Plastic Strain Ratio R For Sheet Metal

Astm e517 standard test method for plastic strain ratio r for sheet metal governs its determination.

Plastic strain ratio r for sheet metal.

Its determination is governed by astm e517 standard test method for plastic strain ratio r for sheet metal. The plastic strain ratio r is a parameter that indicates the ability of a sheet metal to resist thinning or thickening when subjected to either tensile or compressive forces in the plane of the sheet. The r value the plastic strain ratio of sheet metal intended for deep drawing applications is a measure of the resistance to thinning or thickening when subjected to either tensile or compressive forces in the plane of the sheet i e. The lankford coefficient also called lankford value r value or plastic strain ratio is a measure of the plastic anisotropy of a rolled sheet metal this scalar quantity is used extensively as an indicator of the formability of recrystallized low carbon steel sheets.

1 where true width strain e w ln w f w 0 true longitudinal strain e t ln. Simply put it measures the resistance of a material to thinning or thickening when put tension or compression. R value is a very important material property to understand for materials that will be formed into various shapes in their end use. The developed sandwich sheets have a high average plastic strain ratio of 1 55 and a low planar anisotropy of 0 17 which was improved more by 3 2 times than that of 5182 aluminum single sheet.

The plastic strain ratio r indicates the ability of the sheet metal to resist thinning or thickening when being deep drawn into a cup for example the r value is calculated from width and longitudinal strain and is a measure of sheet metal drawability. R value also known as plastic strain ratio is a measurement of the drawability of a sheet metal. This resistance to thinning or thickening contributes to. It is typically advantageous if the material reduces in area a minimal amount when subject to this force meaning a good drawing material has a high r value.

The plastic strain ratio r is considered a direct measure of sheet metal s drawability and is useful for evaluating materials intended for forming shapes by deep drawing see lead photo. It is the ability to maintain thickness as the material is drawn. Astm e517 covers special tension testing for the measurement of the plastic strain ratio r of sheet metal intended for deep drawing applications. Plastic strain ratio r is a measure of the ability of a sheet metal to resist thinning or thickening when subjected to a tensile or compressive force.

The r value is calculated from width and longitudinal strain as a test specimen is pulled in tension. 4 1 the plastic strain ratio r is a parameter that indicates the ability of a sheet metal to resist thinning or thickening when subjected to either tensile or compressive forces in the plane of the sheet.