CRACK INITIATION LIFE OF NOTCHED METALLIC PARTS EXPOSED TO LOW CYCLE FATIGUE

1. Strain Posavljak, Mašinski fakultet Univerziteta u Banjoj Luci, Republic of Srpska, Bosnia and Herzegovina
2. Stevan Maksimović, Vojnotehnički Institut Beograd, Serbia

The flat specimens with a central hole and one turbojet engine compressor disk have been studied in this paper as representatives of notched metallic parts. In conditions of loading by blocks of positive variable force, the crack initiation life of specimens was determined experimentally. Using different approaches based on low cycle fatigue criteria, crack initiation life of mentioned specimens was estimated also. Original Neubr’s rule and Topper’s and Sonsino-Birger’s modification of this rule, were used for determination of stress-strain response at critical point. Estimation of crack initiation life was carried out using Palmgren-Miner’s rule of linear damage accumulation supported by Morrow’s, Manson-Halford’s and Smith-Watson-Topper’s curves of low cycle fatigue. Experimentally obtained results and results of estimation of crack initiation life were compared and analyzed. It was shown that approach which include Sonsino-Birger’s modification of original Neuber’s rule and Palmgren-Miner’s rule of linear damage accumulation supported by Morrow’s curves of low cycle fatigue, was made the best result of estimation.This approach was used for crack initiation life estimation of the studied turbojet engine compressor disk. For the purpose of estimation, two blocks of rotation frequency were taken in account. One block that represents different engine ground controls and one block that represents different types of flights. Estimated crack initiation life of disk, expressed in flight hours, was compared with statistically processed data about crack initiation life that collected during exploitation.

Ključne rečitestttt :

Tematska oblast: Mehanika i konstrukcije

Uvodni rad: Da

Datum: 15.02.2011.

Br. otvaranja: 999

11th International Conference on Accomplishments in Mechanical and Industrial Engineering

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