Zissimos P. Mourelatos, (Associate Professor) Paras Shah, Prashant Patel; (Graduate Students) Simulation of Piston Secondary Dynamics, Piston – Bore Contact and Piston Slap

Motivation Piston slap is an NVH phenomenon that is a strong customer dissatisfier (unusual engine noise). Noise is an important contributor to Quality, Reliability, and Durability (QRD) Piston slap is a significant contributor to the total Engine Noise, specially at cold start.

Engine “Piston – Bore” Interaction Noise Generation Mechanism

Objectives Simulate piston secondary motion Determine side thrust forces due to piston - cylinder liner contact Reduce piston slap excitation. Predict engine block vibration due to side thrust forces

Engine “Piston – Bore” Interaction Effects

Engine Piston Noise Sources Piston Dynamic Forces

Theoretical Aspects Kinematics: Crank-slider mechanism Piston secondary motion Piston dynamics model Engine piston-bore interaction effects Skirt - liner dynamic interaction forces

Piston Dynamic Contact Analysis Optimization of Skirt Profile for Minimum Contact Pressure

Analysis Piston skirt elastic deformation Asperity contact analysis Engine block vibration Thermal deformation Piston-skirt ElastroHydroDynamic (EHD) lubrication

Piston Temperature Distribution Skirt Thermal Deformation (Thrust Side) Piston Temperature Distribution

Schematic: Crank Slider Mechanism Skirt Contact Forces on Thrust side for various Clearances

Uncertainty in Piston Design Sensitivity analysis of piston design parameters on piston slap excitation under uncertainty