Every Reliability Engineer will be familiar with the Weibull Analysis. Most of us even have an Excel template laying around that we refer to!
The problem is, that when we have to handle Suspended data (e.g. components that haven’t failed yet at time of observation), the Excel sheet must use VBA in the background if the user wants a “single-button” tool.
Find below a link to download a VBA driven Weibull Calculator I developed a while back. This tool is a “Single -Button” calculator but is powerful enough to handle “Suspended data” for a more comprehensive analysis.
This calculator outputs:
-Weibull Plot, Beta and Eta Values, R^2 value
-Reliability Function, Survival Function, Hazard Rate and Probability Distribution Charts
Weibull Analysis is one of the most powerful tools a Reliability/ Mechanical Engineer can have in their pocket. Used practically since the 60’s, it was a method of moving away from S-curves and using a distribution that was flexible enough to model infant, random and age related failures.
The outputs of the 2- Parameter Weibull Analysis, Beta and Eta describe the failure rate and Characteristic Life.
These outputs have been used to quantitatively adjust maintenance tactics, spares holding, system reliability and quality control.
Some pitfalls Engineers must consider:
– This type of analysis can only be used at the component-level, not the system level (Don’t go perform a single Weibull analysis on an entire Haul Truck)
-This analysis only works for a single failure mode. If you have multiple failure modes present in your data, the linearized Weibull plot will have an S-bend and a lower R^2 value.
I hope you get as much use out of this as I do!
Download the Calculator HERE. at the end of the article.
Leave a Reply