In materials testing, precision is not just a requirement—it is a legal and structural necessity. Whether determining the yield strength of a new aerospace alloy or testing the elasticity of a polymer, engineers rely on exact stress-strain data. At the center of this data collection is the extensometer, a device designed to measure changes in a material's length.
is often sufficient for general tension testing where high precision in the elastic region is less critical. 🛠️ The Verification Process
The technician applies known displacements to the extensometer using the calibration rig. ASTM E83 requires at least consisting of a minimum of five displacement points spread across the device's measurement range. 4. Mathematical Validation
The operator applies a series of displacements throughout the measuring range of the extensometer.
He nodded, signed the form, and handed it back. "Most students just find a PDF and skim the abstract. You actually used it." astm e83 pdf
The heart of the ASTM E83 standard is its classification matrix. Extensometers are not simply labeled "accurate" or "inaccurate." Instead, they are assigned a class based on their maximum permissible error. The standard defines . Extensometer Class Maximum Error of Gauge Length Fixed Error (whichever is greater) Relative Error (whichever is greater) Typical Application Class A ±plus or minus ±plus or minus 0.00001 in. / 0.00025 mm ±plus or minus 0.1% of value High-precision research calibration Class B-1 ±plus or minus ±plus or minus 0.0001 in. / 0.0025 mm ±plus or minus 0.5% of value Determining Modulus of Elasticity (Metals) Class B-2 ±plus or minus ±plus or minus 0.0002 in. / 0.0050 mm ±plus or minus 0.5% of value Modulus testing with longer gauge lengths Class C ±plus or minus ±plus or minus 0.001 in. / 0.025 mm ±plus or minus 1.0% of value Routine tensile testing, Yield Strength Class D ±plus or minus ±plus or minus 0.01 in. / 0.25 mm ±plus or minus 1.0% of value High-elongation materials (Rubbers/Plastics) Class E ±plus or minus ±plus or minus 0.1 in. / 2.5 mm ±plus or minus 1.0% of value Very high strain or elastomeric testing Understanding Fixed vs. Relative Error
If the system is subjected to an that could alter its structural alignment.
Free PDFs are usually:
The extensometer, calibrator, and environment must sit in a temperature-controlled room (typically ) long enough to eliminate thermal expansion errors. In materials testing, precision is not just a
If an extensometer miscalculates strain, calculations for Yield Strength, Young’s Modulus (Modulus of Elasticity), and Elongation at Break will be incorrect.
Applies at larger displacements where the error is calculated as a percentage of the actual reading.
This is the "how-to" manual for technicians executing the test.
You can purchase and download the most up-to-date version of the PDF directly from the ASTM store website. is often sufficient for general tension testing where
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This verification must be performed periodically (typically annually) and after any major repair or recalibration.
The standard is frequently revised to address emerging technologies. The (ASTM E83-23) introduced Annex A1 , which specifically focuses on the verification requirements for optical extensometers, emphasizing the importance of consistent setup to account for variables that impact digital device performance. As of early 2025, the newest edition is listed as ASTM E83-25 . Critical Role in Material Testing
State whether measurements are recorded in SI units or US customary units. 2. Verification Apparatus & Traceability
: The highest precision class. Reserved for ultra-precise research, calibration laboratories, and determining elastic modulus on highly rigid materials.