Piston impacts against the cylinder liner are the most significant sources of mechanical noise in internal combustion (IC) engines. Traditionally, the severity of impacts is reduced through the modification of physical and geometrical characteristics of components in the piston assembly. These methods effectively reduce power losses at certain engine operating conditions. Frictional losses and piston impact noise are inversely proportional. Hence, the reduction in power loss leads to louder piston impact noise. An alternative method that is robust to fluctuations in the engine operating conditions is anticipated to improve the engine's noise, vibration and harshness (NVH) performance, while exacerbation in power loss remains within the limits of conventional methods. The concept of targeted energy transfer (TET) through the use of nonlinear energy sink (NES) is relatively new and its application in automotive powertrains has not been demonstrated yet. In this paper, a TET device is conceptually designed and optimized through a series of parametric studies. The dynamic response and power loss of a piston model equipped with this nonlinear energy sink is investigated. Numerical studies have shown a potential in reducing the severity of impact dynamics by controlling the piston's secondary motion.

The impulsive behavior of the piston in the cylinder liner plays a key role in the noise, vibration, and harshness (NVH) of internal combustion engines. There have been several studies on the identification and quantification of piston impact action under various operation conditions. In the current study, the dynamics of the piston secondary motion are initially explored in order to describe the aggressive oscillations, energy loss, and noise generation. The control of piston secondary motion (and thus, impacts) is investigated using a new passive approach based on energy transfer of the highly transient oscillations to a nonlinear absorber. The effectiveness of this new method for improving the piston impact behavior is discussed using a preliminary parametric study that leads to the conceptual design of a nonlinear energy absorber.