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

2. 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.

3. Engine “Piston – Bore” Interaction Noise Generation Mechanism

4. 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

5. Engine “Piston – Bore” Interaction Effects

6. Engine Piston Noise Sources Piston Dynamic Forces

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

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

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

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

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

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