Overview
ISO 1922:2018 - Rigid cellular plastics - Determination of shear properties specifies a laboratory procedure to determine the shear strength, and optionally the shear modulus and shear strain, of rigid cellular plastics (rigid foams). The standard describes specimen geometry, apparatus and machine requirements, conditioning, test procedures (two alternative methods), calculation formulas and reporting requirements. It is intended for consistent, repeatable measurement of shear behavior in rigid cellular plastics.
Key topics and technical requirements
- Scope: Procedure for shear strength; provisions for shear modulus and shear strain.
- Test arrangements: Two assemblies - single shear (one test specimen) and double shear (two shear planes).
- Single specimen dimensions: length 250 mm, width 50 mm, thickness (25 ± 0.5) mm.
- Double specimen: length 250 mm, width 50 mm, thickness as produced.
- Apparatus:
- Test machine capable of steady movement at (1 ± 0.5) mm/min parallel to specimen axis.
- Machine force measurement conforming to class 1 of ISO 7500-1.
- Rigid specimen supports (flat metal plates) and universal joint adaptors to ensure alignment.
- Measurement procedures:
- Procedure A: records displacement of the movable plate (recommended for shear strength only).
- Procedure B: uses an extensometer (±1% precision) to measure relative displacement - recommended when calculating shear modulus and strain.
- Adhesive requirements: Adhesive bond between supports and specimen must have shear strength and modulus significantly greater than the test material (see Annex A for recommended adhesives/methods).
- Conditioning and environment: Typical test climates include (23 ± 2) °C / (50 ± 10)% RH or alternative specified ranges; tests must be conducted at conditioning conditions.
- Sampling & repeatability: Test sets of five specimens; reject failures at adhesive interface and repeat so that five valid results remain. The standard notes the precision and bias are unknown; results should not be used for dispute resolution.
- Calculations: Shear strength τ = F / A (with A = l × b for single, 2 × l × b for double). Shear modulus and strain formulas provided in the standard.
Applications
- Characterizing shear performance of rigid cellular plastics used in insulation, sandwich panels, structural core materials, and building products.
- Material development, quality control, specification compliance, and comparative testing of foam formulations and manufacturing batches.
- Input data for structural design, finite-element models, and failure analysis where core shear is critical.
Who uses this standard
- Materials and mechanical engineers, test laboratories, R&D teams, manufacturers of rigid cellular plastics and composite panels, certification bodies, and procurement/specification engineers.
Related standards
- ISO 1923 - Determination of linear dimensions for cellular plastics and rubbers (used for specimen measurements).
- ISO 7500-1 - Calibration and verification of static uniaxial testing machines (force-measuring system requirements).