Fracture Mechanics of Composite Repair Methods for Steels and Structures - Research Paper

Introduction

I would like to investigate the Fracture Mechanics of composite repair methods for steels and structures. Fracture mechanics as a field of mechanics deals with the study of the propagation of cracks in solid materials. It involves the application of experimental solid mechanics to determine the resistance to fracture by a particular material and the analytical solid mechanic's method to compute the driving force on a crack. By exploring the behavior of ductile materials under heavy loadings with a stress concentration and a crack, fracture mechanics helps in predicting the growth rate of a crack for the specific loading and the condition of the material. Fracture mechanics assist in determining a safe condition or the need for repair before any serious safety impact arises. It also aids in predicting the time to failure thereby allowing economical management of the situation. Among the typical failure modes of composite repairs especially in gas and oil pipelines is the blister formation underneath the repair. In this case, the failure of the repair can be as a result of the excess critical pressure leading to critical energy release rate for the crack propagation. Fracture Mechanics of composite repair methods for steels and structures is, therefore, a very critical area of research whose success would spur an invaluable knowledge and help in managing the real-life situations of failure that are likely to occur as a result of the composite repair for steels and structures.

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My research sets out to explore how the composite repair methods can be enhanced to effectively produce more resilient steels and structures that are more resistant to failures. For that reason, my research will focus on the appropriate means of ensuring effective maintenance of the steels and structures to help solve the current emerging maintenance failures. Composite repair methods have ever since been the critical and integral aspect in the maintenance and service of the growing fleets in the automotive, civil aerospace and marine composite vehicle industries. Scarf and bonded repair, for example, have been particularly attractive from technological standpoints and strength restoration that allow the one-sided access with minimal effects on the outer shape of the structure. It is normally applied in the repair of the high-pressure gas transmission lines, repair of metallic airframe components, operational aircraft, corroded steel pipelines, scarf joints, as well as oilfield pipelines. However, the composite repair methods do not result in the everlasting solution for the problem faced. The methods used are the latest known ways of repair and maintenance. However, due to the frequently emerging failure situations in most companies around the world, including the ones with which I have ever worked, there is an urgent need to come up with more sustainable ways to reinforce what we already use and even go beyond to develop the longer lasting solutions to the problems we face. This to me is more important that I want to keenly go about this research process with utmost care to bear substantial results. During my research period, I will consider several methods of composite repair that are usually applied. The basic types of composite repair methods include cosmetic, resin injection, semi-structural plug and patch, structural mechanically-fastened doubler, structural bonded external doubler, and structural flush repair. By enhancing these composite repair methods, it will serve as the major breakthrough and the basic step in protecting our capital resources as well as the environment from disastrous impacts of failure.

The research is based on the self-motivated drive to bring a long lasting solution to the current rampant situations of failures that we observe from different industries. The oil and gas pipelines need to be well secured to avoid any forms of failure which if occur, lead to adverse environmental damage as well as loss of massive resources. Therefore, this research project is not only important but necessary for getting the long lasting solution by causing major improvements to the methods firms to use around the world.

Many scholars have conducted extensive research on this field with a specific concentration on the various methods of composite repairs. Djukic, Sum, Leong, and Gibson (2015) in their book entitled "Clamp and overwrap repairs of oilfield pipelines: In Rehabilitation of Pipelines Using Fiber-reinforced Polymer (FRP) Composites," explored various current and emerging composite repair methods especially for the pipelines with much concentration given to clamp and overwrap methods. Djukic et al. (2015) observed that the composite repair methods provide significant advantages over metal such as smaller relative density with water, reduced weight, and higher resistance to corrosion. In their research, Colombi et al. (2015) found that these methods were very significant because they allowed proper rehabilitation of wall thinning as well as through-wall damage over water over various conditions in the subsea and the splash zone. Despite the seeming perfection of these composite methods, Djukic et al. (2015) noted some challenges associated with these methods upon which they called for further research to help solve. The main weaknesses observed in these methods include excessive internal and external corrosion, dents, abrasion, erosion, and cracks especially if left unmonitored for a long time. By using these composite repair methods, firms are put on toes to conducting regular check-ups to determine if they are in the right conditions for proper functioning. This process takes a lot of money to facilitate especially on a regular fashion thereby, increasing the costs for repair and maintenance of assets of the firm. According to Anderson (2017), failure to repair such pipeline defects might lead to disastrous consequences both to the equipment operators and the asset owners. Solution measures include either replacement or repairs which can sometimes be very expensive to implement. Iarve, Breitzman, and Ripberger (2015) also conducted informative research in this field. In their book entitled, "Tensile failure of composite scarf repair: In Structural Integrity and Durability of Advanced Composites," Iarve et al. (2015) explored the mechanics of the composite scarf repair method under tensile loading both with and without the overplies for ply orientations particularly for the non-traditional patches. Scarf and bonded composite repair methods were explored. These composite repair methods are crucial for the repair and maintenance of the fleet in the automotive, civil aerospace, as well as the marine composite vehicle industries. According to Wang et al. (2015), bonded and scarf composite repair methods are crucial especially from strength restoration to the technological standpoints. They allow one-sided access with minimal effects on the external shape of the structure. They performed the three-dimensional non-linear analysis to predict any possible composite repair failure. To achieve the baseline, Iarve et al. (2015) made a critical comparison between the open-hole scarfed panels with the panels repaired through the standard ply-by-ply replacement patch composition. They then performed the multidimensional optimization to determine the repair patch ply orientation which reduces the von Mises stress in the adhesive. The optimized stacking sequences enabled them to achieve 60% strength restoration prediction for the flush repair, and 90% prediction for the single-ply thickness overply repair. In this research, they intended to illustrate different variables of design for the efficient design of the composite repairs with special concentration on the composition of the repair patch. There are still chances to find ways of improving the effectiveness of these methods to minimize tensile failure and make the structures more durable and convenient. Baker (2014), in his book entitled "Repair of metallic airframe components using fiber-reinforced polymer (FRP) composites: In Rehabilitation of Metallic Civil Infrastructure Using Fiber Reinforced Polymer (FRP) Composites," conducted an in-depth research on the effectiveness of the fibre reinforced polymer composites in comparison to the Type B steel sleeves. In this research, the fiber-reinforced polymer composites were found to be very efficient in repair. The composite repair methods are effective contemporary ways of maintaining pipelines. However, the drawbacks associated with these methods are very costly for most companies. There is an opportunity for further research on ways of minimizing the repair and maintenance costs through enhancing the efficiency and effectiveness of these methods. Sirimanna et al. (2015), in their research entitled "Fiber-reinforced polymer (FRP) repair systems for corroded steel pipelines: In Rehabilitation of Pipelines Using Fiber-reinforced Polymer (FRP) Composites," noted that the fiber-reinforced polymer is efficient and effective for the repair and maintenance of the corroded steel pipelines. The technologies of un-bonded composite repair provide effective solutions for the internal repair of steel pipelines with efficiency and a wide range of applicability. These methods if well maintained and improved can bring a long-lasting solution for the oil and gas pipelines. These are just some of the research articles done in this field. However, many other researchers and scholars have extensively explored ways of optimizing maintenance of the pipelines. Besides, I have also been exposed to a lot of understanding in Failure Analysis of Metals. The course in Root Cause Analysis (RCA) enabled me to develop a broad understanding of the approach on how to identify the ultimate source and cause of an outage. While taking these courses, I got a wide range of information concerning the concepts of fracture mechanics which further inspired my interests to obtain more substantial knowledge in this field. I have found research fascinating from my Master of Science course in Engineering Management during which, I attained good grades in my chosen modules like Advanced Maintenance Practice and Engineering Operations Management. These modules exposed me to carry out a lot of research to determine the most effective way and means of enhancing the maintenance practice and management of failure situations.

Newcastle University is the most appropriate institution to undertake this research. Fracture Mechanics of composite repair methods for steels and structures has been my interest area of research since the time while I was taking my Bachelor's Degree in Mechanical Engineering. I desire to give my best to this research. Doing so would require partnership with the most appropriate institution with the capabilities and capacity to inspire my confidence and trust in what I can do to attain a higher level of excellence. The following are the major reasons why I chose Newcastle University for my Ph.D. studies. First, Newcastle University is known for its world-class reputation for its excellence in research. In the latest Research Excellence Framework, the university was rated number 16th for their advanced research among all the universities in the UK. This would inspire my research capabilities and transform my study into actual success. Besides, Newcastle University provides high quality teaching which enhances students' experience. This commitment can be justified by the various accreditations, awards as well as the results from the various student surveys. In addition to that, Newcastle University's Gold Award in the Teaching Excellence Framework (TEF) reveals much more reasons to partn...