This paper presents a static test rig called “Octopus” designed for the validation of numerical models aimed at calculating nonlinear dynamic response bladed disk with underplatform dampers (UPDs). The supports on fixture and each UPD is pressed against blade platforms by wires pulled dead weights. Both excitation system measurement are noncontacting. features design setup noncontacting generated electromagnets placed under blade. A traveling wave according to desired engine order shifting...

Abstract A joint between two components can be seen as a means to transmit dynamic information from one side the other. To identify joint, reverse process called decoupling applied. This is not straightforward coupling, especially when substructures have three-dimensional characteristics, or sensor mounting effects are significant, interface degrees-of-freedom (DoF) inaccessible for response measurement and excitation. Acquiring frequency functions (FRFs) at DoF, therefore, becomes...

This paper focuses on flexible friction dampers (or “strips”) mounted the underside of adjacent turbine blade platforms for sealing and damping purposes. A key parameter to ensure a robust trustworthy design is correct prediction maximum frequency shift induced by strip damper coupling blades. While this topic has been extensively addressed rigid dampers, both experimentally numerically, no such investigation available as far are concerned. builds authors’ prior experience with investigate...

Results of X-ray residual stress measurements on Inconel 718 turbine shaft samples are here proposed. The paper presents part the EU STREP project VERDI activity, where aim was to supply those who numerically simulate machining process with an experimental database proved reliability. Measurements were planned a set machined different levels cutting speed and feed rate. Due attention given assessment uncertainty results. A surface values depth profiles is presented estimated both values. be...

The paper presents the experimental activity about dynamic response of blades a gas turbine for power generation carrying underplatform dampers. final aim is to provide an data base validate results numerical tool which calculates with have fir tree attachments and asymmetric damper fitted between blade platforms. behavior detected by campaign on two mounted in test rig. Stepped sine measurements are performed closed-loop control system excitation amplitude. Different levels amplitude...

The paper presents an original multiple excitation system based on electromagnets with force control. is specifically designed in order to investigate the dynamics of bladed disks, since it mimics existing a real engine. Moreover, suitable for forced response tests disks nonlinear dynamic response, like case presence friction contacts, amplitude exciting known good precision. For this purpose, device called force-measuring electromagnet (FMEM) was and employed during calibration. applied...

The paper shows the results of experimental activity about dynamics a stage counter-rotating turbine an open rotor architecture engine. tests presented here explore dynamic behavior simplified stage. test show and highlight importance presence dry friction for vibration damping.

The purpose of this paper is to offer a practical demonstration how essential preoptimization in the design underplatform dampers for turbine blades. Preoptimization can be thought as “prescreening” which allows excluding, since early stages, high number poorly performing damper–platform configurations. This concept, previously presented by authors, here extended and its generality all blade bending modes rigorously demonstrated. addresses test case where introduction curved-flat necessary...

Abstract Underplatform dampers are used to limit the resonant vibration of turbine blades. In recent years, various strategies have been implemented maximize their damping capability. Curved-flat preferred ensure a predictable bilateral contact, while pre-optimization procedure was developed exclude all those cross-sectional shapes that will bring damper roll and thus amount dissipated energy. The bases its predictions on assumption effective width flat contact interface corresponds nominal...

Finding efficient and accurate solution methods for nonlinear equilibrium equations is a challenging task. This the case of systems with friction-induced nonlinearities, e.g., friction-damped turbomachinery assemblies automotive applications such as brakes. In order to tackle this strategic task, several have been developed, both in time frequency domains. Time marching are regarded most option, but their computational cost becomes prohibitive when friction nonlinearities present. poses...

This paper deals with the dynamic of blades strip dampers. The purpose is 1) to present results numerical calculation, 2) demonstrate need for experimental data on blade-strip contact be used as input 3) propose a new test rig design obtain them and 4) key components rig. forced responses two coupled by damper are calculated at different excitation centrifugal force values. dependence parameter values confirmed in this significant reference case. then proposed: both blade frequency response...

The present paper is focused on the post processing of data coming from Blade Tip-Timing (BTT) sensors in case where two very close peaks are frequency response vibrating system. This type dynamic with can occur quite often bladed disks. It related to fact that disk not perfectly cyclic symmetric and so called “mistuning” present. A method based fitting BTT by means a 2 degrees freedom (2DOF) model proposed. Nonlinear least square optimization technique employed for identification vibration...