Author(s)

M. Bily, V. Kliman & J. Prohacka

Abstract

Optimal fatigue limit improvement of components with a mandrelized hole M. Bily, V. Kliman, J. Prohacka Institute of Materials and Machine Mechanics of the Slovak Academy of Sciences, Racianska 75, 836 06 Bratislava, Slovak Republic ABSTRACT A model of fatigue limit improvement by hole mandrelizing is proposed containing residual stress (strain), stress-strain curve transformation, structural material changes, material fatigue properties and technological factors. The role of each factor is assessed using the Haigh diagram and the optimal mandrel oversize, yielding the maximum fatigue limit increase, is determined. Theoretical conclusions are experimentally veri- fied at aluminium alloy specimens with a hole. INTRODUCTION Cold hole mandrelizing is commonly used for enhancement of fatigue properties of components, consisting in drawing an oversize mandrel through a lubricated hole (Fig. 1). Although this techniques

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