Limits...
Computational Modeling to Predict Fatigue Behavior of NiTi Stents: What Do We Need?

Dordoni E, Petrini L, Wu W, Migliavacca F, Dubini G, Pennati G - J Funct Biomater (2015)

Bottom Line: However, their effectiveness is still debated in the clinical field.However, confidence in numerical methods is only possible after verification and validation of the models used.For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milan 20133, Italy. elena.dordoni@hotmail.it.

ABSTRACT
NiTi (nickel-titanium) stents are nowadays commonly used for the percutaneous treatment of peripheral arterial disease. However, their effectiveness is still debated in the clinical field. In fact a peculiar cyclic biomechanical environment is created before and after stent implantation, with the risk of device fatigue failure. An accurate study of the device fatigue behavior is of primary importance to ensure a successful stenting procedure. Regulatory authorities recognize the possibility of performing computational analyses instead of experimental tests for the assessment of medical devices. However, confidence in numerical methods is only possible after verification and validation of the models used. For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process. Hence, special attention should be paid to the accuracy of the description of the device geometry and the material properties implementation into the numerical code, as well as to the definition of the fatigue limit. In this paper, a path for setting up an effective numerical model for NiTi stent fatigue assessment is proposed and the results of its application in a specific case study are illustrated.

No MeSH data available.


Related in: MedlinePlus

(a) CAD model of NiTi specimen for static and fatigue characterization. The significant dimension of gauge length (L), wires width (W) and thickness (Th) are reported. (b) Symmetrical FE model of a tensile test up to 5%: the total maximum strain, uniform and distributed along each wire, is equal to 4.459%, which means that almost the whole load applied to the specimen is transferred on its gauge length.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4493513&req=5

jfb-06-00299-f007: (a) CAD model of NiTi specimen for static and fatigue characterization. The significant dimension of gauge length (L), wires width (W) and thickness (Th) are reported. (b) Symmetrical FE model of a tensile test up to 5%: the total maximum strain, uniform and distributed along each wire, is equal to 4.459%, which means that almost the whole load applied to the specimen is transferred on its gauge length.

Mentions: A specimen having nine wires along the circumference with cross-section of 0.2 mm × 0.2 mm and gauge length equal to 10 mm was designed (Figure 7a), considering that the load full-scale range of the testing machine was 1500 N.


Computational Modeling to Predict Fatigue Behavior of NiTi Stents: What Do We Need?

Dordoni E, Petrini L, Wu W, Migliavacca F, Dubini G, Pennati G - J Funct Biomater (2015)

(a) CAD model of NiTi specimen for static and fatigue characterization. The significant dimension of gauge length (L), wires width (W) and thickness (Th) are reported. (b) Symmetrical FE model of a tensile test up to 5%: the total maximum strain, uniform and distributed along each wire, is equal to 4.459%, which means that almost the whole load applied to the specimen is transferred on its gauge length.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4493513&req=5

jfb-06-00299-f007: (a) CAD model of NiTi specimen for static and fatigue characterization. The significant dimension of gauge length (L), wires width (W) and thickness (Th) are reported. (b) Symmetrical FE model of a tensile test up to 5%: the total maximum strain, uniform and distributed along each wire, is equal to 4.459%, which means that almost the whole load applied to the specimen is transferred on its gauge length.
Mentions: A specimen having nine wires along the circumference with cross-section of 0.2 mm × 0.2 mm and gauge length equal to 10 mm was designed (Figure 7a), considering that the load full-scale range of the testing machine was 1500 N.

Bottom Line: However, their effectiveness is still debated in the clinical field.However, confidence in numerical methods is only possible after verification and validation of the models used.For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process.

View Article: PubMed Central - PubMed

Affiliation: Laboratory of Biological Structure Mechanics, Department of Chemistry, Materials and Chemical Engineering 'Giulio Natta', Politecnico di Milano, Milan 20133, Italy. elena.dordoni@hotmail.it.

ABSTRACT
NiTi (nickel-titanium) stents are nowadays commonly used for the percutaneous treatment of peripheral arterial disease. However, their effectiveness is still debated in the clinical field. In fact a peculiar cyclic biomechanical environment is created before and after stent implantation, with the risk of device fatigue failure. An accurate study of the device fatigue behavior is of primary importance to ensure a successful stenting procedure. Regulatory authorities recognize the possibility of performing computational analyses instead of experimental tests for the assessment of medical devices. However, confidence in numerical methods is only possible after verification and validation of the models used. For the case of NiTi stents, mechanical properties are strongly dependent on the device dimensions and the whole treatments undergone during manufacturing process. Hence, special attention should be paid to the accuracy of the description of the device geometry and the material properties implementation into the numerical code, as well as to the definition of the fatigue limit. In this paper, a path for setting up an effective numerical model for NiTi stent fatigue assessment is proposed and the results of its application in a specific case study are illustrated.

No MeSH data available.


Related in: MedlinePlus