ENGINEERING TRANSACTIONS
ROZPRAWY INŻYNIERSKIE
A QUARTERLY JOURNAL
- A. Ambroziak:
Identification and validation of damage parameters for elasto-viscoplastic Chaboche model
- J. Gołaś:
Influence of transverse shearing and rotary inertia on vibrations of a fibrous composite beams
- J. Lin, A.D. Foster, Y. Liu, D.C.J. Farrugia, T.A. Dean:
On micro-damage in hot metal working. Part 1: Experimental investigation
- M.R. Khoshravan, A. Yourdkhani:
Numerical modeling of delamination in GFRP composites
- S. Srinivas, T. Malathy, P.L. Sachdev:
On pulsatile hydromagnetic flow of an Oldroyd fluid with heat transfer
- A. Ambroziak:
Identification and validation of damage parameters for elasto-viscoplastic Chaboche model
- The aim of the paper is to propose an improved procedure of damage
material parameters identification of the Chaboche model, coupled with
the concept of isotropic damage model proposed by Amar and Dufailly [2].
The proposed approach has been implemented into subroutines of the FE
MSC.Marc code, as the user's viscoplastic subroutine UVSCPL, and has
been used to perform FE static and dynamic computations. The paper gives
a brief description of the Chaboche model including damage. The results are
also presented of FE dynamic analyses using the respective UVSCPL subroutine. Analyses have been made for the nickel-based superalloy INCO718 and for steel. The numerical examples prove that the proposed identification
approach is effective and the numerical implementation is correct.
Contents
- J. Gołaś:
Influence of transverse shearing and rotary inertia on vibrations of a fibrous composite beams
- The aim of the paper was determination of the influence of transverse
shear deformation and rotary inertia on the natural frequencies and on the
values of displacements of beams made of fibrous composites reinforced with
layers of long fibres. It was assumed that the matrix of the composite beam
possesses linear elastic and transversally isotropic properties. Moreover, a
reinforcement in the form of layers composed of long fibres symmetrically
located in the cross-section was considered. In order to describe the displacement and strain state of the matrix, the Timoshenko theory was applied. Using the complete analytical solutions obtained in the paper, the accuracy analysis of the results was performed and compared with the theory of Bernoulli beams.
Contents
- J. Lin, A.D. Foster, Y. Liu, D.C.J. Farrugia, T.A. Dean:
On micro-damage in hot metal working. Part 1: Experimental investigation
- Damage constitutive equations are formulated to model the evolution of
grain boundary and plasticity-induced damage for free-cutting steels under
hot forming conditions. During high temperature, high strain rate deformation, material degradation has characteristics of both creep damage at grain boundaries, and ductile damage surrounding hard inclusions. This has been experimentally observed and is reported in the companion paper. This paper describes the development of unified viscoplastic-damage constitutive
equations, in which the nucleation and growth of both damage types are
considered independently. The effects of deformation rate, temperature, and
material microstructure on damage evolution are modelled. The proposed
damage evolution equations are combined with a viscoplastic constitutive
equation set, enabling the evolution of dislocation hardening, recovery, recrystallisation, grain size, and damage to be modelled. This set of unified, mechanism-based, viscoplastic damage constitutive equations is determined
from experimental data of a free-machining steel for the temperature range
1173-1373 K. The fitted model is then used to predict damage and failure
features of the same material tested using a set of interrupted constant strain
rate tests. Close agreement between the predicted and experimental results
is obtained for all the cases studied.
Contents
- M.R. Khoshravan, A. Yourdkhani:
Numerical modeling of delamination in GFRP composites
- Polymer matrix composites have become highly relevant structural materials. However, high performance laminates are quite susceptible to transverse cracking and delamination. Transverse cracks may cause significant
stiffness losses, accelerate environmentally induced degradation and generate delamination. The characterization and modeling of fracture behavior is thus highly relevant for the design of composite parts. In this paper,
the delamination phenomena in the Mixed Mode I+II which is one of the
important cause of failure in multilayer composites, are studied. The composite is a GFRP (Glass Fiber Reinforced Plastic) and are studied under static monotonic loading. Using the Irwin-Kies criteria, usual laws of elasticity and VCCT (Virtual Crack Closure Technique), based on finite element
method, the SERR (Strain Energy Release Rate) in Mode I, Mode II, and
four ratio Modes (GI=GII) are evaluated. The finite element analysis of
test bars is carried out using ANSYS5.5 software in two dimensions, and
the appropriate boundary conditions are chosen. Our numerical results are
compared with known experimental ones and with application of the local
effects, such as three-dimensional (3D) effect in the width of the test bar
with the shape of MMB (Mixed Mode Bending) specimen, scattering be-
tween experimental and numerical results is evaluated and discussed. For
the 3D effect, the variation of the stress components in the mid-plane of
specimen in which delamination occurs, versus the width of specimen, is
obtained. Then the variation of strain energy release rate in different ratio
Modes, in the width of test bars is calculated.
Contents
- S. Srinivas, T. Malathy, P.L. Sachdev:
On pulsatile hydromagnetic flow of an Oldroyd fluid with heat transfer
- The problem of heat transfer to pulsatile flow of hydromagnetic viscoelastic fluid has been studied. Expressions for the velocity, temperature distribution and mass flow rate are obtained. The rate of heat transfer at the
plates has also been calculated. These expressions are evaluated numerically for various values of the parameters. The influence of pertinent parameters on temperature, heat transfer coefficient and mass flux has been studied and
numerical results obtained are presented graphically.
Contents
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