Basics
Time
Figure 2.17 Repeated Load Tension
as the maximum allowable load. Figure 2.18 shows one result of fatigue exam- ination in this way. In the figure, the vertical axis is P max and the horizontal axis is the number of repetitions. When the repetitions are less than 10 4 times, the test results fluctuate greatly. Therefore, these figures are practically useless, and are not shown here. In the previous paragraph, we need to be alert to what the JIS regulation is really saying: “JIS B 1801-1990 defines...P max = 2.2 P a as the maximum allow- able load.” This is set up with wrapping transmission as a model (as shown in Figure 2.15), and with the supposition that the smaller load side tension is 10 percent of the larger load side tension. In actual practice, even if we use wrapping transmission, the smaller load side tension may be almost zero; and in the case of hanging or lifting, the chain’s slack side also doesn’t receive any load. In these cases, the conditions can be shown as a dotted line (Figure 2.17); chain load = 2 P a' and P min = 0; therefore 2P a' < P max .
Range with Failure
Tensile Strength
Endurance Limit Range without Failure
Cycles
Figure 2.18 Fatigue Strength
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