Statistical Unbalance Prediction for Blisk Balancing Land Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for balancing blisks are inefficient and costly due to their complexity and high potential for non-conformance, and existing methods for predicting unbalance are overly conservative, resulting in excessive balancing lands that counteract the weight savings of blisks.
Innovation Solution
A method that predicts initial unbalance in bladed disks or rings by defining a statistical distribution of mass moment weights, restricting it to a selected range, and calculating the initial unbalance using Monte Carlo simulations, allowing for the reduction of balancing lands while ensuring all blisks can be balanced.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional methods are used to predict initial unbalance in blisks, then all possible unbalance cases are covered, but the size of balancing lands becomes excessively large (65-83% larger than necessary)
Solution Approach 1:
The patent changes the approach from deterministic worst-case parameter analysis to statistical parameter distribution analysis. By defining probability distributions for blade mass moments and using Monte Carlo simulation, the method transforms the parameter prediction from conservative extreme values to statistically probable values, reducing balancing land size while maintaining adequate reliability.
Solution Approach 2:
The patent replaces the mechanical/deterministic calculation method with a computational statistical method. Instead of using deterministic formulas that assume worst-case scenarios, the invention uses Monte Carlo simulation to model the actual probabilistic nature of manufacturing variations, achieving more accurate and less conservative predictions.
2Weight of moving object
If blisks are used instead of conventional rotors with detachable blades, then weight is reduced by 20-60%, but manufacturing complexity and cost increase significantly
Solution Approach 1:
The patent merges the blade and disc into a single integrally formed component (blisk), eliminating the need for detachable blade attachments. This consolidation removes fixtures, fasteners, and assembly interfaces, achieving weight reduction of 20-60% while the statistical balancing method helps manage the increased manufacturing complexity through optimized balancing land design.
3Power
If blisks are used instead of conventional rotors, then thrust to weight ratio increases, but it becomes impossible to balance by interchanging blades
Solution Approach 1:
The patent applies preliminary action by predicting and compensating for unbalance during the design and manufacturing phase. The statistical method calculates probable unbalance characteristics before the blisk is produced, allowing balancing lands to be designed into the component that pre-compensate for expected variations, eliminating the need for post-assembly blade interchangeability.
4Reliability
If sacrificial balancing lands are provided on blisks, then unbalance can be corrected, but the component becomes heavier than necessary
Solution Approach 1:
The patent applies partial action by providing only the minimum necessary balancing land mass required to correct the statistically predicted unbalance, rather than over-designing with excessive balancing land. The Monte Carlo simulation determines the actual needed compensation, allowing balancing lands to be sized appropriately without adding unnecessary weight.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A method for predicting initial unbalance in a component comprising one or more elements, the method comprising: defining a statistical distribution of a mass moment weight of each of the one or more elements; restricting the statistical distribution to a selected range; and calculating an initial unbalance of the component for the restricted distribution of the one or more elements.