Determining the strength value of the gear material Most applications use the conventional design ISO area, but how to deal with the reliability data is completely different. The strength distribution is almost normal distribution in the literature [1], and Mischke and Whittaker have proved that the three-parameter Weibull distribution can Properly build a model of the data to fit the fatigue life. More logarithmic normal distributions are used in China [4, 5]. Some authoritative literatures in China believe that the Pdf (probability density function) of the gear fatigue limit region is logarithmic normal distribution [4, 5], and the calculation of the stress H deviation from the lognormal distribution is introduced into the model variation coefficient VHM=0.04. Compensation correction. This means that the author has a large approximation of the assumption that the fatigue strength of the gear is logarithmic. The ISO area does not specify the type of distribution, which is considered to be correct according to the most common normal distribution [1]. Because this expensive set of fatigue limit areas is first provided for the conventional design of gears, it is obviously handled in the normal case under the normal distribution type. Different processing methods, the data is very different, will lead to serious wrong results. Is a normal distribution.
Method (1): Calculate as follows: X=250Y1=1.4375(X-200) 530Y2=1.4375(X-200) 705Y=(Y1 Y2)/2=689.375N/mm2Sy=(Y-Y1)/U= The calculated value of 376183N/mm2 is consistent with the value. The test is consistent with the ISO [area] value in [6]. Method (2): According to the calculation method in [4], the result is: mean Y = 875.4 N/mm2, standard deviation Sy = 88 N/mm2. The calculation results are compared with the test results in [7]: 38SiMnMo alloy steel tempered gear, HB=2505, mean Y=693N/mm2.
It can be seen that the data gap between the different treatment methods is very different.
Conclusion (1) A new method and method for determining the strength statistics of gear material strength for gear reliability design by the effective ISO test gear strength value region are proposed. (2) 32 easy computer mechanisms are derived. And practical mathematical model for engineering reliability design; (3) Because the gear transmission uses a large amount of surface, the model is easy to be computerized and the data is reliable and practical, and the product economy and efficiency are considerable.
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