Study on Local Strain Field Intensity Approach for Prediction Fatigue Life of Crankshaft Based on Mechanical Mechanics

Abstract

The bending fatigue limit moment and crack initiation life of 4105 crankishaft in five groups of bending moments are obtained by resonant bending fatigue tests first. Then, the static finite element calculation using sub-model is performed to get the strain distributions in every test load. The results show that in the region where stress concentrate, the strain field could be seen as plane strain state. So two dimensional strain field intensity model is selected. In order to remove the influences of size and surface conditions, the radius of strain field is determined with the strain distribution under the low-life test load. After that, the local strain field intensities under each test load are calculated with the radius of strain field. Finally, the strain-life curve of material is modified by the fatigue intensity limit of crankshaft, and the predicted life agree with the test results.

Rapid evaluation of fatigue limit on thermographic data analysis

“…So it is a very hard task to use traditional methods to optimize fiber proportion and ply scheme of composites. Therefore, various theories and rapid methods have been developed to estimate fatigue limit in a short time for both metallic materials and composites, such as X-ray method [4][5][6][7], acoustic emission method [8][9][10][11], mechanical analysis method [12][13][14][15], simulation method [16][17][18][19], and infrared thermographic method. Among that, the thermography method which is based on self-heating phenomena is most widely used in engineering applications, such as Luong's method [20][21][22][23] and Risitano's method [24][25][26][27][28].…”