- Type of paper
: Paper in journal
Title: Influence of the Shear on Torsion of a Thin-Walled Rod of
Open Cross-Section
- Authors:
- PAVAZZA, RADOSLAV (35240)
Journal: Strojarstvo
Number: 3,4
ISSN: 0562-1887
Volume: 35
Year: 1993
Pages: from 103 to 109
Number of references: 8
Language: hrvatski
Summary: In the special case of torsion of a thin-walled rod of open
cross-section, where pure torsional compnent can be neglected in relation
to the warping component, there may be found a full analogy between the
torsion of a thin-walled rod of open cross-section and that of the bending
of the rod. The paper considers analogy of the bending with influence of
shear of a rod to the influence of the shear (by warping component) on
torsion of a thin-walled rod of open cross-section. Derived components -
differential equations, internal force factors and displacements - are
analogus to the components of bending with the influence of the shear.
Consequently, between the torsion with influence of shear of a thin-walled
rod of open cross-section and that of bending with influence of shear of a
rod is in full analogy also.
Keywords: bending, analogy of, shear, thin-walled rod of open cross-section, torsion
- Type of paper
: Paper in journal
Title: Modelling of Ship's Bottom Structures by Plane Systems of
Thin-walled Girders of Open Cross-section
- Authors:
- PAVAZZA, RADOSLAV (35240)
- PLAZIBAT, BOŽE (80666)
- MATOKOVIĆ, ADO (106924)
Journal: Strojarstvo
Number: 1,2
ISSN: 0562-1187
Volume: 35
Year: 1993
Pages: from 11 to 17
Language: hrvatski
Summary: This paper presents analogy between torsion and bending of
thin-walled girder of open cross-section, in case when the torsional
stiffenss is low compared to the warping stiffness. The plane system of
thin-walled girder of open section with the program for personal computer
is given. The modelling of plated structures by plane thin-walled girders
of open-section is illustrated in case of ship's bottom structures. The
results were verifed by finite element method, employing membrane elements.
Keywords: plane system, ship's bottom structure, thin-walled girder of open cross-section
- Type of paper
: Paper in journal
Title: Elastic buckling of internally pressurized imperfect
torispherical shell
- Authors:
- SORIĆ, JURICA
Journal: Computational Mechanics
Number: 3
ISSN: 0178-7675
Volume: 8
Year: 1991
Pages: from 161 to 171
Number of references: 27
Language: engleski
Summary: The elastic stability of an imperfect torispherical shell
subjected to internal pressure was analyzed numerically using the finite
element method. Imperfection patterns affine to the buckling mode in the
bifurcation points of the perfect structure where studied and internal
pressure-nodal displacement curves obtained for the pre- and postbuckling
regions of the computation model. The effect of the imperfection pattern
amplitude on the critical pressure and postbuckling minimum was analyzed.
The imperfection sensitivity was presented graphically.
Keywords: torispherical shell, finite element method, elastic stability, internal pressure
- Type of paper
: Paper in journal
Title: On The Effect of Fibre Directions in Laminated Composite
Torispherical Shells
- Authors:
- SORIĆ, JURICA
- SMOJVER, IVICA (900490)
Journal: Engineering Computations
Number: 1
ISSN: 0264-4401
Volume: 12
Year: 1995
Pages: from 85 to 94
Number of references: 12
Language: engleski
Summary: A linear and geometrically non-linear computation of a
laminated composite torispherical shell subjected to internal pressure was
performed by using the layered finite element whose formulation is based on
degeneration principle. Geometric non-linearity in terms of large
deformation with total Lagrangian formulation was taken into account. The
effect of the lamination schemes on geometric non-linear behaviour and
stress resultant distributions was analysed.The fibre directions have not a
great infulence on the shape of load-displacement curves. In contrast to
the hoop stress resultant distribution, the moment distribution is
significantly infulenced by the lamination schemes. The infulence of the
lamination schemes on bending moments is greater in linear computations.
Likewise, the effect of the fibre orientation is greater on the hoop than
on the meridional moment distribution. In unsymetric laminated shells the
values of the hoop momnets exceeded those of the meridional moments which
is a considerable difference from metallic isotropic shells.
Keywords: laminated composite torispherical shell, symetric lay-up, unsymetric lay-up, hoop stress resultant distribution, moment distribution
- Type of paper
: Paper in journal
Title: Numerical Analysis of Thin-walled Beam Structures
- Authors:
- HEIDL, IVAN (15440)
- TONKOVIĆ, ZDENKO (187173)
Journal: Strojarstvo
Number: 1,2
ISSN: 0562-1887
Volume: 36
Year: 1994
Pages: from 49 to 53
Number of references: 6
Language: hrvatski
Summary: The paper is based on the application of substructures
method in determination of deformations and strenghts distribution in the
joint area of open thin walled rodes. Calculation of such a structure
follows the Wlassov's theory, bat in the joint area the finite elements
method is applied. The connection between the two areas is given by a
hybride calculation model which gives in matrix form basis for making of an
adequate computer program.
Keywords: finite element method, substructures method, thin-walled rod structure
- Type of paper
: Paper in journal
Title: Modelling of Elastoplastic State in a Continuum by the
Finite Element Method
- Authors:
- PUSTAIĆ, DRAGAN (73411)
- ŠTOK, BORIS
Journal: Strojarstvo
Number: 5,6
ISSN: 0562-1887
Volume: 33
Year: 1991
Pages: from 315 to 323
Number of references: 6
Language: hrvatski
Summary: The paper deals with basic equations of the finite element
method used in the analysis of stresses and strains in a continuum in which
the plastification process is being carried out. By deriving the
experession for the elastoplastic matrix Dep the general approach has been
shown, afterwards, the matrix is formed for the cases of general
three-dimensional state of stress and plane state of stress. Several
numerical examples are also given. Thin plates with different geometrical
discontinuities such as a circular hole, an elliptical hole and a crack are
considered. The discretization has been carried out by the finite elements,
then,the analysis of stresses and strains. The local plastic zones around
the discontinuities are defined as well.
Keywords: continuum, modelling of Finite Element Method, mathematical modelling, plasticitiy
- Type of paper
: Paper in journal
Title: The Analysis of Some Fracture Mechanics Parameters by the
Application of the Theory of Functions of a Complex Variable
- Authors:
- PUSTAIĆ, DRAGAN (73411)
Journal: Strojarstvo
Number: 1,2
ISSN: 0562-1887
Volume: 35
Year: 1993
Pages: from 31 to 39
Number of references: 25
Language: hrvatski
Summary: The article deals with the analyitical determination of
stresses, strains, displacements and some fracture mechanics parameters in
thin infinite cracked plates. It is supposed that the magnitude of external
loading is big enough that a local plastic zone in the neighbourhood of the
crack tip is formed. A variation of the magnitude and the shape of the
local plastic zone around the crack tip such as the crack tip opening
displacement (CTOD) in dependence upon the variation of the magnitude of
the external loading of the plate have been investigated. The analysis of
the stress intensity factor has been performed. The analysis has been
performed using the analytical methods of the theory of functions of a
complex variable. To describe the plastification process in a plate with an
embedded crack the Dugdale model originally based on the Tresca yield
criterion has been utilized. The influence of the loading parallel to the
crack surface has been also analysed using so called modified Dugdale model
based on the von Mises yield criterion.
Keywords: conformal mapping, Dugdale's model, fracture mechanics, theory of functions of a complex variable, Westergaard's method
- Type of paper
: Paper in journal
Title: Reliability Estimation of the Components of Electrical
Rotating Machines Based on the Accumulation Theory of Microcracks and
Propagation Analysis of Fatigue Cracks
- Authors:
- PUSTAIĆ, DRAGAN (73411)
Journal: Strojarstvo
Number: 1,2
ISSN: 0562-1887
Volume: 36
Year: 1994
Pages: from 33 to 44
Number of references: 14
Language: hrvatski
Summary: Fatigue cracks and some other similar non-homogeneities
are often, unavoidable escorts of some components of electrical rotating
machines. This particularly refers to eletrical generators because they
have long lifetime and meet many accidental states. In case of repairs and
revitalization it is most important to estimate the nature, magnitude and
state of stresses in such non-homogeneities and their environment as well
as in order to predict crack propagation. In this paper the working life
and the fatigue reliability of some main components of the electrical
rotating machine based on the accumulation theory of microcracks is
evaluated. Also, different models of propagation of the fatigue cracks
caused by cyclic stresses are analysed by which the remaining lifetime may
be foreseen.
Keywords: crack propagation, cyclic stresses, electrical rotating machines, fatigue life, fatigue reliability of structure, microcraks, accumulation theory of
- Type of paper
: Paper in journal
Title: A Contribution to the Nonlinear Analysis of Compound Shell
Structures
- Authors:
- SORIĆ, JURICA
Journal: Strojarstvo
Number: 1,2
ISSN: 0562-1887
Volume: 36
Year: 1994
Pages: from 23 to 31
Number of references: 11
Language: hrvatski
Summary: Finite element formulation providing solution of
geometrically and materially nonlinear problems is presented. The
geometrically nonlinear theory of small rotation and elastic-plastic
material model based on the isotropic strain hardening and Von Mises yield
criterion were applied. The effect of geometric and material nonlinearity
on the internal force distribution in an internally pressurized
torispherical shell was investigated. It was found out that the geometric
nonlinearity increases with increase in the ratio of cylindrical shell
diameter to wall thickness which, in turn, yields lower stress resultants
and moments in relation to linear analysis. The spreading of plastic
regions has no significant influence on these differences. In the case of
bending moments the differences in the values obtained by geometrically
linear and nonlinear computations tend to some increase with an increase of
plastic regions, while in case of hoop stress resultants even a relative
decrease regarding the elastic response may occur. Nonlinear analysis
constributes to an optimization of presented compound shell structures.
Keywords: finite element method, geometric nonlinearity, material nonlinearity, nonlinear analysis, shell structure, torispherical shell, toroidal shell
- Type of paper
: Paper in journal
Title:
- Authors:
- SORIĆ, JURICA
Journal: Thin-Walled Structures
ISSN: 0263-8231
Volume: 23
Year: 1995
Pages: from 57 to 66
Number of references: 16
Language: engleski
Summary: The imperfection sensitivity of torispherical shells
subjected to internal pressure was investigated numerically, using the
finite element displacement method. Imperfection patterns affine to the
first buckling mode at the bifurcation points of the perfect structure were
considered. Load-normal displacement curves were obtained for the pre- and
postbuckling regions of the perfect computation models with different
imperfection amplitudes. The dependence of the critical pressure and the
postbuckling minimum on the imperfection amplitudes was presented
graphically. Torispherical shells subjected to internal pressure failed to
demonstrate any significant imperfection sensitivity for the imperfection
patterns analysed.
- Type of paper
: Paper in journal
Title: Physically and Geometrically Nonlinear Load-Carrying
Behavior of Shells of "Klopper" Shape
- Authors:
- SORIĆ, JURICA
Journal: Stahlbau
Number: 5
Volume: 63
Year: 1994
Pages: from 140 to 146
Number of references: 15
Language: njemački
Summary: Geometrically linear and geometrically nonlinear
elastic-plastic computations of internally pressurized torispherical shells
of "Klopper" shape are performed. Finite element approach with layered
doubly curved shell element is applied. The isotropic strain hardening with
von Mises yield criterion and geometrically nonlinear Donnel-Marguerre's
theory are assumed. Influence of the yield stress and strain hardening of
the material model on the stress resultants distribution and spread of
plastic regions are investigated. Change of the plastic regions produces a
redistribution of internal forces. Geometric nonlinearity has a significant
influence on the load-carrying capacity of very thin "Klopper" heads.
- Type of paper
: Paper in proceedings
Title: MODELLING OF STRUCTURES MADE FROM NON-LINEAR ELASTIC
MATERIALS
- Authors:
- PUSTAIĆ, DRAGAN (73411)
- Editors
- SMOLČIĆ ŽERDIK, ZORA
- Smolčić Žerdik, Zora
Proceedings title: ZBORNIK RADOVA FAKULTETA STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU
Language: hrvatski
Place: Zagreb
Year: 1993
ISBN/ISSN: 0350-3097
Pages: from 31 to 44
Summary: In engineering practice the problem of calculating strenght
of different structural components is often an imperative. It is of special
interest when a structural component is made from the material for which
the Hook's law is not valid. In the paper different statically determined
and statically undetermined structures made from non-linear elastic
material are analyzed. The strength of these structures is calculated for
the basic modes of loading such as axial loading, bending and torsion.
Keywords: non-linear elastic material, axial loading, bending, torsion
- Type of paper
: Paper in proceedings
Title: A YIELD CRITERION OF ISOTROPIC MATERIALS WITH DIFFERENT
TENSILE AND COMPRESSIVE YIELD POINTS
- Authors:
- ALFIREVIĆ, IVO (303)
- Editors
- SMOLČIĆ ŽERDIK, ZORA
Proceedings title: ZBORNIK RADOVA FAKULTETA STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU
Language: hrvatski
Place: Zagreb
Year: 1992
ISBN/ISSN: 0350-3097
Pages: from 5 to 10
Summary: General tensor expression for a yield criterion containing
stress tensor raised to the zeroth, first and second power has been
considered. If tensile and compressive plasticity (strength) properties are
different, then three independent parameters rather then one, as it is the
case of materials with equal tensile and compressive properties, have to be
used. It is convenient to define these properties as tensile and
compressive yield points as well as shearing yield point. Furthermore, it
has been shown that the first stress invariant explicity influences
yielding, unlike materials with equal tensile and compressive properties.
Keywords: yield criterion, tensile and compressive plasticity, yield point
- Type of paper
: Paper in proceedings
Title: COMPARISON OF THEORETICAL AND NUMERICAL -ITERATIVE
SOLUTION OF ELASTO-PLASTIC BENDING OF A CANTILEVER
- Authors:
- ŠOMOĐI, ŽELJKO
Proceedings title: Zbornik radova VII jugoslavenskog simpozija o teoriji plastičnosti
Language: hrvatski
Place: Pula
Year: 1991
Pages: from 61 to 65
Meeting: Jugoslavenski simpozij o teoriji plastičnosti
Held: from 06/05/91 to 06/07/91
Summary: The paper brings the solution of elasto-plastic bending of
a cantilever beam with square cross-section in two ways: theoretically and
numerically by means of the finite-difference method and iteration
procedure based on variable elastic parameters. The comparison of results
shows the infuluence of discretization and convergence criterion upon the
accuracy of the numerical solution.
Keywords: cantilever beam, elasto-plasticity, numerical-iterative solution, finite differences
- Type of paper
: Paper in proceedings
Title: ON NUMERICAL ANALYSIS OF THIN-WALLED BEAM STRUCTURES
- Authors:
- HEIDL, IVAN (15440)
- TONKOVIĆ, ZDENKO (187173)
- Editors
- Smolčić Žerdik, Zora
Proceedings title: ZBORNIK RADOVA FAKULTETA STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU
Language: hrvatski
Place: Zagreb
Year: 1992
ISBN/ISSN: 0350-3097
Pages: from 29 to 36
Summary: The method of substructure is used to determine stress and
strain distribution in the joints of open thin-walled bars. General
analysis of structure is based on the teory of Wlassov. Local analysis in
the field of joints is performed by the finite element method. Connection
two field description hybrid calculation model which in matrix form gives
base for making adequate computer program.
Keywords: method of substructure, open thin-walled bars, finite element method
- Type of paper
: Paper in proceedings
Title: On Nine Noded Element for Analysis of Laminated Composite
Shells
- Authors:
- SMOJVER, IVICA (900490)
- SORIĆ, JURICA
- ALFIREVIĆ, IVO (303)
- Editors
- SORIĆ, JURICA
- VRANKOVIĆ, NIKOLA
Proceedings title: Zbornik radova 1. kongresa Hrvatskog društva za mehaniku
Language: engleski
Place: Zagreb
Year: 1994
ISBN/ISSN: 953-96243-0-4
Pages: from 47 to 54
Meeting: 1. KONGRES HRVATSKOG DRUŠTVA ZA MEHANIKU
Held: from 09/14/94 to 09/17/94
Summary: The paper presents 9 noded Lagrangian element with 45
D.O.F. used for analysis of laminated composite shells. The element is
based on the principle of degeneration, enabling analysis of thick and thin
shells. Developed routines were written in MATLAB with intention of
translation such a code in some of higher programming languages like C or
FORTRAN 90. Results for orthotropic layered material models were presented
and have shown good agreement with available references.
Keywords: laminated composite shell, principle of degeneration, linear elasticity, Matlab
- Type of paper
: Paper in proceedings
Title: ON MIXED INTERPOLATION OF EIGHT-NODE SHEAR-BENDING PLATE
ELEMENT
- Authors:
- TONKOVIĆ, ZDENKO (187173)
- SORIĆ, JURICA
- HEIDL, IVAN (15440)
- Editors
- SORIĆ, JURICA
- VRANKOVIĆ, NIKOLA
Proceedings title: ZBORNIK RADOVA 1. KONGRESA HRVATSKOG DRUŠTVA ZA MEHANIKU
Language: engleski
Place: Zagreb
Year: 1994
ISBN/ISSN: 953-96243-0-4
Pages: from 39 to 46
Meeting: 1. KONGRES HRVATSKOG DRUŠTVA ZA MEHANIKU
Held: from 09/14/94 to 09/17/94
Summary: This paper presents eight-node, 24-d.o.f. quadrilateral
shear-bending Reissner-Mindlin plate element valid for the analysis of
thick to thin plates. The formulation of the element is derived from a
displacement variational principle using mixed interpolation strategy in
order to eliminate undesirable locking effect. The standard mixed
interpolation was improved by the new location of the discrete points what
leads to the insensitivity to the mesh distortion.
Keywords: finite element method, Mindlin-Reissner plates, "shear-locking", mixed interpolation
- Type of paper
: Paper in proceedings
Title: FINITE ELEMENT FOR THICK PLATES ANALYSIS
- Authors:
- HEIDL, IVAN (15440)
- TONKOVIĆ, ZDENKO (187173)
- Editors
- SMOLČIĆ ŽERDIK, ZORA
Proceedings title: ZBORNIK RADOVA FAKULTETA STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU
Language: hrvatski
Place: Zagreb
Year: 1994
ISBN/ISSN: 1330-4364
Pages: from 13 to 20
Summary: By applying the Mindlin-Reissner theory the isoparametric
eight-node quadrilateral finite element for linear thick and thin plates is
derived. The formulation of the element is based on the displacement method
using mixed interpolation in order to eliminate the "shear-locking"
problem. The derived has very good convergence characteristics for both
thick and thin plates, passes the patch tests and has no extra zeroenergy
modes. The mixed interpolation criteria used for this element may be very
simply applied to the design of four-node, triangular and other finite
elements.
Keywords: finite element method, Mindlin-Reissner plates, "shear-locking", mixed interpolation
- Type of paper
: Paper in proceedings
Title: ELASTIC STABILITY OF COMPRESSED MULTISPAN BARS
- Authors:
- SAUCHA, JURAJ (83322)
- Editors
- SORIĆ, JURICA
- VRANKOVIĆ, NIKOLA
Proceedings title: ZBORNIK RADOVA 1. KONGRESA HRVATSKOG DRUŠTVA ZA MEHANIKU
Language: engleski
Place: Zagreb
Year: 1994
ISBN/ISSN: 953-96243-0-4
Pages: from 558 to 563
Meeting: 1. KONGRES HRVATSKOG DRUŠTVA ZA MEHANIKU
Held: from 09/14/94 to 09/17/94
Summary: The paper deals with the problem of elastic stability of
multispan bars with various lenghts and flexural rigidities of the spans
and with constant compressive longitudinal forces in the spans. Especially
the bars with hangovers and fixed ends are studied. The equations which
enable the determination of the critical load are derived.
Keywords: elastic stability, buckling of multispan bars
- Type of paper
: Paper in proceedings
Title: DISPLACEMENTS AND STRAINS OF THIN WALLED BARS OF OPEN
CROSS SECTION IN THE GENERAL CASE OF LOADING
- Authors:
- SAUCHA, JURAJ (83322)
- Editors
- SMOLČIĆ ŽERDIK, ZORA
Proceedings title: ZBORNIK RADOVA FAKULTETA STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU
Language: hrvatski
Place: Zagreb
Year: 1994
ISBN/ISSN: 1330-4364
Pages: from 45 to 52
Summary: The paper deals with the derivation of the expressions
defining displacements and strains of thin-walled bars of open cross
section on the general case of loading. Displacements are derived from the
components of the finite strain tensor. Based of the introduced assumptions
concerning displacements and strains of the bar three dimensional problem
is reduced to one dimensional problem. The derived expressions provide the
basis for the analysis of elastic stability of the thin-walled bars of open
cross section.
Keywords: elastic stability, thin walled bars of open cross section, displacements and strains
- Type of paper
: Paper in proceedings
Title: DERIVATION OF THE EQULIBRIUM EQUATIONS OF THIN-WALLED BARS
OF OPEN CROSS SECTION BY THE 2nd ORDER
- Authors:
- SAUCHA, JURAJ (83322)
- Editors
- SMOLČIĆ ŽERDIK, ZORA
Proceedings title: ZBORNIK RADOVA FAKULTETA STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU
Language: hrvatski
Place: Zagreb
Year: 1994
ISBN/ISSN: 1330-4364
Pages: from 53 to 60
Summary: The paper deals with the derivation of the equilibrium
equations of thin walled bars of open cross section in the general case of
loading. First the internal forces acting in the cross section of the
deformed bar have been determined by means of the reduction of elementary
normal and shearing forces. Afterwards the equilibrium equations were
derived through consideration of the equilibrium of displaced element of
the bar. The obtained equations provide the basis for the analysis of
elastic stability of the thin-walled bars of open cross section.
Keywords: elastic stability, thin-walled bars of open cross section, equlibrium equations
- Type of paper
: Paper in proceedings
Title:
- Authors:
- AGIĆ, ANTE (137300)
Proceedings title: 2nd EUROPEAN SOLID MECHANICS CONFERENCE ABRSTRACT BOOK
Language: engleski
Place: Genova, Italia
Year: 1994
Meeting: European Solid Mechanics Conference
Summary: A numerical method has proposed for modeling mechanical
behavior natural composites based on a volume fraction mixture theory. A
displacement based finite element formulation has used to solve numerically
the constituent balance equations. Nodal degrees of freedom reperesent the
constituent displacements of the multiphase continua. The interactions
between matrix and fibbers at a point in the mixture have described by the
diffusion constitutive relations for the momentum supply terms. The natural
leather, as mixture of open structure collagen fibbers partially filled
with oils and greases have used as a model for the collagen-based
composite. The stress gradient and microstructure tensors have determined
as result's comparison between experimental and numerical stress-strain
data.
Keywords: natural composites, volume fraction mixture theory, finite element method, natural leather
- Type of paper
: Paper in proceedings
Title:
- Authors:
- AGIĆ, ANTE (137300)
Proceedings title: PROCEEDINGS 10th INTERNATIONAL SYMPOSIUM ON BIOMEDICAL ENGINEERING
Language: engleski
Place: Zagreb
Year: 1994
Pages: from 79 to 82
Meeting: 10th INTERNATIONAL SYMPOSIUM ON BIOMEDICAL ENGINEERING
Summary: Many injure in running have related to insufficient
shock-absorbtion properties of the shoes. A critical test for shoes is how
well they absorb the shock and transmit the force thorough the body. The
aim of this study was to develop a mathematical tool that could be explain
the shock isolation phenomena in athletic shoes. The idealized shock
isolation system has considered to have composed of a rigid mass (human
body) supported on a rigid foundation by a single isolator (atletic shoe)
undergoing unidirectional dynamic motion. Linear stiffens element in
parallel with a pneumatic damping element has used to characterize the
isolator. Shock excitation has defined in terms of cosine pulse
displacement upon a fundation. The residual shock amplification curves for
displacement and acceleration for isolation system in terms of the relative
values of the shock pulse time duration and the isolation system natural
period has presented.
Keywords: running shoe, shock isolation, pneumatic damping, air-bag
- Type of paper
: Paper in proceedings
Title: VISCOELASTIC BEHAVIOR OF THE DEGRADABLE POLYMERS
- Authors:
- AGIĆ, ANTE (137300)
Proceedings title: 13. DANI DRUŠTVA PLASTIČARA I GUMARACA, ZBORNIK RADOVA
Language: hrvatski
Place: Zagreb
Year: 1995
Pages: from 58 to 61
Meeting: 13. DANI DRUŠTVA PLASTIČARA I GUMARACA
Summary: The generalized stress-strain constitutive equations for
degradable viscoelastic continua have developed by use inernal variable's
formalism. The behaviors of the material have uniquely defined by the
structure of the free energy and evolution equations for internal
coordinates (constitutive equations on the microscopic level). The
equivalent microscopic behavior as accompanied degradation mechanism has
described by set of internal variables (free volume, viscous damping,
damage, crosslink density). The nonlinear behavior has described by three
thermodynamics tensor functions and by generalized shift factors. Some
experimentally detected anomaly under degradative enviroment has been
explaned by proper microstructure's models.
Keywords: nonlinear viscoelasticity, degradation, internal coordinates
- Type of paper
: Paper in proceedings
Title: A SIMPLIFIED MODEL FOR NUMERICAL ELASTOPLASTIC PLANE
STRESS ANALYSIS
- Authors:
- ŠOMOĐI, ŽELJKO
- Editors
- SORIĆ, JURICA
- VRANKOVIĆ, NIKOLA
Proceedings title: ZBORNIK RADOVA 1.KONGRESA HRVATSKOG DRUŠTVA ZA MEHANIKU
Language: engleski
Place: Zagreb
Year: 1994
ISBN/ISSN: 953-96243-0-4
Pages: from 139 to 144
Meeting: 1. KONGRES HRVATSKOG DRUŠTVA ZA MEHANIKU
Held: from 09/14/94 to 09/17/94
Summary: A simplified numerical model is presented based on the
backward Euler iteration in which the complete iterative process is
restricted to the plane sigma3=0 in the principal stress space. Initial
stiffness method is used, implying puerly elastic prediction in every
iteration step, in conjunction with the modified radial return. The yield
limit update in the plastic range is performed as isotropic hardening based
on the equivalent total strain. The procedure is illustrated in the common
example of the tension strip with circular notches.
Keywords: plane stress, elstoplasticity, numerical model
- Type of paper
: Paper in proceedings
Title: THE ANALYISIS OF THE CRACK TIP OPENING DISPLACEMENT (CTOD)
AND THE MAGNITUDE OF THE PLASTIC ZONE AROUND A CRACK TIP BASED ON DUGDALE'S
STRIP YIELD MODEL AND THE ESTIMATION OF HER RELIABILITY
- Authors:
- PUSTAIĆ, DRAGAN (73411)
- Editors
- VRANKOVIĆ, NIKOLA
- SORIĆ, JURICA
Proceedings title: ZBORNIK RADOVA 1. KONGRESA HRVATSKOG DRUŠTVA ZA MEHANIKU
Language: engleski
Place: Zagreb
Year: 1994
ISBN/ISSN: 953-96243-0-4
Pages: from 496 to 504
Meeting: 1. KONGRES HRVATSKOG DRUŠTVA ZA MEHANIKU
Held: from 09/14/94 to 09/17/94
Summary: The article deals with the analytical determination of
stresses and displacements and some other fracture mechanics parameters,
such as: the crack displacement (COTD) and the magnitude of the plastic
zone around a crack tip, in thin infinite cracked plates. The plates are
loaded biaxially at the crack surface is free of loading. It is supposed
that the magnitude of applied loading will be caused the apperrance of the
plastic deformations in the neighbourhood of the crack tip. In this paper
are used the analytical methods based on the theory of the functions of a
complex variable. For describing of the plastification process in an
infinite plate with an embedded crack the Dugdales strip yield model
originally based on the Tresca yield criterion has been utilized. The
influence of the remote normal traction which is parallel to the crack
surface, on those parameters, has also been investigated. In connection
with this purpose, it has been necessaryly to modify the original Dugdale
strip yield model and to apply the von Mises yield criterion.
Keywords: fracture mechanics, Dugdale's strip yield model, theory of functions of a complex variable, crack tip opening displacement, plastic zone around the crack tip
- Type of paper
: Paper in proceedings
Title: THE YIELD CRITERIA MODIFICATION IN A FORM SUITABLE FOR
NUMERICAL COMPUTATION
- Authors:
- PUSTAIĆ, DRAGAN (73411)
- Editors
- SMOLČIĆ ŽERDIK, ZORA
Proceedings title: ZBORNIK RADOVA FAKULTETA STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU
Language: hrvatski
Place: Zagreb
Year: 1995
ISBN/ISSN: 1330-4364
Summary: The basic constitutive equations of the flow theory for the
stress and strains amalysis in the plastic range are stated in this paper.
In order to achieve this aim it is necesarryly some yield criteria to
modify in an alternative form which is suitable for incorporating in the
existing algorithmus for the stress and strain analysis, in a continuum in
which an elastic-plastic deformations are appeared. This transformation of
the yield criteria is a basic purpose of this paper. A few numerical
examples are presented in order to illustrate the application of some yield
criteria, in which the stress fields are computed, using the finite element
method.
Keywords: theory of plasticity, yield criterion, Von Mises, Tresca, Mohr-Coulomb, Drucker-Prager, finite element method
- Type of paper
: Paper in proceedings
Title: APPLICATION OF TENSOR FORMULATION TO THE ANALYSIS OF
COMPOUND SHELL STRUCTURES
- Authors:
- SORIĆ, JURICA
- TODOROVIĆ, GORAN
- Editors
- SMOLČIĆ ŽERDIK, ZORA
Proceedings title: ZBORNIK RADOVA FAKULTETA STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU
Language: hrvatski
Place: Zagreb
Year: 1994
ISBN/ISSN: 1330-4364
Pages: from 5 to 12
Summary: The basic equations of theory of thin shells in tensor
formulation were presented. The differential eqations for the solution of
the problem of symmetrical deformation of shells of revolution were
developed. The advantage of tensor notation in comparison to classic theory
of shells was demonstrated. By using the object oriented programming the
program for the computation of compound shell structures was developed,
where the system of differential equations was solved by finite difference
method. The program validity was checked by comparison of the obtained
results with other available solutions.
- Type of paper
: Paper in proceedings
Title:
- Authors:
- SORIĆ, JURICA
- Editors
- VRANKOVIĆ, NIKOLA
- SORIĆ, JURICA
Proceedings title: ZBORNIK RADOVA 1. KONGRESA HRVATSKOG DRUŠTVA ZA MEHANIKU
Language: engleski
Place: Zagreb
Year: 1994
ISBN/ISSN: 953-96243-0-4
Pages: from 71 to 78
Meeting: 1. KONGRES HRVATSKOG DRUŠTVA ZA MEHANIKU
Held: from 09/14/94 to 09/17/94
Summary: The contribution presents a numerical concept for the
geometrically nonlinear elastic-plastic analysisof shell structures. The
constitutive equation for an elastic-plastic material model was derived
using von Mises yield criterion and assuming isotropic strain hardening. A
doubly curved layered finite element based on a tensororiented displacement
formulation was presented. Its efficiency is demonstrated by the
computation of compound shell structures in the form of torispherical
heads. The hoop stress distribution and the spreading of plastic regions
through the shell thickness were computed.
- Type of paper
: Ph.D.
Title: Contribution to the analysis of elastic stability of beams
of thin-walled open cross-section
Faculty: FAKULTET STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU Sveučilište u Zagrebu
Author: SAUCHA JURAJ
Date of defense: 03/18/93
Language: hrvatski
Number of pages: 156
Summary: The thesis consideres the lateral torsional buckling of
beams of thin-walled open cross-sections simultaneously subjected to
transverse load and compressive axial load. The interaction of axial and
transverse load in critical combination has been investigated in great
number of cases. It was determined that only in some particular cases exact
interaction could be, mostly roughly, aproximated by linear interaction.
Generally, the exact and the linear interaction differd to such a degree
that it made impossible the determination of the critical combined load on
the basis of the values of critical loads of axial force and transverse
loading applied separately.
Keywords: elastic stability, lateral torsional buckling, beams of thin walled cross-section, interaction of axial and transverse load in critical combination
- Type of paper
: Ph.D.
Title:
Faculty: FAKULTET STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU Sveučilište u Zagrebu
Author: AGIĆ ANTE
Language: hrvatski
Summary: The analysis of stress-strain behaviours of viskoelastic
bodies is studied in this work. By appliying the method of internal
thermodynamics of continua, the general equations of nonlinear viscoelastic
behavior are developed. The formalisms of internal variables made it
possible to incorporate the effect of humidity, damage, aging or other
phenomena into the constitutive equations. The isotropic viscoelastic
continuum is described by three termodynamic functions and the
superposition factor. The constitutive equations which are developed
represent the basic elements of numerical model of thermoviscoelastic
behavior. Interpolation of he dispalcement field and geometry of the body
is performed by the finite element method. Nonlinear equations are solved
by incremental procedure. For each time step the equilibrium value of
stress and strain and the participating increment of material time was
iteratively determined. For the plane stress and plane strain, as well as
for axially simetric three dimensional bodies, computer program was
developed. Program was tested by the illustrative example of the analysis
of stress-strain in viscoelastic cylinder caused by transient temperature
field.
Keywords: nonlinear viscoelasticity, internal coordinates, finite element methods, thermodynamics of continuua
- Type of paper
: M.A.
Title: FINITE ELEMENT FOR ANALYSIS OF SHELL STRUCTURES MADE OF
LAYERED FIBRE COMPOSITES
Faculty: FAKULTET STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU Sveučilište u Zagrebu
Author: SMOJVER IVICA
Date of defense: 12/22/94
Language: hrvatski
Number of pages: 103
Summary: Elastic anisotropy and orthotropy have been defined and
corresponding material matrices have been shown. Certain phenomena and
problems usually treated by micromechanical approach have been stated. Rule
of mixtures, that defines material matrix for layered fiber composites
using mechanical properties of fiber and matrix, has been explained. Forces
and moments appearing in layered fiber composites have been calculated, and
coupling effects distinctive for composites have been explained. Failure
criteria have been explained and critically evaluated. Isoparametric
composite shell/plate finite element based on the degeneration principle
has been derived. Efficient and accurate algorithm has been implemented
that defines fiber angle at each point of layered shell continuum. Based on
this theory, finite element has been programmed and results evaluated and
compared with available references.
Keywords: laminated fibre composites, micromechanics, macromechanics, degeneration principle, shell finite elements
- Type of paper
: M.A.
Title: FINITE ELEMENT FOR THICK PLATES ANALYSIS
Faculty: FAKULTET STROJARSTVA I BRODOGRADNJE SVEUČILIŠTA U ZAGREBU Sveučilište u Zagrebu
Author: TONKOVIĆ ZDENKO
Date of defense: 10/28/94
Language: hrvatski
Number of pages: 115
Summary: By applaying the Mindlin-Reissner theory the isoparametric
eight-node quadrilateral finite element for linear thick and thin plate
structures is derived. The formulation of the element is based on the
displacement method using mixed interpolation in order to eliminate the
"shear-locking" problem. To calculate the bending stiffnes matrix, the
displacement and the rotations are independently approximated and described
by the same interpolation functions as the element geometry. In the shear
stiffness matrix, a new modified shear strain-displacement matrix is
introduced, for the derivation of which the displacement and the rotations
are approximated by different interpolation functions. A new interpolation
function with a polynomial one order higher than that for the rotations is
assumed for the displacement. The Kirchhoff hypothesis is constrained to
the few discrete points which are located at the edges and at the centre of
the element. The derived element has very good convergence characteristics
fot both thick and thin plates, passes the patch tests and has no extra
zero-energy modes. The example of the circural plates analysis. The element
renders some lesser results when tested for the sensitivity to mesh
distortions. By varying discrete point locations on the element edges and
by reduced integration of stiffness matrix, its characteristics are not
improvement. In order to improve element characteristics in the mesh
distorsions analysis, the element with the discrete points in the numerical
integration Gauss points is derived. Reduced integration is applied to
determining the element stiffness matrix that leads to the additional
zero-energy mode which disappears in a mesh of the finite elements. The
mixed interpolation criteria used this element may be very simply applied
to the design of four-node, triangular and other finite elements.
Keywords: finite element method, Mindlin-Reissner plates, "shear-locking", mixed interpolation
