Evaluating risk of fatigue fractures in cardiovascular implants via nonclinical testing is essential to provide an indication of their durability. This is generally accomplished by experimental accelerated durability testing and often complemented with computational simulations to calculate fatigue safety factors (FSFs). While many methods exist to calculate FSFs, none have been validated against experimental data. The current study presents three methods for calculating FSFs and compares them to experimental fracture outcomes under axial fatigue loading, using cobalt-chromium test specimens designed to represent cardiovascular stents. FSFs were generated by calculating mean and alternating stresses using a simple scalar method, a tensor method which determines principal values based on averages and differences of the stress tensors, and a modified tensor method which accounts for stress rotations. The results indicate that the tensor method and the modified tensor method consistently predicted fracture or survival to 107 cycles for specimens subjected to experimental axial fatigue. In contrast, for one axial deformation condition, the scalar method incorrectly predicted survival even though fractures were observed in experiments. These results demonstrate limitations of the scalar method and potential inaccuracies. A separate computational analysis of torsional fatigue was also completed to illustrate differences between the tensor method and the modified tensor method. Because of its ability to account for changes in principal directions across the fatigue cycle, the modified tensor method offers a general computational method that can be applied for improved predictions for fatigue safety regardless of loading conditions.

References

References
1.
Nakazawa
,
G.
,
Finn
,
A.
,
Vorpahl
,
M.
,
Ladich
,
E.
,
Kutys
,
R.
,
Balazs
,
I.
,
Kolodgie
,
F.
, and
Virmani
,
R.
,
2009
, “
Incidence and Predictors of Drug-Eluting Stent Fracture in Human Coronary Artery a Pathologic Analysis
,”
J. Am. Coll. Cardiol.
,
54
(
21
), pp.
1924
1931
.
2.
Popma
,
J.
,
Tiroch
,
K.
,
Almonacid
,
A.
,
Cohen
,
S.
,
Kandzari
,
D.
, and
Leon
,
M.
,
2009
, “
A Qualitative and Quantitative Angiographic Analysis of Stent Fracture Late Following Sirolimus-Eluting Stent Implantation
,”
Am. J. Cardiol.
,
103
(
7
), pp.
923
929
.
3.
Aoki
,
J.
,
Nakazawa
,
G.
,
Tanabe
,
K.
,
Hoye
,
A.
,
Yamamoto
,
H.
,
Nakayama
,
T.
,
Onuma
,
Y.
,
Higashikuni
,
Y.
,
Otsuki
,
S.
,
Yagishita
,
A.
,
Yachi
,
S.
,
Nakajima
,
H.
, and
Hara
,
K.
,
2007
, “
Incidence and Clinical Impact of Coronary Stent Fracture After Sirolimus-Eluting Stent Implantation
,”
Catheter. Cardiovasc. Interventions
,
69
(
3
), pp.
380
386
.
4.
Umeda
,
H.
,
Gochi
,
T.
,
Iwase
,
M.
,
Izawa
,
H.
,
Shimizu
,
T.
,
Ishiki
,
R.
,
Inagaki
,
H.
,
Toyama
,
J.
,
Yokota
,
M.
, and
Murohara
,
T.
,
2009
, “
Frequency, Predictors and Outcome of Stent Fracture After Sirolimus-Eluting Stent Implantation
,”
Int. J. Cardiol.
,
133
(
3
), pp.
321
326
.
5.
Ohya
,
M.
,
Kadota
,
K.
,
Tada
,
T.
,
Habara
,
S.
,
Shimada
,
T.
,
Amano
,
H.
,
Izawa
,
Y.
,
Hyodo
,
Y.
,
Miyake
,
K.
, and
Otsuru
,
S.
,
2015
, “
Stent Fracture After Sirolimus-Eluting Stent Implantation
,”
Circ.: Cardiovasc. Interventions
,
8
(
8
), p.
e002664
.http://circinterventions.ahajournals.org/content/8/8/e002664
6.
Kan
,
J.
,
Ge
,
Z.
,
Zhang
,
J.-J.
,
Liu
,
Z.-Z.
,
Tian
,
N.-L.
,
Ye
,
F.
,
Li
,
S.-J.
,
Qian
,
X.-S.
,
Yang
,
S.
, and
Chen
,
M.-X.
,
2016
, “
Incidence and Clinical Outcomes of Stent Fractures on the Basis of 6,555 Patients and 16,482 Drug-Eluting Stents From 4 Centers
,”
JACC: Cardiovasc. Interventions
,
9
(
11
), pp.
1115
1123
.
7.
Kuramitsu
,
S.
,
Hiromasa
,
T.
,
Enomoto
,
S.
,
Shinozaki
,
T.
,
Iwabuchi
,
M.
,
Mazaki
,
T.
,
Domei
,
T.
,
Yamaji
,
K.
,
Soga
,
Y.
, and
Hyodo
,
M.
,
2015
, “
Incidence and Clinical Impact of Stent Fracture After PROMUS Element Platinum Chromium Everolimus-Eluting Stent Implantation
,”
JACC: Cardiovasc. Interventions
,
8
(
9
), pp.
1180
1188
.
8.
Duda
,
S.
,
Pusich
,
B.
,
Richter
,
G.
,
Landwehr
,
P.
,
Oliva
,
V.
,
Tielbeek
,
A.
,
Wiesinger
,
B.
,
Hak
,
J.
,
Tielemans
,
H.
,
Ziemer
,
G.
,
Cristea
,
E.
,
Lansky
,
A.
, and
Bérégi
,
J.
,
2002
, “
Sirolimus-Eluting Stents for the Treatment of Obstructive Superficial Femoral Artery Disease: Six-Month Results
,”
Circulation
,
106
(
12
), pp.
1505
1509
.
9.
Gray
,
W. A.
,
Feiring
,
A.
,
Cioppi
,
M.
,
Hibbard
,
R.
,
Gray
,
B.
,
Khatib
,
Y.
,
Jessup
,
D.
,
Bachinsky
,
W.
,
Rivera
,
E.
, and
Tauth
,
J.
,
2015
, “
SMART Self-Expanding Nitinol Stent for the Treatment of Atherosclerotic Lesions in the Superficial Femoral Artery (STROLL): 1-Year Outcomes
,”
J. Vasc. Interventional Radiol.
,
26
(
1
), pp.
21
28
.
10.
Ohki
,
T.
,
Angle
,
J. F.
,
Yokoi
,
H.
,
Jaff
,
M. R.
,
Popma
,
J.
,
Piegari
,
G.
, and
Kanaoka
,
Y.
,
2016
, “
One-Year Outcomes of the US and Japanese Regulatory Trial of the Misago Stent for Treatment of Superficial Femoral Artery Disease (OSPREY Study)
,”
J. Vasc. Surg.
,
63
(
2
), pp.
370
376.
11.
Sarkadi
,
H.
,
Berczi
,
V.
,
Kollar
,
A.
,
Kiss
,
D.
,
Jakabfi
,
P.
,
Végh
,
E. M.
,
Nemes
,
B.
,
Merkely
,
B.
,
Hüttl
,
K.
, and
Dósa
,
E.
,
2015
, “
Safety, Clinical Outcome, and Fracture Rate of Femoropopliteal Stenting Using a 4F Compatible Delivery System
,”
Eur. J. Vasc. Endovascular Surg.
,
49
(
2
), pp.
199
204
.
12.
Davaine
,
J.-M.
,
Querat
,
J.
,
Kaladji
,
A.
,
Guyomarch
,
B.
,
Chaillou
,
P.
,
Costargent
,
A.
,
Quillard
,
T.
, and
Gouëffic
,
Y.
,
2015
, “
Treatment of TASC C and D Femoropoliteal Lesions With Paclitaxel Eluting Stents: 12 Month Results of the STELLA-PTX Registry
,”
Eur. J. Vasc. Endovascular Surg.
,
50
(
5
), pp.
631
637
.
13.
Carter
,
A.
,
2009
, “
Drug-Eluting Stent Fracture Promise and Performance
,”
J. Am. Coll. Cardiol.
,
54
(
21
), pp.
1932
1934
.
14.
Cheng
,
C. P.
,
Choi
,
G.
,
Herfkens
,
R. J.
, and
Taylor
,
C. A.
,
2010
, “
The Effect of Aging on Deformations of the Superficial Femoral Artery Resulting From Hip and Knee Flexion: Potential Clinical Implications
,”
J. Vasc. Interventional Radiol.
,
21
(
2
), pp.
195
202
.
15.
Cheng
,
C. P.
,
Wilson
,
N. M.
,
Hallett
,
R. L.
,
Herfkens
,
R. J.
, and
Taylor
,
C. A.
,
2006
, “
In Vivo MR Angiographic Quantification of Axial and Twisting Deformations of the Superficial Femoral Artery Resulting From Maximum Hip and Knee Flexion
,”
J. Vasc. Interventional Radiol.
,
17
(
6
), pp.
979
987
.
16.
Nikanorov
,
A.
,
Schillinger
,
M.
,
Zhao
,
H.
,
Minar
,
E.
, and
Schwartz
,
L. B.
,
2013
, “
Assessment of Self-Expanding Nitinol Stent Deformation after Chronic Implantation Into the Femoropopliteal Arteries
,”
EuroIntervention
,
9
(
6
), pp.
730
737
.
17.
Nikanorov
,
A.
,
Smouse
,
H. B.
,
Osman
,
K.
,
Bialas
,
M.
,
Shrivastava
,
S.
, and
Schwartz
,
L. B.
,
2008
, “
Fracture of Self-Expanding Nitinol Stents Stressed In Vitro Under Simulated Intravascular Conditions
,”
J. Vasc. Surg.
,
48
(
2
), pp.
435
440
.
18.
Ganguly
,
A.
,
Simons
,
J.
,
Schneider
,
A.
,
Keck
,
B.
,
Bennett
,
N. R.
,
Herfkens
,
R. J.
,
Coogan
,
S. M.
, and
Fahrig
,
R.
,
2011
, “
In-Vivo Imaging of Femoral Artery Nitinol Stents for Deformation Analysis
,”
J. Vasc. Interventional Radiol.
,
22
(
2
), pp.
244
249
.
19.
Smouse
,
H. B.
,
Nikanorov
,
A.
, and
LaFlash
,
D.
,
2005
, “
Biomechanical Forces in the Femoropopliteal Arterial Segment
,”
Endovascular Today
,
4
(
6
), pp.
60
66
.http://evtoday.com/2005/06/EVT0605_F3_Smouse.html/
20.
Ansari
,
F.
,
Pack
,
L. K.
,
Brooks
,
S. S.
, and
Morrison
,
T. M.
,
2013
, “
Design Considerations for Studies of the Biomechanical Environment of the Femoropopliteal Arteries
,”
J. Vasc. Surg.
,
58
(
3
), pp.
804
813
.
21.
Kapnisis
,
K. K.
,
Halwani
,
D. O.
,
Brott
,
B. C.
,
Anderson
,
P. G.
,
Lemons
,
J. E.
, and
Anayiotos
,
A. S.
,
2013
, “
Stent Overlapping and Geometric Curvature Influence the Structural Integrity and Surface Characteristics of Coronary Nitinol Stents
,”
J. Mech. Behav. Biomed. Mater.
,
20
, pp.
227
236
.
22.
Collins
,
J. A.
,
1993
, “
High Cycle Fatigue
,”
Failure of Materials in Mechanical Design
,
Wiley
, Hoboken, NJ, pp.
178
254
.
23.
Mitchell
,
M. R.
,
1996
, “
Fundamentals of Modern Fatigue Analysis for Design
,”
ASM Handbook
, Vol.
19
,
ASM International
, Materials Park, OH, pp.
227
249
.
24.
Pelton
,
A. R.
,
Fino-Decker
,
J.
,
Vien
,
L.
,
Bonsignore
,
C.
,
Saffari
,
P.
,
Launey
,
M.
, and
Mitchell
,
M. R.
,
2013
, “
Rotary-Bending Fatigue Characteristics of Medical-Grade Nitinol Wire
,”
J. Mech. Behav. Biomed. Mater.
,
27
, pp.
19
32
.
25.
Fatemi
,
A.
, and
Socie
,
D. F.
,
1988
, “
A Critical Plane Approach to Multiaxial Fatigue Damage Including Out‐of‐Phase Loading
,”
Fatigue Fract. Eng. Mater. Struct.
,
11
(
3
), pp.
149
165
.
26.
ASTM,
2013
, “Standard Guide for In Vitro Axial, Bending, and Torsional Durability Testing of Vascular Stents,”
American Society of Testing and Materials International,
West Conshohocken, PA, Standard No.
ASTM F2942
.https://www.astm.org/Standards/F2942.htm
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