1,720,987 research outputs found
Design analysis tool for unit cost modelling: a tool for unit cost estimation of gas turbine design within Rolls-Royce
No full textA Metric-based approach to Concept Design
No full textThis paper details work undertaken in the development of a new design method, termed CODA (COncept Design Analysis), to aid the conceptual design and selection phase within new product development. The paper discusses how CODA has evolved from the QFD(Quality Function Deployment) technique, as first proposed by Akao & Mizuno8, and outlines how the new methodology integrates the quality loss function approach as described by Taguchi14 and the work into customer preference trends as described by Kano15, 16.
Some key weaknesses of QFD are identified. A demonstration of how CODA addresses these limitations is shown. A number of simple design examples are given which demonstrate how the ‘voice of the customer is deployed within CODA and how the technique is applied. The paper goes on to discuss the use of optimisation techniques to find trade-off values for complex designs. Finally the paper briefly suggests where CODA fits within an overall concept design process and how it should be applied to develop high value products
Project failure: the planning paradox
No full textThis paper describes the development of a fundamentally novel project representation. It explains the rationale behind this new approach and discusses the problems faced by organisations undertaking the development of large complex projects.
Parallels are drawn between Computational analysis such as Computational Fluid Mechanics (CFD) and Finite Element Analysis and programme management networks.
The paper discusses the use of this new representation implemented as a software tool and reports briefly on the experiences of using it on industry projects
Stress analysis of shaft-tube bonded joints using a variational method
No full textFunctionally modulus graded bondline (FMGB) adhesives can be employed in bonded joints to reduce stress concentration and, hence, achieve higher joint strength. This study presents an analytical framework for the stress analysis of a shaft-tube bonded joint based on a variational technique which minimises the complimentary energy of the bonded system. This cylindrical assembly consists of similar or dissimilar adherends and a FMGB adhesive. The effect of functional grading of adhesive elastic modulus on the peak stresses and their distributions in the adhesive layer are studied. The joint with various modulus grading profiles 15is assessed and the results are compared with a onventional mono-modulus bondline (MMB) adhesive joint. Stress analysis indicates that the peel and shear peak stresses in the FMGB are much smaller and their distributions along bondlength are more uniform than those of MMB adhesive joints under the same axial tensile load. Numerical examples are provided to illustrate the effects of geometrical and material properties on the distributions and intensities of stresses in the bondline. Furthermore, optimal peel and shear strengths of the joint can be achieved by spatially controlling the modulus of the adhesive
On axisymmetric adhesive joints with graded interface stiffness
No full textAn improved analytical model is presented for the stress analysis of interface stiffness graded axisymmetric adhesive joints. The governing integro-differential equation of the problem is obtained through a variational method which minimizes the complementary energy of the bonded assembly. The joint is composed of similar or dissimilar polar anisotropic and/or isotropic adherends and a functionally modulus graded bondline (FMGB) adhesive. The elastic modulus of the adhesive is functionally graded along the bondlength by assuming smooth modulus profiles which reflect the behavior of practically producible graded bondline. Influence of non-zero radial stresses in the bonded system on shear and normal stresses is evaluated. The stress distribution predicted by this refined model is compared with that of mono-modulus bondline (MMB) model for the same axial tensile load in order to estimate reduction in shear and normal stress peaks in the bondline and the adherends. A systematic parametric study indicates that an optimum joint strength can be achieved by employing a stiffness graded bondline with an appropriate combination of geometrical and material properties of the adherends. This model can also be applied to examine the effects of loss of interface stiffness due to an existing defect and/or damage in the bondlin
Modeling of modulus graded axisymmetric adhesive joints
No full textThis study presents a refined theoretical framework for the stress analysis of modulus graded axisymmetric adhesive joints which takes into account the radial stresses in the bonded assembly. This semi-analytical is based on a variational method which minimizes the complementary energy of the bonded system. The joint consists of similar or dissimilar polar anisotropic composite adherends or metallic adherends and a functionally modulus graded bondline (FMGB) adhesive. The elastic modulus of the adhesive is functionally graded along the bondlength by assuming smooth modulus profiles which reflect the behavior of practically producible graded bondline. The stress distribution predicted by this refined model is compared with that of MMB model which also accounts for in the bonded system to estimate reduction in shear and peel stress peaks in the bondline. The axisymmetric stress analysis reveals that the peel and shear stress peaks in the FMGB are much smaller and the stress distribution is more uniform along its length than those of mono-modulus bondline (MMB) adhesive joints under the same axial tensile load. A systematic parametric study has been conducted by selectively perturbing the material and geometrical properties of the joint in order to study their influence onstress distribution in the bondline. Furthermore, the results suggest that the peel and shear strengths can be optimized by spatially controlling the modulus of theadhesive
Applying multiobjective cost and weight optimization to the initial design of turbine disks
Full text linkAerospace design optimization typically explores the effects of structural performance and aerodynamics on the geometry of a component. This paper presents a methodology to incorporate manufacturing cost and fatigue life models within an integrated system to simultaneously trade off the conflicting objectives of minimum weight and manufacturing cost while satisfying constraints placed by structural performance and fatigue. A case study involving the design of a high pressure turbine disk from an aircraft engine is presented. Manufacturing cost and fatigue life models are developed in DECISIONPRO, a generic modeling tool, wheras finite element analysis is carried out in the Rolls-Royce PLC proprietary solver SC03. A multiobjective optimization approach based on the nondominated sorting genetic algorithm (NSGA) is used to evaluate the Pareto front for minimum cost and volume designs. A sequential workflow of the different models embedded within a scripting environment developed in MATLAB is used for automating the entire process
Mapping customer needs to engineering characteristics: an aerospace perspective for conceptual design
Full text linkDesigning complex engineering systems, such as an aircraft or an aero-engine, is immensely challenging. Formal Systems Engineering (SE) practices are widely used in the aerospace industry throughout the overall design process to minimise the overall design effort, corrective re-work, and ultimately overall development and manufacturing costs. Incorporating the needs and requirements from customers and other stakeholders into the conceptual and early design process is vital for the success and viability of any development programme. This paper presents a formal methodology, the Value-Driven Design (VDD) methodology that has been developed for collaborative and iterative use in the Extended Enterprise (EE) within the aerospace industry, and that has been applied using the Concept Design Analysis (CODA) method to map captured Customer Needs (CNs) into Engineering Characteristics (ECs) and to model an overall ‘design merit’ metric to be used in design assessments, sensitivity analyses, and engineering design optimisation studies. Two different case studies with increasing complexity are presented to elucidate the application areas of the CODA method in the context of the VDD methodology for the EE within the aerospace secto
Life cycle cost modelling as an aircraft design support tool
No full textThis article summarizes the work that has been carried out as part of the FLAVIIR project, a 5-year research programme looking at technologies for future unmanned air vehicles (UAVs). This is a UK Engineering and Physical Sciences Research Council funded project sponsored by BAE systems. A framework to estimate the life cycle cost of UAVs is presented. The acquisition costs are estimated using a hierarchical structure and a discrete simulation model is used to estimate the maintenance and operation costs. The architecture to estimate the life cycle cost and the associated models are described. A framework is presented in which the cost models developed can be integrated into the design process to facilitate the comparison between different configurations. It is then demonstrated how this framework can be used to perform trade-off analysis and cost-based optimization
A cost based methodology for design optimization
No full textDesign optimization algorithms have traditionally focused on lowering weight and improving structural performance. Although cost is a vital factor in every emerging design, existing tools lack key features and capabilities in optimizing designs for minimum product cost at acceptable performance levels. This paper presents a novel methodology for developing a decision support tool for designers based on manufacturing cost. The approach focuses on exploiting the advantages offered by combining parametric CAD, Finite element analysis, feature based cost estimation and optimization techniques within a single automated system. This methodology is then applied in optimizing the geometry for minimum manufacturing cost of an engine mounting link from a Rolls-Royce civil aircraft engin
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