ASTM D695
Standard Test Method for Compressive Properties of Rigid Plastics
Summary Description
The ASTM D695 test standard specifies the characterization of compressive properties of unreinforced and reinforced rigid plastics. The test is performed by applying a compressive load to a standard specimen. Common properties that reference ASTM D695 include the compressive modulus, compressive strength and strain at yield or rupture (if observed), engineering compressive stress-strain curve, true compressive stress-strain curve (calculated), and offset yield stress and strain in compression.
Additional Test Standards of Relevance
- ISO 604
Characterization Measurements and Relevant Tests
DatapointLabs offers a number of tests that address different properties covered under the ASTM D695 standard. These include the following characterization measurements [bracketed links refer to relevant tests in the DatapointLabs Test Catalog]:
Compressive Modulus
- Compressive modulus of elasticity [M-012]
Compressive Strength
- Compressive modulus of elasticity, as well as compressive strength and compressive strain at yield or rupture (if observed) [M-031]
Compressive Stress-Strain (General, Foams)
- Compressive modulus, engineering compressive stress-strain curve, true compressive stress-strain curve (calculated), compressive strength and strain at yield or rupture (if observed), offset yield stress and strain in compression [M-210]
- Compression testing of foams: compressive modulus, engineering compressive stress-strain curve, unloading compressive stress-strain curve, compressive strength and strain at yield or ultimate, and offset yield stress and strain in compression at quasi-static speeds [M-215]
High-Speed Compressive Stress-Strain (Foams)
- Compression testing of foams: compressive modulus, engineering compressive stress-strain curve, compressive strength and strain at yield or ultimate, and offset yield stress and strain in compression at crosshead speeds up to 1m/s and strain rates up to 100/s [M-233]
Biaxial Tension via Uniaxial Compression
-
[Uniaxial compression with lubricated platens is equivalent to biaxial
tension]
Compressive modulus, engineering compressive stress-strain curve, true compressive stress-strain curve (calculated), compressive strength and strain at yield or rupture (if observed), offset yield stress and strain in compression [M-211]
Test Procedure and Equipment Used
The specific test procedure will vary by test and the individual test webpages (linked to above and below) should be consulted for relevant descriptions. In general, a universal testing machine (UTM) is used to determine the appropriate compressive property or properties under measure. The test specimen is placed between compression platens, which may be unlubricated or lubricated as appropriate to the test, and compressed at a constant cross-head speed to yield or rupture. A compressometer is used to measure compressive strain. For high-speed compressive characterization, an Instron 8872 servohydraulic UTM is used.
Sample Conditioning and Non-Ambient Testing
Sample conditioning, if required, is carried out following specimen preparation in accordance with ASTM D618. Typical conditioning selections are ‘dry as molded’ (low humidity storage at 23°C) and 40 hours at 23°C and 50% relative humidity. Non-ambient testing may be carried out at any temperature between -53°C and 200°C.
Test Specimen Specification and Description
Specimen specifications under ASTM D695 are as follows:
- Compression bars specified by ASTM D695; see Compression Bars for further details
- Compression prisms, typically 25.4mm (1”) diameter x 12.7mm (0.5”) thickness; see Compression Prisms for further details
- Foam disks, typically 50mm diameter x 3.2mm thickness; see Compression Disks for further details
Characterization Measurement Descriptions
Typical characterization measurements under ASTM D695 include:
- Compressive Modulus: The ratio of compressive stress (load) to the corresponding strain (compression), measured below the elastic limit of a material
- Compressive Strength at Yield: The maximum compressive stress at the point where a material transitions from elastic to plastic behavior (Yield Point)
- Compressive Strain at Yield: The maximum strain at the point where a material transitions from elastic to plastic behavior (Yield Point)
- Compressive Ultimate Strength: The maximum compressive stress at the point of material rupture
- Compressive Ultimate Strain: The maximum strain at the point of material rupture
- Engineering Compressive Stress-Strain Curve: The graphical relationship between stress and strain in a material under compressive load, based on the original cross-section of the test specimen
- True Compressive Stress-Strain Curve: The graphical relationship between stress and strain in a material under compressive load, calculated from the engineering compressive stress-strain curve
- Offset Yield Stress in Compression: The offset yield method determines the yield point by the intercept of the stress-strain curve and a line with slope corresponding to the elastic modulus and a strain offset (nominally 0.2%); the offset yield stress is the stress at the determined intercept
- Offset Yield Strain in Compression: The offset yield method determines the yield point by the intercept of the stress-strain curve and a line with slope corresponding to the elastic modulus and a strain offset (nominally 0.2%); the offset yield strain is the strain at the determined intercept
Complete Listing of DatapointLabs Tests Referencing ASTM D695
The entire list of tests in the DatapointLabs test catalog that reference ASTM D695 are as follows:
