ENGINEERING TRANSACTIONS
ROZPRAWY IN¯YNIERSKIE - TRAITE d'INGENIERIE
A QUARTERLY JOURNAL
- P. Aliawdin, Y. Muzychkin:
Limit analysis of structures with destructible elements under impact loadings
- L.C. Forde, W.G. Proud, S.M. Walley, P.D. Church, R. Cornish:
Reverse ballistic impact studies of thin plate perforation
- E. Cadoni, S. Antonietti, M. Dotta, D. Forni:
Strain rate behaviour of three rocks in tension
- W. Moæko, Z.L. Kowalewski:
Dynamic compression tests - current achievements and future development
- C. Vela, J.A. Rodríguez-Martínez, A. Rusinek:
FE analysis on the formation of plastic instabilities in dynamically expanded copper rings
- P. Aliawdin, Y. Muzychkin:
Limit analysis of structures with destructible elements under impact loadings
- Limit states and identification of structures with shock- or
seismic-protected system under dynamic loadings are discussed. Such
structures include both the destructible (elastic-brittle) and
indestructible (elastic-plastic) elements. A mathematical model and
algorithm for solving shakedown problem of bearing capacity of systems with
destructible elements are suggested. Next the propagation of vibrations from
impacts of Minsk subway trains into nearby skeleton of 9-storied building is
investigated. The experimental data for this building are received. Then the
propagation of vibrations is analyzed numerically. Finally, a technique of
minimax to evaluate dynamic elastic modules of concrete in the considered
structure elements is used.
Contents
- L.C. Forde, W.G. Proud, S.M. Walley, P.D. Church, R. Cornish:
Reverse ballistic impact studies of thin plate perforation
- Full-scale ballistic experiments using tungsten rods and rolled homogeneous
armour (RHA) steel plates are expensive to perform. For this reason, a study
has been performed into the possibility of using less expensive, more easily
available metals in small-scale laboratory experiments. The metal pairs
chosen listed in order as armour/penetrator materials were: RHA
steel/tungsten, dural/mild steel, and copper/aluminium. In order to be able
to use as many diagnostics as possible (including high speed photography,
VISAR, stress gauges) the reverse ballistic configuration was used. This
configuration also allowed the determination of the high rate, low strain
mechanical properties of mild steel to be determined. Finally, a comparison
was made between experiment and numerical predictions made using a modified
Armstrong-Zerilli constitutive model for the RHA steel/tungsten pair. The
model was found to underpredict the penetration, probably because failure
mechanisms were not incorporated.
Contents
- E. Cadoni, S. Antonietti, M. Dotta, D. Forni:
Strain rate behaviour of three rocks in tension
- The paper presents the dynamic characterization in tension of three rocks
under medium and high strain-rates. The tests have been carried out by means
of the JRC-Split Hopkinson Tension Bar and an Hydro-Pneumatic Machine,
installed in the DynaMat Laboratory of the University of Applied Sciences of
Southern Switzerland. The dynamic direct tension tests have been performed
at 3 different strain rates (0.1, 10, 100 strain/second) on an orthogneiss,
for loading directions 0°, 45° and 90° respect to the
schistosity, and two different types of marble. Results of the tests show a
significantly strain-rate sensitive behaviour, exhibiting dynamic tensile
strength increasing with strain-rate. In order to describe the strain rate
behaviour of these rocks, the dynamic increase factors in function of the
strain rates for tensile strength have been used.
Contents
- W. Moæko, Z.L. Kowalewski:
Dynamic compression tests - current achievements and future development
- In this paper a modified arrangement of the DICT technique was introduced.
Miniaturization of bar and use of shadow principle to make a measurement of
displacement allow to obtain strain rate up to 2.2 x 105 s-1.
Commonly used methods of elimination of friction, inertia and adiabatic
heating were presented. In order to estimate the rate sensitivity of a
material (tantalum), quasi-static and SPHB tests were performed at room
temperature within the rate spectrum ranging from 5 x 10-4 s-1 to
103 s-1. The final true stress versus true strain curves at different
strain rates were corrected to a constant temperature and zero friction.
Contents
- C. Vela, J.A. Rodríguez-Martínez, A. Rusinek:
FE analysis on the formation of plastic instabilities in dynamically expanded copper rings
- In this work the influence of the constitutive
description in numerical simulations of the radial expansion of annealed
OFHC copper rings has been studied. For that task, three
physical-based constitutive models are implemented into the FE code
ABAQUS/Explicit and applied to define the thermo-viscoplastic behaviour of
the material in the simulations. These are those due to Rusinek et al.
[A. Rusinek, J.A. Rodríguez-Martínez, A. Arias, A thermo-viscoplastic constitutive model for FCC metals with application to OFHC copper, Int. J. Mech. Sci., 52, 120-135, 2010], Nemat-Nasser and Li
[S. Nemat-Nasser, Y. Li, Flow stress of FCC polycrystals with application to
OFHC Copper, Acta Mater., 46, 565-577, 1998] and Voyiadjis and Almasri
[G.Z. Voyiadjis, A.H. Almasri, A physically based constitutive model for fcc
metals with applications to dynamic hardness, Mech. Mater., 40, 549-563, 2008].
The attention is primarily focussed on analyzing the influence of the
material description on the strain localization process. Notable differences
are observed in the response of the specimen under loading depending on the
constitutive relation used. The numerical study indicated that the
constitutive model controls the flow localization, defines the strain of
instability and determines the number of necks formed. The causes which
reside behind such decisive role played by the constitutive relation are
investigated. It has been found that the rate sensitivity definition governs
the models' predictions for the strain localization process.
Contents
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