Basics
JIS Tensile Strength
Min. Tensile Strength
Avg.Tensile Strength
Tensile Strength
Figure 2.3 Tensile Strength
Reporting Tensile Strength Point B, shown in Figure 2.2, the maximum tension point, is also called the ultimate tensile strength. In some cases, point B will come at the same time as point C. After breaking a number of chains, a tensile strength graph shows a normal distribution (Figure 2.3). The average load in Figure 2.3 is called the average tensile strength, and the lowest value, which is determined after statistically examining the results, is called the minimum tensile strength. JIS (Japanese Industrial Standard) also regulates minimum tensile strength, but it is much lower than any manufactur- er’s tensile strength listed in their catalogs. “Maximum allowable load,” shown in some manufacturer’s catalogs, is based on the fatigue limit (see Basics Section 2.2.2). This value is much lower than point A. Furthermore, in the case of power transmission chain, point A is usually 70 percent of the ultimate tensile strength (point B). If the chain receives greater tension than point A, plastic deformation will occur, and the chain will be nonfunctional. Using Tensile Strength Information For the sake of safety, you should never subject chains to tension greater than half the average tensile strength— not even once. If the chain is inadver- tently loaded that high, you should change the whole chain set. If the chain is repeatedly subjected to loads greater than the maximum allowable load, fatigue failure may result. When you see tensile strength graphs or stress-strain graphs, you should be aware of the following facts: 1. Every manufacturer shows the average tensile strength in its catalog, but it is not unusual to find that the value listed may have been developed with sales in mind. Therefore, when comparing chains from different manufacturers, check the minimum tensile strength.
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