Thrust reversers are commonly fitted to jet engines and are subjected to pressurised hot airflows when in operation. As a safety-critical aircraft part, accurate assessments of the working stresses is essential.
The task related to a new engine thrust reverser structure design and the engineering challenges on this for Jesmond Engineering included the construction of a fully operational Thrust Reverser Finite Element Model, subjected to all critical flight and ground load conditions. These conditions included internal pressure, external pressure, thermal loading and inertial loading.
Jesmond Engineering initially constructed the Finite Element Model (FEM), and verified this model by applying test load cases and comparing the resulting deflections and strains with those measured during physical testing. Some minor adjustments were then made to the model to ensure that a good correlation was achieved with the test results. Load cases represented the aircraft flight and ground conditions in the stowed and deployed configurations. In addition, special load cases covered scenarios such as bolt failure or engine fire. The load cases were made up of a combination of inertial loading, thermal loading and aerodynamic internal and external pressures.
Results from the FEA showed good correlation with the test results and the full Quality Assurance Checking of the model completed the FEM task, prior to the results being used for Static and Fatigue & Damage Tolerance check stress analysis.
The FEM results were subsequently used as part of the Static and Fatigue check stress analysis by the client. The FEM and stress calculations formed a crucial part of the client’s Thrust Reverser certification and airworthiness process.
