TY - JOUR T1 - The study of the effect of bandwidth and loading level parameters of random load histories on the fatigue crack growth in a CT specimen by the central limit theory TT - بررسی تاثیر پارامترهای پهنای باند و سطح بارگذاری اتفاقی بر رشد ترک خستگی در یک نمونهCT با استفاده از تئوری حد مرکزی JF - mdrsjrns JO - mdrsjrns VL - 13 IS - 6 UR - http://mme.modares.ac.ir/article-15-8951-en.html Y1 - 2013 SP - 20 EP - 29 KW - random loading KW - bandwidth parameter KW - loading level KW - fatigue crack growth KW - Central Limit Theory N2 - In this paper, the effect of bandwidth and loading level parameters changes of random load histories on the fatigue crack growth is studied by the central limit theory. In this method, the life probabilistic distribution and probability of failure function and reliability function are derived by the central limit theory. The walker equation is used to account the stress ratio effect in the fatigue crack growth rate equations. Then, the theoretical results are verified by the test results in the three random loading conditions with the various bandwidths and loading levels. A good agreement among the theory and test results was observed. The probability of failure and reliability diagrams via number of cycles is presented too. M3 ER -