This conference paper was submitted for presentation at the NAFEMS World Congress 2025, held in Salzburg, Austria from May 19–22, 2025.

Abstract

Systems designed for impact applications, such as rotary hammers or demolition hammers, are employed extensively within the construction industry. The development of such systems requires comprehensive testing, which is essential for acquiring valuable insights during the development process and validating the final product. Conventionally, tests are conducted using materials such as natural stone or concrete. However, tests with such materials present significant drawbacks, including environmental pollution, limited reproducibility due to heterogeneous materials, and the inability to conduct long-term tests, due to destruction. Furthermore, the utilisation of substitute workpieces, such as the system Dynaload, is also associated with limitations. One such limitation is that it lacks the capacity for adjustment to imitate different materials. In order to develop a substitute workpiece that ensures the reproducibility of environmentally friendly and realistic test conditions, it is essential to ascertain precisely which force characteristics the workpiece is subjected to. However, thus far, no suitable method for directly measuring contact forces has been identified. To address this problem, a computer-aided simulation that models the components and their interactions has been created. A rotary hammer was selected as an example. The objective of the simulation is to replicate the force waves generated by the rotary hammer, which leads to the contact forces between the tool and the workpiece. In order to parameterise the simulation, measurements were conducted in accordance with the European Standard for Testing of Mechanical Properties of Materials (EPTA 05/2009). This standard permits the documentation of force waves transmitted through a rod. While direct measurement of contact forces at the tool-workpiece interface is not a viable option, the analysis of these force waves allows for the validation of the transferred energy and momentum changes within the system. The EPTA tool, as defined in EPTA 05/2009, was incorporated into the simulation and employed as a measuring instrument in actual tests. The change in momentum in the EPTA tool was determined from both the measurement data and the simulation and compared with each other in order to assess the degree of correlation between the two. The impact velocity of the flying piston in the simulation was adjusted so that the changes in momentum from the simulation and measurement were in accordance with each other. To validate the simulation, the force waves on the real and the simulated EPTA tool were compared. The resulting coefficient of determination was 83.9%, and the relative standard error was 2.4%. These values demonstrate a high level of agreement between simulation and reality. The simulation of the force waves generated by the percussion mechanism of the rotary hammer and transmitted to the EPTA tool is adequate, allowing for the reasonable assumption that the contact forces between the tool and a specified workpiece are also correctly simulated. In the subsequent step, a virtual substitute workpiece can be modelled to obtain the correct parameter set for different materials.