Vibration measurement and signal analysis methods are common to evaluate the functionality and characteristics of technical components in different industrial and scientific areas. Modal analysis for example is a standard method to characterize the dynamic behavior of a structure and enables the development of validated bone models. The state of the art of analyzing bone structures does not include the modal damping, although it has a significant influence on the dynamic characteristics. Within the presented investigations, the modal analyses have been performed contactless with respect to excitation and response acquisition, which implies that there are no influences of shakers or sensor couplings. Therefore, an automatic impulse hammer and a 3D Scanning Laser Doppler Vibrometer were used for excitation and response detection. Various supports of the test specimens, surface pretreatments, excitation points and excitation impulses were examined to optimize the measurement setup and process. Experimental modal analysis data were analyzed by curve fitting methods to determine the modal parameters. To evaluate different structures and effects of damping, 3D printed artificial bones and animal in vitro bones were used to perform the measurements. To produce the cortical layer of the artificial bone models, volume models were generated based on medical image data and printed by polyamide-based selective laser sintering. The cancellous bone was represented by different foam fillings for the artificial bones. Thereby, the variation of the porosity was achieved by using different mixing ratios of polyurethane foam and hardener. Furthermore, the modal damping parameters were determined from the measurement of animal bones. The measurement time was optimized during the practical implementation of the parameter determination to minimize the influence of drying and decomposition processes on the measurement results.

No abstract

No abstract

PMSM drives are widely used in powertrains for hybrid and battery electric vehicles. Tonal noise radiation of the drive results from magnetic force excitations in the air-gap of the machine. As previous work has shown it is possible to reduce magnetic noise by the injection of current harmonics in specific orders. Therefore feed-forward voltage harmonics can be used. The determination of amplitudes and phases on a drive test bench or vehicle test however is a complex and time-consuming task. The paper contributes by giving a framework to identify the necessary orders, amplitudes and phases with the help of detailed machine models. Simulation and measurement results are presented to prove the injection method's feasibility and to show that multiple orders can be reduced. In result an improved drive control can actively reduce noise without any additional hardware or cost.

No abstract