Overview
ISO 7797:1985 specifies a standardized method for measuring the breaking load and deflection at break of cross‑country skis under a quasistatic bending load. The procedure defines test apparatus, load‑application points, conditioning, test speeds and reporting requirements for skis for adults, juniors and children. It explicitly excludes ski structures that exhibit relatively high plastic deformation (for example skis with steel edges or aluminium skins).
Key topics and technical requirements
- Scope: Quasistatic determination of resistance to breaking (breaking, delamination, buckling) for defined parts of cross‑country skis.
- Test apparatus: usually a tensile tester with a special bending fixture including:
- two adjustable supports (at least one a low‑friction roller),
- a load cell (range ≥ 10 000 N) for FB1 and FB2,
- displacement gauge for deflection measurement,
- a ram plate (steel plate 4 mm + hard rubber 3 mm, Shore A 95 ± 5 per ISO 868),
- load‑displacement recorder to plot load‑deflection curves.
- Load application geometry:
- FB1 (ski forebody): load applied midway between supports spaced 200 mm apart; the forebody load point is defined relative to a reference line and binding mounting area.
- FB2 (centrepart): load applied midway between supports spaced 500 mm apart; load point located relative to the binding mounting point according to ISO 7264.
- Test procedure:
- Condition skis to (23 ± 5) °C and (−10 ± 2) °C for at least 2 hours each.
- Apply load at a rate that increases deflection by 25 mm/min while recording the load‑deflection curve.
- Evaluation and reporting:
- Report average breaking loads (FB1, FB2) and deflection at break (fB1) from six skis (three pairs) with standard deviation.
- Test report must include reference to ISO 7797, manufacturer/model, length, test temperature, load‑deflection charts and any deviations from standard procedure.
Applications & users
- Useful to ski manufacturers, R&D teams, quality control labs and test houses for:
- validating ski stiffness distribution, breaking strength and deformation characteristics against design targets,
- production quality assurance and comparative product testing,
- regulatory or safety documentation for cross‑country skis (excluding heavily plastic‑deforming constructions).
- Also relevant for material engineers and product certification bodies assessing structural failure modes (breaking, delamination, buckling).
Related standards
- ISO 868 - Plastics: Shore durometer indentation hardness (used for the ram plate rubber specification).
- ISO 7264 - Cross‑country skis: dimensions of the binding mounting area (used to locate load application points).
Keywords: ISO 7797:1985, cross‑country skis testing, breaking load, deflection at break, quasistatic load, ski durability, load‑deflection curve, ram plate, conditioning temperature.