Nowadays, more and more mechanical applications require not only better wear performing chains but also better fatigue performing chains. The last few years have seen the spread of new analysis techniques which have been made widely available with the arrival of high performance PCs. These techniques are known as 3D dynamic simulation and finite element analysis. The paper will describe how 3D dynamic simulation can help to determine the load cycles in a chain and how these loads are used in a finite element analysis to improve the fatigue performance of the chain. The paper will go on to illustrate the different stages of a complete fatigue improvement cycle for a leaf chain and also for the multiple strands roller chains. Finite element analysis allows the optimisation of each single component and to look at the end result on the whole chain. It will be seen that new chain designs can improve the endurance limit up to 50% and that the new designs stay mainly within the ISO dimensional specifications. Those standards are ISO 606 for the roller chains and ISO 4347:2004 for the leaf chains. In addition, it will be demonstrated how the theoretical results are validated by specific test methods. Fatigue performance test method is, since 2004, described in the ISO 15654:2004. Furthermore, a full description of the method will be explained in this paper: 3D dynamic simulation of a drive; Fatigue test according to ISO 15654:2004 of the original chain; FEA of the original chain design; Soderberg diagram analysis; FEA of new designs; Soderberg diagram analysis and comparison with the original diagram; Fatigue test acc. to ISO 15654:2004 of the new designs to validate the calculation; Finally, two practical case studies will show how the above method can be used. The first case study is concerned with the fatigue improvement of a leaf chain, the BL566. The second case study will show how the fatigue performance of a duplex chain, the 08B-2 narrow, has been improved to satisfy customer requirements.
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