Browsing by Author "Hameed, Prof. A."
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Item Open Access The effects of 3D printed material properties on shaped charge liner performance(Cranfield University, 2019) Agu, Henry; Hameed, Prof. A.; Appleby-Thomas, Gareth J.Shaped charges operate by explosively loading a (typically metallic) liner to produce a jet travelling at extremely high velocity (9-12 km/s). Such explosive loading involves highly non-linear transient phenomena. As such, a very wide range of physical processes must be considered to enable accurate characterisation of such events – with material behaviour within these (pressure / strain-rate) regimes providing insight into problems ranging from shaped charge performance itself through to formation of new material phases at high pressures. Unlike other high strain impact events, the shaped charge phenomenon results in hydrodynamic material flow of the liner which is an integral aspect of the shaped charge design. As such, the study of shaped charge liners has been the subject of numerous scientific research studies for over 50 years since its discovery. When explosively loaded, the liner is stretched extensively during their elongation to form a jet. The jet length depends on the ductility of the liner material, and this is strongly linked to the microscopic crystal structure, which depends on the original material properties and the processes used to produce the liners. There are several processes currently used for liner production. This thesis outlines the different liner production techniques, their advantages/disadvantages and explores the potential of employing additive manufacturing (3D printing) technique for shaped charge liner production. As 3D printed parts are being considered as a possible replacement for conventionally processed parts, this PhD work fits into this long-term vision; with built parts compared in density and mechanical strength to their bulk material equivalents. More so, 3D printing is shown to present some potential benefits for the production of efficient liners including high precision, cost-effectiveness and the potential to realise customized geometries. The use of fine powders may also allow alternative microstructures to be produced with potentially interesting results. This element of the study forms the first part of this thesis, aimed at investigating the mechanism elucidating the performance of 3D printed liners processed through direct metal laser sintering process (selective laser sintering) and filament deposition modelling processes (Polylactic Acid). The next part of this work provided additional insights on the additive manufactured processed employed through investigation of the dynamic behaviour of polylactic acid, employed in the filament deposition modelling process and static (optical and scanning micrographs) observation of the laser sintered liners in their as - manufactured and deformed state, in comparison with traditional machined liners. Autodyn 2D numerical hydrocode was employed to understand how temperature influences the deformation pattern (grain refinement); providing new insights on liner deformation. Finally, a novel computational technique to determine the Virtual Origin of shaped charges was developed to provide a ready route to predict more accurate SC performance.Item Open Access Health and usage monitoring system for military vehicles(Cranfield University, 2019) Al Abri, M. S.; Hameed, Prof. A.; Thirulogasingam, Thiru; Khanal, B.The aircraft industry has been able to adopt improved maintenance and logistics planning as a result of the technological advances in Integrated Modular Avionics (IMA) and Equipment Health Monitoring (EHM). Same cannot be said about the land system. In the land environment, military vehicles are well behind in achieving the same abilities and hence, the problem of inefficiency in the maintenance and logistics for land based system needs to be addressed. To address this and assess the viability of integrating HUMS and Autonomic Logistics on military land vehicles, this project was proposed. Three main contributions from this research which adds to the knowledge are: (1) assessment of some real system failure which could lead to a poor operational readiness, (2) evaluation of how HUMS can improve the availability and operational readiness and reduction in maintenance cost that leads to the development of cost model and (3) a use of case studies to evaluate degradation of systems under consideration and how their continuous monitoring can help reduce the maintenance cost. A cost modelling study presented a simple and effective method to analyse the financial implication of integrating HUMS system was proposed for military land vehicles. The model provides logical steps to estimate the yearly repair costs, operational availability and the overall costs to understand the financial implication of HUMS integration over the whole service life. The model was also used to assess the financial viability of integrating HUMS in other military platforms e.g. light armoured vehicle, Piranha and Main Battle Tank, Challenger 2. In both the cases, the analysis showed significant financial savings in the long term. A case study was conducted on two different military vehicles to identify the frequency of different systems and sub-systems failures. The 20 challenger 2 and 40 Piranha were studied over the period of 10 years of service time. Study has found that cooling-, lubrication- and the suspension- system were the mostly affected systems in those particular vehicles. An experimental protocol was developed to study the failure detection techniques for the suspension system. The frequency response function was used to identify the failure of the damper and hence the suspension system. The study has observed the changes in the resonance frequency of the failed suspension system with different excitation magnitudes. Effect of vibration waveform was observed to be negligible. However, the small changes in the resonance frequencies using different magnitudes of base excitation seems to suggest the excitation magnitude has the potential to identify the failure based on the frequency response function.Another experimental protocol was developed to examine the failure detection technique for the cooling system of the military vehicle. When the failure was introduced to the cooling system, the significant variations in the temperature were observed for all the engine running conditions at the lab as well as the test with the vehicle running in the field. The variations observed in the temperature measured in different locations in the cooling system could be used to diagnose an early stage of failure in the cooling system, and it can be used to take a preventive action before the actual failure occurs.Item Open 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, Prof. A.; 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.