ISO 22459:2020

Overview

ISO 22459:2020 specifies a standardized tensile test method to determine the distribution of tensile strength and rupture (tensile) strain of filaments within a continuous ceramic multifilament tow at ambient (room) temperature. The method applies to dry tows of continuous ceramic filaments that behave linearly elastic up to failure and are assumed to act freely and independently under load. Outputs characterize filament-level variability (Weibull parameters) and are intended for reinforcement assessment of advanced/fine ceramics.

Key topics and technical requirements

• Test principle: Load a multifilament tow in tension at constant displacement; record force–displacement and extract the nonlinear domain caused by progressive filament failures. Use sampled steps of the curve to obtain two-parameter Weibull distributions for filament rupture strain and strength.
• Specimens and gauge length: Primary tests use 200 mm gauge length specimens; 100 mm and 300 mm specimens are used to determine load-train compliance.
• Specimen types: Examples include window-type (clamped between plates) and cylindrical-end specimens for gripping and handling.
• Apparatus: Testing machine must measure force and displacement (or direct tow elongation); comply with ISO 7500-1 (grade 1 or better). Digital data recording is recommended.
• Compliance correction: Measured displacement normally includes load-train and grip contributions (load train compliance). If tow elongation is measured directly (extensometer on tow), set load-train compliance to zero.
• Validity limits: Method requires a clear nonlinear domain in force–displacement due to progressive filament failure; if nonlinear behavior is absent, the method is not applicable.
• Statistical outputs: Filament rupture strain distribution, filament strength distribution, average and mean filament strengths (Weibull-based). Initial tow cross-sectional area is required for strength calculations.
• Comparisons and exclusions: Results are not equivalent to strengths of embedded tows (see ISO 24046) and cannot be directly compared with monofilament tests per ISO 19630 because of differing test conditions.

Practical applications and users

• Material characterization and R&D for advanced ceramics / technical ceramic composites
• Quality assurance and batch verification of ceramic filament tows
• Input data for composite design and structural reliability models (filament-level strength distributions)
• Test laboratories, composite manufacturers, materials scientists, and standards/qualification engineers involved in reinforcement selection and performance assessment.

Related standards

• ISO 7500-1 - calibration/verification of tension/compression machines
• ISO 10119 - carbon fibre density determination (referenced)
• EN 1007-2 - methods for reinforcements (linear density)
• ISO 24046 - strengths of embedded tows (under preparation)
• ISO 19630 - monofilament tensile testing (for comparison context)

Keywords: ISO 22459:2020, fine ceramics, advanced ceramics, ceramic filaments, multifilament tow, tensile strength distribution, rupture strain, Weibull distribution, tensile test, load train compliance.