Joseph Butterfield

Optimization of aircraft fuselage assembly process using digital manufacturing

The work demonstrates the benefits of using digital methods for the development and optimization of large assembly manufacturing networks. Although an aircraft assembly has been used for this work, the methods and advantages of digital manufacturing techniques, which are demonstrated here, are equally applicable to any large assembly process, such as those used in the automotive, railway, and shipbuilding industries. The introduction of manufacturability into the design arena using advanced computer aided methods means that manufacturing engineers can operate more directly in assembly planning and concurrent engineering design. Network analyses carried out on the final assembly operations for a regional jet fuselage section using a methodical, step by step approach, shows that the process efficiency for workers carrying out fitting operations can be more than doubled when compared to existing shop floor performance figures. The more efficient use of operator time results in a simulated 19% improvement in financial efficiency, as the actual working hours required for assembly are reduced to below budgeted levels. The simulation predicts that these results can be achieved with one final assembly station. With two stations currently in use for the fuselage section, this means that a significant financial saving is possible in tooling expenditure.

Aircraft Cost Modelling using the Genetic Causal Technique within a Systems Engineering Approach

The paper is primarily concerned with the modelling of aircraft manufacturing cost. The aim is to establish an integrated life cycle balanced design process through a systems engineering approach to interdisciplinary analysis and control. The cost modelling is achieved using the genetic causal approach that enforces product family categorisation and the subsequent generation of causal relationships between deterministic cost components and their design source. This utilises causal parametric cost drivers and the definition of the physical architecture from the Work Breakdown Structure (WBS) to identify product families. The paper presents applications to the overall aircraft design with a particular focus on the fuselage as a subsystem of the aircraft, including fuselage panels and localised detail, as well as engine nacelles. The higher level application to aircraft requirements and functional analysis is investigated and verified relative to life cycle design issues for the relationship between acquisition cost and Direct Operational Cost (DOC), for a range of both metal and composite subsystems. Maintenance is considered in some detail as an important contributor to DOC and life cycle cost. The lower level application to aircraft physical architecture is investigated and verified for the WBS of an engine nacelle, including a sequential build stage investigation of the materials, fabrication and assembly costs. The studies are then extended by investigating the acquisition cost of aircraft fuselages, including the recurring unit cost and the non-recurring design cost of the airframe sub-system. The systems costing methodology is facilitated by the genetic causal cost modeling technique as the latter is highly generic, interdisciplinary, flexible, multilevel and recursive in nature, and can be applied at the various analysis levels required of systems engineering. Therefore, the main contribution of paper is a methodology for applying systems engineering costing, supported by the genetic causal cost modeling approach, whether at a requirements, functional or physical level.

Intelligent Assembly Time Analysis Using a Digital Knowledge-Based Approach

The implementation of effective time analysis methods fast and accurately in the era of digital manufacturing has become a significant challenge for aerospace manufacturers hoping to build and maintain a competitive advantage. This paper proposes a structure oriented, knowledge-based approach for intelligent time analysis of aircraft assembly processes within a digital manufacturing framework. A knowledge system is developed so that the design knowledge can be intelligently retrieved for implementing assembly time analysis automatically. A time estimation method based on MOST, is reviewed and employed. Knowledge capture, transfer and storage within the digital manufacturing environment are extensively discussed. Configured plantypes, GUIs and functional modules are designed and developed for the automated time analysis. An exemplar study using an aircraft panel assembly from a regional jet is also presented. Although the method currently focuses on aircraft assembly, it can also be well utilized in other industry sectors, such as transportation, automobile and shipbuilding. The main contribution of the work is to present a methodology that facilitates the integration of time analysis with design and manufacturing using a digital manufacturing platform solution.

Use of Digital Manufacturing to Improve Operator Learning in Aerospace Assembly.

The process of learning in any manufacturing enterprise contributes significantly to product lead times, final cost and ultimately, competitiveness. It effects all contributors to the product development cycle including individual operators and supervisors on the shop floor, as well as those involved in the upstream disciplines of engineering, tooling design, methods, production control and design. Any improvement in learning can significantly reduce the number of hours tied up in the learning curve thereby reducing costs, especially in the preliminary stages of new product manufacture. A relatively small percentage improvement in the time taken to build the first five fuselage assemblies for a regional aircraft would result in a financial saving that is of the order of

An Integrated Approach to the Conceptual Development of Aircraft Structures Focusing on Manufacturing Simulation and Cost Analysis

100k. The primary goal of this work is to quantify any benefits that an animated, digital instructional format can have on aerospace assembly learning when compared to more traditional, paper based instructions. Hard copy, illustrated assembly instructions and digital, animated assembly instructions were authored for two engineering assemblies. The first was a relatively simple rear wheel hub from the Queen’s University Belfast, Formula Student racing car the second was the more complex apron and uplock assembly from the Bombardier RJ900 Regional Jet. Controlled experiments were carried out to measure the build times that resulted from the use of each of the two instruction types. The results showed that the average time taken to complete five builds was faster for the groups using digital, animated instructions. This was the case for both the wheel hub and the aircraft panel. The total time taken to carry out the thirty builds for the wheel hub was 20% lower for the group using digital instructions. For the less intuitive panel build, the total time taken to carry out the twenty builds was 14% lower for the group using digital instructions. These results clearly demonstrate that the use of animated build instructions can improve build times. The improvement in learning is less for the more complex aircraft panel assembly.

Enabling value co-production in the provision of support service engineering solutions using digital manufacturing methods

In an increasingly competitive market place manufacturers in the aerospace industry need to improve the efficiency of their product development methods. With fewer new aircraft being developed, innovation needs to switch from product to process technologies such as design, development and manufacturing planning in order to improve efficiency and reduce cost. This paper describes a product development methodology based on automatically generated CAD data which can be used for the structural analyses of and manufacturing planning for, aircraft fuselage sections. The introduction of manufacturability into the design arena makes concurrent engineering design, manufacturing planning and process validation possible before committing to the costly activities of making prototypes and tooling. Network analyses carried out on simulated assembly operations for a regional jet fuselage section, shows that labour utilization can be significantly improved when compared to a real assembly process with a 19% improvement in financial efficiency. The simulation predicts that these results can be achieved with a single final assembly jig. As two jigs are currently used for this assembly operation in reality this result represents a significant financial saving.

Thermoforming carbon fibre-reinforced thermoplastic composites

Traditional engineering business models in aerospace manufacture and deliver finished equipment to the customer. Service provision is typically limited to procedural documentation and providing spare parts to the end user. Commercial pressures have resulted in end users structuring their own core business activities resulting in the need for original equipment manufacturer (OEM) to integrate and manage support service activities in partnership with the customer to deliver the availability of the equipment. This improves the probability of commercial success for the OEM through shared operational risks while reducing the cost of ownership for the customer. This paper applies four of the seven attributes of value co-creation (AVCs) developed by Ng, Nudurupati, and Tasker (2009) required for an integrated and partnered approach to service provision between the OEM and the customer. It also shows how these are supported through applying digital manufacturing methods for the design and implementation of complex service processes.

Developing a Capability Function Relating Aircraft Systems Cost Overruns to Aircraft Design Parameters

The use of carbon fibre composites is growing in many sectors but their use remains stronger in very high value industries such as aerospace where the demands of the application more easily justify the high energy input needed and the corresponding costs incurred. This energy and cost input is returned through gains over the whole life of the product, with for example, longer maintenance intervals for an aircraft and lower fuel burn. Thermoplastic composites however have a different energy and cost profile compared to traditional thermosets with notable differences in recyclability, but this profile is not well quantified or documented. This study considers the key process control parameters and identifies an optimal window for processing, along with the effect this has on the final characteristics of the manufactured parts. Interactions between parameters and corresponding sensitivities are extracted from the results.

An Analytical Study of Surplus Value using a Value Driven Design Methodology

Cost overruns and delays are threatening the economic stability of aerospace programs. In order for programs to be successful overruns in cost and time must be eradicated or managed effectively through realistic Life Cycle Costing methodologies. Being aware of their impact at the earliest stage of development ensures that realistic budgets can be assigned and potential problems can be identified and planned for before they major issues. Using Life Cycle Costing methodologies, the basis of a new capability function aimed at accounting for cost overruns and delays upfront within life cycle management procedures will be introduced. Using gathered data, the main drivers of cost and delay will be identified and their effect on Life Cycle Cost assessed before being included within the new function which aims to achieve the highest economically valuable aircraft and program through the application of value engineering principles.

The Effect of Using Animated Work Instructions Over Text and Static Graphics When Performing a Small Scale Engineering Assembly

People are now becoming more environmentally aware and as a consequence of this, industries such as the aviation industry are striving to design more environmentally friendly products. To achieve this, the current design methodologies must be modified to ensure these issues are considered from product conception through to disposal. This paper discusses the environmental problems in relation to the aviation industry and highlights some logic for making the change from the traditional Systems Engineering approach to the recent design paradigm known as Value Driven Design. Preliminary studies have been undertaken to aid in the understanding of this methodology and the existing surplus value objective function. The main results from the work demonstrate that surplus value works well bringing disparate issues such as manufacture and green taxes together to aid decision making. Further, to date studies on surplus value have used simple sensitivity analysis, but deeper consideration shows non-linear interactions between some of the variables and further work will be needed to fully account for complex issues such as environmental impact and taxes.