CERES is a European Union funded project in which the major engine manufacturers in Europe (Rolls Royce, UK; MTU, Germany; SNECMA, France) are participating to advance the existing technology in rotordynamics by producing improved engine dynamic models for engine response prediction purposes.

Currently, the validation process for aero-engine structures is based on several test methods, including static strength and flexibility measurements, vibration modal tests and tests where the engine is run with deliberately seeded out of balance. Static flexibility measurement, and especially engine running tests, are expensive and have long lead times for them to be realised.

In CERES, vibration modal tests on smaller sub-assemblies and individual structural components are used to obtain a valid model for an aero-engine assembly such that it can be used in engine response predictions.

The research at the Vibration UTC mainly focuses on how to design optimum modal tests for components and sub-assemblies such that critical information about the engine’s rotor dynamic behaviour can be obtained from the component and sub-assembly level modal test for model validation.

The design of optimum tests for components and subassemblies is divided into three major sub-tasks in CERES. In the first sub-task, design FE models’ simulations are used to identify the optimum test configurations for the component and subassembly modal tests. At the UTC, new pioneering methods are developed and used to identify these optimum test configurations.

In the second sub-task, once the appropriate test configuration(s) for the component have been identified, the test set-up is optimised using design FE models so that all the necessary information can be obtained from the modal test. Again, new methods are developed in CERES for this optimisation process. 

Finally, once the components have been validated using modal tests, the interfaces connecting them need to be validated using some form of test procedure. However, unlike the components which exhibit linear behaviour, the interfaces behave predominantly in a nonlinear fashion. In CERES, new testing and characterisation techniques are developed to obtain information about the interfaces’ behaviour to validate their corresponding analytical models.

The prediction of aircraft engine dynamics using these validated models are crucial for the design and production of safer, lighter and more efficient aero-engine structures. This will allow the aero-engine industry to shorten the time required for engine development and thereby to reduce the time to market. Furthermore, this will contribute to the reduction of costs in production and maintenance.