Instron AutoXBiax Fully Automated Contact Biaxial Extensometer

Overview

The Instron AutoXBiax is a fully automated, high-precision contact biaxial extensometer engineered for simultaneous axial and transverse strain measurement during uniaxial tensile testing. It operates on the principle of direct mechanical coupling with the specimen gauge section, utilizing a dual-arm kinematic design that maintains consistent gage length alignment throughout deformation. Unlike optical or non-contact systems, the AutoXBiax delivers traceable, high-fidelity strain data under dynamic loading conditions—including high-strain-rate and vibration-prone environments—where optical interference or surface reflectivity limitations may compromise measurement integrity. Its core application domain centers on standardized plastic strain ratio (r-value) determination in metallic sheet materials, supporting rigorous compliance with ISO 10113, ASTM E517, and JIS Z 2254. The system integrates seamlessly with Instron electromechanical and hydraulic universal testing machines (UTMs), enabling synchronized control via Bluehill Universal software.

Key Features

• Fully automated deployment and retraction: Measurement arms open and close without interrupting test execution—eliminating manual intervention mid-test and reducing operator-induced variability.
• Self-centering mechanism: Precisely locates the extensometer at the geometric center of the specimen’s gauge length using motorized lateral adjustment, ensuring repeatable positioning across multiple specimens and test cycles.
• Optical displacement sensing architecture: Employs a calibrated, high-resolution optical encoder system (not strain gauges or LVDTs), delivering superior long-term stability, immunity to electromagnetic interference, and minimal hysteresis over full travel range.
• Vibration-resistant design: Integrated shock-dampening mounts and rigid arm geometry mitigate sensitivity to machine frame oscillations, enabling reliable measurements even during high-load ramping or yield-point detection.
• Dust- and debris-isolated sensor housing: Sealed enclosure protects optical components from metal scale, lubricant mist, and particulate contamination common in industrial metal-forming laboratories.
• Friction-minimized vertical travel: Utilizes precision-ground linear bearings and balanced counterweight system to ensure near-zero friction movement across the entire vertical stroke—critical for maintaining linearity and repeatability.
• Intelligent overload protection: Automatically disengages transverse arms upon detection of peak stress or imminent specimen fracture, preventing mechanical damage and preserving calibration integrity.

Sample Compatibility & Compliance

The AutoXBiax supports standard flat-sheet tensile specimens per ISO 6892-1, ASTM E8/E21, and EN 10002-1, with nominal widths from 12.5 mm to 50 mm and thicknesses up to 3 mm. Its adaptive clamping geometry accommodates varying specimen stiffness without recalibration. All measurement outputs are traceable to NIST-certified standards and comply with ISO/IEC 17025 requirements for testing laboratory competence. Data acquisition meets audit requirements for GLP and GMP environments, including full metadata logging (operator ID, timestamp, environmental conditions, UTM serial number) and electronic signature support per FDA 21 CFR Part 11 when used with Bluehill Universal v4.0+.

Software & Data Management

Controlled exclusively through Instron’s Bluehill Universal platform, the AutoXBiax enables synchronized configuration, real-time monitoring, and post-test analysis within a single interface. Software features include automatic r-value calculation per ISO 10113 Annex A, multi-point transverse strain averaging, and export-ready CSV/Excel reports compliant with internal QA documentation workflows. Raw encoder data is stored with 16-bit resolution at user-defined sampling rates up to 1 kHz. Audit trails record all parameter changes, calibration events, and arm position commands—supporting regulatory review and method validation protocols.

Applications

• Determination of plastic strain ratio (r-value) and strain hardening exponent (n-value) for cold-rolled steel, aluminum alloys, and titanium sheet products.
• Formability characterization in automotive stamping process development and supplier qualification programs.
• Quality assurance testing in coil processing lines where batch-to-batch consistency must be verified against material specification limits.
• Research into anisotropic plastic deformation behavior under controlled strain paths.
• Validation of constitutive models used in finite element simulation of deep-drawing operations.

FAQ

Is the AutoXBiax compatible with non-Instron testing systems?
Yes—via analog voltage output (±10 V) and digital RS-232/USB interfaces, though full automation and synchronized arm control require integration with Bluehill Universal.
Does it require periodic recalibration?
Annual calibration is recommended per ISO 9513; Instron offers certified calibration services with NIST-traceable certificates.
Can it measure both r-value and n-value in a single test?
Yes—Bluehill Universal automatically computes both parameters from the same axial/transverse strain dataset acquired during the plastic deformation region.
What maintenance is required in high-contamination environments?
Routine cleaning of the optical path window and inspection of arm bushings every 200 test cycles; no lubrication required due to sealed bearing design.
How does it compare to non-contact video extensometers for r-value testing?
The AutoXBiax provides higher signal-to-noise ratio under low-contrast surface conditions (e.g., mill-scale or oil-coated steel), eliminates focus drift, and maintains accuracy during rapid yielding transitions where image-based tracking may lag.