Vibro-Acoustic Characterisation of Lightweight Structures: A Numerical-Experimental Approach 2012-01-1526

In many industrial applications, such as in the automotive and machine building industry, there is a continuous push towards lightweight materials motivated by material and energy savings. This increased use of lightweight materials, however, can strongly compromise the Noise, Vibration and Harshness (NVH) performance of the final products. Especially in times where the NVH performance not only receives a higher legislative attention, but also becomes a commercial differentiator, this also represents a key point of attention for designers and directs research activities towards new experimental and numerical techniques to accurately predict the NVH performance of lightweight systems as early as possible in the design process.

The presented work discusses novel measurement setup, specifically developed for examining the vibro-acoustic behavior of lightweight structures. The test stand consists of a concrete cavity of 0.83 m₃. At its front wall, test specimens of variable size and thickness can be inserted. This test setup allows applying both acoustic and structural excitation. Among others it allows the evaluation of vibro-acoustic Insertion Loss (IL) over a wide frequency range taking into account the effect of acoustic cavity modal loading, as is often the case in real life applications of the tested materials such as for vehicle trimming.

The particular shape of the cavity also allows for the use of efficient simulation techniques for steady-state numerical analysis. The Wave-Based Method (WBM) has shown a superior computational efficiency as compared to the classical element-based techniques for problems of moderate geometric complexity, making mid-frequency analysis feasible. The combination of the highly efficient WBM and the novel test setup enables in situ material characterization, both for internal acoustical problems as well as for transmission cases.