Andrew Levers

Analysis of the effects of controlled shot peening on fatigue damage of high strength aluminium alloys

The use of two micro-mechanical models for notch sensitivity and fatigue life allowed the development of boundary conditions that would evaluate potential life improvement after controlled shot peening (CSP) in high strength aluminium alloys. The boundary conditions describe the state of equal weight between surface roughening and residual stresses and the implication of material and loading parameters. From the boundary conditions, the performance of CSP on crack arrest and fatigue life can be investigated.

The emergence of sustainable manufacturing practices

Sustainable manufacturing appears to be a rapidly developing field and it would be expected that there is a growing body of knowledge in this area. Initial examination of the literature shows evidence of sustainable work in the areas of product design, supply chain, production technology and waste avoidance activities. Manufacturers publish metrics showing significant improvements in environmental performance at high level but information on how these improvements are achieved is sparse. Examining peer-reviewed publications focused on production operations there are few cases reporting details and there has been little prior analysis of published sustainable manufacturing activity. Moreover, the mismatch between academic and practitioner language leads to challenges in interpretation. This article captures and analyses the types of sustainable manufacturing activities through literature review. In turn, this can help manufacturers to access examples of good practice and help academics identify areas for future research.

Zero carbon manufacturing facility - Towards integrating material, energy, and waste process flows

Abstract The increasing pressure on material availability, energy prices, as well as emerging environmental legislation is leading manufacturers to adopt solutions to reduce their material and energy consumption as well as their carbon footprint, thereby becoming more sustainable. Ultimately manufacturers could potentially become zero carbon by having zero net energy demand and zero waste across the supply chain. The literature on zero carbon manufacturing and the technologies that underpin it are growing, but there is little available on how a manufacturer undertakes the transition. Additionally, the work in this area is fragmented and clustered around technologies rather than around processes that link the technologies together. There is a need to better understand material, energy, and waste process flows in a manufacturing facility from a holistic viewpoint. With knowledge of the potential flows, design methodologies can be developed to enable zero carbon manufacturing facility creation. This paper explores the challenges faced when attempting to design a zero carbon manufacturing facility. A broad scope is adopted from legislation to technology and from low waste to consuming waste. A generic material, energy, and waste flow model is developed and presented to show the material, energy, and waste inputs and outputs for the manufacturing system and the supporting facility and, importantly, how they can potentially interact. Finally the application of the flow model in industrial applications is demonstrated to select appropriate technologies and configure them in an integrated way.

Finite element analysis of shot peening

Abstract The shot peening process is largely used for the surface treatment of metallic components with the aim of increasing surface toughness and extending fatigue life. A secondary consequence of the process is that the residual stress distribution developed within the material may induce distortion of the component. This effect may therefore be used constructively in the straightening and forming of thin flexible metallic structures. In this paper, the various techniques available for modelling the effect of peening with finite elements are discussed. In particular, a method of simulating the effect of peening on large flexible panels is presented. Analyses are shown in which a novel loading is applied to finite element meshes in order to produce the desired residual stress distribution. Results from tests are compared to finite element analyses and preliminary results of large scale analyses are presented.

Predicting the interfaces between fatigue crack growth regimes in 7150-T651 aluminium alloy using the fatigue damage map

Abstract The fatigue damage map (FDM) is used to establish the domains of different crack growth regimes including microstructural dependent (short), microstructural independent (long) and non-propagating cracks. The FDM is applied over a wide range of applied stresses to determine the extent of each domain from crack instability to crack arrest. Two important boundaries of the FDM are examined in this paper—the crack arrest curve and the transition from short to long crack growth. The accuracy of the model predictions are evaluated through crack arrest experiments and fractographic examination of failure cracks.

Development of new damage tolerant alloys for age-forming

The suitability of age forming for the shaping of damage tolerant structures is investigated by formulating and testing new alloy-age forming combinations. The alloy formulation process is driven initially by modelling of strength and semi-quantitative understanding of other microstructure-property relations. Using this a range of Al-Cu-Mg-Li-(Zr-Mn) based alloys predicted to provide yield strengths in aged condition comparable with incumbent 2024-T351 alloy for lower wing skins are selected. It is shown that several of these new alloys after artificial aging representative of age-forming have proof strength (PS), fatigue crack growth resistance (FCGR) and toughness that are comparable or better than 2024-T351. UTS to PS ratios of the new alloys are lower than 2024-T351.

Industrial ecology at factory level: a prototype methodology

The concept of sustainable manufacturing is a form of pollution prevention that integrates environmental considerations in the production of goods while focusing on efficient resource use. Taking the industrial ecology perspective, this efficiency comes from improved resource flow management. The assessment of material, energy and waste resource flows, therefore, offers a route to viewing and analysing a manufacturing system as an ecosystem using industrial ecology biological analogy and can, in turn, support the identification of improvement opportunities in the material, energy and waste flows. This application of industrial ecology at factory level is absent from the literature. This article provides a prototype methodology to apply the concepts of industrial ecology using material, energy and waste process flows to address this gap in the literature. Various modelling techniques were reviewed and candidates selected to test the prototype methodology in an industrial case. The application of the prototype methodology showed the possibility of using the material, energy and waste resource flows through the factory to link manufacturing operations and supporting facilities, and to identify potential improvements in resource use. The outcomes of the work provide a basis to build the specifications for a modelling tool that can support those analysing their manufacturing system to improve their environmental performance and move towards sustainable manufacturing.

Barriers to industrial energy efficiency

Purpose – The purpose of this research is to capture organisational barriers that can inhibit energy reduction in manufacturing. Energy consumption is a significant contributor to the economic and environmental components of industrial sustainability, and there is a significant body of knowledge emerging on the technical steps necessary to reduce that consumption. Achieving technical success requires organisational alignment, without which barriers to energy efficiency can be experienced. Design/methodology/approach – The research uses a theory building–theory testing cycle to propose and then verify existence of barriers to industrial energy efficiency. Literature review is used to build potential organisational barriers that can arise. The existence of barriers is then verified in industrial energy reduction projects using interview, observation and document analysis. Findings are validated by company staff. Findings – From the literature barriers that can be related to energy reduction, projects are un...

Numerical and experimental investigation of aircraft panel deformations during riveting process

In collaboration with Airbus-UK, the dimensional growth of aircraft panels while being riveted with stiffeners is investigated. Small panels are used in this investigation. The stiffeners have been fastened to the panels with rivets and it has been observed that during this operation the panels expand in the longitudinal and transverse directions. It has been observed that the growth is variable and the challenge is to control the riveting process to minimize this variability. In this investigation, the assembly of the small panels and longitudinal stiffeners has been simulated using static stress and nonlinear explicit finite element models. The models have been validated against a limited set of experimental measurements; it was found that more accurate predictions of the riveting process are achieved using explicit finite element models. Yet, the static stress finite element model is more time efficient, and more practical to simulate hundreds of rivets and the stochastic nature of the process. Furthermore, through a series of numerical simulations and probabilistic analyses, the manufacturing process control parameters that influence panel growth have been identified. Alternative fastening approaches were examined and it was found that dimensional growth can be controlled by changing the design of the dies used for forming the rivets.

Potential applications of peen forming finite element modelling

Peen forming is a versatile and flexible manufacturing process commonly used in the aerospace industry to shape wing skins and rockets panels. Development of peening parameters needed to obtain a specific component shape can be both costly and challenging due to the use of empirical methods which involve large quantities of physical experiments coupled with trial and error processing of prototype components. Many iterations are often required to get the desired shape with no guarantee that a specific component geometry can be achieved. Reliable numerical simulations could substantially reduce the time, cost and risk associated with process development. The purpose of this study is to further investigate the use of numerical tools to model the peen forming process. This work combines static and dynamic simulation techniques to predict the development of curvature on representative wing skin panels that include features such as integral stiffeners. This work illustrates the considerable potential of finite element simulations to determine the process parameters needed to produce a component design, and substantially reduce the dependence upon physical testing.