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Titolo:
Failure mode transition speeds in an impact loaded prenotched plate with four thermoviscoplastic relations
Autore:
Batra, RC; Jaber, NA;
Indirizzi:
Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, Blacksburg, VA 24061 USA Virginia Polytech Inst & State Univ Blacksburg VA USA 24061 VA 24061 USA
Titolo Testata:
INTERNATIONAL JOURNAL OF FRACTURE
fascicolo: 1, volume: 110, anno: 2001,
pagine: 47 - 71
SICI:
0376-9429(200107)110:1<47:FMTSIA>2.0.ZU;2-K
Fonte:
ISI
Lingua:
ENG
Soggetto:
BRITTLE-DUCTILE TRANSITION; PROPAGATING SHEAR BANDS; HIGH-STRAIN RATES; VOID NUCLEATION; FLOW RULES; FRACTURE; GROWTH; DEFORMATIONS; STEEL; NOTCH;
Keywords:
finite element solution; microporous thermoviscoplastic material transient plane strain deformations; brittle and ductile failures;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Engineering, Computing & Technology
Citazioni:
43
Recensione:
Indirizzi per estratti:
Indirizzo: Batra, RC Virginia Polytech Inst & State Univ, Dept Engn Sci & Mech, M-C 0219, Blacksburg, VA 24061 USA Virginia Polytech Inst & State Univ M-C 0219 Blacksburg VA USA 24061
Citazione:
R.C. Batra e N.A. Jaber, "Failure mode transition speeds in an impact loaded prenotched plate with four thermoviscoplastic relations", INT J FRACT, 110(1), 2001, pp. 47-71

Abstract

Four different thermoviscoplastic relations, namely, the Litonski-Batra. Johnson-Cook, Bodner-Partom and the power law are used to model the thermoviscoplastic response of a material. Each one of these relations accounts forstrain hardening. strain-rate hardening and thermal softening of the material. The material parameters in these relations are found by solving an initial-boundary-value problem corresponding to simple shearing deformations so that the computed effective stress vs, the effective plastic strain curves match closely with the experimental data of Marchand and Duffy who testedthin-walled HY-100 steel tubes in torsion. These four viscoplastic relations are used to analyze dynamic thermomechanical deformations of a prenotched plate impacted on the notched side by a cylindrical projectile made of the same material as the plate. The impact loading on the contact surface is simulated by prescribing the time history of the normal component of velocity and null tangential tractions. A plane strain state of deformation is assumed to prevail in the plate and its deformations are studied for different values of the impact spc rd. The in-house developed finite element code employs constant strain triangular elements, one point integration rule, anda lumped mass matrix. The Lagrangian description of motion is used to describe deformations of the plate. The coupled nonlinear partial differential equations are first reduced to coupled nonlinear ordinary differential equations (ODEs) by using the Galerkin approximation. The ODEs are integrated by using the stiff solver, LSODE, which adaptively adjusts the time: step size and computes the solution within the prescribed accuracy. Results computed with the four constitutive relations are found to be qualitatively similar to each other and the general trends agree with the experimental observations in the sense that at low speed of impact, a brittle failure ensues ata point on the upper surface of the notch tip. However. at high impact speeds, a ductile failure in the form of a shear band initiates first from a point on the lower surface of the notch tip. The predicted speed at which the failure mode transitions from brittle to ductile is different for the four viscoplastic relations. The effects of the notch tip radius and the yieldstrength of the material in a quasistatic simple tension/compression test on the failure-mode transition speed have been ascertained.

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Documento generato il 27/11/20 alle ore 01:19:37