Two Strip Setting-Up and Verification Program for Peening Intensity

Author:  Dr. David Kirk | Coventry University
Source:  The Shot Peener magazine, Vol 39, Issue 1, Winter 2025
Doc ID:  2025006
Year of Publication:  2025
Abstract:  
INTRODUCTION The most accurate method of estimating peening intensity is to produce and analyze a saturation curve constructed from the arc heights of four (or preferably more) peened Almen strips. There are, however, situations where it is expedient to employ a quicker, albeit less accurate, method. These include when a new set-up is being developed and when an established set-up has to be periodically verified. This article presents a simple computer program that optimizes two-strip setting-up and verification testing. Fig.1 shows the basic features of peening intensity estimation based on the arc heights of four Almen strips peened for different time periods. These time periods can be actual times but are commonly integral numbers of passes or strokes of the shot stream over the Almen strip. The peening intensity is preferably estimated as the unique ‘time’ for which doubling that time produces a precise 10% increase in arc height. That unique time, T, will rarely coincide with an integral number of passes. Moreover, each strip’s arc height falls somewhere within an error band. Computer programs, such as the Solver suite, easily and objectively derive the unique peening intensity, H, that occurs at the defined time, T. The required objective is that H shall lie between userdefined upper and lower values. A feature of saturation curves is that, for a steady shot stream, they all have a characteristic shape. This shape corresponds to a mathematical equation. The set of data points (arc height versus peening time) can be computer fitted to a known mathematical equation.


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