Standard Test Method for Compressive Properties of Rigid Plastics

ASTM D 695, Standard Test Method for Compressive Properties of Rigid Plastics  

Compressive properties include compressive strength, modulus of elasticity, yield stress, and deformation beyond yield point. The ASTM procedure covers determinations of all of them. In all cases, tested specimens are loaded in compression at relatively low uniform rates of straining or loading. Compressive yield point is the first point on the stress-strain curve at which an increase in strain occurs without an increase in stress. In other words, it is the load under which the specimen starts to move continuously without an increase in the load. Also, many plastic materials will continue to deform in compression until a flat disk is produced, without breaking of the specimen. In those cases the compressive stress (nominal) increases steadily in the process, without failure of the material. Compressive strength typically has no meaning in such cases. 

The ASTM test describes in detail the apparatus for measuring compressive properties, preparation of test specimens, conditioning, and procedures. The standard test specimen is recommended to be in the form of a right cylinder or prism whose length 

0 (cylinder) in size. Though, for different types of compressive behavior, the ASTM recommends different sizes of the specimens. 

The compressive strength is calculated by dividing the maximum compressive load by the original minimum cross-sectional area of the specimen. The compressive yield strength is calculated in the same manner, but instead of compressive load at break, the compressive load at the yield point is used. The compressive modulus of elasticity is calculated in the usual manner, by dividing the compressive stress taken as a point on the initial linear portion of the load-deformation curve by the corresponding strain. 

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ASTM (1984) D695-80. Annual Book of A STM Standards, Section 8, Standard Test Method for Compressive Properties of Rigid Plastics, ASTM, pp. 290-297. 

Standard test method for compressive properties of rigid plastics... 

ASTM D 695-08 (2008), Standard test method for compressive properties of rigid plastics, ASTM, West Conshohocken, PA. 

ASTM D 1621-73 (1979) Standard Test Method for Compressive Properties of Rigid Cellular Plastics, 4 pp (DOD Adopted) (FSC 9330) (MR) (Comm D-20)... 

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