Using rain-flow counting methods for process wear out studies

Using rain-flow counting methods for process wear out studies

Guest Post Prepared by Eugene Danneman, Wind Wear LLC

Introduction

Analyzing and visualizing data that is related to equipment wear-out (fatigue stage) over a specific time span is a challenge. Analyzing systems, equipment and components exposed to spectrum loading as opposed to uniform cyclical loading that span years or decades or centuries requires a special approach. Think of roads, bridges and other assets with long life spans that are susceptible to wear out mechanisms caused by external and internal loads, varying load durations, temperature swings and corrosion.

For complex processes that consist of many pieces of equipment and components, it is often useful to take time history data and convert it to a count of the tensile and compressive cycles that equipment was exposed to. That data may be mechanical, thermal, electrical, chemical or some combination of forces that cause the irreversible degradation of the component material being studied. Historical throughput or production data is often the easiest to gather and analyze for “40,000 foot” cycling studies where one significant digit and one order of magnitude accuracy is adequate.

The rain-flow-counting algorithm (also known as the “rain-flow counting method”) is used in the analysis of fatigue data…