The fatigue strength test is considered to be the closest test method to the actual use of the chain.
Since the chain is constantly moving during use, it is also necessary to understand the fatigue life and endurance limit of the chain.
The purpose of this test is to find out under what tensile load on the chain will (theoretically) never break.
For general chains (excluding stainless steel chains), the fatigue strength is equivalent to the maximum allowable load.
Fatigue test method
1. Conformity Test
According to the Conformity test method specified in ISO 15654, the test is carried out with reference to the minimum fatigue strength (Fd) specified in ISO 606 and ISO 4347 to verify whether the chain complies with ISO 606 and ISO 4347.
The test method is to test 3 chains and pass 3 million cycles.
2. Staircase Test
The test can better obtain the actual fatigue strength of the chain.
According to the Staircase test method stipulated in ISO 15654, the test load is tested in stages from large to small (or from small to large) in an arithmetic progression method, and the ascending or descending load progression is determined based on whether it passes 10 million cycles. The fatigue test will be calculated after the tests are done.
The load, waveform and calculation methods of the fatigue test will be further explained below.
Fatigue test procedure
1. Determine the test conditions, as shown in the figure below:
2. Determine the ascending and descending load progression(d)
3. Start testing.
If the chain breaks less than 10 million cycles, replace to a new one and lower the load by one level and retest.
If the chain is not broken after 10 million cycles, replace to a new one as well and increase the load by one level and test again.
4. Required sample pieces
5. Correct the maximum load (Fmax) of the test to the fatigue strength according to the formula
6. Calculate the average fatigue strength, standard deviation and minimum fatigue strength
MAXTOP’s Fatigue testing machines
The fatigue testing machine is based on the principle of electromagnetically driven mechanical resonance to generate dynamic test force.
In the test, a high frequency cycle fatigue test is performed on the chain stretching and relaxing repeatedly.
MCC now has two new fatigue testing machines, namely 2.5 tons (25 kN) and 20 tons (200 kN) fatigue testing machines.
