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Abstract: To evaluate precisely the dynamic fracture toughness of a brittle material in the tests with short time-to-fracture, both tup and anvil forces have to be known. Unfortunately, the anvil force is rarely registered by the standard impact testing equipment. The method for numerical evaluation of the support reactions by using registered tup force and the calculated specimen modal parameters is proposed. It assumes that the contact between the specimen and the supports can be described by the quasi-static Hertz's theory. Both linearized and nonlinear relations for the specimen-support contact compliance are considered. The efficiency of the method has been verified by processing the results of two three-point-bend impact tests reported by Bohme and Kalthoff. The influence of the various calculation parameters (number of eigenmodes taken into account, time step size) and the specimen geometry (length of the specimen overhangs) on the accuracy of determination of the anvil force and dynamic stress intensity factor variation with time is investigated.
B I B L I O G R A F I A[1], Wada H., Takagi Y., Nishimura T., A simple procedure for the determination of dynamic stress intensity factors by finite element method (an investigation of availability for the mode I deformation), Trans. Jpn. Soc. Mech. Engng. A 50, 455, 1984, 1425 - 1429, [in Japanese]
[2], Sahraoui S., Gillaizeau F., Numerical simulation of the Charpy impact testing, Engng. Fract. Mech. 33, 6, 1989, 871 - 876
[3], Yamada T., Fukuda Y., Sakurai D., Takeda N., Kishi T., Dynamic fracture toughness evaluation procedure of nodular graphite cast iron by an impact response curve method, J. Jpn. Inst. Met. 54, 3, 1990, 292 - 300
[4], Marur P.R., On the effects of higher modes in analysis of three point bend testing, Int. J. Fract. 77, 2, 1996, 367 - 379
[5], Böhme W., Kalthoff J.F., The behaviour of notched bend specimens in impact testing, Int. J. Fract. 20, 4, 1982, R139 - R143
[6], Rokach I.V., A method for determining of the time dependence of the dynamic stress intensity factor in impact test, Physicochem. Mech. Mater. 24, 6, 1988, 64 - 69, [in Russian, Engl Transl: Sov Mater Sci 1988
24(6):597-601]
[7], Rokach I.V., Numerical simulations of experiments on determination of dynamic fracture toughness of materials, Problemy Prochnosti 19, 7, 1992, 22 - 26, [in Russian, Engl Trans: Problems Strength 1992
19(7)]
[8], Oda J., Taniguchi Y., Hanzawa M., Simple evaluation method for the dynamic stress intensity factor in the impact-point bending test, Trans. Jpn. Soc. Mech. Engng. 57, 533, 1991, 64 - 71, [in Japanese]
[9], Stöckl H., Numerical simulation of brittle fracture in impacted bend specimens, Bilek V., Buhar J., Dynamical Mechanical Properties and Fracture Dynamics of Engineering Materials, 1983, 56 - 63, CSAV
[10], Peuser T., Dynamic analysis of impact test specimen, Sih G.C., Sommer E., Dahl W., Application of Fracture Mechanics to Materials and Structures, 1983, 455 - 465, Martinus Nijhoff Publishers
[11], Rokach I.V., Numerical evaluation of the anvil force for precise processing of the impact fracture test data, Petit J., Mechanisms and Mechanics of Damage and Failure, 1996, 449 - 454, EMAS
[12], Rokach IV. On the accurate determination of contact compliance for impact test modelling. Int J Solids Struct, submitted for publication
[13], Andreikiv A.E., Rokach I.V., A simplified method of determining the time dependence of the stress intensity factor in support-free impact bend testing of beam specimens, Physicochem. Mech. Mater. 25, 5, 1989, 42 - 51, [in Russian, Engl Trans: Sov Mater Sci 1989
25(5):477-85]
[14], Rokach I.V., A simplified method of determining the time dependence of the dynamic stress intensity factor in testing beam specimens in three-point bending, Physicochem. Mech. Mater. 26, 3, 1990, 79 - 83, [in Russian, Engl Trans: Sov Mater Sci 1990
26(3):320-4]
[15], Rokach I.V., Modal approach for processing one- and three-point bend test data for DSIF-time diagram determination. Part I--Theory. Part II--Calculations and results, Fatigue Fract. Engng. Mater. Struct. 21, 8, 1998, 1007 - 1026
[16], Kishimoto K., Aoki S., Sakata M., Simple formula for dynamic stress intensity factors of pre-cracked Charpy specimen, Engng. Fract. Mech. 13, 3, 1980, 501 - 508
[17], Rokach I.V., Estimation of the three-dimensional effects for the impact fracture specimen, Arch. Mech. Engng. 43, 2-3, 1996, 241 - 252
[18], Rokach IV. , DSIFcalc--a free computer program for processing data obtained during impact fracture tests, 1998. Available from: , http://www.tu.kielce.pl/~rokach/dsifcalc.htm