Analysis of the thermal stress state �of the ICE piston skirt in critical cases

Vyacheslav Pylyov

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International scientific and practical conference �ENERGY SYSTEMS AND ALTERNATIVE ENERGY SOURCES ‘2025 (ESAES – 2025)

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National Technical University “Kharkiv Polytechnic Institute”

Department of Heat Engineering and Energy-Efficient Technologies

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Kharkiv , March 11-12, 2025

Topic of Interest: Scientific research, diagnostics, testing, operation and reliability of energy systems

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

Scuffing and seizures on the outer surface of the piston skirt� on both the pressure and anti-thrust sides

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

The cause of such damage is considered to be

overheating of the piston pin bed in the piston bosses

due to:

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• mechanical overload of the connecting rod bearing

caused by combustion process deviations

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• failure of the lubrication

due to malfunction of the oil jet nozzle or

insufficient pressure created by the oil pump

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• insufficient lubrication during the initial engine startup

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

Ensuring reliable operation of the critical area of a piston skirt

Creep limit at zero creep rate

Criterion of the thermally stressed state of the design

Piston to cylinder liner hot clearance

Acceptable change in clearance in operation

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

Geometrical model of the piston

D = 120 mm

S = 140 mm

d_p = 42 mm

h_s = 86 mm

АK12M2MgN

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

temperature

thermal stress

Stage 1 – Regular operation

30 kW per cylinder

creep limit criterion (8) is reached

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

Stage 1 – Regular operation

Angle 30°

Angle 75°

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

Stage 2 – Disruption of heat transfer

on the surfaces of the piston pin bed

Angle 50°

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

Stage 3 – Impairment of oil cooling,

at angle 30°

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Oil temperature 95°C

Oil temperature 50°C

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ANALYSIS OF THE THERMAL STRESS STATE �OF THE ICE PISTON SKIRT IN CRITICAL CASES

THANK YOU FOR YOUR ATTENTION !

The criterion of exceeding the creep limit is proposed to be used in case of malfunction of ICE systems for analysis of a piston skirt reliability .

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The determining parameter according to the criterion of exceeding the creep limit is thermal stress. It is shown that there is no correlation between the radial thermal deformations of the piston skirt and thermal stresses.

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The location of critical areas of the skirt in the event of a fault emerging has been determined. Simulation results are in full correlation with the observations in ICE maintenance practice regarding the places of occurrence of scuffing and seizures on the piston skirt, as well as with the proposed explanation of the reasons for the loss of reliability.