Browsing by Author "Lockett, Helen L."
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Item Open Access Aircraft assembly process design for complex systems installation and test integration.(Cranfield University, 2019-04) Li, Tao; Lockett, Helen L.; Lawson, CraigThe assembly line planning process connects product design and manufacturing through translating design information to assembly integration sequence. The assembly integration sequence defines the aircraft system components installation and test precedence of an assembly process. From a systems engineering view point, this activity is part of the complex systems integration and verification process. At the early conceptual design phase of assembly line planning, the priority task of assembly process planning is to understand product complexities in terms of systems interactions, and generate the installation and test sequence to satisfy the designed system function and meet design requirements. This research proposes to define these interactions by using systems engineering concept based on traceable RFLP (Requirement, Functional, Logical and Physical) models and generate the assembly integration sequence through a structured approach. A new method based on systems engineering RFLP framework is proposed to generate aircraft installation and test sequence of complex systems. The proposed method integrates aircraft system functional and physical information in RFLP models and considers these associated models as new engineering data sources at the aircraft early development stage. RFLP modelling rules are created to allow requirements, functional, logical and physical modes be reused in assembly sequence planning. Two case studies are created to examine the method. Semi- structured interviews are used for research validation. The results show that the proposed method can produce a feasible assembly integration sequence with requirements traceability, which ensures consistency between design requirements and assembly sequences.Item Open Access An aircraft design for maintainability methodology integrated with computer aided design(Cranfield University, 2012-11-06) Lockett, Helen L.; Estefani, J.; Reytérou, E.Maintenance typically represents 10 – 25% of the direct operating cost of an aircraft and minimizing maintenance cost is therefore an important driver for aircraft design. This paper presents a methodology for Design for Maintainability that uses an accessibility checklist for maintainability assessment at the preliminary design stage, and a maintenance task time prediction method that can be used at the detailed design stage. Both elements of the methodology use Computer Aided Design to assess virtual maintenance operations for accessibility and human performance. The methodology provides a basis for the comparison of design alternatives with respect to maintainability.Item Open Access Aircraft wing build philosophy change through system pre-equipping of major components(Society of Automotive Engineers, 2016-09-27) Judt, David M.; Forster, Kevin; Lockett, Helen L.; Lawson, Craig P.; Webb, PhilipIn the civil aircraft industry there is a continuous drive to increase the aircraft production rate, particularly for single aisle aircraft where there is a large backlog of orders. One of the bottlenecks is the wing assembly process which is largely manual due to the complexity of the task and the limited accessibility. The presented work describes a general wing build approach for both structure and systems equipping operations. A modified build philosophy is then proposed, concerned with large component pre-equipping, such as skins, spars or ribs. The approach benefits from an offloading of the systems equipping phase and allowing for higher flexibility to organize the pre-equipping stations as separate entities from the overall production line. Its application is presented in the context of an industrial project focused on selecting feasible system candidates for a fixed wing design, based on assembly consideration risks for tooling, interference and access. Further industrial, human and cost factors are discussed to establish project competiveness. The main findings show a potential to reduce assembly time of systems equipping operations by 30% together with a lower ergonomic impact score. The paper also presents design rules derived from the case study towards a system design for a pre-equipping build philosophy. Primarily, cross component interfaces should be avoided as much as possible. Access for phase one structural operations need to be considered as well as major component jig pickup points. To increase system installation independence, layout considerations of components should lead to sufficient access to all components at any installation stage.Item Open Access Computational design process modelling(2006-12-01T00:00:00Z) Guenov, Marin D.; Libish; Tang, Dunbing; Lockett, Helen L.In the conceptual design phase, relatively simple equations and functions (or compiled code) are used to describe the aircraft and to perform trade-off studies. The latter require an optimal execution sequence in order to reduce computational cost and design time, respectively. The focus of this paper is the dynamic derivation of the optimal computational plan for each study so that the designer could focus on designing the aircraft rather than managing the process flow. Two methodologies, the Design Structure Matrix (DSM) and the Incidence Matrix are used for the computational process modeling. The incidence matrix describes the relationship between variables and equations/models. The DSM has been used to express the dependency relationships between the models and also, after manipulation, to produce the solution process. The designer specifies the independent (known) variables first. Then the variable flow is modeled using the Incidence Matrix Method (IMM). It determines how data flows through the models, and also identifies any strongly connected components (SCCs). The second step is to rearrange all equations/models hierarchically in order to reduce the feedback loops in each of the identified SCCs. This is achieved by the application of a genetic-based algorithm. Subsequently all SCCs and noncoupled models are assembled into a macro model which forms a global DSM. The global DSM is further rearranged to obtain an upper triangular matrix which defines the final model execution sequence. A simple aircraft sizing example is presented to illustrate the proposed method and algorithm. Advantages of the method include improved efficiency and the ability to deal with both algebraic and numerical models as well as with multiple outputs per model.Item Open Access Design for wire + arc additive manufacture: design rules and build orientation selection(Taylor & Francis, 2017-08-20) Lockett, Helen L.; Ding, Jialuo; Williams, Stewart W.; Martina, FilomenoWire + Arc Additive Manufacture (WAAM) is an additive manufacturing technology that can produce near net-shape parts layer by layer in an automated manner using welding technology controlled by a robot or CNC machine. WAAM has been shown to produce parts with good structural integrity in a range of materials including titanium, steel and aluminium and has the potential to produce high value structural parts at lower cost with much less waste material and shorter lead times that conventional manufacturing processes. This paper provides an initial set of design rules for WAAM and presents a methodology for build orientation selection for WAAM parts. The paper begins with a comparison between the design requirements and capabilities of WAAM and other additive manufacturing technologies, design guidelines for WAAM are then presented based on experimental work. A methodology to select the most appropriate build orientation for WAAM parts is then presented using a multi attribute decision matrix approach to compare different design alternatives. Two aerospace case study parts are provided to illustrate the methodology.Item Open Access Design for wire and arc additive layer manufacture(2010-04-19T00:00:00Z) Mehnen, Jorn; Ding, J.; Lockett, Helen L.; Kazanas, P.; Bernard, A.Additive Layer Manufacture (ALM) is a technique whereby freeform structures are produced by building up material in layers. RUAM (Ready-to-Use Additive Layer Manufacturing) is an innovative concept for building large scale metal ready-to- use parts. The design for RUAM has several process steps: the geometric design of the parts taking the complex process behaviour of the arc welding process into account; FEM to predict temperature and stress distributions to minimise part distortions; and efficient robot tool path design. This paper covers these essential design steps from a technical as well as practical point of view.Item Open Access Digital assembly process design for aircraft systems(Cranfield University, 2012-01) Li, Tao; Lockett, Helen L.The research described in this thesis concentrates on the development of an integrated assembly process design for aircraft systems. Assembly process design is one of the most important and complicated activities in aircraft manufacturing. Many solutions are suggested in previous research to develop process design method. But gaps are found in assembly process design of aircraft system in following studies. In this research, an integration approach which combined with product development philosophy, design for assembly method and digital assembly technology is proposed to solve the issues in the whole product development lifecycle. Three case studies from different design phase are used to examine the integrated process design method. The research results demonstrate that the proposed digital process design method can be used to develop manufacturing strategies of system assembly in early design phase, and improve the accuracy and operability of assembly instructions according to 3-D assembly process plans in detailed design phase. The product design also benefits from this method in terms of correcting design errors in the concurrent engineering process. A proposed process planning system framework based on lightweight CAD is developed in this research. The customized assembly representation of 3DVIA system illustrates the advantages of lightweight CAD when applying in shop floor.Item Open Access Early cost estimation for additive manufacture(Cranfield University, 2012-09) Zhai, Yun; Lockett, Helen L.Additive Manufacture (AM) is a novel manufacturing method; it is a process of forming components by adding materials. Owing to material saving and manufacturing cost saving, more and more research has been focused on metal AM technologies. WAAM is one AM technology, using arc as the heat sources and wire as the material to create parts with weld beads on a layer-by-layer basis. The process can produce components in a wide range of materials, including aluminum, titanium and steel. High deposition rate, material saving and elimination of tooling cost are critical characteristics of the process. Cost estimation is important for all companies. The estimated results can be used as a datum to create a quote for customers or evaluate a quote from suppliers, an important consideration for the application of WAAM is its cost effectiveness compared with traditional manufacture methods. The aim of this research is to find a way to develop a cost estimating method capable of providing manufacturing cost comparison of WAAM with CNC. A cost estimation model for CNC machining has been developed. A process planning approach for WAAM was also defined as part of this research. An Excel calculation spreadsheet was also built and it can be easily used to estimate and compare manufacture cost of WAAM with CNC. Using the method developed in this research, the cost driver analysis of WAAM has been made. The result shows that reduced material cost is the biggest cost driver in WAAM. The cost comparison of WAAM and CNC also has been made and the results show that with the increase of buy-to-fly ratio WAAM is more economical than CNC machining.Item Open Access Experimental investigation into aircraft system manual assembly performance under varying structural component orientations(SAGE, 2019-10-18) Judt, David M.; Lawson, Craig; Lockett, Helen L.Installation of aircraft wing systems is a bottleneck in the assembly process. This phase is typically composed of many work packages, taking hundreds of man-hours per wing. In addition to this volume of work, tasks are specialized and completed in a difficult environment in terms of access and visibility. In current industrial practice, the wing is mounted horizontally on a transport trolley, which exposes the workforce to prolonged periods of overhead working. Future wing designs may consider a pre-equipping build philosophy, where systems are installed to major structure assemblies before the wing box is assembled. This allows for a change in the orientation and position of the major structure and provides new freedoms in assembly station design and layout. This research presents results of experiments to investigate manual assembly performance of aircraft wing systems, under varying wing structure orientation. A mock-up of a section of an A320 aircraft wing front spar, mounted on a rotation device, functions as the testbed. Manual installation activities are then conducted to emulate real aircraft system equipping for electric harnesses, raceways and hot air ducts. The results show a best-case assembly performance change of 36% for electric system installation activities of cable harnesses and raceway housing components. Tilted and horizontal orientations of the structure show the highest time reductions, with the vertical orientation either non-conclusive or increasing the assembly time. The outcomes of this study are intended to aid in effective trade-off decision making for future wing systems and assembly station layouts from the perspective of structural orientation and assembly task interaction.Item Open Access A framework to inform PSS Conceptual Design by using system-in-use data(Elsevier Science B.V., Amsterdam., 2012-05-01T00:00:00Z) Hussain, Romana; Lockett, Helen L.; Annamalai Vasantha, Gokula VijaykumarBoth the Product-Service System (PSS) literature and industry express a need to close the design loop by using product-in-use data to inform PSS Conceptual Design. Nevertheless, how to actually accomplish this is largely unknown. This research makes use of the literature as well as findings from interviews and case studies with industry as the basis for a framework which could utilise system- in-use (rather than just product-in-use) data from in-service records and receiver needs regarding the use of large, capitalintensive, technical assets to generate solutions which could aid the conception of PSS at the Conceptual Design stagItem Open Access Hybrid design based on wire and arc additive manufacturing in the aircraft industry(Cranfield University, 2012-12) Chen, Jian; Mehnen, Jorn; Lockett, Helen L.Wire and Arc Additive Manufacturing (WAAM) is a developing rapid prototyping and manufacturing technology which allows the production of large custom-made metal parts with high deposition rates, a major concern of the aircraft industry. Despite this, there is little research on the design method and application of WAAM technology in the aircraft industry. The overall research aim is to develop a step-by-step design method to create and assess hybrid design solutions based on WAAM technology. The main objectives are to: (i) analyse existing design methods and software tools; (ii) collect and analyse technical data about aircraft structure design and WAAM process; (iii) develop a hybrid design method based on WAAM technology; (iv) validate the developed design method through industrial case studies. These four objectives were achieved through the adoption of a four-phase research methodology. A hybrid design method was developed based on mature design models such as the VDI 2221model, BS 7000 design model and Pahl and Beitz’s design model and required prior knowledge of WAAM technology and aircraft structure design. This design method includes a hybrid design model and a WAAM feature based design guideline which enables the designers to create hybrid design solutions step by step and assess the proposed solutions by using the evaluation matrix chart. Hybrid design in this research encompasses design for hybrid manufacturing processes, which means that an object is to be designed partly made from prefabricated or off-the-shelf parts and partly added by WAAM process. Furthermore, Finite Element Analysis is introduced in the design method to check the performance of the preliminary design and the final design. Three case studies were carried out to verify the developed hybrid design method. The integral panel, a typical structure in aircraft, demonstrates the significant cost advantage of WAAM technology. The pylon frame and forward fitting are the structural parts provided by the Chinese aircraft industry. It shows that the cost of the final design is significantly lower than that of the preliminary design. In addition, topology optimisation is applied to achieve lower weight. The hybrid design method is validated through academic experts and industrial experts. This research project has contributed to an effective design method based on WAAM technology in the aircraft industry.Item Open Access Investigation of a path planning solution for wire + arc additive manufacture.(Cranfield University, 2018-12) Michel, Florent; Lockett, Helen L.; Ding, JialuoWire + Arc Additive Manufacturing (WAAM) has become a crucial asset for industrial manufacturing in the field of medium to large metallic deposition thanks to its high-rate deposition of various metals, its low-cost equipment and a potentially unlimited build volume. A key element for commercial deployment is to develop an intuitive path planning software, which can determine the optimal deposition strategy, whilst respecting WAAM’s constraints inherent to arc welding deposition. Traditional approaches to additive manufacturing path planning are often derived from CNC machining, but these strategies are incompatible with some fundamental characteristics of WAAM. For this reason, the present work aims to investigate a path planning solution entirely focused on the WAAM requirements. The architecture of a Path Generator Framework for WAAM is, thus, first introduced to offer complete freedom of path planning development all along this study. To validate the developed framework, a feature- based approach is presented: this allows the fast and efficient deployment of the WAAM technology for a limited range of geometric features and sets up the basis of path planning for WAAM. Then, a more flexible solution called Modular Path Planning is introduced to incorporate the modularity of feature-based design into the traditional layer-by-layer build strategy. By assisting the user in dividing each layer into individual deposition sections, this method enables users to adapt the path strategy to the targeted geometry allowing the construction of a wide variety of complex geometries. Finally, a deep learning solution called DeepWAAM is proposed to reach, in the future, a fully automated path planning solution for WAAM by automatically dividing build layers into deposition sections with no need for user intervention.Item Open Access A knowledge based expert system for moulded part design(Design Society, 2007) Guenov, Marin D.; Lockett, Helen L.In today's competitive market many consumer products are designed with complex curved shapes to meet customers' demands for styling and ergonomics. These styled products are commonly manufactured using moulding processes because they can produce a wide range of freeform shapes at relatively low cost. However, although injection moulding and metal casting allow a great deal of design freedom they also make significant demands on the designer to ensure that parts are designed with due regard for manufacturability. This paper describes a knowledge based moulding advisor that has been developed to provide design for moulding advice to designers during the design process. The main contributions of the research are the development of a hierarchical knowledge representation to allow moulding advice to be generated at different levels of detail and the integration of the expert system with a geometric part description extracted from a Computer Aided Design (CAD) solid model. A demonstrator for the manufacturing advisor has been implemented using the expert system shell CLIPS and integrated with CAD using feature recognition. The moulding advisor is able to generate tailored design for moulding advice for a range of manufacturing processes and materials and evaluate the manufacturability of a designed part at the feature level. The paper provides a case study for a simple moulded test part.Item Open Access A knowledge based manufacturing advisor for CAD(Cranfield University, 2005-07) Lockett, Helen L.; Guenov, Marin D.This thesis presents a knowledge based manufacturing advisor for Computer Aided Design. The aim of the project has been to develop techniques that can help designers to evaluate the manufacturability of moulded parts during the design process. One of the major achievements in the research has been the development of a novel feature recognition approach to allow moulding features to be recognised from a CAD model. Existing feature recognition techniques are not appropriate for moulded parts and a new feature recognition approach has been developed that uses a mid-surface abstraction from the CAD solid model as the basis for feature recognition. The feature recognition methodology presented in this research is a graph based technique that uses an attributed mid-surface adjacency graph as the basis for feature recognition. Feature recognition algorithms have been developed for a range of common moulding features. Two evaluation techniques are presented that measure the quality of the feature recognition results and provide a confidence measure for the manufacturing advice that is generated. The first evaluation technique uses the Hausdorff distance to measure the similarity of the mid-surface model to the CAD solid model that was used to generate it, and the second uses a face mapping technique to evaluate the completeness of the feature recognition results. A demonstrator for the knowledge based manufacturing advisor has been developed which incorporates the feature recognition software and an expert system for moulding advice. The expert system provides an interactive software environment in which the user can input details about their part design, and receive tailored manufacturing advice for a range of moulding processes. The demonstrator has been tested on a range of realistic moulded parts.Item Open Access Maintainability prediction for aircraft mechanical components utilising aircraft feedback information(Cranfield University, 2011-09) Wan Husain, Wan Mohd Sufian Bin; Lockett, Helen L.; Fielding, JohnThe aim of this research is to propose an alternative approach to determine the maintainability prediction for aircraft components. In this research, the author looks at certain areas of the maintainability prediction process where missteps or misapplications most commonly occur. The first of these is during the early stage of the Design for Maintainability (DfMt) process. The author discovered the importance of utilising historical information or feedback information. The second area is during the maintainability prediction where the maintenance of components is quantified; here, the author proposes having the maximum target for each individual maintainability component. This research attempts to utilise aircraft maintenance historical data and information (i.e. feedback information systems). Aircraft feedback information contains various types of information that could be used for future improvement rather than just the failure elements. Literature shows that feedback information such as Service Difficulty Reporting System (SDRS) and Air Accidents Investigation Branch, (AAIB) reports have helped to identify the critical and sensitive components that need more attention for further improvement. This research consists of two elements. The first is to identity and analyse historical data. The second is to identify existing maintainability prediction methodologies and propose an improved methodology. The 10 years’ data from Federal Aviation Administration (FAA) SDRS data of all aircraft were collected and analysed in accordance with the proposed methodology before the processes of maintainability allocation and prediction were carried out. The maintainability was predicted to identify the potential task time for each individual aircraft component. The predicted tasks time in this research has to be in accordance with industrial real tasks time were possible. One of the identified solutions is by using maintainability allocation methodology. The existing maintainability allocation methodology was improved, tested, and validated by using several case studies. The outcomes were found to be very successful. Overall, this research has proposed a new methodology for maintainability prediction by integrating two important elements: historical data information, and maintainability allocation. The study shows that the aircraft maintenance related feedback information systems analyses were very useful for deciding maintainabilityeffectiveness; these include planning, organising maintenance and design improvement. There is no doubt that historical data information has the ability to contribute an important role in design activities. The results also show that maintainability is an importance measure that can be used as a guideline for managing efforts made for the improvement of aircraft components.Item Open Access A modular path planning solution for Wire + Arc Additive Manufacturing(Elsevier, 2019-05-11) Michel, Florent; Lockett, Helen L.; Ding, Jialuo; Martina, Filomeno; Marinelli, Gianrocco; Williams, Stewart W.Wire + Arc Additive Manufacturing (WAAM) has proven its capability to build medium to large metallic parts thanks to its high-rate deposition and its potentially unlimited build volume. Moreover, the low-cost equipment and the ability to deposit various metals make WAAM a strong candidate to become a standard industrial process. However, like all Additive Manufacturing (AM) technologies, the key to manufacturing suitable parts lies in the generation of an optimised path that guarantees a uniform defect-free deposition. Most AM technologies have been able to use traditional path strategies derived from CNC machining, but the specificities inherent to the arc deposition make the use of those solutions unreliable across a variety of topologies. Nevertheless, studies have shown that superior results can be achieved by using a feature-based design approach, but developing a path strategy for each new geometry would be a very time-consuming task. Therefore, this paper introduces the Modular Path Planning (MPP) solution that aims to incorporate the modularity of feature-based design into the traditional layer-by-layer strategy. By dividing each layer into individual deposition sections, this method allows users to adapt the path planning to the targeted geometry allowing the construction of a wide variety of complex geometries. This paper also proposes a software implementation that limits user interventions and reduces user inputs to basic CAD modelling operations. Moreover, the MPP has been compared to a traditional path planning solution and used to build a complex part for industry.Item Open Access Product service systems and supply network relationships: an exploratory case study(MCB University Press, 2011-03-01T00:00:00Z) Lockett, Helen L.; Johnson, Mark; Bastl, Marko; Evans, StephenPurpose - In recent years there has been increasing interest in Product Service Systems (PSS) as a business model for selling integrated product and service offerings. To date there has been extensive research into the benefits of PSS to manufacturers and their customers, but there has been limited research into the effect of PSS on the upstream supply chain. It is this gap that this research seeks to address. Design/Methodology/Approach - The research uses case based research which is appropriate for exploratory research of this type. In depth interviews were conducted with key personnel in a focal firm and two members of its supply chain and the results were analysed to identify emergent themes. Findings - The research has identified differences in supplier behaviour dependent on their role in PSS delivery and their relationship with the PSS provider. In particular it suggests that for a successful partnership it is important to align the objectives between PSS provider and suppliers. Originality/ value - This research provides a detailed investigation into a PSS supply chain and highlights the complexity of roles and relationships among the organisations within it. It will be of value to other PSS researchers and organisations transitioning to the delivery of PSS. Keywords - Product Service Systems, Servitization, Supply Networks, Relationships, Case Study, Product LifecycleItem Open Access A rapid product development environment for post-graduate student aircraft design projects(2005-10-27T00:00:00Z) Lockett, Helen L.; Fielding, JohnPost-graduate education in aircraft design needs to prepare students for their future roles as professional engineers in the aerospace industry. A key requirement from industry is for students to learn how to deal with realistic open ended design problems during their University education, and group design projects have been shown to provide an excellent means to develop these skills. Cranfield University has a long history of teaching aircraft design using group design projects. This paper describes a recent initiative to extend the scope of the group design projects at Cranfield to incorporate rapid prototyping activities and give students hands-on experience of translating a digital design into a physical prototype.Item Open Access System-in-use methodology : a methodology to generate conceptual PSS (Product-Service Systems) and conventional designs using systems-in-use data(Cranfield University, 2013-03) Hussain, Romana; Lockett, Helen L.; Kingston, Jennifer; Alcock, Jeffrey R.Industries want to add value to their offerings but to do this, rather than just accepting customer requirements, they now need to know how their products and/or services have been embedded within their customer’s process to achieve a goal that the customer has; any gaps within the process then present an opportunity for the provider to fill these gaps. The System-In-Use (SIU) Methodology presented in this thesis facilitates customer issues in “pulling” the supply chain into creating new solutions as well as the supply chain “pushing” new value propositions into improving customer processes. It does this by drawing on a detailed theory of value and capability which was developed as part of this research. The method has been applied in five industries in processes encompassing high value-assets with very positive outcomes for each of the stakeholders involved: notably, three solutions have been adopted in industry for which a KT-Box award was granted by Cambridge University. Cont/d.Item Open Access Using requirement-functional-logical-physical models to support early assembly process planning for complex aircraft systems integration(Elsevier, 2020-01-10) Li, Tao; Lockett, Helen L.; Lawson, CraigThe assembly line process planning connects product design and manufacturing through translating design information to assembly integration sequence. The assembly integration sequence defines the aircraft system components installation and test precedence of an assembly process. This activity is part of the complex systems integration and verification process from a systems engineering view. In this paper, the complexity of modern aircraft is defined by classifying aircraft system interactions in terms of energy flow, information data, control signals and physical connections. At the early conceptual design phase of assembly line planning, the priority task is to understand these product complexities, and generate the installation and test sequence that satisfies the designed system function and meet design requirements. This research proposes a novel method for initial assembly process planning that accounts for both physical and functional integrations. The method defines aircraft system interactions by using systems engineering concepts based on traceable RFLP (Requirement, Functional, Logical and Physical) models and generate the assembly integration sequence through a structured approach. The proposed method is implemented in an industrial software environment, and tested in a case study. The result shows the feasibility and potential benefits of the proposed method.