Session: 24-01 Additive Manufacturing - Session 1

Paper Number: 122766

122766 - Effect of Heat Treatment and Multiple Passes Through Resonance on Damping and Vibration Frequencies of Additively Manufactured Structure With Inherent Damping 

To meet current market demands, modern engines need: to operate with higher load, operate at higher firing temperatures, to startup and shutdown faster and more frequently. Therefore, the blade must be more often designed as the resonance-proof component under circumstances of the variable engine speed and varying thermal conditions. One of solutions to this challenge is damping optimization through advanced design of parts. Additive Manufacturing (AM) provides additional design space and capabilities for blading engineers. Introduction of inherent damping (energy dissipation between loose, non-melted metal powder particles) can increase damping by more than one order of magnitude comparing to ‘solid’ component. On the other hand AM parts often require additional Heat Treatment (HT) or Hot Isostatic Pressing (HIP) to reduce residual stresses and porosity. Additionally, components are affected by multiple passes through resonance and long-term exposure to vibrations during their service life. All these factors can cause changes in the powder: wear, compaction, fragmentation of compaction, micro-welding, sintering, sinter cracking and fragmentation. The changes are affecting damping and dynamic characteristics of structure.

Several mock-up components has been studied. Three designs have been manufactured using LPBF technology: a baseline ‘solid’ beam, beam with one large pocket with loose powder, beam with sixteen small pockets with pins and loose powder. All beams where then scanned using Computed Tomography (CT) in as-built condition. Then, the damping ratio has been assessed for all components using electrodynamic shaker – the response was measured by laser vibrometer. The third beam (with sixteen small pockets) was subjected to Heat Treatment, CT-scanned and tested again. Several sweeps through resonance were executed and CT-scans were performed on this mock-up. The results of shaker tests show significant damping ratio changes: almost complete disappearance of inherent damping after HT, partial restoration of inherent damping after first resonance passing and damping changes during further runs. Performed CT-scans show formation of the powder sinter after HT and progressive sinter fragmentation caused by resonance passing cycles.

Presenting Author: Grzegorz Moneta Lukasiewicz Research Network – Institute of Aviation,

Presenting Author Biography: Dr. Grzegorz currently holds a position as a Head of Numerical Analysis and Design Department in the Lukasiewicz Research Network – Institute of Aviation. The main area of his interest are topics related to Additive Manufacturing technologies, especially: coupling simulations with experiments, development of novel NDT methods, industrialization, practical solutions for the industry. Previously he was working by industrialization of SLM technology for leading turbomachinery companies, like Alstom Power Switzerland and Ansaldo Energia Switzerland. He earned his PhD degree at Warsaw University of Technology in 2019 for dissertation topic "Damping Optimization of Turbine Blades Vibrations".

Authors:

Grzegorz Moneta Lukasiewicz Research Network – Institute of Aviation,
Slawomir Cieslak Lukasiewicz Research Network – Institute of Aviation
Wojciech Wdowinski Lukasiewicz Research Network – Institute of Aviation
Maciej Malicki Lukasiewicz Research Network – Institute of Aviation
Sebastian Szalkowski Lukasiewicz Research Network – Institute of Aviation
Michal Fedasz Lukasiewicz Research Network – Institute of Aviation
Sebastian Piecka Lukasiewicz Research Network – Institute of Aviation
Konrad Raczko Lukasiewicz Research Network – Institute of Aviation
Jakub Pilczynski Lukasiewicz Research Network – Institute of Aviation