Abstract
This paper describes a casting technique for fabricating high-quality plastic structural models and presents results on the use of such specimens to parametrically study the effect of base-ring stiffness on the critical buckling pressure of a ring-stiffened conical shell. The fabrication technique involves machining a metal mold to the desired configuration and vacuum drawing the plastic material into the mold. A room-temperature-curing translucent thermoset epoxy was the casting material selected. The casting technique allows many high-quality specimens to be produced and each specimen is capable of being repeatedly tested without failure. The conical shell was modified for successive tests by machining the epoxy base-ring configuration to reduce its stiffness. A shell-of-revolution computer program which uses a nonlinear axisymmetric prebuckling strain field to obtain a bifurcation-buckling solution was used to guide the selection of configurations tested. The shell experimentally exhibited asymmetric collapse behavior and the ultimate load was considerably higher than the analyticalbifurcation prediction. The asymmetric buckling-mode shape, however, initially appeared at a pressure near the analysis-bifurcation solution. Comparison of experimental and analytical prebuckling strains at pressure magnitudes below the initiation of asymmetric collapse showed good agreement.
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Symbols The units used for physical quantities defined in this paper are given in the International System (SI) of Units. Correlation between this system and U.S. Customary Units is given in Ref. 1.d=depth of conical-shell base ringd r =reference depth of conical-shell base ringE=modulus of elasticityn=circumferential wave numbers=meridional shell coordinateS L =total meridional shell lengtht=shell thicknessw=displacement normal to shell\(\bar w\)=initial imperfection measured normal to shell ε=strain\(\varepsilon _\Upsilon \)=ring circumferential strain\(\varepsilon _s \)=meridional strain\(\varepsilon _\theta \)=circumferential strain θ=circumferential coordinate
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Williams, J.G., Davis, R.C. Buckling experiments on stiffened cast-epoxy conical shells. Experimental Mechanics 15, 329–338 (1975). https://doi.org/10.1007/BF02318873
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DOI: https://doi.org/10.1007/BF02318873