Resonance magnification test in lightweight construction.
Vibration test, component test, high accelerations
The objective of the resonance magnification test is to establish a shaker design, with which a high acceleration load can be applied to a sample at a fixed frequency. More than ten times the maximum acceleration of the shaker with simultaneously high number of oscillations is possible. To accomplish this task, scientists at Fraunhofer LBF determine the setup in advance using numerical simulation to set the desired frequency and estimate the reliability of the structure in relation to the load. This saves time and costs.
Due to the broad positioning of Fraunhofer LBF in the fields of environmental simulation, durability, numerical simulation and individual complex component manufacturing, it is possible to run a test setup with test specimen at the desired frequency in resonance. The generated forces are held consistently low due to the lightweight construction of the moving masses, so that with relatively little effort components can be harmoniously excited using smaller shaker components with very high accelerations up to 1000 g.
Numerical simulation for precise configuration
To configure the overall design, a numerical simulation is performed beforehand to estimate various parameters of the design, which are instrumental for the resonance frequency. If narrower tolerances are desired, the validation of the numerical model can be carried out with the individual setup. To ensure that the desired test duration can be achieved, the simulation can be used to estimate the load on the individual test setup components in advance. In a validation experiment, the simulation can be improved and the maximum increase in the necessary acceleration can be compared to the maximum shaker acceleration.
Simulation of the test setup for individual resonance ranges.
Resonance magnification: With little energy, small components can be loaded with up to 1000g over a high number of sinusoidal oscillating cycles.
Experimental design for carrying out experiments for very high accelerations.
Variations of the setup for numerical validation.
Test setup in lightweight construction
Thanks to the in-house laser sintering system, parts of the test setup can be constructed as a complex monolithic block. This cuts the weight and thus reduces the load on the shaker; at the same time, the load capacity of the test setup increases in resonance. Thanks to many years of experience in the field of dynamic load application, moving parts can be designed safely.
Excitation in resonance
Depending on the customer's request, a fixed frequency can be maintained for the harmonic excitation, or a maximum amplitude with frequency tracking can be set up within predefined limits. Depending on the application and use of the component to be tested, it may be necessary to apply more precise excitation through higher oscillations with accuracy within on Hz, and to implement it on the test stand. The acceleration amplitude on the test specimen is regulated according to the specifications. It is also possible to stimulate a maximum acceleration at a slightly variable frequency with tracking of the frequency in resonance. The focus here is on the high acceleration amplitude that is supposed to be exerted on the component.
With the resonance magnification test, Fraunhofer LBF offers the possibility to excite components harmonically monofrequently with high acceleration. The excitation frequency is determined through a targeted test setup design in conjunction with the test component according to customer requirements. This makes it possible with to exert loads up to 1000 g with relatively little energy on small components sinusoidally over a high number of oscillating cycles. This is particularly interesting for electronics components that are installed on or near high-speed electric motors.
“Due to the collaborative efforts of different disciplines at Fraunhofer LBF, it is possible to design test specifications according to our requirements, to use existing testing equipment and test them outside of standard specifications. Due to the close solution-oriented collaboration, objectives can be adapted and implemented as needed for the particular situation.” Dr. Mark Heilig, Technical Analysis/Systems Analysis, C.& E. Fein GmbH
- Dr. Jürgen Nuffer
- Phone: +49 6151 705-281