Title:
|
Impact dynamics of rods, beams and panels.
|
A methodology to study the impact dynamics of rods, beams and panels using
modern numerical solution technique and instrumentation is developed. The numerical
study is carried out using the commercial finite element package ABAQUS.
The general approach of this tool is illustrated and verified for the static analysis
of the stress distribution in a castellated beam and for the dynamic analysis of a
cantilevered beam subjected to multiple impact loading.
The finite element analysis technique is used to assess the optimal performance of
steel plate panels of different cross-sections and thicknesses under the same blast
loading conditions. Also, the structural response of folded plate panels of different
cross-sections and thicknesses subjected to various blast pressures is studied numerically
and compared with the existing experimental measurements. It is shown
that the strength to weight ratio of the folded plate panels is higher than those
of the single and double plate panels and that the folded plate panel is the more
blast-resistant design.
Stress wave propagation in circular mild steel rods is studied both numerically and
experimentally. The rods are impacted longitudinally using spherical balls. The Hertzian law of impact and the associated non-linear ordinary differential equation
of motion are used to determine the force-time history of impact. This force-time
history is used in a finite element analysis of the rods to predict the propagation
of pulses in the rods. The use of finite element simulation in predicting the wave
propagation phenomena and its application to non-destructive testing (NDT) of
rods and bars is demonstrated. For the experimental measurements, the stress
waves propagated in rods and bars are monitored using PZT patches of size 5x3
mm which are calibrated by means of a finite element approach and by the use of
a standard wire-resistance strain gauge.
A time domain, frequency domain, regression analysis and autocorrelation procedures
are developed to detect defects in rods and bars using wave propagation
data. The defects are introduced in the form of slots. By analysing the stress wave
data for the defect-free rods and bars and for the rods and bars with defects, it is
possible to pinpoint the location of the defects. The results show that defects can
be identified using any of the procedures and that their location can be estimated
using the time domain technique. It is also shown that a high degree of correlation
is obtained between measured and predicted characteristics.
|