Automotive companies are searching for new, innovative materials that attempt to redefine what is traditionally associated as a ‘luxury material’. Market research shows that future customers will demand tangible sustainability in vehicle interiors through the use of eco-friendly materials. However, research has also identified customer scepticism towards the quality of green products sold by luxury brands. The perception of quality is typically determined by peripheral and sensorial product properties such as styling, shape and touch. The uncertainty of new materials compounded by the need to balance sustainability, sensory and emotional appeal mean it is no longer possible to rely on the designers’ intuition and experience to evaluate materials. Rigorous, robust methods which include both objective material assessments and the quantification of subjective, sensory and experiential attributes will maximize the chance of successful adoption by customers. They can also offer further insight, such as demonstrating that the Perceived Quality (PQ) of a cheaper material can be improved just by making the material softer using a foam backing, as was found in this research. To address this, a new process has been developed to measure the perceived haptic quality of soft automotive interior materials. Studies were conducted in the UK and Hong Kong to generate user-defined metrics. Of these metrics, roughness and hardness had the largest impact on PQ, so mechanical testing was conducted to obtain objective measurements of both. The subjective and objective measurements were found to correlate strongly, implying that objective measurements alone could indicate a customer’s opinion of these materials. The final stage of the process introduces a statistical model which uses the objective data to predict PQ scores. This is based around an Artificial Neural Network validated as accurate to within 4.5%. A graphical user interface was designed so practitioners can use the model to predict how customers may respond to a new material or a change in the surface characteristics of an existing material, without needing to conduct the initial customer research. The process has been integrated in part within the sponsor company and has influenced future research and business strategy in this area.

Although flutter analysis is a relatively old problem in aviation, it is still challenging, particularly with the advent of composite materials and requirements for high-speed light airframes. The main challenge for this problem is at the transonic flow region. The transonic flow, being non-linear, poses a great challenge over traditional linear theories which fail to predict the aerodynamic properties accurately. Aerospace has been one of the primary areas of applications to take advantage of composite materials with the aim to reduce the total mass and improve control effectiveness. This work takes advantage of CFD methods advancement as the main flow solver for non-linear governing equations. In order to investigate the dynamic behaviour of composite aircraft wings, the dynamic stiffness method (DSM) for bending-torsion composite beam is used to compute the free vibration natural modes. The main objective of this work is coupling the dynamic stiffness method (DSM) with high fidelity computational fluid dynamics models in order to predict the transonic flutter of composite aircraft wings accurately and efficiently. In addressing the main aim of this study, Euler fluid flow solvers of an open source CFD code called OpenFOAM has been coupled with elastic composite wing, represented by the free vibration modes computed by DSM. The first part of this study is devoted to investigating the free vibration characteristics of two types of aircraft, namely sailplane type and transport airliner type. Two models of each type have been analysed and contrasted, which revealed the significance of the natural modes of aircraft wings and how these modes inherently capture the essential characteristics of the system. Then to validate the CFD code, two pitching and self-sustained two degrees of freedom airfoils under different flow condition have been modelled. The results have been compared against experimental measurements and numerical data from the literature which showed good agreement for the predicted force coefficients. Finally, the model has been extended to study a complete aircraft wing. Both metallic and composite Goland wings have been investigated under a wide range of flow conditions. The composite wing has been investigated using different material coupling values to show their effect on its aeroelastic behaviour. The results showed the significant influence of the material coupling on the aeroelastic characteristics of composite wings.

Motivated by the enlarged design space and additional flexibility offered by the latest advances in manufacturing techniques, especially Additive Manufacturing (AM), this thesis investigates a novel turbine end-wall aerothermal management method with the engineered surface structures, through closely coupled experi-mental and numerical studies. A 90-degree turning duct and a linear turbine cascade test section were employed for the experimental research in a low-speed wind tunnel. Duct and turbine end-wall heat transfer and cooling effectiveness were measured by transient Infrared Thermography. PIV measurement was conducted to obtain the exit flow field. Computational fluid dynamics (CFD) simulations were performed using ANSYS FLUENT to compliment the experimental findings. The flow solver uses the finite volume method to solve the three-dimensional Reynolds-Averaged Navier-Stokes (RANS) equations. The k-ω shear stress transport (SST) turbulence model was validated and chosen for all the numerical studies. The secondary flow control principle of the engineered surface structure in the simplified duct is revealed through a detailed investigation of the flow produced by multiple small surface structures. The CFD and PIV measurement results consistently show that addition of the engineered surface structure on end-wall can effectively reduce the magnitude of streamwise vorticity associated with the secondary flow and alleviate its lift-off motion. For turbine cascade applications, it can be observed that the strength of the passage vortex is effectively reduced, and the passage vortex loss core moves closer to the end-wall with the addition of the engineered surface structure. The purge air cooling enhancement by the engineered surface structure is then studied. The purge air cooling flow becomes more attached to the end-wall and covers a larger wall surface area with the added end-wall rib structures. Both experimental and numerical results reveal a consistent trend on improving film cooling effectiveness and net heat flux reduction (NHFR). This novel concept was success-fully demonstrated in a more realistic turbine cascade case. Enhanced cooling effectiveness and net heat flux reduction were obtained from both experimental data and CFD analysis. The additional surface features were proved to be effective in reducing the passage vortex and providing more coolant coverage without introducing additional aerodynamic loss. The overall Net Heat Load Reduction for the 90-degree turning duct and the turbine cascade is increased by 11% and 2% respectively.

As projected manufacturing rates for commercial aircraft increase to levels of multiple ship sets per day from individual manufacturing facilities, GE Aviation have expressed the need for a shift in composites secondary structure manufacturing philosophy. Traditional manufacturing processes tend to be touch labour intensive and hence costly. The manual placement of large numbers of individual ply profiles, lengthy debulking operations and complex cure cycles, result in excessive component lead times and manufacturing costs. As a result, direct labour cost is a major factor in the total economies of production processes. The implementation of industrial robotics has proved highly successful in automotive manufacturing, and various methods for automating individual aspects of the composites manufacturing process have been suggested. Technical cost modelling has been used to anticipate the production costs of a prototype secondary structure component, as supplied by GE Aviation, through direct simulation of the existing manufacturing process. This work has clearly highlighted the potential for cost and cycle time reductions if process automation can be successfully introduced. Observation of the existing manufacturing process has allowed three alternative manufacturing scenarios to be considered with respect to cost-effectiveness and feasibility, whilst highlighting long term cost benefits. Investigations have been undertaken to identify and evaluate alternative material and processing methodologies ranging from resin infused woven dry fabrics to UD prepreg tape and tow. In addition, candidate processing routes have been systematically evaluated using design of experiments techniques, which focussed on assessing the feasibility and technology readiness of robotic deposition and consolidation methodologies, including pick and place and debulking. Process automation in these areas has the potential for total component cost and cycle time reductions in the order of 2.8 to 21.6 and 0.6 to 63.4 per cent respectively. The quasi-static mechanical testing of a range of face sheet materials has provided a performance assessment based on tensile, compressive and shear properties and laminate Vf. Findings suggest that materials offering increased suitability for automation typically have reduced mechanical performance when compared to candidate prepregs; tensile modulus and strength reductions of 5 and 34 per cent were reported when comparing a 6k woven 2X2 twill fabric and equivalent prepreg respectively. Furthermore, 26 and 4 per cent reductions in tensile modulus and 38 and 40 per cent reductions in tensile strength were observed for 179 and 318gsm UD NCF, when compared with a candidate UD prepreg. Data has also been presented on the effect of varying the traditional consolidation frequency and methodology. While earlier findings suggest that debulking has little effect on the laminate tensile modulus; ply compaction level varies considerably. Furthermore, it has been shown that on-the-fly consolidation, using a robotically mounted, roller-based end effector has the advantages of mechanical performance retention, cycle time reduction and repeatable laminate post cure thickness. In addition, when compared with candidate woven and UD prepreg laminates manufactured using the traditional vacuum bagging approach; equivalent tensile modulus, strength and fibre volume fraction have been observed and with less variability. Handling characteristics inherent to vacuum and needle grippers, including pickup performance, defined as the pickup or holding force required to overcome fabric weight, shear force performance; the maximum force that can be exerted on the fabric before the onset of slip, and the accuracy with which non-rigid-materials (NRMs) can be handled, have also been considered. The achievable positional accuracy of robotically pick and placed prepreg plies greatly exceeds that of dry fabrics in all cases and with less variability, irrespective of the gripping mechanism used. Vacuum grippers exhibit more uniform positional error and increased positional accuracy when handling dry fabrics, whilst needle grippers outperformed the vacuum alternative when handling prepregs, irrespective of form. Robotic pick and place solutions offer low variability in ply positional error with a guaranteed placement accuracy of ±0.8mm and ±2.3mm for prepregs and dry fabrics respectively. Characterisation of the gap type defect and butt and overlapping joining methodologies has provided a performance trend based on ply positional error. Quasi-static mechanical testing has revealed that laminates with equivalent tensile modulus to an un-spliced control could be achieved. However, significant reductions in the tensile strength and an increase in overall laminate thickness and thickness variation highlighted the negative effect of ply splicing on laminate performance. However, it has been shown that a robotic placement accuracy of ±0.8mm gives rise to acceptable tensile strength reductions in candidate prepreg laminates. The up-scaling of laminate level robotic manipulators has been discussed and addressed in conjunction with the commissioning of a flexible robotic manufacturing cell, facilitating the manufacture of full-scale secondary structure aerospace components. Comparisons have been made between a benchmark prepreg panel, manufactured using traditional manual methods and alternative dry fabric and prepreg panels manufactured using increased levels of process automation. In each case, manufacturing feasibility, mechanical performance and component geometric accuracy have been assessed. It has been shown that there are significant advantages to be gained from the implementation of robotic automation within the traditional manufacturing process. Component cost and cycle time reductions, coupled with the processing and performance advantages and increased suitability to automation of woven dry fibre materials are clear. Findings which support a key driver of this project, which seeks to justify alternative dry fabrics as a viable alternative to traditional prepreg broadgoods for the manufacture of secondary structure aerospace components.

Because of their considerably higher fuel efficiency compared to turbofans, turboprop aircraft are the best choice for short and middle-haul flights. Yet, propeller acoustic emissions need to be reduced to comply with future noise certification standards, and to improve the comfort of passengers and crew. The CFD solver of the University of Glasgow, HMB3, was first validated for propeller aerodynamics and acoustics against JORP and IMPACTA wind tunnel data, and then employed for comparing different innovative designs and installation options to identify the quietest solution. OSPL and frequency tonal spectra were directly computed from (U)RANS results. Cabin noise was estimated via experimental transfer functions. The design of the propeller is the key to decrease the emitted sound at source level. A blade design that moves the loading inboard and operates at lower rotational speed yielded relevant noise gains (up to 6 dB in OSPL) without strong performance penalties. Hub configurations meant to redistribute the acoustic energy over more frequencies did not clearly appear more pleasant for passengers. The presence of the airframe modifies the propeller inflow, and causes additional noise sources as well as sound waves reflections. The need of simulating the whole airplane in real operating conditions to accurately estimate in-flight noise was shown. For a twin-engined high-wing aircraft with propellers in phase at cruise conditions, the counter-rotating top-in layout was found the quietest, with a benefit in interior OSPL of more than 4 dB compared to co-rotating propellers. The inboard-up propeller rotation led louder noise because of the higher blade loading on the fuselage side, and of constructive sound waves interferences. The latters are instead used favorably from propeller synchrophasing, promoting noise cancellation. This strategy was shown to provide more than 3 dB of OSPL noise reduction inside the cabin on co-rotating propellers, whereas propellers in-phase appeared the best operating option for the counter-rotating top-in layout.

The phenomenon of cavitation is of great importance when ship propellers and rudders are considered, as it can often be the cause of vibrations, noise, reduced efficiency and even erosion in some instances. The underlying fracture mechanisms of erosion, however, have not been fully understood yet. As such, this study aims to expand our knowledge regarding the fracture mechanisms of common shipbuilding alloys and explore whether cavitation erosion can be monitored, by using the relevant quantitative and qualitative data. As such, an experimental test rig was built, based on the induction of cavitation by ultrasonic means, in order for a series of tests, including mass loss and acoustic emission measurements as well as microscopic observations to be conducted. Due to the interest of BAE Systems, a number of protective coatings were also examined under an analogous context. Specimens were initially exposed to ultrasonically induced cavitation under identical experimental conditions. Mass loss was periodically measured thus materials were categorized in that respect while the positive effect of cathodic protection on the resulting erosion was confirmed. Examination through optical and scanning electron microscopes was also conducted thus the fracture mechanisms and macroscopic characteristics of cavitation erosion were identified, for each of the examined materials. Results showed that, erosion initiates through plastic deformation (orange peeling) before proceeding into ductile and brittle, due to work hardening, fracture, whereas the extent and crack propagation characteristics of each phase, depend on the material’s mechanical properties and crystalline structure. Acoustic emissions were also examined, with the aim of, characterizing the materials and potentially be utilized for erosion monitoring. Upon the successful establishment of acoustic thresholds for cavitation erosion, in the case of small specimens, a small model rudder was also examined under an analogous context, although in that instance, cavitation localization was also considered, through a triangulation source location technique. In that instance, cavitation induced erosion, was effectively monitored and characterized both in terms of intensity and location. A model rudder twice as large as the small one was also examined in order for any possible scale effects to be identified. Cavitation induced erosion, was again effectively monitored, both in terms of intensity and location, although results indicated that the method should be optimized, with respect to the parameter of size. As such, the future researcher could further promote the evolvement of the aforementioned ship rudder monitoring system, by means of optimizing the analytical procedures in order to overcome any possible scale effects, further adapting the characteristics of the system to match the size of the objects to be monitored and eventually lead to the full – scale application of the system. The conduction of sea trials would also be of great benefit and importance towards the direction of forming a solid cavitation erosion monitoring system.

A method to design foot trajectory in Cartesian coordinates for a six-leg walking machine is presented in this thesis. The walking machine is based on the geometry of the darkling beetle. The walking procedure developed by Y.S. Baek is introduced first to provide step length and leg swing time for foot trajectory planning. This procedure also supplies required parameters to describe the relationship between feet and body during locomotion. The trajectory of a single foot consists of the path and its temporal attributes, that is, velocity and acceleration. Several methods and constraints for path and velocity profile design are discussed. Software developed in Microsoft Quick C is used to generate and animate on the screen a single desired foot trajectory applied to each of the six legs by combining paths and velocity profiles. The generated trajectory is converted to joint coordinates to provide necessary data for leg control. Since a single foot trajectory is applied to three pairs of legs of different design, three sets of joint coordinate sequences are produced. Furthermore, each leg consists of three segments and three joints necessitating nine control sequences altogether. Half-ellipse and trochoidal paths are interpolated with 5th and 6th order polynomials to determine minimum required joint acceleration. All paths and their first and second derivatives are required to be smooth. The effect of body pitch are also examined. / Graduation date: 1995

Thesis (Ph. D.)--University of Texas at Austin, 2003. / Vita. Includes bibliographical references. Available also from UMI Company.

Thesis (M.S.)--West Virginia University, 2001. / Title from document title page. Document formatted into pages; contains xvi, 112 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 85-87).

Thesis (M.S.)--West Virginia University, 2003. / Title from document title page. Document formatted into pages; contains x, 100 p. : ill. (some col.). Vita. Includes abstract. Includes bibliographical references (p. 82-84).