Global Active Structural Acoustic Control

Dr. Scott D. Sommerfeldt
Department of Physics and Astronomy
Brigham Young University

Active structural acoustic control (ASAC) refers to the process of actively controlling the vibration of a structure in a manner that attenuates the sound radiating from that structure.  There are numerous applications for this type of active control, such as minimizing the sound radiation from an aircraft fuselage, a door panel, a power transformer, and other structures.  One obvious method for attenuating the sound radiated is to control the structure so that it does not vibrate.  However, such an approach is very difficult to implement, and it is also very inefficient since not all structural vibration radiates acoustically.  ASAC addresses this problem by trying to identify the mechanism(s) leading to acoustic radiation, and directly controlling those mechanisms to minimize the radiation.  This presentation will overview efforts at BYU to develop an active control technique referred to as the Weighted Sum of Spatial Gradients (WSSG) method, which is designed to yield global attenuation of the acoustic field.  The WSSG method has been applied to both flat structures (plates), as well as curved structures (cylindrical shells), and has been shown to closely approximate the optimal control that can be achieved by minimizing the radiated sound power – something that can be done numerically, but not in practice.  The concepts behind the WSSG method will be presented, along with results obtained showing the effectiveness of the control.