Florek, Jason R.. Study of simplified models of aircraft structures subjected to generalized explosive loading. Retrieved from https://doi.org/doi:10.7282/T3X34XWV
DescriptionThis dissertation develops a simple methodology for estimating the maximum elastic-plastic deformation of thin, rectangular plates due to an exponentially decaying pressure pulse. Initially, only small plates, representative of aircraft skin panels, and uniformly distributed pressures are examined. The deflections predicted by this procedure are compared with those attained from finite element analysis for various plate dimensions and blast intensities. Material properties and boundary conditions are also varied. It is found that the current, clamped single-degree-of-freedom model is generally a much better predictor of deflection than its simply supported counterpart, although both show average errors of less than 15% compared to finite element results. The deviations between all of the models tend to decrease as surface area decreases, or as plate thickness and aspect ratio increase. A means of approximating permanent plate deflection is also suggested, which favorably compares with previously published experimental results for square, aluminum plates.
The aforementioned procedure is then extended for use with larger geometries, namely a wider fuselage section and a panel of an onboard luggage container, and nonuniform pressures. A generalized distribution function is developed to account for nonuniformities consistent with detonations at a small standoff distance. Moreover, two normalized criteria are proposed to determine when these nonuniformities can be ignored. In addition, large discrepancies are found in calculated deflections when incorporating the current structural model and the blast parameter data from two commonly used sources for both uniform and nonuniform loading cases. As a result, uncertainties in these data are thoroughly examined, which leads to confidence bounds being placed on all calculated deflections through a Monte Carlo scheme. This, in turn, allows for the generation of probability of failure curves.
Suggestions for improving the current loading and structural models are also discussed. Finally, the method of analysis for plates is preliminarily extended for the blast loading of thin, cylindrical shells. The various topics covered and simplified models proposed are useful to both the experimentalist and designer of blast resistant structures.