Strength optimisation of chains and D-rings using additive manufacturing

Abstract

The Regional Technological Institute in Pilsen investigates the optimisation of chains and D-rings. A traditional chain and D-ring are shaped into a loop and are closed by a welding operation. The welding operation leaves behind a seam that reduces the strength of both products. This defect leads to an early failure in the area of the weld. In the agricultural and transport industry, this can lead to dangerous situations due to the presence of higher loads.

This project tries to eliminate this defect for both products with the help of additive manufacturing and to propose further optimisations.

Initially, the products are modelled and produced by DMLS with the same original dimensions. These models are tested on static and cycling load and compared to their traditional variant with a UTM. Finally, a price estimation is made of the optimised products.

The tensile tests show that the break does not occur at the original position of the weld but at the the point of highest stress. Thus the weakness originating from the weld is eliminated. Also, the printed products are stronger than the traditional ones. More specifically for static loads, the chain is 2,5 times as strong and the D-ring is 5 times as strong. After quantifying the number of products per print the price of the chain, with a length of 7,41 m, is equal to €141,04 per meter and the price of a D-ring equals €31,73.

Finally, Some suggestions are made to optimise the design of both products accomplished with generative design.