## 3 Results and Discussion
### Findings from the Performed Dynamic Calibration  
The compliant structures presented in literature (Section 1) have been investigated in specific test ranges. For the use of AIEs as interface elements in vibration testing further application requirements must be fulfilled. An increase in the investigated force, displacement and frequency range of the test object leads to the necessity to calibrate the test benches in the entire test range. Investigations of the FRFs AS, MI and AM show deviations from the ideal behavior of a freely vibration mass. Calibration quantities can be calculated by the known systematic deviation from the ideal behavior.  
The investigations on the vibrating mass and the compliant elements have shown the influence and resulting possibilities on the measurement results by mass cancellation and _measurement systems FRF_\(HI_{pp}\). To make sure that these influences do not only apply to one specific sensor and measuring system, the investigation was carried out on the two clearly different systems presented. This led to different calibration values for \(HI_{pp}\) and \(m_{sensor}\). Consequently, the calibration quantities must be determined for each configuration. Even if the test setup is not changed, \"frequent checks on the calibration factors are strongly recommended\" [26].  
The _measurement systems FRF_\(HI_{pp}\) is determined only for the test data of the freely vibration mass, and is limited at its ends. Furthermore, the function \(HI_{pp}(f)\) depends on the data accuracy from which it is created. The residual should be determined from using sufficient data and the accuracy should be evaluated. The _measurement systems FRF_\(HI_{pp}\) and its values are determined over frequency. Non-systematic errors and non-linearly dependent correlations cannot be described or compensated. For example, non-linear friction effects of the test bench between sensor positions cannot be represented. Such effects should only be attributed to the test element. The test results of four different masses and two different compliant elements on both test rigs showed almost linear effects in the  
Figure 10: Apparent Stiffness directly measured \(AS_{meas.}\) and calibrated \(AS_{testobj.}\) of the compliant element A at the low frequency test bench.  
lower and medium frequency range. In high frequency ranges above 300 Hz deviations of the vibrating mass could be attributed to non linearity.  
[PERSON] [26] already mentioned, with regards to the calibration by mass cancellation, that \"a calibration procedure of this type has the distinct advantage that it is very easy to perform, and that it can be carried out in situ with all the measurement equipment\" [26]. Further, the additions by the _measurement systems__FRF__HI__pp_ by [PERSON] [27] can be performed directly with all the measurement equipment. For the calibration, the test object must be replaced by a freely vibrating mass and the two relevant quantities are then measured. The measurement of the test object can be performed immediately. The calibration can be calculated afterwards and later applied to the measurement results of the test object. Even if the evaluation of the test results becomes more complicated due to the determination of the calibration values, it is still easy to implement in testing.