Foam compression fixtures are designed for indentation and compression testing of expanded cellular materials. Standards that require this style of fixture include ASTM D 3574, ASTM D 5672, ISO 2439 and ISO 3386.
The major items of the fixture include a perforated loading table and a circular indentor/ anvil. The 203 mm diameter upper anvil incorporates a swivel joint. The base table is perforated with 6.5 mm holes spaced on 20 mm centers and is elevated from the mounting surface to allow for rapid air escape from the specimen.
Principle of Operation
The specimen is placed on the perforated table that is attached to the instrument base. The indentor is brought down in contact with the specimen to establish a reference height. This is allowed by a series of preconditioning loading segments and a test loading sequence. Data is captured during the test loading
sequence which generally includes a dwell time.
Results are then calculated which commonly include loads at defined % indentations or deflections.