###### Abstract
In this case the tested elements react under one of its natural frequency, not over a frequency range. [PERSON] et al. [17] developed an adjustable fluid damper and investigate it from 0.2 to 3 Hz. In this range the intended viscous and visco-elastic damping behavior is found. Testing in higher frequency ranges could probably also reveal effects of the inertia of the fixtures, oil and piston. [PERSON] et al. [18] designed a controlled magnetorheological fluid damper and investigated its behavior from 1 to 4 Hz. [PERSON] et al. [19] developed a magnetorheological elastomer-fluid system with variable stiffness and damping behavior, the system is validated at 0.5, 1 and 2 Hz. [PERSON] et al. [20] developed a shock absorber with magnetorheological fluid. They tested their system at a frequency range from 0.1 to 2 Hz, taking a stiffness and damping coefficient into account. The inertia of the bordering structures of a quarter-car model are modeled [21]. Effects of inertia of the element itself are neglectable here. These would be required for the testing of AIEs in higher frequencies. [PERSON] and [PERSON] [22] present the design and experiment of a mechanism with a wide-range variable stiffness for semi-active vibration systems. They show the capability of absorbing vibrations from an excitation source with a frequency from 8.1 to 17.2 Hz [22]. In particular, the wide range of stiffness is of interest for use as an AIE as an interface in vibration testing. [PERSON] et al. [23] show their development of a vibration isolator with controllable stiffness. Test results of the dynamic behavior up to a frequency of 14 Hz are shown. They provide detailed information about the test setup and the isolation of the excitation vibration test rig, but no detailed information about the calibration and mass cancellation of the fixtures and measurement system. [PERSON] et al. [24] present detailed test results of a variable stiffness mechanism over a frequency range from 2 to 20 Hz, from which many dynamic properties can be derived. Deviations between simulation and test results are mentioned and attributed to friction. The preceding calibration of the measuring systems is not discussed. The calibration presented in this paper may help to find reasons for this deviation. In summary, it can be concluded that most adjustable compliant structures are tested statically or in the lower frequency range. In this range, the behavior is mostly dominated by stiffness, while damping and inertia are of minor relevance. For the dynamic testing of the AIEs their mechanical properties must be known over a much wider range. Furthermore, special focus should be placed on their characterization, as they are to be later used in experimental setups themselves and possible errors in characterization could multiply. The challenge is that to study AIEs over a wide range of frequencies, a procedure is needed that takes stiffness, damping and inertia into account, as well as measurement errors and influences of fixtures on the test bench. In the domain of vibration testing for the characterization of the biodynamic response of hand-arm systems [PERSON] et al. [25] encountered a similar problem. Stiffness, damping and inertias over frequency are also determined when studying hand-arm systems. Beyond this, they addresses considerable differences among reported data of biodynamic responses of hand-arm systems. They \"believe that a significant portion of these differences are likely the result of instrumentation and data processing problems\" [25]. The approach of [PERSON] et al. [25] to calibrate the biodynamic response is promising in the application to machine elements such as AIEs. In this publication, the approach is applied to the investigation of AIEs. For this the procedure is modified to provide reliable results in a wide range of test conditions of AIEs. The approach itself and its modifications as well as its applicability to vibration testing are discussed.