PREDICTION OF SHORT FATIGUE CRACK PROPAGATION ON THE BASE OF NON-LOCAL FRACTURE CRITERION A.I. Nosikov 1 , A.S. Semenov 2* , B.E. Melnikov 2 , T.P. Rayimberdiyev 3 1 Rolls-Royce Deutschland Ltd & Co KG, Hohemark str. 60–70, Oberursel, 61440, Germany; 2 Peter the Great St. Petersburg Polytechnic University, Politekhnicheskaya 29, St. Petersburg, 195251, Russia; 3 Ahmet Yesevi University, B. Sattarkhanov 29, Turkestan, 161200, Kazakhstan *e-mail: semenov.artem@googlemail.com Abstract. Models of short fatigue crack propagation, taking into account the non-monotonic crack growth rate and predicting an existence of one or several threshold stress intensity factors, are considered. The models are formulated on the base of Leonov-Panasyuk-Dugdale formalism with using the non-local fracture criterion. A comparison of the obtained results with experimental data are given and discussed. 1. Introduction The problem of short fatigue cracks has received considerable attention due to inability of linear elastic fracture mechanics for the correct description of short cracks anomalous beha- vior. The short fatigue cracks demonstrate non-monotonic behavior including acceleration, deceleration to crack arrest, or deceleration followed by acceleration. The long fatigue cracks do not propagate at levels below the threshold stress intensity factor range Kth, whereas it is known that short cracks grow below Kth [1]. The paper proposes a model of short fatigue crack, which describes the deceleration stage below Kth and acceleration stage above Kth. The condition of the crack growth is obtained on the base of a non-local fracture criterion [2] in combination with Leonov- Panasyuk-Dugdale crack model [3, 4]. The obtained analytical evaluating the threshold stress intensity factor Kth is in a good agreement with experimental data 2. Non-local fracture criteria The correct analysis of the short fatigue crack behavior leads to a necessity to take into account the microstructure of material. In this case, the elementary act of failure is supposed to cover some representative volume of material (grain, structural element) instead of one material point, and the process of failure is determined by the cumulative stress-strain state of representative volume as a whole. The non-local failure condition initially was proposed by Wieghardt [5]. The first practical application and revealing of averaging area size dependence on micro-structure of material was done by Neuber [6]. Original physical interpretation and modifications of the criterion were offered by Novozhilov [7]. The application of non-local failure criterion to the analysis of short fatigue cracks propagation in the form of d*-concept was proposed by Sähn [8] and developed in [9-11]. In general, the non-local measure of stress-strain state B is defined by the equation [2, 11]: Materials Physics and Mechanics 31 (2017) 44-47 Received: September 30, 2015 © 2017, Peter the Great St. Petersburg Polytechnic University © 2017, Institute of Problems of Mechanical Engineering