Abstract:
The properties of polyurethane impregnated Kevlar 29 bed were determined
using Woven Fabric Micromechanics (WFM.) These properties were used to perform a
linear static analysis on loaded coal-beds to compare maximum vertical deflection and
stress distribution of single-bed model and double-bed model. Studies related to effect
of radius of curvature of bed, effect of thickness of bed, effect of number of elements
and effect of pressure on the maximum vertical deflection were done on the double-bed
model.
Geometrically nonlinear analysis was performed and compared with linear static
analysis. The results from linear static analysis and geometrically nonlinear analysis
were compared with the results from one-dimensional shallow shell equations and one-dimensional
nonlinear membrane equations respectively. Studies show that the effect of
geometrically nonlinear response was insignificant at low pressures but pronounced at
very high pressures, for a configuration of the double-bed model.
Free vibration analysis with lumped mass approach was performed on an
undamped coal bed to extract the natural frequencies of the empty bed. Comparison of
driving frequency with the lowest natural frequency revealed that forced vibration
analysis (dynamic analysis) is essential to obtain realistic maximum vertical displacement
response. Forced vibration analysis using direct-integration method was performed on
an undamped double-bed model subjected to an alternating and sinusoidal load pattern
at a driving frequency of 25 Hz. Results from forced vibration analysis show that the
maximum vertical deflection occurred in the transient region of the response and
exceeded the static response (obtained from the same loading conditions as the forced
vibration case), by approximately 25%. However the system met the design constraints
initially laid down. Further recommendations on the present problem were made to
improve the design and analysis.
