Search Results

The rising demand for civil aircraft leads to the development of flexible and adaptive production systems in aviation industry. Due to economic efficiency, operational accuracy and high performance these manufacturing and assembly systems must be technologically robust and standardized. The current aircraft assembly and its jigs are characterized by a high complexity with poor changeability and low adaptability. In this context, the use of industrial robots and standardized jigs promise highly flexible and accurate complex assembly operations. This paper deals with the flexible and adaptable aircraft assembly based on industrial robots with special end-effectors for shaping operations. By the development and use of lightweight gripper system made of carbon fiber reinforced plastics the required scaling, robustness and stiffness of the whole assembly system can be realized.

This paper studies the feasibility and potential benefits of aligning recycled carbon fibres, in the form of short individual filaments, to manufacture fibre reinforced polymer composites. A review of fibre alignment processes is presented to provide insight into the different alignment technologies. The main focus is on wet hydrodynamic processes, which offer a high degree of alignment for discontinuous fibres. The process parameters that govern the alignment efficiency are also reported. The effect of alignment on fibre packing efficiency in the manufacture of composites is included, together with a report of preliminary fibre alignment results obtained from three different alignment processes.

The deterioration of combustion stability as lean operating limits and misfire conditions are approached has been investigated experimentally. The study has been carried out on spark ignition engines with port fuel injection and four-valves-per-cylinder. Test conditions cover fully-warm and cold operation, and ranges of air/fuel ratio, exhaust gas recirculation rates and spark timing. An approximate method of calculating gas/fuel ratio is described. This is used to show that combustion stability, characterised by the coefficient of variation of i.m.e.p., is a function of calculated gas/fuel ratio and spark timing until near to the limit of stability. A rapid deterioration in stability and the onset of weak, partial burning occurs at a gas/fuel ratio between 24:1 and 26:1 under fully-warm operating conditions, and around one gas/fuel ratio lower under cold operating conditions.

The increased severity and prevalence of insoluble deposits formed on fuel injectors in gasoline direct injection (GDI) engines precipitates negative environmental, economic and healthcare impacts. A necessary step in mitigating deposits is to unravel the molecular compositions of these complex layered materials. But very little molecular data has been acquired. Mass spectrometry shows promise but most techniques require the use of solvents, making them unsuited for analyzing insoluble deposits. Here, we apply the high mass-resolving power and in-situ analysis capabilities of 3D OrbitrapTM secondary ion mass spectrometry (3D OrbiSIMS) to characterize deposits formed on the external tip and internal needle from a GDI injector. This is the first application of the technique to study internal GDI deposits. Polycyclic aromatic hydrocarbons (PAHs) are present up to higher maximum masses in the external deposit.

The dilution of lubricating oil by fuel has adverse effects on engine wear, oil lubricity, air/fuel ratio control and feedgas emissions. Dilution is one of the factors limiting oil change intervals. The level and rate of accumulation depend on engine operating conditions and patterns of vehicle use. The work reported here develops and evaluates an empirical model to predict accumulation characteristics. This is aligned to requirements for predictions of dilution build-up in service. Predictions are shown to be in good agreement with data given in the literature. The model is used to investigate the influence of patterns of vehicle use on dilution.

Studies of diesel system deposits continue to be the subject of interest and publications worldwide. The introduction of high pressure common rail systems resulting in high fuel temperatures in the system with the concomitant use of fuels of varying solubilizing ability (e.g. ULSD and FAME blends) have seen deposits formed at the tip of the injector and on various internal injector components. Though deposit control additives (DCAs) have been successfully deployed to mitigate the deposit formation, work is still required to understand the nature and composition of these deposits. The study of both tip and internal diesel injector deposits (IDID) has seen the development of a number of bench techniques in an attempt to mimic field injector deposits in the laboratory. One of the most used of these is the Jet Fuel Thermal Oxidation Tester or JFTOT (ASTM D3241).

There is a growing demand for composites to be utilised in the production of large-scale components within the aerospace industry. In particular the demand to increase production rates indicates that traditional manual methods are no longer sufficient, and automated solutions must be sought. This typically leads to automated forming processes where there are a limited number of effective options. The need for forming typically arises from the inability of layup methods to produce complex geometries of structural components. This paper reviews the current state of the art in automated forming processes, their limitations and variables that affect performance in the production of large scale components. In particular the paper will focus on the application of force and heat within secondary forming processes. It will then review the effects of these variables against the structure of the required composite component and identify viability of the technology.

This paper describes work being conducted by OC Robotics and Airbus to develop snake-arm robots to conduct assembly tasks within wing boxes - an area currently inaccessible for automation. The composite, single skin construction of aircraft structures presents new assembly challenges. Currently during box close-out it is necessary for aircraft fitters to climb into the wing box through small access panels and use manual or power tools to perform a variety of tasks. In future wing designs it may be that certain parts of the wing do not provide adequate access for manual assembly methods. It is also known that these manual interventions introduce health and safety concerns with their associated costs. Snake-arm robots provide a means to replace manual procedures by delivering the required tools to all areas of the wing box. Such a development has broader implications for aircraft design and assembly.

This paper describes work being conducted by OC Robotics and Airbus to develop snake-arm robot technology suitable for conducting automated inspection and assembly tasks within wing boxes. The composite, single skin construction of aircraft structures presents new challenges for robotic assembly. During box close-out it is necessary for aircraft fitters to climb into the wing box through a small access panel and use manual or power tools to perform a variety of tasks. These manual interventions give rise to a number of health and safety concerns. Snake-arm robots provide a means to replace manual procedures by delivering the required tools to all areas of the wing box. The advantages of automating in-wing processes will be discussed. This paper presents early stage results of the demonstration snake-arm robot and outlines expectations for future development.

A new method of installing LGP collars onto titanium lock bolts has been brought into production in the Airbus wing manufacturing facility in Broughton, Wales. The feed system involves transporting the collar down a rectangular cross-sectioned hose, through a rectangular pathway in the machine clamp anvil to the swage die without the use of fingers or grippers. This method allows the reliable feeding the collars without needing to adjust the position of feed fingers or grippers relative to the tool centerline. Also, more than one fastener diameter can be fed through one anvil geometry, requiring only a die change to switch between certain fastener diameters. In our application, offset and straight stringer geometries are accommodated by the same anvil.

Airbus commercial wings are assembled manually in dedicated steel structures. The lead time to design, manufacture and commission these fixtures is often in excess of 24 months. Due to the nature of these fixtures, manufacturing is slow in responding to changes in demand. There is underused capacity in some areas and insufficient ramp-up speed where increased production rate is needed. Reconfigurable Manufacturing Systems and Reconfigurable Assembly Systems (RAS) provide an approach to system design that provides appropriate capacity when needed. The aim of the paper is to review RAS technologies that are suitable for cost-effective wing structure assembly and what knowledge gaps exist for a RAS to be achieved. The paper examines successful cases of RAS and reviews relevant system design approaches. Cost savings are acknowledged and tabularised where demonstrated in research. The research gaps to realising a RAS for wing assembly are identified and different approaches are considered.

The thermal efficiency of an internal combustion engine at steady state temperatures is typically in the region of 25-35%[1]. In a cold start situation, this reduces to be between 10% and 20% [2]. A significant contributor to the reduced efficiency is poor performance by the engine lubricant. Sub optimal viscosity resulting from cold temperatures leads to poor lubrication and a subsequent increase in friction and fuel consumption. Typically, the engine lubricant takes approximately twenty minutes [3] to reach steady state temperatures. Therefore, if the lubricant can reach its steady state operating temperature sooner, the engine's thermal efficiency will be improved. It is hypothesised that, by decoupling the lubricant from the thermal mass of the surrounding engine architecture, it is possible to reduce the thermal energy loss from the lubricant to the surrounding metal structure in the initial stages of warm-up.

This paper describes a high-speed electrical machine for an aircraft starter-generator. A surface mounted permanent magnet machine is designed to have minimal rotor losses and a novel cooling system for the stator. An inner stator sleeve is adopted to allow for a flooded stator whilst minimizing rotor windage losses. Different slot-pole combinations are compared in view of attaining an optimal combination that provides minimum losses whilst satisfying the electromagnetic, mechanical and thermal constraints.

This paper will present the latest development of a configurable and modular steel construction system for use in frameworks of flexible fixtures of the kind called Affordable Reconfigurable Fixtures (ART). Instead of a dedicated aircraft fixture, which is very time consuming and expensive, the ART fixtures enable affordable construction from a standard component kit, by solving the main drawbacks of traditional tooling. In early 2009 Airbus UK built the first steel modular fixture for the aerospace industry. The project was a partnership with DELFOi and Linköping University in a project called ReFlex, Reconfigurable Flexible Tooling. A paper was presented in the last year SAE conference which explained about the project in overall. The construction system called BoxJoint has recently been tested in some manufacturing areas at Airbus UK and also been applied in the production at Saab Aerospace Linköping Sweden.

The Airbus A400m has carbon fibre wing panels on both the upper and lower surfaces. When manufactured, these panels come supplied with various lugs on the periphery of the panel. Some are used for lifting the panel, some are used for indexing the panel; however, all lugs must be removed at some time during wing build. Lug thickness varies from 4mm to 14mm; in addition, many lugs must be cut to a 2D profile rather than just straight. The main challenge of the project was to deliver a tool that was small, portable and compact, but that could also accurately slot thick carbon fibre panels, without de-lamination, leaving a good surface finish. The solution was an air powered routing hand tool that was mechanically guided along a 2D path using a cam profile. Special diamond grit cutters were used to cut the initial slot and reduce the machining forces to a bare minimum, with the finishing cut done using a PCD router bit to obtain a good surface finish.

Reconfigurable tooling frames consisting of steel box sections and bolted friction clamps offer an opportunity to replace traditional expensive welded steel tooling. This well publicized reconfigurable reusable jig tooling has been investigated for use in the assembly of a prototype compound helicopter wing. Due to the aircraft configuration, the wing design is pinned at both ends and therefore requires a higher degree of end to end accuracy, over the 4m length, than conventional wings. During the investigation some fundamental issues are approached, including: Potential cost savings and variables which effect the business case. Achievable Jig accuracy. Potential sources of instability that may affect accuracy over time. Repeatability of measurements with various features and methods. Typical jig stability over 24hrs including effects of small temperature fluctuations. Deflections that occur due to loading.

The influence of size and concentration of carbon nanoparticle on the viscosity of an SAE 5W-30 lubricant oil has been investigated experimentally. Data were collected for oil samples drawn from sump of light duty automotive diesel engines. The average size of soot particles in the used oil samples was in the range of 180-320nm with concentrations ranging from 0 to 2 percentage by weight (wt. %.). A Brookfield DV-II Pro rotary viscometer was used to measure dynamic viscosity at low shear rates and temperatures of 40°C and 90°C. Nanoparticle concentration and particle size distribution were evaluated using Thermo-Gravimetric Analysis (TGA) and Dynamic Light Scattering (DLS) respectively. The viscosity of suspensions of graphite powder in lubricant oil was also investigated for concentrations ranging from 0 to 2 wt. %. The results show that dynamic viscosity increases with increasing soot content and decreasing temperature.

This paper details the development of a user-friendly computerised tool created to evaluate the Manufacturing Readiness Levels (MRL) of an emerging technology. The main benefits achieved are to manage technology development planning and tracking, make visually clear and standardised analysis, and improve team communication. The new approach is applied to the Technology Readiness Levels (TRL), currently used by Airbus Research & Technology (R&T) UK. The main focus is on the improvement of the analysis criteria. The first phase of the study was to interpret the manufacturing criteria used by Airbus at TRL 4, including a brief benchmarking review of similar practices in industry and other Airbus' project management tools. All information gathered contributed to the creation of a complete set of criteria.

Electric machines offering a high power density are required for aerospace applications. Soft magnetic material with a high saturation flux density is one of the key component which is required to realize these power density targets. The need for a high saturation flux density necessitates the use of cobalt iron lamination over the conventional silicon steel. However, cobalt iron is very expensive i.e. order of 10 in comparison to silicon steel. Stator segmentation is identified as an appropriate method to reduce the wastage and cost associated with lamination. Consequently, in this paper, stator segmentation is analyzed on a 1.35 MW, 16-pole 48-slot propulsion machine. The impact of manufacturing is accounted by controlling the resulting airgap between the segmented structures. Electromagnetic performance for various segmented topologies are compared in terms of torque, torque ripple, and iron loss.

Electric machines in aerospace applications are subjected to extremely high operating temperatures. This increases coercivity or decreases saturation flux density of the electrical steel resulting in increased core loss. The need for high power density and increased operating speed favours the use of thin gauge Silicon Steel (Si-Fe) and Cobalt Iron (Co-Fe) laminations for aerospace applications. Therefore, the variation in iron loss is studied for three grades of Si-Fe laminations by subjecting them to controlled ageing in laboratory. The analysis is also provided over a range of flux density and frequency to generalize the phenomenon over the operating domain. The results of ageing the laminations are in turn used to predict the degradation in performance of a 1.15 MW, 16-pole 48-slot propulsion machine for aerospace application. The degradation is estimated in terms of variation in iron loss.