Interior Noise Analysis And Control Of An Excavator Cab Based On Structure-Acoustic Sensitivity

With the widespread use of a variety of construction machineries in recent years, the NVH (Noise, Vibration and Harshness) characteristics of these common construction machineries, such as the excavators, dozers and loaders, are increasingly emphasized. The mathematical relationship between the noise signal at the Driver’s Right Ear (DRE) and design variables of the typical components of an excavator (cab, upper-frame, shell and vibration-absorbers, etc.), which is always referred to as a Design Sensitivity Analysis (DSA), is actually an significant section of a construction machinery’s NVH characteristics and a necessary premise to specifically improve the performance of those related structures. With the help of DSA, it is much more effective and efficient to reduce the interior noise of the cab, which is beneficial to enhance the driving comfort of the vehicles as well as guarantee the operational security of the machineries.Combining the structural finite element method and the acoustical finite element method, the structure-acoustic coupling model of a hydraulic crawler excavator is established, on the basis of which the NVH characteristics of this excavator are analyzed. Primarily, a theoretical framework of the structure-acoustic Integrated Design Sensitivity Analysis (IDSA), which is corresponding to the cab, is proposed and its physical meanings and engineering implications are then discussed. Furthermore, the IDSA to the interior noise of the cab is formulated whereby the interdependence between the peak values of the Sound Press Level (SPL) signals at the DRE and the design variables, namely the main sizes of upper-frame/shell and the stiffness/damping parameters of the vibration-absorbers, is investigated. As a result, several essential variables that have a particularly noticeable impact on the objection function (known as the SPL at the DRE) are discerned. Finally, the IDSA-based excavator structure improvement scheme is introduced and is subsequently applied to the above-mentioned selected variables in a series of simulation. As is indicated by the results of the simulation, the peak values of the SPL signal at the DRE present an obvious downward trend, which is also testified by the experimental data collected in a following test on a rectified prototype excavator.The total SPL at the DRE has reduced 4.98 dB and 2.3 dB in simulation and test, respectively. Meanwhile, the NVH development cycle of the excavator has been comparably shortened. In addition, the IDSA method, which is based on the finite element method rather than the commonly used boundary element method, which is mathematically difficult to implement, has been proven to be an feasible solution to the sensitivity study of a large complex structure like an excavator. In general, the IDSA-based excavator structure improvement scheme is quite practicable in engineering application.