Evaluation of THOR-50M-RS under reclined seating conditions.

OBJECTIVE

Testing was conducted to evaluate the performance of the THOR-50M for Reclined Seating (THOR-50M-RS) with modifications to allow for a more realistic posture and impact response under reclined seating conditions. Results were compared to tests conducted with PMHS under the same conditions.

METHODS

Nine frontal sled tests were conducted using the THOR-50M-RS in a controlled response seat with the seatback angle set to 45 degrees. Three tests were conducted under each of three conditions: (1) nominal 32 km/h delta V, 4.5 kN seatbelt load limiter (LL), knee bolster condition 1 (180 mm spacing); (2) nominal 50 km/h delta V, 2.7 kN LL, knee bolster condition 1; and (3) nominal 50 km/h delta V, 2.7 kN LL, knee bolster condition 2 (100 mm spacing). The ATD was positioned using a seating procedure based on data from volunteers in reclined seats. THOR-50M-RS instrumentation prioritized channels that could be directly compared to PMHS tests, such as head, T1, and pelvis accelerations. Ten cameras were used to track matching kinematic targets for comparison. Emphasis was placed on qualitative comparison of the head, spine, hip, and knee kinematics, but differences were also quantified using Correlation and Analysis (CORA) techniques. Injury assessment reference values (IARVs) were also calculated.

RESULTS

The ATD showed good repeatability within test conditions. Minor durability issues included pelvis flesh damage that was repaired and did not reoccur, as well as upper thigh flesh fraying at the rear seams. Comparison to kinematics from PMHS tests run in the same conditions indicated that the response of the THOR-50M-RS generally aligned well with the PMHS signals. However, the initial narrow width of PMHS corridors often led to low CORA scores, with a range of 0.03 to 0.98 across all test conditions and signals.

CONCLUSIONS

The THOR-50M-RS was able to meet target postures in reclined seats and showed good repeatability within a given test condition. These tests demonstrate the challenges of designing effective occupant protection systems for occupants in reclined postures, with chest and lumbar spine injury measures exceeding recommended limits (derived for non-reclined modes) in the higher-speed (50 km/h) testing condition.