The dynamic response of blast-loaded monolithic and composite plated structures
File(s)
Author(s)
McCallef, Karl
Type
Thesis
Abstract
The scope of the thesis is to investigate the dynamic behaviour of plated structures when
subjected to blast loading, focusing in particular on localised blast loading. Two main categories
of plated structures are investigated, viz. monolithic plates and composite plates.
The thesis includes a literature survey of existing works on the subject, which concludes that
there is no available method of describing a localised blast load arising from a given charge size,
geometry and stand-off distance from target. The review also investigates analytical methods
for predicting displacement of plates subjected to blast, assuming rigid-plastic behaviour and
the concept of using dimensionless parameters to predict such displacements. The survey also
reviews material models for composites and damage mechanisms for these materials.
On the basis of these findings, the thesis proposes a systematic method of mathematically
describing the spatial and temporal variations of a localised blast load from a known set of
threat parameters (explosive type, quantity, size and stand-off distance). The method is
validated by comparison of numerical results using the proposed loading function implemented
in a finite element analysis software with experimental results of blast loads on steel plates.
This leads to the first study, which focuses on the performance of monolithic plates subjected to
a blast load of the form described above. Existing formulations for uniform loading found in the
literature are extended to consider this new form of loading. Various plate thicknesses are
investigated (thick, moderately thick and thin) and it is found that good correlation is achieved
with numerical results, even when the blast load is simplified into an impulsive one.
The performance of composite plates under blast loading is also investigated, focusing primarily
on a new high-performance composite material (namely, Dyneema HB26). Material
characterisation and blast loading tests were carried out and these were used to develop a
material model for Dyneema, which is validated using finite element simulations. Its
performance is numerically compared with mild and armour (Armox 370T Class 1) steel plates
of equal areal density and it is found that Dyneema offers an improvement over mild steel, but
armour steel plates lead to the least permanent midpoint deflection. Using dimensionless
parameters, a simple design guideline is provided to estimate the deflection for a given plate
geometry made of a monolithic or composite material subjected to a specific blast load. The use
of this guideline was also illustrated by considering various threats and using the proposed
method to recommend various plate thicknesses required for different material systems to meet
a specified damage limitation.
Furthermore, a numerical-analytical method is proposed to predict the occurrence of Mode I
delamination (or separation between the plies) in the early-time response of laminated
composite materials, by means of stress propagation analysis.
subjected to blast loading, focusing in particular on localised blast loading. Two main categories
of plated structures are investigated, viz. monolithic plates and composite plates.
The thesis includes a literature survey of existing works on the subject, which concludes that
there is no available method of describing a localised blast load arising from a given charge size,
geometry and stand-off distance from target. The review also investigates analytical methods
for predicting displacement of plates subjected to blast, assuming rigid-plastic behaviour and
the concept of using dimensionless parameters to predict such displacements. The survey also
reviews material models for composites and damage mechanisms for these materials.
On the basis of these findings, the thesis proposes a systematic method of mathematically
describing the spatial and temporal variations of a localised blast load from a known set of
threat parameters (explosive type, quantity, size and stand-off distance). The method is
validated by comparison of numerical results using the proposed loading function implemented
in a finite element analysis software with experimental results of blast loads on steel plates.
This leads to the first study, which focuses on the performance of monolithic plates subjected to
a blast load of the form described above. Existing formulations for uniform loading found in the
literature are extended to consider this new form of loading. Various plate thicknesses are
investigated (thick, moderately thick and thin) and it is found that good correlation is achieved
with numerical results, even when the blast load is simplified into an impulsive one.
The performance of composite plates under blast loading is also investigated, focusing primarily
on a new high-performance composite material (namely, Dyneema HB26). Material
characterisation and blast loading tests were carried out and these were used to develop a
material model for Dyneema, which is validated using finite element simulations. Its
performance is numerically compared with mild and armour (Armox 370T Class 1) steel plates
of equal areal density and it is found that Dyneema offers an improvement over mild steel, but
armour steel plates lead to the least permanent midpoint deflection. Using dimensionless
parameters, a simple design guideline is provided to estimate the deflection for a given plate
geometry made of a monolithic or composite material subjected to a specific blast load. The use
of this guideline was also illustrated by considering various threats and using the proposed
method to recommend various plate thicknesses required for different material systems to meet
a specified damage limitation.
Furthermore, a numerical-analytical method is proposed to predict the occurrence of Mode I
delamination (or separation between the plies) in the early-time response of laminated
composite materials, by means of stress propagation analysis.
Version
Open Access
Date Issued
2013-10
Date Awarded
2013-02
Copyright Statement
Attribution NoDerivatives 4.0 International Licence (CC BY-ND)
Advisor
Louca, Luke
Sponsor
Engineering and Physical Sciences Research Council
Defence Science and Technology Laboratory (Great Britain)
Publisher Department
Civil and Environmental Engineering
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)