Adhesives in Marine Engineering

Jan R Weitzenböck

• Publisher: Woodhead Publishing
• Year: 2012
• Print ISBN:
  9781845694524
• eBook ISBN:
  9780857096159
• Topic: Technology & Engineering
• Subtopic: Materials Science
• Index: Technology & Engineering

As a method of joining with economic, performance-related and environmental advantages over traditional welding in some applications, adhesive bonding of joints in the marine environment is increasingly gaining popularity. Adhesives in marine engineering provides an invaluable overview of the design and use of adhesively-bonded joints in this challenging environment.After an introduction to the use of adhesives in marine and offshore engineering, part one focuses on adhesive solution design and analysis. The process of selecting adhesives for marine environments is explored, followed by chapters discussing the specific design of adhesively-bonded joints for ship applications and wind turbines. Predicting the failure of bonded structural joints in marine engineering is also considered. Part two reviews testing the mechanical, thermal and chemical properties of adhesives for marine environments together with the moisture resistance and durability of adhesives for marine environments.With its distinguished editor and international team of expert contributors, Adhesives in marine engineering is an essential guide for all those involved in the design, production and maintenance of bonded structures in the marine environment, as well as proving a key source for academic researchers in the field. - Provides an invaluable overview of the design and use of adhesively-bonded joints in marine environments - Discusses the use of adhesives in marine and offshore engineering, adhesive solution design and analysis, and the design of adhesively-bonded joints for ship applications and wine turbines, among other topics - Reviews testing the mechanical, thermal and chemical properties of adhesives for marine environments, together with the moisture resistance and durability of these adhesives

Part 1

Design and Analysis

1

Introduction to Using Adhesives in Marine and Offshore Engineering

J.R. Weitzenböck, Det Norske Veritas AS, Norway

Abstract:

The chapter provides a brief overview of the use of adhesives in marine and offshore engineering. Firstly, some basic terms for adhesive bonding are defined, followed by a general overview of future technology development that may influence the use of materials and joining methods such as adhesive bonding. Next, a state of the art study is presented on the actual and potential use of adhesives, based on the literature and the author’s personal experience, followed by a brief outline of the certification and approval regimes for bonded structures. Finally, an outlook and references are presented for further information for the interested reader.

Key words

adhesive bonding

ship building

wind turbines

offshore engineering

design for adhesive bonding

international regulations

1.1 Introduction

During the design, fabrication and modification of ships and offshore structures there are innumerable joining tasks to assemble the structure and to install equipment. The vast majority will be done using welding and perhaps some other mechanical joining process such as bolting or riveting. However, there are situations where these joining processes are not the best option. Typically this is for the assembly of lightweight structures based on thin materials or material combinations such as composite and steel that cannot be welded. However, to be successful, adhesively bonded connections not only need to have sufficient mechanical strength and long-term performance, but they first and foremost have to be economically viable.

What do we mean by ‘adhesive’? According to Adams et al. (1997), ‘an adhesive can be defined as a polymeric material which, when applied to surfaces, can join them together and resist separation’. Adams and co-workers describe structural adhesives ‘as one used when the load required to cause separation is substantial such that the adhesive provides for the major strength and stiffness of the structure’. The structural members of the joint, which are joined together by the adhesive, are the adherends. Adhesion as such is used widely on marine structures. One example is corrosion prevention coatings. However, for the purpose of this book we will focus on load-bearing applications with structural adhesives. The simplest joint configuration is the single lap joint as shown in Fig. 1.1.

1.1 A single lap joint and its main parameters: F = tensile load, d = thickness of layer, S = thickness of adherend, b = width of joint, l₀ = length of overlap region, γ = shear strain in adhesive, Δ = shear displacement due to F(from Weitzenböck and McGeorge, 2005).

Why are adhesives being considered? The joining process is a consequence of the materials used. In the case of adhesive bonding this could mean that the plates are too thin to weld, a particular material combination that cannot be welded, requirement for smooth surfaces for aesthetic reasons, to avoid hotwork and risk of fire and finally corrosion management where the adhesive provides an insulating layer to avoid galvanic corrosion. No joining process comes without weaknesses. An adhesively bonded joint usually requires the adherends to overlap, the strength is temperature dependent and fabrication requires careful process control. Furthermore, there is a shortage of skilled designers and shipyard workers. A good discussion of the pros and cons can be found in Lees (1990) which is still relevant today despite its age.

1.2 The need for adhesive bonding in the maritime and offshore industries

The aim of this section is to examine the motivation for using adhesive bonding. Adhesive bonding is an enabling technology allowing novel designs by joining multi-materials and lightweight materials. However, adhesive bonding is not a technology driver – adhesives are not used for the sake of using adhesives. A pertinent question therefore is what are the important industry trends and drivers that might affect and possibly favour the use of adhesive bonding in marine engineering. Future technology development is shaped by how the ‘world’ or society at large develops. DNV’s Technology Outlook (DNV Research and Innovation, 2011) identified seven megatrends that are believed to have a significant impact on that development until 2020. These mega-trends are: population, economy, governance, information technology, energy, natural resources, climate change (see DNV Research and Innovation (2011)).

Based on these mega-trends, scenarios were developed to evaluate the impact on future technology development. Technology uptake was assessed for different industry sectors; three of these industry sectors fall within the scope of this book: maritime, oil and gas and wind energy. The list below shows technologies within these three industry sectors that may potentially be relevant for adhesive bonding, as they require joining of either multimaterials or lightweight materials:

• The low energy ship. It is anticipated that in order to save weight and hence reduce fuel costs, the use of lightweight and hybrid materials will become more widespread.

• The green-fuelled ship. Significant reductions in emissions such as SO_x and particles can be achieved by switching to natural gas. The liquid natural gas (LNG) tanks used today require considerably more space than a diesel tank. New LNG tank concepts are under development using new material combinations to improve the current situation.

• The Arctic ship. Increased operations in the Arctic will require novel evacuation vessels that can also travel over ice, not just water. A number of material and joining issues are anticipated.

• The virtual ship. The use of integrated ship design tools will become more commonplace. This implies that joining processes including adhesive bonding also need to be modelled in the design tools.

• Subsea production. Deployment of much larger subsea processing equipment is predicted, and with it comes the need for larger housing that is both water- and pressure-proof.

• Arctic offshore development. Significant research and development is underway to qualify and characterise materials for the use in Arctic operations. An increase in use of lightweight materials such as composites and aluminium is predicted. This puts tough new requirements on the materials and joining methods such as adhesives, i.e. toughness at low temperatures. However, there is some experience of using adhesives for LNG containment systems at much lower temperatures (at about − 163°C).

• Smart blade design. More sophisticated blade designs are anticipated within the next decade. This includes actuators for active control or new geometries or fibre lay-ups that react to different loadings and wind speeds. These new designs will impose new requirements on the bonded joints used in the blades.

The list above is a discussion of the technology developments identified in DNV’s Technology Outlook. It serves as an illustration on how new designs and material choices open up new possibilities for adhesives joining, but is by no means an exhaustive list. Further examples are shown later on in this chapter.

1.3 Potential uses of adhesives in the maritime and offshore industries

1.3.1 Maritime industry

There are a number of actual and potential applications for adhesive bonding in the maritime industry. However, this section will not focus on composite structures onboard ships. Composites are only mentioned when they are to be joined by adhesive bonding. More information about composite applications including sandwich construction is found in Weitzenböck et al. (2010) or for the sandwich plate system (SPS) panels in Welch (2005). One of the first general reviews of marine applications of adhesive bonding was by Wacker (2000). He reported the bonding of window panes, propeller shafts and FRP pleasure boats. There are some earlier accounts of using adhesives in a marine environment for particular applications. Reavey (1981) summarises many years of experience of bonding hovercraft structures successfully, mainly aluminium honeycomb. Even though these structures resemble aircraft structures, they are used...

Table of contents

• Cover image
• Title page
• Table of Contents
• Copyright
• Contributor Contact Details
• Preface
• Part 1: Design and Analysis
• Part II: Testing and Characterisation
• Index