Vibration Characteristics Analysis And Robust Optimization Design Of Mistuned Bladed Disk System

Bladed disk is an important component in engine, the vibration fatigue of blade is always a vitalreason affecting the safety and reliability of engine. Because of manufacture tolerances, wear andmaterial properties, there is small difference between blades (usually below5%), namely themistuning. The vibration localization phenomenon caused by mistuning will results in High CycleFatigue, which has been investigated for decades and yet there is no effective ways to suppress theHCF. In this paper, the conception of robust design will be applied to mistuned bladed disk to analyzethe characteristics of bladed disk and the way of reducing vibration, and explore the possible methodto suppressing the vibration, which will be important in the design of bladed disk.A variety of reasons can lead to mistuning, such as manufacture errors of the length, width andheight of blade, and the blade and disk relative position--blade stagger angle error. In general, theblade mistuning is simulated by changing the elastic modulus of blades, and basic consistentconclusions have got. This paper focuses on a new mistuning—blade stagger angle mistuning andcompare it with blade mistuning.The essence of mistuning is the problem of uncertainty in structural dynamics, the investigationof uncertainty is generally doing under the view of probability and statistics to study the distributionand characteristics. As uncertainty cannot be eliminated, effective vibration suppression method is themain tool to improve the dynamic performance of structure. Robust design is an effective way, robustdesign has been used widely in control theory and structural mechanics, but relatively few instructural dynamics, this paper will apply the Taguchi method to study robustness in this area.Taguchi method is an effective method to improve robustness of the system, it mainly dividesinto the system design, parameter design and tolerance design. In the parameter design, orthogonalexperiment is an effective method, which can effectively reduce the number of experiments andobtain sensitivity of each parameter. In addition, after considering multiple parameter uncertainty inthe uncertainty problem, how to determine the influences of different parameters on the systemperformance has important guiding significance to the actual parameter control.The related concepts on mistuning are introduced in detail. Research progresses and methods arecompared and analyzed. Vibration characteristics of bladed disks are analyzed from a mathematicalmodel; blade mistuning and stagger angle mistuning are studied comparatively. Results indicate that,stagger angle mistuning has little effect to natural frequencies, but has a great effect on the blade response. The forced response will increase with stagger angle mistuning errors. Then, concepts ofrobust design and orthogonal experiment are introduced and the robust design of mistuned bladeddisks using Taguchi method is discussed. In parameter design, based on orthogonal experiment, theinfluences of various parameters on the response are analyzed and a solution that can improve thesystem robustness effectively is got. In tolerance design, orthogonal experiment is extended in orderto analyze multiple parameter uncertainty, which provides an effective method for practicaluncertainty parameter tolerance control.