My background is mostly test engineering & test management. I worked with Reliability Engineers in the old company but now am trying to find my own way through the Weibull statistical labyrinth. In the old company I worked for we had several years of prior fatigue data with similar designs to fall back on and now that data has gone away with the demise of the old company. We’re early in the design phases and don’t have physical test samples yet, still trying to budget test and prototype cost at this point for a similar part at a new company.

So let’s say we have budgeted 5 samples for fatigue life testing of a simple welded steel structure with well-defined loads and constraints. I would like to be able to prove 90% reliability with 90% confidence to 1x expected life of product.

Given the Weibayes equations I’ve found I can play around with cycle count to get various reliability percentile but I have to guess at Beta (slope). Anyone know where I can find examples of “typical” Weibull Beta for welded tubular structures?