51. Field and Numerical Testing of the BWE SchRs4600.50 Dynamic Behavior

Surface mining machines are the largest mechanical engineering structures. Bucket wheel excavators operating in lignite mines are continually exposed to dynamic loads. Moreover, nearly all structures are over 10 years old. The methods used in design and construction did not cover the dynamic behavior of machines, which resulted in problems in their operation and decreased durability. The tendency to optimize and increase the operational time of machines is currently also visible in the field of surface mining. As a result the machines which have been operating for many years are subject to investigation. The SchRs (Schaufelradbagger auf Raupenschwenkbar) 4600.50 excavator, which is over 120 m long, 64 m high and weighs approximately 5,000 tons (excluding the dumping bridge), was investigated with regard to vibrations. Operational modal analysis was performed with 15 measurement points in different directions. This approach allowed to determine the variability of the dynamic characteristics of the machine in terms of operational conditions. Simultaneously a numerical model was prepared. Eventually, it was possible to compare and correlate both the numerical and experimental models and to establish the differences based on the operational load acting on the structure.