ASTM E83 Standard Practice for Verification and Classification of Extensometer Systems

Get Certified ASTM E83 for Accurate Extensometer Performance and Reliable Material Testing

ASTM E83 testing helps confirm that an extensometer measures strain within a known accuracy class. As a result, laboratories can trust the strain data behind their mechanical property results. Moreover, a classified extensometer supports quality control in engineering and materials testing. Experienced analysts follow the standard and report clear results. Therefore, users can choose the right extensometer for each test.

• Material type: Extensometer systems that measure strain in tensile or compressive testing. The practice applies to extensometers with definite gauge points. It does not cover bonded resistance strain gauges that sit directly on a specimen.
• Purpose: Calibrating, verifying, and classifying extensometer systems. The practice sorts each system into a class based on its errors. It is not a complete purchase specification.
• Property evaluated: The strain measurement error of the extensometer system. ASTM classifies systems by the maximum error of strain indicated. The classes are A, B-1, B-2, C, D, and E.
• Method: The apparatus applies controlled displacements to a simulated specimen and measures those displacements accurately. The analyst compares the extensometer readings with the applied displacements. The full standard gives the verification requirements.
• Typical test surface: The extensometer attaches to a simulated specimen in the verification apparatus, not to a real test specimen. ASTM states that the apparatus applies controlled displacements to this simulated specimen. The full standard describes the fixture details.
• Limitations: The practice applies only to instruments that record values proportional to length change. It does not calibrate bonded resistance strain gages that sit directly on a specimen, and ASTM points to Test Method E251 for those. The standard also does not address every safety concern, so users set their own safety practices.
• Applications: Calibrating and verifying extensometers in testing laboratories. Supporting quality checks in materials testing facilities. Supporting research and development in industries such as aerospace, automotive, and construction.

What are the Uses of ASTM E83 Testing?

This practice gives laboratories a standard way to check extensometer accuracy. ASTM classifies systems by their errors, so users can match a system to a test. Therefore, the practice supports several practical uses. The main uses include the following.

• Calibrates extensometer systems used in tensile and compressive testing
• Verifies that an extensometer meets the requirements of an accuracy class
• Classifies systems as Class A, B-1, B-2, C, D, or E by maximum strain error
• Categorizes systems into Type 1, Type 2, or Type 3 by gage length
• Supports quality control in materials testing laboratories
• Supports research and development in material science
• Helps match an extensometer to the accuracy a test requires

Why is ASTM E83 Important?

Mechanical property tests depend on accurate strain measurement. An extensometer with unknown errors can distort values such as modulus of elasticity, yield strength, and elongation. This practice solves that problem by calibrating, verifying, and classifying extensometer systems. Therefore, laboratories know the error of the system they use. In addition, the classes help users choose an extensometer that fits the accuracy a test requires.

ASTM E83 Testing Process and Data Collection

A technician first prepares the verification apparatus and mounts the extensometer on the simulated specimen. The technician then applies controlled displacements and records the extensometer reading at each step. Next, the analyst compares each reading with the measured displacement and calculates the error. Finally, the analyst assigns the extensometer to a class and reports the result. Therefore, data collection centers on the applied displacement, the extensometer reading, and the calculated error.

Common Challenges and Troubleshooting in ASTM E83

Setup accuracy is the main challenge. Poor mounting or misalignment can change the extensometer reading and affect the classification. As a result, a laboratory may assign the wrong class to a system. To troubleshoot, technicians mount the extensometer securely and align it carefully. In addition, they use an apparatus that measures displacement accurately, as ASTM requires. Moreover, they control temperature changes in the test area, because these changes can affect readings. Users also set their own safety practices, since the standard does not address every safety concern.

• The laboratory reports the assigned accuracy class, including Class A, B-1, B-2, C, D, or E, based on the applicable maximum permissible strain-measurement error. Analysts use this classification to assess the extensometer system’s accuracy.
• Analysts identify the extensometer type alongside its accuracy class. Types 1, 2, and 3 describe the applicable gauge-length categories, so reporting both designations provides a clearer description of the calibrated system.
• Technicians document gauge length in mm or inches, calibration measurements, indicated strain, reference displacement, and calculated measurement errors. They record calibration conditions and equipment identification to support traceability.
• Engineers evaluate whether the assigned accuracy class meets the intended test’s measurement requirements. More stringent accuracy requirements may apply when determining elastic modulus or other properties that depend on precise strain measurements.
• Analysts report strain as a dimensionless quantity and maintain consistent calibration procedures regardless of whether displacement measurements use SI or US customary units. Analysts consider the applicable class and extensometer configuration when interpreting measurement reliability.

FAQs

What does ASTM E83 cover?

ASTM E83 covers the calibration, verification, and classification of extensometer systems based on their strain measurement errors. It helps determine whether an extensometer meets the accuracy requirements for its intended use. The practice supports reliable strain measurements during material testing.

What classes does ASTM E83 define?

ASTM E83 defines Classes A, B-1, B-2, C, D, and E based on maximum permissible strain measurement errors. It also classifies extensometer systems into Types 1, 2, and 3 according to gauge length. These classifications help users identify the appropriate system for their measurement requirements.

Which instruments does ASTM E83 cover?

ASTM E83 covers instruments that indicate or record values proportional to changes in length during tensile or compressive strain measurements. It does not cover bonded resistance strain gauges attached directly to a specimen. Users should check the practice’s scope to confirm whether their instrument qualifies.

What factors affect the cost of extensometer verification?

The cost of extensometer verification depends on the number of instruments, their gauge lengths, and the required reporting details. Different verification requirements may also affect the overall cost. The testing laboratory can provide a quote based on the instruments and services required.

How long does extensometer verification take?

The turnaround time depends on the number of extensometers, the verification requirements, and laboratory availability. Instrument configuration and reporting needs may also affect the schedule. Confirm the expected completion time with the testing laboratory before submitting the instruments.

Direct Link to ASTM E83 PDF