Overview
ISO 26203-1:2025 - Metallic materials - Tensile testing at high strain rates - Part 1: Elastic-bar-type systems provides guidelines for determining stress–strain characteristics of metallic sheet materials using elastic-bar-type systems for high strain‑rate tensile testing. The standard covers dynamic testing methods for strain‑rate regimes relevant to crashworthiness and other high‑rate events (the document scope addresses strain rates above approximately 10^2 s⁻¹) and notes applicability to other tensile test‑piece geometries beyond flat specimens.
Key topics and technical requirements
- Principles and scope
- Rationale for elastic‑bar systems versus servo‑hydraulic systems when measuring forces at high strain rates.
- Emphasis on avoiding signal perturbation from elastic wave reflections and ensuring valid force equilibrium.
- Apparatus and system design
- Requirements and guidance for elastic bars used as force‑measuring devices, wave propagation considerations, and displacement measurement techniques (including non‑contact optical/laser methods and wave‑based calculations).
- Test pieces
- Guidelines on test‑piece shape, gauge length, parallel section, and preparation tailored for dynamic loading to reduce stress inhomogeneity.
- Calibration and measurement
- Calibration of force and displacement measurement systems; reference to ISO 7500‑1 for force calibration.
- Methods to reduce noise and ensure accurate timing and signal acquisition.
- Procedure and evaluation
- Mounting, loading (examples include one‑bar and split Hopkinson bar methods), data recording, post‑test evaluation and calculation of engineering stress–strain and strain‑rate metrics.
- Reporting
- Required test report items to ensure reproducibility and suitability for simulation input.
- Informative annexes
- Quasi‑static comparison, one‑bar example, and split Hopkinson bar (SHB) example with bibliographic references.
Practical applications and users
- Applications
- Generating high‑rate stress–strain data for vehicle crashworthiness simulations, ballistic and impact studies, metal forming at high speeds, and research on strain‑rate sensitivity.
- Who should use it
- Materials scientists, mechanical testing laboratories, automotive safety engineers, research institutions, and quality/control engineers who require validated high strain‑rate tensile data for metallic sheets.
- Developers and users of finite element models needing reliable input for dynamic material behavior.
Related standards
- ISO 26203‑2 (servo‑hydraulic and other high‑rate systems) - complementary methods for high strain‑rate tensile testing.
- ISO 7500‑1 - calibration and verification of force‑measuring systems referenced in ISO 26203‑1.
- ISO 6892‑1 - quasi‑static tensile testing (for comparative context and lower strain‑rate testing).
Keywords: ISO 26203-1, tensile testing, high strain rates, elastic-bar-type systems, metallic materials, stress–strain, split Hopkinson bar, dynamic tensile testing, crashworthiness, strain‑rate sensitivity.