A new test specimen for a tensile test of industrial graphite is introduced using experiment and finite element results. The most influencing factors on the tensile strength of the test specimens are considered and the number of tests, which are necessary to optimize the tensile strengths are reduced based on the design of experiment using the Taguchi method and the effects of all factors on strength of test samples are studied. Comparison of the predicted strengths based on the Taguchi approach with the measured experimental results and finite element analysis shows a good correlation between them. In addition, results show that the new introduced specimen makes a 33% increase in the probability of fracture of the test specimens in gage length and the measured tensile strengths are 20% higher than those measured using the standard of the American Society for Testing and Materials.
BrocklehurstJDarbyM. Concerning the fracture of graphite under different test conditions. Mater Sci Eng1974; 16: 91–106.
2.
IshiharaMSumitaJShibataT. Principle design and data of graphite components. Nucl Eng Des2004; 233: 251–260.
3.
Berto F and Lazzarin P. Recent developments in brittle and quasi-brittle failure assessment of engineering materials by means of local approaches. Mater Sci Eng R 2013.
4.
AyatollahiMRAlihaMRM. Mixed mode fracture analysis of polycrystalline graphite – A modified MTS criterion. Carbon2008; 46: 1302–1308.
5.
AyatollahiMBertoFLazzarinP. Mixed mode brittle fracture of sharp and blunt V-notches in polycrystalline graphite. Carbon2011; 49: 2465–2474.
6.
BertoFLazzarinPAyatollahiM. Brittle fracture of sharp and blunt V-notches in isostatic graphite under pure compression loading. Carbon2013; 63: 101–116.
7.
LazzarinPBertoFAyatollahiM. Brittle failure of inclined key-hole notches in isostatic graphite under in-plane mixed mode loading. Fatigue Fract Eng Mater Struct2013; 36: 942–955.
8.
BertoFLazzarinPAyatollahiM. Brittle fracture of sharp and blunt V-notches in isostatic graphite under torsion loading. Carbon2012; 50: 1942–1952.
9.
BertoFLazzarinPMarangonC. Brittle fracture of U-notched graphite plates under mixed mode loading. Mater Des2012; 41: 421–432.
10.
AyatollahiMRTorabiAR. Failure assessment of notched polycrystalline graphite under tensile-shear loading. Mater Sci Eng A2011; 528: 5685–5695.
11.
YoonJHByunTSStrizakJP. Characterization of tensile strength and fracture toughness of nuclear graphite NBG-18 using subsize specimens. J Nucl Mater2011; 412: 315–320.
12.
MostafaviMSchmidtMMarsdenB. Fracture behaviour of an anisotropic polygranular graphite (PGA). Mater Sci Eng A2012; 558: 265–277.
13.
MostafaviMMcDonaldSÇetinelH. Flexural strength and defect behaviour of polygranular graphite under different states of stress. Carbon2013; 59: 325–336.
14.
MostafaviMMcDonaldSMummeryP. Observation and quantification of three-dimensional crack propagation in poly-granular graphite. Eng Fract Mech2013; 110: 410–420.
15.
LiuDMostafaviMFlewittPE. Fracture characterisation of reactor core graphite under biaxial loading. Key Eng Mater2014; 577: 485–488.
16.
HindleyMPMitchellMNErasmusC. A numerical stress based approach for predicting failure in NBG-18 nuclear graphite components with verification problems. J Nucl Mater.436(1–3): 175–184.
17.
HindleyMPMitchellMNBlaineDC. Observations in the statistical analysis of NBG-18 nuclear graphite strength tests. J Nucl Mater2012; 420: 110–115.
18.
SatoSKurumadaAKawamataK. Thermal shock resistances and fracture toughnesses of graphites and C/C-composites as plasma-facing first wall components for fusion reactor devices. Fusion Eng Des1990; 13: 159–176.
19.
SatoSImamuraYKawamataK. Irradiation effects on thermal shock resistance and fracture toughness of HTGR-graphite. Nucl Eng Des1980; 61: 383–397.
20.
PriceR. Statistical study of the strength of near-isotropic graphite, San Diego, CA: General Atomic Co., 1976.
21.
MitchellBSmartJFokS. The mechanical testing of nuclear graphite. J Nucl Mater2003; 322: 126–137.
22.
Strizak J. The effect of volume on the tensile strength of several nuclear grade graphites. In: Proceedings of IAEA specailist's meeting on the present status of graphite development for gas-cooled reactors, JAERI Tokai, Japan, 9–12 September 1991.
23.
HoF. Modified Weibull theory for the strength of granular brittle material, San Diego, CA: General Atomic Co., 1979.
24.
HindleyMPGroenwoldAABlaineDC. Optimisation of the link volume for weakest link failure prediction in NBG-18 nuclear graphite. Nucl Eng Des2014; 274: 10–19.
25.
ASTM. Standard test method for tensile stress-strain of carbon and graphite. ASTM C749 - 08(2010)e1, West Conshohocken, PA: ASTM International, 2010.
26.
PunmiaBCJainAK. Mechanics of materials, New Delhi, India: Laxmi Publications Pvt Limited, 2002.
27.
RossPJ. Taguchi techniques for quality engineering: Loss function, orthogonal experiments, parameter and tolerance design, New York, NY: McGraw-Hill, 1996.
28.
RoyRK. Design of experiments using the Taguchi approach: 16 steps to product and process improvement, New York, NY: Wiley, 2001.
29.
MahapatraSSPatnaikA. Study on mechanical and erosion wear behavior of hybrid composites using Taguchi experimental design. Mater Des2009; 30: 2791–2801.
30.
MohantyDSilAMaitiK. Development of input output relationships for self-healing Al2O3/SiC ceramic composites with Y2O3 additive using design of experiments. Ceram Int2011; 37: 1985–1992.
31.
RoutAKSatapathyA. Study on mechanical and tribo-performance of rice-husk filled glass–epoxy hybrid composites. Mater Des2012; 41: 131–141.
32.
ShokriehMMHeidari-RaraniMShakouriM. Effects of thermal cycles on mechanical properties of an optimized polymer concrete. Constr Build Mater2011; 25: 3540–3549.
33.
YousefiehMShamanianMSaatchiA. Optimization of the pulsed current gas tungsten arc welding (PCGTAW) parameters for corrosion resistance of super duplex stainless steel (UNS S32760) welds using the Taguchi method. J Alloys Compd2011; 509: 782–788.
