TY  - EJOU
AU  - Ding, Shuiting 
AU  - Zuo, Liangliang 
AU  - Li, Guo 
AU  - Li, Zhenlei 
AU  - Xia, Shuyang 
AU  - Bao, Shaochen 

TI  - On	the	Fatigue	Damage	of	GH4169	Based	on	Thermodynamic	Entropy	 Generation
T2  - The International Conference on Computational \& Experimental Engineering and Sciences

PY  - 2023
VL  - 25
IS  - 1
SN  - 1933-2815

AB  - This	 paper	 presents	 the	 assessment	 of	 fatigue	 damage	 for	 GH4169	 under	 cyclic	 loading	 based	 on	
thermodynamic	 entropy	 generation	 at	 elevated	 temperature.	 According	 to	 the	 second	 law	 of	
thermodynamics,	fatigue	crack	propagation	is	an	irreversible	thermodynamic	dissipative	process	in	which	
damage	accumulates	and	entropy	generates	with	each	cycle	until	fracture	occurs.	In	this	work,	crack	growth	
process	is	 simulated	 by	 commercial	 finite	 element	 software	 ABAQUS,	 and	 the	 concept	 of	 cyclic	 entropy	
generation	rate	 (CEGR)	is	proposed	 to	present	 the	entropy	generation	of	 the	crack	 tip	region	in	a	single	
loading	cycle,	where	the	calculation	of	CEGR	is dependent	on the	evolution	data of stress,	plastic	strain	rate	
and	temperature at the	crack	tip	region.	The	accumulated	entropy	generation	of	crack	growth	process	is	
obtained	by	integrating	CEGR. The	influence	of	temperature	and	the	amplitude of	uniform far-field	stress	on	
CEGR	and	accumulated	entropy	generation	is	discussed.	Results	indicated	that the rise of	temperature	and	
the	increase of far-field	stress amplitude	can	both	increase the	dissipation of	plastic	strain	energy	at	crack	
tip	 region,	 leading to the increase of CEGR eventually. When the temperature	 and the far-field	 stress
amplitude remain	unchanged	in	fatigue	progress,	CEGR	increases	continuously	until	fracture	occurs.	Results	
showed	that	the	entropy	generation	per	unit	crack	length	ds/da is	almost	a	constant	in	crack	growth	process.	
The	 fatigue	 fracture	 entropy	 (accumulated	 entropy	 generation	 at	 fracture	 point) has	 an	 approximate	
quadratic	function	relationship	with	the	amplitude	of	uniform	far-field	stress.	The	fatigue	damage	is	defined	
as the	ratio	of	accumulated	entropy	generation	to	fatigue	fracture	entropy in	this	paper,	and	an	estimation	
model	for	fatigue	damage	using the	normalized	cycles	N/Nf is	proposed. The	estimated	fatigue	damage	is	
compared to	literatures.
KW  - Fatigue	damage;	crack	propagation;	entropy	generation;	elevated	temperature

DO  - 10.32604/icces.2023.09911