Z2-graded structures | ScienceGate

The behavior of functionally graded structures has received a great deal of attention in recent years. Usually, these structures are made out of a composite material with a modulus of elasticity, a Poisson’s ratio, and a density that vary through the thickness. The non-uniformity through the thickness introduces coupling between the transverse deformations and the deformations of the mid-surface. Previous publications have shown how to account for these added complexities and have presented extensive results in tabular form. In this article, available results are used to show that the behavior of functionally graded shells is similar to that of homogeneous isotropic shells. It is well known that for isotropic shells, results can be presented in non-dimensional form so that, once results are obtained for one material, they can be simply scaled to obtain the corresponding results for shells made out of another material. The same can then be done for functionally graded shells. In addition, if functionally graded shells behave like homogeneous shells, no new method of analysis is required. The second part of the paper examines why this is true.

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Evidence for pyroclastic emplacement of the Crowsnest Formation, Alberta

Canadian Journal of Earth Sciences ◽

10.1139/e96-055 ◽

1996 ◽

Vol 33 (5) ◽

pp. 715-728 ◽

Cited By ~ 6

Author(s):

R.N. Adair ◽

R.A. Burwash

Keyword(s):

Elevated Temperatures ◽

Pyroclastic Flows ◽

Coarse Grained ◽

Rock Fragment ◽

Fine Grained ◽

Rock Fragments ◽

Explosive Phase ◽

Graded Structures ◽

Textural Evidence ◽

Charred Wood

The middle Cretaceous Crowsnest Formation west of Coleman, Alberta, is composed of bedded alkaline volcanic deposits containing heterolithic volcanic rock fragments and crystal clasts. Comparison with modern examples of subaerial pyroclastic rocks suggests that pyroclastic flows, surges, fallout of material from vertical eruption columns, and minor mud flows emplaced the deposits. Textural evidence in the form of plastically deformed volcanic fragments, chilled deposit margins, baked rock fragment margins, recrystallization, and the presence of charred wood and charred wood molds indicate emplacement at elevated temperature. Massive deposits containing a fine-grained basal zone are interpreted as the product of pyroclastic flows, whereas deposits characterized by a block-rich base overlain by a thin layer of block-depleted stratified material are interpreted as the product of density-stratified surges. Deposits exhibiting pronounced stratification were emplaced by ash-cloud surges. Thickly bedded breccias exhibiting rheomorphic textures were emplaced as vent-proximal pyroclastic flows. Deposits characterized by parallel beds and graded structures are interpreted as fallout tephra deposits, and deposition by lahars is indicated by coarse-grained beds that lack evidence for emplacement at elevated temperatures. The eruptions of the Crowsnest Formation were cyclical. An initial explosive phase generated deposits by pyroclastic flows, surges, fallout, and lahars. As an eruption progressed, it evolved into a poorly gas-charged effusive stage that emplaced coarsely porphyritic domes, plugs, spines, and vent-proximal lava flows. Subsequent eruptions destroyed the effusive vent facies deposits and produced abundant heterolithic clasts typical of the formation.

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