Dynamic inelastic response and failure of structural elements.
The dynamic shear response and failure of structural elements under
transverse impact loads are studied in the present work.
The dynamic shear response is one of the important response modes in
structural elements under transverse impact loads, which may lead to various shear
failures depending on the loading rates and intensities. Transverse shear localization
phenomena, which are represented by a shear hinge, have been observed in several
structural elements when subjected to transverse dynamic loading and are studied in
this thesis. The features of a stationary shear hinge are illustrated using a rigid,
perfectly plastic simplification. The dimensions of a shear hinge for several structural
elements are estimated both theoretically and numerically. It is shown that there
exists a fixed shear hinge length for a given two-dimensional structural element. The
length of a shear hinge is determined by its bending and shearing properties which
can be obtained from a quasi-static analysis. When the shear hinge length has been
determined, the conventional rigid-plastic method can be used to calculate the shear
strain and shear strain rate within the shear hinge during the shear response phase.
These theoretical results are employed to model Menkes and Opat' s beam problem
to find two possible failure mechanisms, i.e., ductile shear failure and adiabatic shear
failure and the associated transition conditions.
A double-shear beam(DSB) subjected to a transverse projectile impact is
studied experimentally and numerically in order to provide a more fundamental
understanding on the features of structural failure in a localised shear zone. Both
ductile tensile failure and adiabatic shear banding failure are found in the shear notch
section. An analytical model and FEM simulation are developed to predict the DSB
response and failures. The theoretical background of the strain energy density failure
criterion is discussed and verified in this problem. Among the failure criteria
examined in the current study, the strain energy density failure criterion is observed
to give reasonable predictions for the failure initiation.