A mechanics-aided test method for measuring the fracture toughness of shape memory alloys, the deformation/failure response of which violates basic assumptions of ASTM standards for measuring fracture toughness in conventional ductile materials, has been recently proposed. The proposed methodology relies on the resistance curve format of ASTM standards, but differs from it in the determination of the elastic part of the J value, for both stationary and advancing cracks, in an effort to accommodate the transformation/orientation-induced changes in the apparent elastic properties. This article discusses the proposed modifications to ASTM standards, that is, the expected degree of improvement in the measurement accuracy, the need for further ones regarding the uncertainty as to where to specify the fracture point on the obtained resistance curve, the specimen thickness requirement to ensure a conservative, constraint-independent measurement, and the temperature dependence of the measurements.
ASTM E1820 (2016) Standard test method for measurement of fracture toughness.
2.
BaxevanisTLagoudasD (2015) Fracture mechanics of shape memory alloys: review and perspectives. International Journal of Fracture191(1–2): 191–213.
3.
BaxevanisTParrinelloALagoudasD (2016) On the driving force for crack growth during thermal actuation of shape memory alloys. Journal of the Mechanics and Physics of Solids89: 255–271.
4.
ClarkeGAndrewsWParisP, et al. (1976) Single specimen tests for determination. In: RiceJR (ed.) Mechanics of Crack Growth. West Conshohocken, PA: ASTM International, pp. 27–42.
5.
ErnstHParisPLandesJ (1981) Estimations on J-integral and tearing modulus T from a single specimen test record. In: RobertsR (ed.) Fracture Mechanics. West Conshohocken, PA: ASTM International, pp. 476–502.
6.
GollerthanSYoungMBarujA, et al. (2009) Fracture mechanics and microstructure in NiTi shape memory alloys. Acta Materialia57(4): 1015–1025.
7.
HaghgouyanBHayrettinCBaxevanisT, et al. (2019) Fracture toughness of NiTi: towards establishing standard test methods for phase transforming materials. Acta Materialia162: 226–238.
8.
HaghgouyanBJapeSBaxevanisT, et al. (2019) Stable crack growth in NiTi shape memory alloys: 3D finite element modeling and experimental validation. Smart Materials and Structures28(6): 064001.
9.
HutchinsonJParisP (1979) Stability analysis of J-controlled crack growth. In: LandesJBegleyJClarkeG (eds) Elastic-Plastic Fracture. West Conshohocken, PA: ASTM International, pp. 37–64.
10.
IlliopoulosASteubenJKirkT, et al. (2017) Thermomechanical failure response of notched NiTi coupons. International Journal of Solids and Structures125: 265–275.
11.
JapeSBaxevanisTLagoudasC (2016) Stable crack growth during thermal actuation of shape memory alloys. Shape Memory and Superelasticity2: 104–113.
12.
JoyceJGudasJ (1979) Computer interactive of testing navy alloys. In: LandesJBegleyJClarkeG (eds) Elastic-Plastic Fracture. West Conshohocken, PA: ASTM International, pp. 451–468.
13.
LagoudasD (ed.) (2008) Shape Memory Alloys: Modelling and Engineering Applications. New York: Springer.
14.
LagoudasDHartlDChemiskyY, et al. (2012) Constitutive model for the numerical analysis of phase transformation in polycrystalline shape memory alloys. International Journal of Plasticity32–33: 155–183.
15.
LiFShihCNeedlemanA (1985) A comparison of methods for calculating energy release rates. Engineering Fracture Mechanics21: 405–421.
16.
MalettaCSgambitterraENiccoliF (2016) Temperature dependent fracture properties of shape memory alloys: novel findings and a comprehensive model. Scientific Reports6: 17.
17.
ParisPTadaHZahoorA, et al. (1979) The theory of instability of the tearing mode of elastic-plastic crack growth. In: LandesJBegleyJClarkeG (eds) Elastic-Plastic Fracture. West Conshohocken, PA: ASTM International, pp: 5–36.
18.
ParksD (1977) The virtual crack extension method for nonlinear material behavior. Computer Methods in Applied Mechanics and Engineering12: 353–364.
19.
PrahladHChopraI (2003) Development of a strain-rate dependent model for uniaxial loading of SMA wires. Journal of Intelligent Material Systems and Structures14(14): 429–442.
20.
RobertsonSMehtaAPeltonA, et al. (2007) Evolution of crack-tip transformation zones in superelastic Nitinol subjected to in situ fatigue: a fracture mechanics and synchrotron X-ray microdiffraction analysis. Acta Materialia55(18): 6198–6207.
21.
RobertsonSPeltonARitchieR (2012) Mechanical fatigue and fracture of nitinol. International Materials Reviews57(1): 1–37.
22.
ShawJKyriakidesS (1995) Thermomechanical aspects of NiTi. Journal of the Mechanics and Physics of Solids43(8): 1243–1281.
23.
ShihCMoranBNakamuraT (1986) Energy release rate along a three-dimensional crack front in a thermally stressed body. International Journal of Fracture30: 79–102.
24.
UngárTFrenzelJGollerthanS, et al. (2017) On the competition between the stress-induced formation of martensite and dislocation plasticity during crack propagation in pseudoelastic NiTi shape memory alloys. Journal of Material Research32: 4433–4442.
25.
VaidyanathanRDunandDRamamurtyU (2000) Fatigue crack-growth in shape-memory NiTi and NiTi-TiC composites. Materials Science and Engineering: A289(1–2): 208–216.
26.
ZhuX (2009) Review: J-integral resistance curve testing and evaluation. Journal of Zhejiang University: SCIENCE A10(11): 1541–1560.
27.
ZhuXJoyceJ (2012) Review of fracture toughness (G, K, J, CTOD, CTOA) testing and standardization. Engineering Fracture Mechanics85: 1–46.
