ENGINEERING TRANSACTIONS
ROZPRAWY INŻYNIERSKIE
A QUARTERLY JOURNAL
- L. Kruszka, G. V. Stepanov, V. V. Kharchenko, V. I. Zubov:
Experimental and computer analyses of impact penetration of a steel rod into heavy
plates of steel and aluminum alloys
- W. Bodaszewski:
Algorithms of the method of statically admissible discontinuous stress fields (SADSF)
Part II. The algorithms for solving limit stress fields around isolated nodes of stress
discontinuity lines
- P. Kołakowski:
Damage identification by the static virtual distortion method
- J. German:
The influence of intralaminar damage on mechanical properties of composite
BRIEF NOTE
- Z. Wesołowski:
Logarithmic screw dislocation
- L. Kruszka, G. V. Stepanov, V. V. Kharchenko, V. I. Zubov:
Experimental and computer analyses of impact penetration
of a steel rod into heavy plates of steel and aluminum alloys
- In the paper some results of experimental and numerical analysis
concerning penetration of a steel rod (with conical and flat-faced
heads) into heavy high-strength steel and AMg6, Al-Zn-Mg and D16
aluminum alloys plates are presented. The calculations are
conducted for relatively low velocities of penetration (200--1000
m/s), so the hydrodynamic component of the pressure on the contact
surface is much lower than the strength of the material with
allowance for viscosity effects. In most variants, the strains in
the rod are assumed to be elastic for revealing effects of
viscosity of the plate material. The resistance to penetration at
its initial stages (prior to the rod plastic flow and fracture) is
found to be determined by the dynamic strength of the plate
material, its viscous component (proportional to the plastic
strain rate) prevailing at the impact velocities of up to 500 m/s.
- From the experimental analysis it follows that the depth of
penetration varies with the velocity, and it is conditioned by
wave processes in the plate, their scale being dependent on its
thickness. Such experimental results are in agreement with results
of computer simulation of the initial stage of rigid rod
penetration in plates of limited thickness.
Contents
- W. Bodaszewski:
Algorithms of the method of statically admissible discontinuous stress fields (SADSF)
Part II. The algorithms for solving limit stress fields around isolated nodes of stress
discontinuity lines
- Summary of Part II: In the paper, the author introduces the sets
of conditions that create the algorithms of the functions on which
one defines the boundary problems met in the search for
discontinuous limit fields existing around isolated nodes. Among
those, there are functions describing states of stress in the
component homogeneous regions, the parameters of lines that
separate these regions, and, first of all, the formulae for
determining the domains based on the general conditions of
existence. These formulae play a key role in numerical
implementations of the method.
- The fields satisfying the Huber-Mises yield condition are of
primary choice however, the derived relationships have a general
meaning. To emphasise this fact one presents not only the areas of
existence valid for the Huber-Mises condition, but also the areas
obtained for several other yield conditions applicable to
plastically homogeneous materials. The knowledge of the areas
opens the possibility of developing the method of search for the
fields that obey these conditions, and for algorithmizing this
method. This could be applied even for the fields that are
characterised by arbitrary, admissible states of stress.
- One also presents, basing on a mathematically complete set of
conditions, typical formulations of problems concerning the fields
around the nodes. One discusses the balance between the set of
conditions and the unknowns, as well as the transformations into
global systems connected with complex fields.
- One consequently applies parametrisation of the yield conditions,
which not only reduces the number of unknowns and leads to simple,
recursive forms of the formulae, but, first of all, makes it
possible to find the formulae for generation of domains, without
which numerical solution of the fields and algorithmization of the
method would not be possible at all.
Contents
- P. Kołakowski:
Damage identification by the static virtual distortion method
- This paper describes the application of a structural reanalysis
technique called the Virtual Distortion Method, coupled with an
optimisation technique called the Gradient Projection Method, to
the damage identification problem for the case of the static
structural analysis. The outline of the Virtual Distortion Method
is provided and the fundamentals of the Gradient Projection Method
are explained. Subsequently the damage identification problem for
the static load case is posed. Numerical example of a truss
structure is demonstrated. Conclusions are presented with the
emphasis on advantages of the employed methods in numerical
computations.
Contents
- J. German:
The influence of intralaminar damage on mechanical properties of composite
- In the paper the damage of fiber-reinforced polymeric matrix
laminates is considered with the aim to examine the change of
their mechanical properties. The damage mode in the form of
intralaminar cracks is described in terms of the damage tensor by
Vakulenko and Kachanov. The crack discontinuity parameter is
estimated in the frames of the linear elastic fracture mechanics.
To derive the constitutive relations, which take into account
stress, strain and developing damage, an approach based on
polynomial invariant functions and irreducible integrity basis by
Adkins is employed. Theoretical results are compared with the
experimental data obtained for carbon/epoxy laminates.
Contents
- BRIEF NOTE
- Z. Wesołowski:
Logarithmic screw dislocation
- Basing on linear elasticity, the displacement field
uz=Bθlnr (in cylindrical coordinates r,
θ, z) was derived. This displacement has a jump on
the half-plane θ=0. Stresses orthogonal to this
discontinuity plane are continuous.
Contents
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