Advanced Hammer Excitation Technique for Impact Modal Testing on Lightweight Materials Using Scalable Automatic Modal Hammer
Experimental Modal Analysis (EMA) on a lightweight material has proven to be very challenging in the recent past. The applications of these materials have increased invariably in various fields and so have a high demand for Research & Development (R&D). A lightweight material is very sensitive in terms of vibration. EMA on these materials in free - free boundary condition is very complicated as the hammer excitation becomes very difficult. In order to acquire valid results, the conditions are modified, and in consequence, obtain inaccurate dynamic characteristics.
Some of the major challenges faced are: (a) material getting displaced from its original position after every hit, (b) difficulties in obtaining a single hit, (c) reproducing the same excitation force level for averaging output response. Overcoming these crucial challenges can result in reducing the inaccuracies in the results. Scalable Automatic Modal hammer (SAM) is developed to overcome these challenges and enables the ability to reproduce the same force level of excitation. This advanced hammer excitation technique has the capability to avoid the double hit, adjust the repeatability of force level and automatizes the entire excitation process.
In this research paper, a light weight material is experimented under free-free boundary condition and the obtained results are analyzed. The input hammer excitation is provided by SAM and the output contactless response is measured by Scanning Laser Doppler Vibrometer (SLDV).
The conclusions provided will reflect the importance of repeatability and reproducibility of hammer excitation force level in order to acquire accurate results. The controlling of SAM, by changing various parameters, in order to precisely excite lightweight structures will be demonstrated.
KeywordsExperimental modal analysis Impact modal testing Validation Lightweight material testing Non-mass-loaded impact
Experimental modal analysis
Finite element analysis
Scalable automatic modal hammer
Scanning laser Doppler vibrometer
Frequency response function
- 1.Office of Energy Efficiency and Renewable Energy, U. S. Department of Energy. Lightweight materials for Cars and Trucks. [Online resource] Available at https://www.energy.gov/eere/vehicles/lightweight-materials-cars-and-trucks (2014). Accessed 23 Sept 2017
- 2.Blaschke, P. et al.: Non-linearity identification of composite materials by scalable impact modal testing. In: Sensors and Instrumentation, Vol. 5, Conference Proceedings of the Society for Experimental Mechanics Series (2017)Google Scholar