Testing the impact performance of a long pocket dual draft gear using digital twin technique

A Digital Twin of a typical 4 car impact testing arrangement as per AAR M-921 or similar is set up to enable investigation of the performance of a dual draft gear as may be fitted in long pocket draft gears as detailed in USA Patent No. 10,086852 B2. Of interest is the combination of very different draft gears and the modelling and numerical problems that may be introduced to modelling with two complex and non-linear devices being modelled in series. The long pocket dual draft gear was fitted to the Hammer car (68.4 tonnes) whilst normal draft gears were fitted to the three Anvil cars (100 tonnes each). The 4-car system was modelled with eight masses using realistic masses for the coupler pairs (300 kg) and a separate mass (50 kg) for the follower that is used to separate the two draft gears in the long pocket in the Hammer car. The modelling approach allowed explicit mathematical models to be used for each individual draft gear and hence retaining of the response complexity in the simulated impact tests. Three very different draft gear types were simulated demonstrating the usefulness of the approach.