ISO 4674-2:2021

Overview - ISO 4674-2:2021 (tear resistance, ballistic pendulum method)

ISO 4674-2:2021 specifies a dynamic test method to determine the tear resistance of rubber- or plastics-coated fabrics using a ballistic pendulum. The method measures the energy transferred when a pendulum applies a sudden force to a notched test piece and uses the amplitude of the first swing to derive the tearing force. Results from this dynamic (pendulum) method are not directly comparable with constant-rate-of-tear methods (see ISO 4674-1).

Key topics and technical requirements

• Test principle: kinetic energy of a falling pendulum tears an initiated notch; the first oscillation amplitude gives the tearing force.
• Apparatus: pendulum test machine with rigid frame, roller bearings, release mechanism, measurement device (mechanical or electronic), knife and jaws. Jaws spacing and alignment, pendulum axis geometry and calibration are specified.
• Critical dimensions and settings (examples from the standard):
  • Clamping faces separation: 2.8 mm ± 0.3 mm
  • Distance from clamping line to pendulum axis: 104 mm ± 1 mm
  • Plane angle to perpendicular: 27.5° ± 0.5°
  • Length to be torn: 43 mm ± 0.5 mm
  • Notch size: 5–15 mm
  • Slit to start tear: 20 mm ± 0.5 mm
  • Recommended pendulum reading range: 15 %–85 % of full scale
• Test pieces and sampling: cut from usable roll width per ISO 2286-2; select ten pieces per series (five longitudinal, five transverse). For coated textiles, avoid using the same yarn column/row in more than one piece per direction.
• Pre-treatment and conditioning:
  • Wet test immersion: 24 h in water (or ≤0.1% surfactant), rinse and test within 1 min.
  • Conditioning: follow ISO 2231 atmospheres; minimum exposure recommended (16 h for one-side coated, 24 h for both sides).
  • Testing temperature: typically 23 ± 2 °C (temperate) or 27 ± 2 °C (tropical/subtropical) where applicable.
• Reporting and calibration: Annex A covers adjustment/calibration; report details of pendulum mass, atmosphere, pre-treatment, and whether results fell within the full-scale reading range.

Applications and who uses ISO 4674-2

• Quality control and acceptance testing for manufacturers of rubber- or plastics-coated fabrics.
• Materials evaluation in R&D comparing tear resistance under dynamic loading.
• Independent test laboratories and conformity assessment bodies performing standardized tear tests.
• Procurement and specifications writers who need an agreed test method for dynamic tear performance.
• Typical product areas include coated textiles used in industrial covers, membranes, tarpaulins and other applications where resistance to initiated tearing under impact-like loads is relevant.

Related standards

• ISO 4674-1 - Rubber- or plastics-coated fabrics - Determination of tear resistance - Part 1: Constant rate of tear methods
• ISO 2231 - Standard atmospheres for conditioning and testing
• ISO 2286-2 - Determination of roll characteristics and sampling

Keywords: ISO 4674-2, tear resistance, ballistic pendulum method, rubber-coated fabrics, plastics-coated fabrics, dynamic tear test, conditioning, wet test, pendulum test.