Compression stresses commonly occur in plastics that are used in structures and in loading applications. In contrast to tensile loading, compressive forces may result in buckling, crushing, or plastic deformation, and a standardized assessment is necessary. ASTM D695 satisfies this requirement by stating a dependable way of determining compressive properties of rigid and semi-rigid plastics. The standard is extensively used in polymer engineering and testing of construction materials and product development to determine the capacity of plastics to withstand compressive loads without collapsing.
Overview of ASTM D695 Standard
ASTM D695 outlines the steps on how to find compressive strength, compressive modulus, and compressive strain of plastics through Method A or Method B, which rely on specimen geometry and test aims. The standard addresses specifications of specimen preparation, testing equipment, alignment, and rate of loading. It can be used mostly on rigid plastics and both thermoplastic and thermosetting materials, and it is not advisable to use material that has extreme creep or instability under compression.
Specimen Preparation
To get the correct results in a compressive test, preparation of the specimen is essential. ASTM D695 defines cylindrical or prismatic specifications to have a specific gradient of the dimensions so that the stress is distributed equally when loading. The specimen can be machined from moulded sheets, plates, or finished components, but it must be ensured that surface defects and residual stress are kept to a minimum.
