Active structural acoustic control for a truck oil pan: Actuator placement and efficiency estimation

The oil pan of large diesel engine trucks is identified as a significant contributor to their external noise radiation. This undesired broadband noise is caused by the oil pan’s structural vibration and cannot be treated effectively by passive measures, especially in the low frequency range up to 500 Hz. In order to address this challenge, an Active Structural Acoustic Control (ASAC) system was to be realized within the European Union (EU) project “Intelligent Materials for Active Noise Reduction” for the oil pan of a Volvo MD13 truck engine. The technological demonstration was conducted in a laboratory test stand and employs piezoceramic patch actuators to alter the vibrations in a broadband noise reduction manner. The following paper focuses on the tasks of deriving actuator placement and estimating respective broadband sound power minimization capability. First, the oil pan’s structural response to typical force excitation at its mounting points was analyzed through finite element simulation, and an actuator placement was derived. The estimation of its sound power minimization capability was then established based on computed structural frequency response functions and numerically derived radiation modes. Finally, the actuator layout was transferred to a serial production oil pan and adjusted by experimental observations.