Excavator exterior noise contribution analysis using angle-based operational acoustic load synthesis.

Since earth moving machines (EMM) are subject to exterior noise (EN) regulations, OEMs need to develop mitigation solutions from an early design stage. It is challenging to predict solution effectiveness at early design stage. Excavators are distinct compared to other EMM as their upper frame rotate while keeping lower frame fixed. ISO 6395(2) or EC/2000/14(1) require EMMs to follow specific operating maneuvers where noise sources change their position, directivity, and speed along the operating cycle. These conditions pose challenges in performing noise contribution analysis as a function of angular position and operating condition. Authors successfully demonstrated Acoustic source quantification and contribution analysis for linearly moving EMMs. However, excavator pose data processing challenges due to angular motion. This work demonstrates the use of frequency domain ASQ for operational acoustic source quantification and use of frequency domain virtual prototype sub structuring approach (VPA) for contribution analysis to target microphones along the cab angular path. The VPA approach allows to swap sources or use of what if scenarios in simulation models to evaluate solutions. This work was performed on a stationary excavator in which the cab and boom were rotated ninety degrees to one side and back to the center position. The test based ASQ and VPA methods were implemented. An acoustic model of the excavator was built, and source-to-target transfer functions were computed as a function of angular position. These transfer functions were validated with test data and used for contribution analysis with various what-if scenarios.