ISO 26203-1:2018

Overview

ISO 26203-1:2018 - Metallic materials - Tensile testing at high strain rates - Part 1: Elastic-bar-type systems - defines standardized methods for determining the stress–strain behaviour of metallic sheet materials under high strain-rate tension using elastic-bar-type apparatus. The standard targets dynamic testing conditions relevant to vehicle crashworthiness and FEA validation, noting the broader relevance of strain rates from 10−3 to 103 s−1 while specifically covering methods for strain rates above 102 s−1. It complements quasi‑static standards (ISO 7500‑1, ISO 6892‑1) and other parts of the ISO 26203 series (e.g., Part 2 for servo‑hydraulic systems).

Key topics and technical requirements

• Test principle: Use of long elastic bars (one‑bar or split Hopkinson bar / SHB) to avoid perturbation from reflected elastic waves so that force measurement reflects the test-piece response.
• Strain‑rate focus: Addresses high strain rates relevant to crash events; identifies 10−3 to 103 s−1 as the most relevant range and specifies methods for testing above 102 s−1.
• Apparatus elements:
  • Elastic bar(s) as force‑measuring device.
  • Input devices (impact/striker or hammer) for open‑loop loading.
  • Clamping/fixture design matched to bar material and diameter to minimise wave‑impedance changes.
  • Force measurement typically via strain gauges on the elastic bars.
• Measurement challenges and mitigations:
  • Wave reflections and signal noise - addressed by bar length selection and measurement location.
  • Rapid displacement/elongation measurement - recommends non‑contact optical/laser methods or displacement inferred from wave propagation data.
  • Test‑piece design - dynamic specimens differ from quasi‑static geometries to achieve valid force equilibrium and homogeneous stress in the gauge section.
• Calibration, procedure and reporting: The standard covers calibration of instruments, mounting, force application, data recording, evaluation of stress–strain curves and required test reporting.

Applications and who uses it

• Primary users: Materials testing laboratories, automotive crashworthiness teams, metallurgists, R&D engineers, and simulation specialists requiring validated high‑rate material input for FEA.
• Practical uses:
  • Generating rate‑dependent stress–strain curves for sheet steels, aluminum and other metallic sheets used in vehicle structures.
  • Validating material models in crash simulation and improving occupant‑safety designs.
  • Interlaboratory comparisons and quality assurance for dynamic tensile properties.

Related standards

• ISO 7500‑1 and ISO 6892‑1 (quasi‑static tensile testing)
• ISO 26203‑2 (servo‑hydraulic and other high‑strain‑rate test systems)
• Relevant literature and annexes in ISO 26203‑1 include examples of one‑bar and SHB methods and a quasi‑static comparison procedure.

Keywords: ISO 26203-1, high strain rate tensile testing, elastic-bar-type systems, split Hopkinson bar, dynamic tensile testing, crashworthiness, metallic sheet materials.