Cold working a hole decreases tendency of fatigue crack near the hole to initiate or growth. It is due to creation some compression tangential residual stresses around the hole. But there are many uncertainties which affect on residual strain and so, residual stress field. In fact these uncertainties lead to have scatter in test results and considering the residual strains and residual stresses as random variables. In this paper strains recorded by strain gages mounted around the hole during cold working process in seven pieces specimens, have been analyzed by statistical tests and stochastic properties of mentioned random variables have been obtained using SPSS software. The residual strains have been distributed by normal probability distribution function.

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