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Translated from Problemy Prochnosti, No. 3, pp. 98 – 104, May – June, 2018.
The paper deals with one of the most important problems of such closely related industries as mechanical engineering and aircraft manufacturing, involving the determination of the service life of components and structures operating under cyclic loading conditions. The presence of local structural and manufacturing stress concentrators greatly complicates the determination of the predicted life of components and structures at their design stage. The burnishing technique, namely, the method of plastic deformation of walls of the hole, aimed at achieving the amount of the residual plastic strain on their surface, is used to strengthen components with holes. The results of low-cycle fatigue tests conducted in repeating tension are presented for flat laboratory specimens of an aircraft aluminum alloy D16chT with a central cylindrical manufacturing hole hardened by burnishing. The burnisher geometry that ensures the required value of the residual plastic strain level (1, 2, and 3%) on the hole surface is calculated. The cyclic tensile loading of specimens at the stresses in a pulsating load cycle was performed in the range of 150 to 270 MPa at a frequency of 3 Hz using the equipment Bi-02-112. The influence of the amount of plastic strain in the burnished hole of the specimen on its cyclic life and fracture as a function of the load value is observed. It is found that due to plastic strain hardening of the surface of manufacturing holes, a local area of compressive residual stresses occur, causing the stress concentration around the manufacturing hole to decrease and the level of limit loads to increase. It is shown that the specimen, having a manufacturing hole hardened by burnishing (up to a plastic strain of 3%) and being cyclically loaded by a tensile stress to 170 MPa, failed not at the hole (the stress concentrator). Both the onset of the microcrack initiation and its further propagation take place in a solid region of the specimen. This is indicative that with a certain amount of residual stresses in the burnished hole, the specimen fracture under low-cycle fatigue becomes insensitive to the presence of this concentrator.
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V. V. Koval’, “Influence of damage on the SSS of the plate with a hole under static loading,” Visn. NTUU “KPI”, Ser. Mashynobuduvannya, No. 50, 162–168 (2007).
V. L. Kalyuzhnyi, I. P. Kulikov, and M. S. Nikolaenko, “Determination of the hardening parameters for the metal around the hole in aluminum sheet blanks,” Visn. NTUU “KPI”, Ser. Mashynobuduvannya, No. 66, 165–172 (2012).
Yu. A. Vorob’ev, V. V. Voron’ko, and V. N. Stepanenko, “Comparative analysis of the methods for burnishing holes,” System. Obrob. Inform., No. 5 (63), 35–38 (2007).
E. Pooladia and Kh. Farhangdoosta, “Residual strains around cold worked holes from statistical view,” Eng. Sol. Mech., 2, 131–138 (2014). CrossRef
A. V. Zarutskyi, “Experimental investigation of the life of specimens with hardened holes. Part 1. Regular loading,” Vopr. Proekt. Proizv. Konstr. Let. Apparat., No. 1 (77), 29–34 (2014).
D. S. Kiva, G. A. Krivov, V. F. Sementsov, et al., Design and Manufacturing Methods to Increase the Fatigue Life of Structural Elements of the Airframe in the Area of Functional Holes [in Russian], KVITs, Kiev (2015).
GOST 25.502-79. Strength Analysis and Tests in Mechanical Engineering. Methods for Mechanical Testing of Metals. Fatigue Testing Methods [in Russian], Valid since January 1, 1981.
V. V. Pimanov, O. V. Timoshenkî, and A. M. Babak, “Investigation on the process of burnishing manufacturing holes in D16chT aircraft alloy,” Visn. NTUU “KPI”, Ser. Mashynobuduvannya, No. 1 (75), 144–150 (2015).
GOST 25.504-82. Strength Analysis and Tests. Methods for Calculating the Fatigue Characteristics [in Russian]. Valid since March 6, 1983.
V. G. Aleksandrov, Handbook of Aircraft Materials [in Russian] Transport, Moscow (1972).
- The Influence of Plastic Deformation on the Low-Cycle Fatigue During the Burnishing of Holes in Flat Specimens of D16chT Steel
O. V. Tymoshenko
V. V. Koval’
A. M. Babak
Quan Fam Dyk
Yu. M. Sydorenko
- Springer US
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