This part of ASTM D1621-04a specifies the test conditions for determining the compressive properties of rigid cellular materials, particularly expanded plastics. Rigid foams are typically used in the construction industry as sound and thermal insulation. Calculations referenced in this standard include
yield points,
compressive strength, and compressive modulus.
Suitable systems for this application include 3300 and 5900 series electromechical testing machines equipped with compression platens. The parallelism of the compression platens is important and it is recommended that a spherical seating style compression platen is utilized along with a rigid platen. The self-aligning nature of this fixture will maximize the contact area between the platen and the specimen. Swivel seating can be placed on the platen attached to the instrument's base or load cell in the moving crosshead. To reduce the possible affects from off-center loading, it is preferred to place the swivel seat in the base.
When two rigid compression platens are used, it is recommended that a strain gauge device, such as a linear variable displacement transformer (LVDT), is used to minimize error due to compliance from the system. However, if you are using
Bluehill® Software, which incorporates a load frame compliance correction calculation, a
deflectometer is not required unless stated so in testing standard.
To make the testing easier, leave a 10 to 30 mm gap between the specimens that allows you to quickly and easily remove the tested specimens and position new ones. The Bluehill preload function automatically moves the upper compression platen down to precisely touch the specimen at a pre-defined load. The preload function reduces the amount of operator interaction, saving time and improving accuracy.