トラクタフレームの構造強度に関する解析 (第3報)

後車軸ハウジングの疲れ強さについて

抄録

As can be seen from the recent trend of weight reduction of existing tractors, it seems necessary to consider the optimal configulation of tractor frame. To develop an approximate method to estimate the fatigue strength, several experiments and analyses were performed taking the rear wheel axis housing for direct research material. The following comments pertain to the specific results in this research.
1) A computer program was successfully developed for solving frequency distribution of actual stress with the peak count method by offline data processing units.
2) Since frequency distribution patterns differ according to the number of sampling data, it would be discerned that around 1500 data are enough to maintain constant distribution pattern.
3) In each test condition, e. g. plowing, rotary tillage and maneuver, frequency distributions are tend to follow Weibull's distribution.
4) Throughont experiments, shape parameter m can be seen within the restricted range, below 1.0. Actual stress which takes place during operation might be characterized to exhibit the excessive stress with higher probability.
5) Using Miner's linear damage law, the life of the rear wheel axis housing was investigated under the assumptions of introducing actual stress. The effect of the number of repeated stress was evident and consequently basic data for the body styling of tractor were obtained.
6) The degree of fatigue seems to be affected considerably depending upon the slope porions of dimensionless S-N diagram or time intensity.