Browsing by Author "Bhatnagar, R."

Now showing 1 - 2 of 2
  • Thumbnail Image
    ItemOpen Access
    Integrated product development methodology using dual mode QFD and functional hierarchy applied to a real case implementation
    (2015-03-18) Al-Bdour, N.; Hameed, Amer; Bhatnagar, R.
    Technological developments are extremely fast paced in the modern world. However, application of new approaches in production of products has to be balanced against economic constraints. Consequently, with the development of new technologies and while striving for effective, efficient and low cost products, new and complex product development methodologies have evolved to develop a concept. Getting to know customer needs and their priorities to establish a new concept is critical in the development process. The research outlined herein utilises the established methodologies of the Kano, Analytic Hierarchy Process (AHP), and Quality Function Deployment (QFD) techniques to identify top-level core user requirements and the technologies that can lead to effective and competitive product development. Application of the above tools has allowed the development of an “Integrated Dual Mode QFD” analysis that offers a more holistic coverage of the customer needs spectrum compared with the traditional QFD, this is done by associating the priorities and competitiveness of individual needs through both of AHP and Kano methods. This approach avoids inconsistencies in customer needs and priorities. Systems specifications obtained from the QFD analysis were used to undertake development of a functional model. This activity links the ‘Whys’ with ‘Hows’ that lead to the development of a system architectural model. Using the above tools, a modular architecture concept has been developed for a Militarised All-Terrain Vehicle (MATV). The architecture offers future variants with improved performance in terms of power, agility, dash speed, reduced weight, mobility based survivability and network-centric communication for better situational awareness. Overall this methodology allows a comprehensive systematic approach to concept development resulting in shorter system design and development time, while ensuring all aspects of customer voices have been taken into account to avoid costly integration issues later in the validation and verification stage.
  • Thumbnail Image
    ItemOpen Access
    Modelling and design of a dual channel magnetorheological damper
    (2013-10-08) Bhatnagar, R.; Hameed, Amer; Purdy, David J.
    A limitation with the current analytical models for predicting the performance of a magnetorheological (MR) damper is that they fail to capture the hysteretic variation of force versus velocity variation correctly. This can significantly underestimate the damper force and overestimate the dynamic range of the device. In this work a transient analytical fluid dynamics model is developed by using a combination of Laplace and Weber transform and Duhamel’s superposition of velocity boundary condition, to overcome these limitations. The solution of the system of nonlinear simultaneous equations, obtained by applying mass flow balance, velocity compatibility conditions and force equilibrium of Bingham plastic plug flow, gives the damper force. This method is shown to generate direct and inverse model of an MR device. The proposed model has been validated against a commercially available MR damper at low speed, to a range of test signals. The mean error using the above model has been shown to be 5% for all the test signals. This compares well with three conventional models which give; transient constant velocity model 35%, quasi static model 35% and phenomenological model 35%. The phenomenological model gives 10% mean error for a sinusoidal input signal. The application of the proposed analytical model has been demonstrated by the design of a novel dual channel damper. The design of the electromechanical components has been shown to be np-hard problem and the optimisation using genetic algorithm has been applied to minimise the volume and electrical time constant. The performance of the dual channel damper has been simulated for various combinations of values of shear yield stress for two channels. Compared to the conventional single channel damper the novel design is shown to give 30% higher damper force, 50% improved dynamic range and limits the effect of transients to within 10% of the damper force. The dual channel damper is an effective solution to resist the onset of turbulent flow in the channels up to 20m/s piston velocity.