【毕设用---外文翻译来源】ANSYS英文论文 (26).pdf

Influence of Contact on the Structural Response of a
Shrouded Fan Blade

W. Scott Zemitis, .
David W. Ballenger
Jan S. Ellis
Belcan Corporation – Advanced Engineering & Technology Division
Abstract
Shrouds are often employed on fans and low-pressure turbines to increase natural frequencies and to
increase damping. Prevention of flutter and minimization of resonant vibration response is critical to
avoiding costly high cycle fatigue problems. Industry experience [Ref. 1] has shown that blade response
can be very sensitive to relatively minor variations in design and operating environment. The goal of this
study is to estimate the variation in low-frequency vibratory response of a shrouded stage 1 fan rotor due to
shroud interface modeling assumptions. In addition to a baseline case that considered no shroud-to-shroud
interaction, four shroud interface conditions were considered that covered a range of reasonable
possibilities: independent guided edges, standard frictionless contact, standard frictional contact (mu=),
standard rough contact (infinite friction). Bonded contact options, putationally attractive, were
not considered since the results can be highly dependent upon the initial shroud geometry. The streamlined
modal cyclic symmetry tools introduced in ANSYS were utilized, and results from both the prestress
and modal analyses were included. The shroud interface assumption was found to have a significant
impact on both the frequency and shape of critical modes, and it was observed that the contact assumption
that most realistically predicts static behavior might not be the best option for the subsequent modal cyclic
symmetry analysis.
Introduction
When analyzing the vibratory response of shrouded gas turbine blades, analysts must choose from several
imperfect options for modeling the blade-to-blade shroud interface. The difficulty arises when the natural
frequencies of a system with active nonl