In this paper strains recorded by strain gages mounted around the hole during cold working process in seven pieces specimens, were analyzed by statistical tests and stochastic properties of mentioned random variables were obtained using SPSS software. | Residual strains around cold worked holes from statistical view Engineering Solid Mechanics 2 2014 131-138 Contents lists available at GrowingScience Engineering Solid Mechanics homepage esm Residual strains around cold worked holes from statistical view E. Pooladia and Kh. Farhangdoosta a Department of Mechanical Engineering Ferdowsi University of Mashhad Mashhad Iran ART ICLE INFO ABSTRACT Article history Cold working a hole decreases tendency of fatigue crack initiation and growth near the hole. It Received September 20 2013 is due to creation of some compressive tangential residual stresses around the hole. But there Received in Revised form are many uncertainties which affect the residual strain and residual stress field. In fact these October 14 2013 uncertainties lead to have scatter in the test results and considering the residual strains and Accepted 22 January 2014 Available online residual stresses as random variables. In this paper strains recorded by strain gages mounted 24 January 2014 around the hole during cold working process in seven pieces specimens were analyzed by Keywords statistical tests and stochastic properties of mentioned random variables were obtained using Cold work SPSS software. The residual strains have been also distributed by normal probability Experimental study distribution function. Residual strain Residual stress Statistical distribution 2014 Growing Science Ltd. All rights reserved. 1. Introduction Cold working process which increases fatigue life of components consists of pushing a mandrel with greater diameter into the hole with smaller size named loading step and then removing it which is called unloading step. During the loading step an annular plastic zone is created around the hole which is surrounded by the remaining elastic region and during the unloading step the elastic region compresses the plastic zone and some residual stresses will be remained around the hole. In fact compressive .
