Overview
ISO 23838:2022 - Metallic materials - High strain rate torsion test at room temperature defines a standardized method for measuring shear mechanical properties of metallic materials under dynamic torsional loading. The standard covers terminology, symbols, the physical principle, apparatus design (torsional split Hopkinson bar, TSHB), test-piece geometry, test procedure, data acquisition, waveform processing, result evaluation and required test reporting. Informative annexes provide examples of TSHB setups, data acquisition guidance and waveform analysis methods.
Key Topics and Requirements
- Scope and terminology: Precise terms and definitions for stress/strain waves, incident/reflected/transmitted waves, and TSHB-specific quantities.
- Principle: Use of elastic torsional wave propagation in long bars to load a short test piece and infer shear stress–strain response from bar strain measurements.
- Apparatus: Components and configuration of a torsional split Hopkinson bar (incident and transmitter bars, loading device, energy storage section) and requirements for bar materials and geometry.
- Test piece: Dimensions, thin‑wall gauge-section definitions, flange geometry and measurement procedures needed to ensure uniform shear deformation.
- Procedure: Calibration, bar alignment checks, temperature recording (room temperature requirement), mounting, dynamic loading and measurement protocols.
- Data processing: Strain measurement on bars, baseline and waveform processing, synchronization of waves, determination of loading duration, and calculation of engineering plastic shear strain, shear stress and average engineering plastic shear strain rate.
- Evaluation & reporting: Criteria for assessing test results and required content of a test report to support reproducibility and traceability.
- Annexes: Informative guidance on TSHB design, data acquisition systems and methods for determining waveform start points.
Applications and Users
ISO 23838:2022 is intended for:
- Materials testing laboratories and research institutes conducting high strain rate torsion testing.
- Engineers and researchers developing or validating constitutive models for dynamic shear behavior.
- Automotive, aerospace, defense and metal‑processing industries concerned with component behavior in dynamic events (e.g., forming, cutting, impact or crash scenarios).
- Quality assurance teams who require standardized dynamic shear property data (yield strength in shear, flow stress, failure strain) for design, simulation and failure analysis.
Related Standards
- ISO 26203-1 and ISO 26203-2 (referenced in the introduction for additional background on dynamic testing and material characterization).
Keywords: ISO 23838:2022, torsional split Hopkinson bar, TSHB, high strain rate torsion test, metallic materials, shear mechanical properties, dynamic torsion testing, waveform processing, engineering plastic shear strain.