an umbilical link. The system has been tested underwater and still being developed by Computerised Information Technology Ltd. [8][20]

Figure 11 The FlexiRiserTest system during underwater trials [Source: FlexiRiverTest Consortium]

The “Magnetic Hull Crawler” – Ship industries [8]

Produced by French company Cybernetix SA, these are the other example of crawler robot that had been design intended to climb up the ships’ hull while making inspection. These crawler had been used because of the difficulty and the safety issues when doing the inspection on hull as it prone to developing defects and cracks due to corrosion. It has a speeds up to 0.3 m/s and also can operate underwater to the depth of 50 m. There are two-colour camera for visual inspection and ultrasonic probes, consists of positioning system to

allow 3D hull thickness mapping. [8][19][20]

Figure 12 The Magnetic Hull Crawler (MHC) [Source: Cybernetix SA]

3. CONCLUSION

This report aims to explore some of the use of mechatronics in NDT and their applications. This report discusses the definition of NDT and various NDT techniques. Then it touches on few of NDT applications which are aircraft, oil and gas, and structures. To further understand mechatronics, this report introduced mechatronic system that helps progress through the report. After understanding the basic, we discuss the main topic which is mechatronics in NDT. We show a few working projects on NDT and how mechatronics help to improve the efficiency and functionalities.

We learned from this report that mechatronics help to move NDT industry forward. There are many new integrated systems that need to be developed in the future and researches that will become very useful in a few years.

In summary, non-destructive testing benefit greatly by using mechatronics as a medium to further expand the industry.

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