Deflectometer: E-ASTM-D695 Model: E-ASTM-D695
For rigid materials, a deflectometer or a compressometer is vital because crosshead travel includes machine compliance (squish). Measuring crushing height is easy with TestVE, but the fixture often obscures the specimen. It only works for unconstrained cylinders/blocks.
Technical Specifications
| Specification | Value |
|---|---|
| Model | E-ASTM-D695 |
| Industry Std | ASTM D695 |
| Test Type | ASTM |
| Family Id | Epsilon 3540 |
| Fixture Type | Deflectometer |
Expert Commentary
The Compliance Paradox: In compression testing of high-strength plastics or composites, the machine squish (compliance) often exceeds the specimen’s actual deformation. ASTM D695 requires a Compressometer or a Deflectometer (Epsilon 3540) to measure the distance between the loading platens directly. Using crosshead travel will lead to a massive underestimation of the Compressive Modulus. The mechanical interface must be perfectly parallel; even a 0.01mm deviation across the platen surface induces localized end-crushing. When testing per the Boeing-modified BSS 7260, the fixture itself (the L-shaped support) often obscures the specimen. In these cases, TestVE can be used if the fixture has a viewing window, allowing for non-contacting strain measurement of the gauge section while the specimen is under lateral support to prevent global buckling.