Unit symbols, ASTM

The representatives of the known structure types are arranged according to a structure symbol which indicates the Bravais lattice and the number of metal and non-metal atoms within the unit cell. The Bravais lattice is designated by a capital letter following the suggestion of the ASTM Committee (435) ... 

The members of an ASTM nomenclature subcommitee of Committee E-4 on crystallography publidied a proposal for structure-type symbols in the ASTM Bulletin (1947). Such a symbol consists of the number of atoms within the unit cell followed... 

The ISA Standards and Practices Department is aware of the growing need for attention to the metric system of units in general, and the International System of Units (SI) in particular, in the preparation of instrumentation standards. The Department is further aware of the benefits to USA users of ISA standards of incorporating suitable references to the SI (and the metric system) in their business and professional dealings with other countries. Toward this end, this Department will endeavor to introduce Si-acceptable metric units in all new and revised standards, recommended practices, and technical reports to the greatest extent possible. Standard for Use of the International System of Units (SI) The Modern Metric System, published by the American Society for Testing Materials as lEEE/ASTM SI IQ-97, and future revisions, will be the reference guide for definitions, symbols, abbreviations, and conversion factors. 

The last important test for evaluating adhesive properties is a cleavage or fracture test. Figure 27.3 shows an example of such a test, the double cantilever beam test. The adherends are usually 1 in. (2.54 cm) wide and the thickness depends on the adherend modulus. Described in Standard Practice ASTM D3433 [9], the test is meant to measure fracture resistance (strain energy release rate) under conditions in which the adherends do not plastically deform. The units of fracture resistance (strain energy release rate) are joules per square meter and this quantity is given the symbol... 

This is a complete system of measurement units including names and symbols for base units from which derived units may be formed so that any physical quantity may be expressed. It includes a system of prefixes by which the base and derived units may be made any convenient size from very small to very large. Finally, the precise basis for its units, and the symbols for expressing them, have received worldwide agreement. It is officially recognized by all industrial nations, is referenced by SAE, ASTM, ASME, and many other societies, is required by ISO in all documents, and is the official basis of our U.S. units (the inch and pound are defined in terms of the metre and kilogram). 

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