Rotating Band Pressures and Engraving Forces in 155mm Artillery Shells

1973 ◽  
Vol 95 (2) ◽  
pp. 124-129 ◽  
Author(s):  
W. F. Hartman ◽  
P. P. Stirbis
Keyword(s):  
Mechanical Properties ◽  
Analytic Method ◽  
Mechanical Stiffness ◽  
Rotating Band ◽  
Good Agreement

The forces retarding the motion of 155mm artillery shells during quasi-static engraving of the rotating band were investigated both experimentally and analytically. The analytic method was based on a determination of the pressures existing between the projectile and the gun tube and the use of this information in a frictional model of the process. The retardation forces predicted in this manner are shown to be in good agreement with the hydrostatic pressures required to engrave the projectile in quasi-static push tests. This model leads to some interesting conclusions regarding alteration of engraving forces. In particular, the model suggests that, for shells similar to those used in this study, the rotating band pressure is more dependent upon the form and mechanical properties of the band than upon the mechanical stiffness of the projectile.

Determination of the Mechanical Properties of Polysilicon Thin Films Using Bulge Testing

1997 ◽  
Vol 505 ◽  
Author(s):  
S. Jayaraman ◽  
R. L. Edwards ◽  
K. J. Hemker
Keyword(s):  
Thin Films ◽  
Mechanical Properties ◽  
Elastic Constants ◽  
Polycrystalline Silicon ◽  
Silicon Substrates ◽  
Bulge Testing ◽  
Good Agreement

ABSTRACTUsing standard deposition and micromachining techniques, silicon substrates with square and rectangular windows covered with membranes of polycrystalline silicon (polysilicon) have been fabricated. Pressure-displacement curves obtained during the bulge testing of membranes with the above geometries have been used to determine the elastic constants E and v of the polysilicon. The results obtained (E = 162± 4 GPa and v = 0.19±0.03) are in good agreement with literature values for bulk polycrystalline silicon.

Mechanical Properties Adaptivity by the Design and Exploitation of Metastable States in a Modular Metastructure

2015 ◽  
Author(s):  
R. L. Harne ◽  
Z. Wu ◽  
K. W. Wang
Keyword(s):  
Mechanical Properties ◽  
Metastable States ◽  
Attractive Potential ◽  
Broad Application ◽  
Module Design ◽  
Design Variables ◽  
Material Systems ◽  
Important Design ◽  
Good Agreement

Recent studies on periodic metamaterial systems have shown that remarkable properties adaptivity and multifunctionality are often products of exploiting internal, coexisting metastable states. Yet to realize such attractive potential, effecting coexisting metastable states in material systems may require the determination of a periodic constituent which promotes a non-uniqueness when composed within the whole system, thus creating a need for costly, multiscale design. To surmount such concerns, this research first focuses on the development of adaptable, metastable modules: once assembled into modular metastructures, synergistic properties adaptation is found to be a natural byproduct of the strategic module design. Using this approach, it is seen that modularity facilitates a direct pathway to create and effectively exploit metastable states for massive, metastructure properties adaptivity, including a near-continuous variation of mechanical properties or stable topologies and adjustable hysteresis. A model is developed to understand the source of the synergistic characteristics, and theoretical findings are found to be in good agreement with experimental results. Important design-based questions are raised regarding the modular metastructure concept, and a genetic algorithm routine is developed to elucidate the sensitivities of the properties variation with respect to the statistics among assembled module design variables. To obtain target multifunctionality and adaptivity, the routine discovers that particular degrees and types of modular heterogeneity are required. Future realizations of modular metastructures are discussed to illustrate the extensibility of the design concept and broad application base.

COMPARATIVE ACTION OF VARIOUS OESTROGENIC COMPOUNDS ON MOUSE VAGINAL SIALIC ACIDS (II)

1969 ◽  
Vol 62 (4) ◽  
pp. 663-670 ◽  
Author(s):  
Lars Carlborg
Keyword(s):  
Sialic Acid ◽  
Response Curve ◽  
Sialic Acids ◽  
Clear Cut ◽  
Suitable Parameter ◽  
Sufficient Degree ◽  
Comparative Action ◽  
Relative Potencies ◽  
Good Agreement

ABSTRACT Oestrogens administered in lower doses than necessary to induce full cornification of the mouse vagina induce mucification. It was shown previously that the degree of mucification could be estimated by quantitative determination of sialic acids. A suitable parameter for oestrogen assay was the measurement of vaginal sialic acid concentration which exhibited a clear cut dose response curve. Eleven assays of various oestrogens were performed with this method. Their estimated relative potencies were in good agreement with other routine oestrogen assays. A statistically sufficient degree of precision was found. The sensitivity was of the same order, or slightly higher, than the Allen-Doisy test.

Basic set of experiments for determination of mechanical properties of sand

2014 ◽  
Vol 62 (1) ◽  
pp. 129-137
Author(s):  
A. Sawicki ◽  
J. Mierczyński
Keyword(s):  
Mechanical Properties ◽  
Soil Mechanics ◽  
Physical And Mechanical Properties ◽  
Local Strain ◽  
Initial State ◽  
Laboratory Equipment ◽  
Additional Information ◽  
Basic Set ◽  
Initial Anisotropy

Abstract A basic set of experiments for the determination of mechanical properties of sands is described. This includes the determination of basic physical and mechanical properties, as conventionally applied in soil mechanics, as well as some additional experiments, which provide further information on mechanical properties of granular soils. These additional experiments allow for determination of steady state and instability lines, stress-strain relations for isotropic loading and pure shearing, and simple cyclic shearing tests. Unconventional oedometric experiments are also presented. Necessary laboratory equipment is described, which includes a triaxial apparatus equipped with local strain gauges, an oedometer capable of measuring lateral stresses and a simple cyclic shearing apparatus. The above experiments provide additional information on soil’s properties, which is useful in studying the following phenomena: pre-failure deformations of sand including cyclic loading compaction, pore-pressure generation and liquefaction, both static and caused by cyclic loadings, the effect of sand initial anisotropy and various instabilities. An important feature of the experiments described is that they make it possible to determine the initial state of sand, defined as either contractive or dilative. Experimental results for the “Gdynia” model sand are shown.

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