Multidisciplinary Design Analysis, Automation and Optimisation of a Thrust Reverser Actuation System
Structural and aerodynamic analysis have always acted separately with one’s results being fed to the other through a drawn out design process. Technology now allows us to use programs such as Microsoft Excel, Visual Basic and Matlab to write command files for these analyses software (CATIA, ANSYS and PATRAN) so to achieve a design process with minimal user input and much more efficient design loop iterations. This project involves using the afore mentioned software to do just that. The problem is the design of a component used during the thrust reversal of an aircraft during its landing phase. The process proposed in this project is robust enough that it is, in essence, a software architecture that can be applied to any multidisciplinary design problem.
After the process for multidisciplinary analysis has been built and the stress and fluids models validated against experiments, sample points of the design space can be analyzed and a surrogate model built. The surrogate model can then act as a pre-design tool allowing the capability of quick exploration of the design space by changing the design variables (customer requirements) to create optimized configurations and therefore decision making.
Regardless of advances made to design and costing methodologies aircraft programs are still overrunning expected cost and time estimates putting tremendous strain on an already over burdened industry and economy. In order to address this problem, potential errors in new designs and processes must be more rigorously investigated earlier in the design process.
Currently this research is investigating using Value Driven Design methodologies in attempt to predict cost and time overruns through the effective use of historical information and preliminary design data. Through the advancement of these methods it is anticipated that preliminary design decisions will be made based on more factually and economically accurate information.
Starting with a Surplus Value function it is suggested that through the use of built in situation specific scaling factors, a robust product and program can be generated that is less sensitive to potential delays and cost impacts.
This research is aimed at reducing the certification time and costs associated with introducing light weight composite materials for aerospace structural applications. Certification requires extensive and lengthy physical testing to understand the performance limitations of the material in the presence of worst case manufacturing defects. It is proposed to capture the key characteristics of manufacturing defects using state of the art non-destructive evaluation techniques and integrate idealised representations with a computer generated virtual test environment, simulating the material and structural response. Such an analysis tool offers the potential to better align current design, manufacturing and certification test methodologies allowing the trade off between material systems and design concepts while reducing the current reliance on expensive physical testing. By reducing certification time and cost, a barrier to the further implementation of efficient composite material systems for aerospace applications may be lowered.
Simulation and process validation techniques are well established when modelling the assembly processes for traditional metallic components both in aerospace and ground transport applications. There is currently a shortcoming in computer aided methods which can simulate the complex behaviours associated with composite components as they are designed and manufactured, prior to final assembly. Digital manufacturing techniques can simulate assembly sequences using ‘as designed’ forms but the reality of using composite components is that part variability can cause problems during assembly as the ‘as manufactured’ form does not match the geometry used for any simulated build validation. For this project, an additional layer of simulation methods and tools will be defined and integrated within a digital manufacturing framework to enable composite part form prediction and assembly analysis. This will cover the current gap between part design and final assembly simulation. Predictive methods for thermoforming-induced deformations on thermoplastic composite parts (CF/PPS) are currently under development to support more realistic composite part forming simulations and assembly build validations.
Automated, Value Driven Design of Future Transport Vehicles for Minimal Lifecycle Impact
Current design processes used within the aviation industry make use of the traditional Systems Engineering (SE) requirements based approach; however, this method does have its limitations as it is unable to account for all design issues such as environmental concerns within the conceptual design phases. These issues are considered towards the end of the design process where any required changes would result in additional expenditure in both time and money.
One way to address this problem would be to use the recently developed Value Driven Design (VDD) process. Unlike SE, this approach strives to design products for maximum value rather than satisfying individual requirements. VDD makes use of a system value model which uses customer requirements as inputs which can then be optimised in order to produce a design with maximum value.
Current work has focused on the development of a VDD system value model known as surplus value. This function accounts for many issues such as passenger costs and airline costs as well as manufacturer costs. Results obtained to date have shown that this method has the ability to help engineers make decisions they would traditionally shy away from. For example, it has been seen that introducing an advanced material may increase manufacturing costs as well as weight; however, it can also increase value when compared to a traditional metallic aircraft.
Future work will aim to modify and enhance this objective function to ensure all issues can be adequately accounted for within the early design stages ultimately resulting in an economically viable, environmentally friendly final design.
Enhancing the effectiveness of the decision making process for vehicle design in the presence of fuzzy requirements
To ensure the successful design of next generation transport vehicles, well-considered complex decisions need to be taken early. However as the design process develops requirements undoubtedly change and may vary considerably from the conceptual design; leading not only to long delays but cost overruns as well. Additionally the designer must also ensure that conflicting requirements such as reducing weight and minimising cost are balanced throughout the entire design stage to guarantee that the final design produces optimum value to the customer. Therefore with the aid of mathematical model and fuzzy logic it is envisaged that difficult design trade-offs and changing requirements can be completed simultaneously with less uncertainty, giving a more robust design.