ISO TR 12351-1999 PDF

Full title and description

ISO/TR 12351:1999 — Road vehicles — Determination of head contact and duration in impact tests. This Technical Report specifies methods to determine the instant of head contact (engagement) and the duration of contact (disengagement) during vehicle impact tests; those timings are used when computing contact head injury criteria (HIC) for crash‑test evaluation.

Abstract

The report describes and compares practical techniques for identifying head engagement and disengagement times in impact tests: a calculation (instrumentation‑based) method using head accelerometers and neck load cells, a visual/film analysis method using high‑speed photography, and an electrical contact method using conductive contacts. The selected timings feed directly into the calculation of contact HIC values.

General information

• Status: Published.
• Publication date: December 16, 1999 (1999‑12).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 43.020 — Road vehicles in general.
• Edition / version: Edition 1 (1999).
• Number of pages: 7 pages.

Scope

ISO/TR 12351:1999 sets out methods for determining the times at which the head first makes contact with a contacting surface (engagement) and the time at which that contact ends (disengagement) in vehicle impact tests. The measured contact intervals are required inputs for computing contact HIC values and other head injury measures. The report compares three approaches (instrumentation calculation, visual/film analysis and electrical contact) and identifies the instrumentation/calculation approach as the preferred technique when appropriate sensors and data acquisition are available.

Key topics and requirements

• Definition of head engagement and disengagement times and their role in contact HIC calculations.
• Recommended instrumentation‑based calculation method: use of triaxial head accelerometers combined with an upper‑neck load cell to derive external resultant contact force.
• Signal processing requirements: filtering of accelerometer/force signals consistent with established channel frequency class (CFC) procedures (see ISO 6487 / CFC classes).
• Contact force thresholds and search levels used in the calculation method (example procedure in the report: contact detected when resultant external contact force exceeds 500 N, with pre/post search levels such as 200 N used to locate engagement/disengagement).
• Visual/film method guidance: requirements for high‑speed camera frame rates (recommendations commonly ≈1 000 frames/s or greater for accurate timing) and time‑base synchronization.
• Electrical contact method: use of conductive coverings or contact strips to register engagement electrically — accurate for engagement timing but potentially less reliable for disengagement.
• Application note: the TR is referenced by other vehicle safety standards that compute HIC and related head criteria, and it provides example algorithms and implementation notes for consistency between laboratories.

Typical use and users

Used by automotive crash‑test laboratories, vehicle safety engineers, biomechanics researchers, standards developers, regulatory testing bodies and dummy/manufacturer test engineers who need consistent, repeatable methods to determine head contact intervals for HIC computations and comparative crashworthiness assessments. The TR supports test procedure development, post processing of impact test data, and inter‑laboratory result comparison.

Related standards

Standards commonly used alongside ISO/TR 12351:1999 include ISO 6487 (instrumentation and signal filtering for impact tests), vehicle occupant protection standards and test method standards that calculate HIC and other injury criteria (for example, clauses in ISO 13232 and other crashworthiness documents reference the head contact timing methods described in this TR). Users should consult the current editions of ISO 6487 and relevant ISO/TC 22/SC 36 documents for harmonized measurement and filtering practices.

Keywords

Head contact timing; engagement time; disengagement time; head contact duration; HIC; head injury criterion; crash test instrumentation; accelerometer filtering; CFC; neck load cell; high‑speed film.

FAQ

Q: What is this standard?

A: ISO/TR 12351:1999 is an ISO Technical Report titled "Road vehicles — Determination of head contact and duration in impact tests" that provides methods to determine when head contact begins and ends during impact testing, used for contact HIC calculations.

Q: What does it cover?

A: It covers three practical approaches for timing head contact in impact tests — an instrumentation/calculation method (preferred when adequate sensors are available), a visual/film analysis method, and an electrical contact method — and gives procedural details (signal filtering, thresholds and timing search procedures) for consistent identification of engagement/disengagement instants.

Q: Who typically uses it?

A: Crash test laboratories, vehicle safety engineers, biomechanics researchers, regulatory bodies, and manufacturers of test dummies and instrumentation use the TR to standardize head contact timing for HIC and related injury calculations.

Q: Is it current or superseded?

A: ISO’s catalogue lists ISO/TR 12351:1999 as a published Technical Report (Edition 1, 1999). There is no indication on the ISO catalogue entry that it has been formally withdrawn or superseded; users should verify the ISO catalogue or national standards bodies for any updates or revisions before use.

Q: Is it part of a series?

A: It is a Technical Report produced under ISO/TC 22/SC 36 (vehicle safety/impact testing) and is commonly referenced alongside other ISO vehicle impact and instrumentation standards (for example ISO 6487 on instrumentation and filtering and various ISO crashworthiness test documents). It complements standards that define HIC computation and instrumentation practice.

Q: What are the key keywords?

A: Head contact timing, engagement/disengagement time, head contact duration, HIC, accelerometer filtering (CFC/ISO 6487), neck load cell, high‑speed film, electrical contact method.