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

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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

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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