2. Map C-NCAP Frontal Crash Test Requirements
Why C-NCAP Frontal Testing Uses Two Configurations
C-NCAP (China New Car Assessment Programme) evaluates frontal crash protection through two complementary full-scale tests: a 100% overlap rigid barrier impact and a 40% overlap offset deformable barrier (ODB) impact. The two tests are not interchangeable variants of the same event — they load the vehicle structure and restraint systems in fundamentally different ways, and a test plan that treats them as a single "frontal test" will misallocate instrumentation, dummy channels, and photo/video coverage.
The 100% rigid barrier test concentrates the entire frontal kinetic energy into a symmetric, fully engaged load path. Both longitudinal rails, the bumper beam, and the firewall see near-equal loading, and the occupant compartment decelerates as a rigid body with minimal yaw. The 40% ODB test deliberately engages only one side of the vehicle against a deformable honeycomb face, producing asymmetric loading, significant yaw rotation, and intrusion concentrated on the struck side. Restraint performance — particularly belt geometry, pretensioner timing, and side-curtain or thorax airbag deployment — is stressed differently in each case.
Configuration Comparison for Test Planning
The table below consolidates the parameters that a test planner must lock down before booking a facility slot. Values reflect the C-NCAP 2021 protocol; always re-verify against the current published protocol revision before committing to a test matrix, because C-NCAP has revised speeds and barrier specifications across editions.
| Parameter | 100% Rigid Barrier (FRB) | 40% Offset Deformable Barrier (ODB) |
|---|---|---|
| Impact speed | 50 km/h ± 1 km/h | 64 km/h ± 1 km/h |
| Barrier type | Full-width rigid concrete block, flat vertical face | Deformable honeycomb face on rigid backing (EEVC-style ODB) |
| Overlap | 100% of vehicle width | 40% of vehicle width, driver side |
| Barrier face dimensions | Wider than vehicle, height ≥ 800 mm above ground | 1000 mm wide × 540 mm high deformable element, 330 mm deep |
| Dummy — driver | Hybrid III 50th percentile male | Hybrid III 50th percentile male |
| Dummy — front passenger | Hybrid III 50th percentile male | Hybrid III 50th percentile male |
| Rear seat occupants | Hybrid III 5th percentile female (where assessed) | Hybrid III 5th percentile female (where assessed) |
| Seat position | Mid-track, manufacturer-specified design position | Mid-track, design position; struck-side seat checked for intrusion clearance |
| Primary structural loading | Symmetric, both rails engaged | Asymmetric, struck-side rail dominant |
| Dominant injury mechanism | Restraint-driven: chest, head, femur from deceleration | Intrusion-driven: lower leg, pelvis, chest from cabin deformation |
Reading the Two Configurations as a Load-Path Diagram
The single most useful planning aid is a top-down view of how each barrier engages the vehicle. The SVG below shows both configurations side by side: the symmetric rail loading of the FRB versus the one-sided engagement and resulting yaw of the ODB. Use it to decide where to place intrusion sensors, which side needs extra high-speed camera coverage, and how to brief the dummy seating and restraint checks.
Translating the Differences into a Test Plan
The configuration differences drive concrete planning decisions. Work through the following checklist when building the test matrix for a C-NCAP frontal campaign:
- Speed and energy budget. The ODB runs 14 km/h faster than the FRB, so kinetic energy at impact is roughly 1.64× higher (energy scales with v²). Barrier crashworthiness, tow system capacity, and post-impact run-out distance must be sized for the ODB case, not the FRB case.
- Barrier procurement. The FRB needs a certified rigid block with a verified flat face; the ODB needs a fresh honeycomb element per test with documented crush strength. Honeycomb is single-use — order spares and record batch numbers.
- Instrumentation placement. For the FRB, symmetric channel allocation across left and right rails and sills is appropriate. For the ODB, concentrate intrusion and accelerometer channels on the struck (driver) side, and add a yaw-rate channel on the vehicle body to capture the rotation.
- Dummy seating and restraint checks. Both tests use Hybrid III 50th percentile males in front and a 5th percentile female in the rear where assessed. In the ODB, verify that the struck-side seat and door trim do not contact the dummy before impact and that the side airbag/curtain deployment path is unobstructed.
- Camera coverage. The FRB benefits from a symmetric overhead and frontal array. The ODB requires an additional struck-side oblique view to capture intrusion and dummy kinematics during yaw.
Verification Before the Test Day
Confirm the following observable conditions during the pre-test setup check; each maps directly to a configuration difference above:
- Impact speed setpoint matches the protocol edition for the chosen configuration (50 km/h FRB, 64 km/h ODB), verified against the tow-system calibration record.
- Barrier face is the correct type and, for the ODB, a new honeycomb element with recorded batch and crush-strength certificate.
- Overlap is measured and documented: full width for FRB, 40% driver-side for ODB, with the measurement datum (vehicle centerline) recorded.
- Dummy positions match the design seating position, and struck-side clearance is confirmed for the ODB.
- Intrusion and yaw channels are enabled and zeroed for the ODB; symmetric rail channels are enabled for the FRB.
If any of these checks fails — for example, an ODB honeycomb element with an expired certificate, or an overlap measurement that drifts outside tolerance — stop and correct before running. A mis-configured frontal test produces data that cannot be scored against the C-NCAP protocol, wasting the dummy, the barrier, and the facility slot.