Determination of a Graph\u27s Chromatic Number for Part Consolidation in Axiomatic Design

Mechanical engineering design practices are increasingly moving towards a framework called axiomatic design (AD). A key tenet of AD is to decrease the information content of a design in order to increase the chance of manufacturing success. An important way to decrease information content is to fulfill multiple functional requirements (FRs) by a single part: a process known as part consolidation. One possible method for determining the minimum number of required parts is to represent a design by a graph, where the vertices are the FRs and the edges represent the need to separate their endpoint FRs into separate parts. The answer is then the chromatic number of such a graph. This research investigates the suitability of using two existing algorithms and a new algorithm for finding the chromatic number of a graph in a part consolidation tool that can be used by designers. The runtime complexities and durations of the algorithms are compared empirically using the results from a random graph analysis with binomial edge probability. It was found that even though the algorithms are quite different, they all execute in the same amount of time and are suitable for use in the desired design tool

Defining next-generation additive manufacturing applications for the Ministry of Defence (MoD)

“Additive Manufacturing” (AM) is an emerging, highly promising and disruptive technology which is catching the attention of the Defence sector due to the versatility it is offering. Through the combination of design freedom, technology compactness and high deposition rates, technology stakeholders can potentially exploit rapid, delocalized and flexible production. Having the capability to produce highly tailored, fully dense, potentially optimized products, on demand and next to the point of use makes this emerging and immature technology a game changer in the “Defence Support Service” (DS2) sector. Furthermore, if the technology is exploited for the Royal Navy, featured with extended and disrupted supply chains, the benefits are very promising. While most of the AM research and efforts are focusing on the manufacturing/process and design opportunities/topology optimization, this paper aims to provide a creative but educated and validated forecast on what AM can do for the Royal Navy in the future. This paper aims to define the most promising next generation Additive Manufacturing applications for the Royal Navy in the 2025 – 2035 decade. A multidisciplinary methodology has been developed to structure this exploratory applied research study. Moreover, different experts of the UK Defence Value Chain have been involved for primary research and for verification/validation purposes. While major concerns have been raised on process/product qualification and current AM capabilities, the results show that there is a strong confidence on the disruptive potential of AM to be applied in front-end of DS2 systems to support “Complex Engineering Systems” in the future. While this paper provides only next-generation AM applications for RN, substantial conceptual development work has to be carried out to define an AM based system which is able to, firstly satisfy the “spares demands” of a platform and secondly is able to perform in critical environments such as at sea

Process comparison study. MSFC Center Director's Discretionary Fund (CDDF)

A process comparison study was conducted using four different advanced manufacturing techniques to fabricate a composite solid rocket booster systems tunnel cover. Costs and labor hours were tracked to provide the comparison between the processes. A relative structural comparison of the components is also included. The processes utilized included filament winding, pultrusion, automated tape laying, and thermoplastic thermoforming. The hand layup technique is also compared. Of the four advanced processes evaluated, the thermoformed thermoplastic component resulted in the least total cost. The automated tape laying and filament winding techniques closely followed the thermoplastic component in terms of total cost; and, these techniques show the most promise for high quality components and lower production costs. The pultruded component, with its expensive tooling and material requirements, was by far the most expensive process evaluated, although the results obtained would not be representative of large production runs

Strategic, tactical decisions and information in Rapid Manufacturing supply chain

The efficiency and agility of its supply chain is vital to the commercial success of any product. Sharing strategic and tactical information effectively within the supply chain is often a key factor in achieving this goal. This paper proposes a framework to identify strategic, tactical decisions and information. The framework is used to conduct a sector based analysis of the Rapid Manufacturing (RM) industry. The decisions and information identified include amongst others various supply chain strategies and technical information

Numerical investigation of high and low pressure tube hydroforming

Hydroforming is one option to reduce vehicle weight while increasing component stiffness and rigidity. This typically involves using a fluid to form a component with high internal pressure. Tube hydroforming has gained increasing interest in the automotive and aerospace industries because of its many advantages such as part consolidation, good quality of the formed part etc. The main advantage is that the uniform pressure can be transferred to whole part at the same time. In low pressure hydroforming, the internal pressure is significantly and the hydroformed section length of line stays almost the same as the circumference of the blank tube. This paper details the comparison between high and low pressure hydroforming. It is shown that the internal pressure and holding force required for low pressure hydroforming process is much less than that of high pressure. Also stress and thickness distribution are more uniform and the process is highly suitable for the forming of advanced high strength steels.<br /

A design framework for additive manufacturing based on the integration of axiomatic design approach, inverse problem-solving and an additive manufacturing database

Additive manufacturing has emerged as an integral part of modern manufacturing because of its unique capabilities and has already found its application in various domains like aerospace, automotive, medicine and architecture. In order to take the full advantage of this breakthrough manufacturing technology, it is imperative that practical design frameworks or methodologies are developed and consequently, Design for Additive Manufacturing (DfAM) has risen to provide a set of guidelines during the product design process. The existing DfAM methods have certain limitations in that the additive manufacturing process capabilities are not taken into consideration in the early design stage effectively and most of them rely on direct application of existing methods for conventional manufacturing. Furthermore, there is a lack of DfAM methods suitable for additive manufacturing novices. To tackle these issues, this study develops a design framework for additive manufacturing through the integration of axiomatic design approach and theory of inventive problem-solving (TRIZ) with the consideration of additive manufacturing environment. This integrated approach is effective because axiomatic design approach can be used to systematically define and analyze the problem, while the inverse problem-solving approach of TRIZ combined with an additive manufacturing database can be used as an idea generation tool that can generate innovative solutions. Finally, two case studies are presented to validate the proposed design framework

Designing end use components for additive manufacturing: navigating an emerging field

Despite much excitement, research and development, Additive Manufacturing (AM) as a series production process for end-use components and products is not yet widespread or considered mainstream. However, there is a clear potential for AM to form a viable alternative to many conventional manufacturing processes, especially in low to medium production volumes. A key enabler for this transformation is the capacity to design components and products that are both able to exploit AM capabilities and avoid its limitations. In recent years, many studies have explored the topic of Design for Additive Manufacturing (DfAM). This report presents an overview of the state of the art of this research area. A systematic review has been carried out to identify the most significant academic studies on the topic. The review resulted in 66 key resources being identified and critically reviewed. These resources have been reviewed and categorised using a generic model of the design process. This categorisation provides and easy and immediate way to map and navigate this emerging field. Consequently, five major research areas are presented: 1. Process planning 2. Detail design 3. Embodiment design 4. Conceptual design 5. Design processes In the discussion, these research areas are examined with the aim of highlighting shortcomings and providing future research directions

Design and evaluation of additively manufactured parts with three dimensional continuous fibre reinforcement.

Additive manufacturing (AM) provides many benefits such as reduced manufacturing lead times, streamlined supply chains, part consolidation, structural optimisation and improved buy-to-fly ratios. Barriers to adoption include high material and processing costs, low build rates, isotropic material properties, and variable processing conditions. Currently AM polymer parts are far less expensive to manufacture than AM metal parts, therefore improving the properties of polymer parts is highly desirable. This paper introduces a design methodology used to integrate continuous reinforcement into AM polymer parts with the aim of improving their mechanical properties. The method is validated with the design and testing of three case studies, a pulley housing, hook and universal joint used to demonstrate the applicability of the method for tensile, bending and torsion loading types respectively. Physical testing showed that it was possible to improve the strength of parts by over 4000%, elongation to failure by over 2000% and stiffness by approximately 200%. In addition a method of integrating condition monitoring capabilities into the parts was demonstrated. An analysis of the specific strength of the parts suggests that the reinforced parts are comparable to aluminium alloys, suggesting that in some cases AM polymer composite parts could supplant more costly metal parts