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.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:488081 |
| Date | January 1997 |
| Creators | Feroz, Kottamal Thanduparakal |
| Publisher | University of Manchester |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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