| Popis: |
Blade vibrations are a concern when designing turbo machinery. Traditionally, different types of dampers are used to dissipate the mechanical energy and reduce the risk of resonances that lead to high cycle fatigue (HCF). In the case of a blisk for which the blades are integral with the disk, the blades and disk are machined from a single forging, or the blades are frictional welded to the disk. This design is being utilized more in Aviation turbo machinery applications such as the Fans, Boosters, and Compressors. Blisks are prone to larger resonance responses in the absence of damping from the dovetail slot interfaces. To combat this potential issue, new coating materials are being developed to increase the damping of the airfoil.To cost effectively assess the damping qualities of these new coatings, a laboratory apparatus and specimen, intended to emulate the typical modes seen during engine operation, were designed and procured. The specimen’s shoulders are sandwiched between two plates and bolted in an effort to eliminate the introduction of twisting or bending. Applying a load to one end of the specimen causes friction between the plates to transmit a uniform tensile load through the specimen. The open face rig design allows access to the specimen so that it can be excited by an external source. This design will allow for damping measurements to be taken of the excited specimen while it is subjected to a static load.The primary purpose of this thesis is to perform experiments with this new rig in order to validate that the device as constructed meets uniaxial loading requirements of the design intent which is to minimize constraint damping while achieving sufficient strain in the specimen. Initial measurements will be needed to verify that the specimen is in pure tension. Then additional data will validate that the specimen experiences sufficient strain.This thesis will document and discuss the evaluation of the facility design. First, a stress analysis will be performed to determine the tensile loads that will be utilized. Then using ANSYS, the facility and specimen are modeled with the expected boundary conditions (which assume the design intent has been met) at the various predetermined loads. From the initial measurements, the boundary conditions are assessed using the stress and strain distributions to verify that the specimen is in pure tension. |
