Virginia Tech-Wake Forest University, Center for Injury Biomechanics, Blacksburg, Virginia 24061, USA.
Traffic Inj Prev. 2012;13(1):72-80. doi: 10.1080/15389588.2011.636592.
Delta-V (ΔV), the magnitude of the velocity change experienced by a vehicle during a crash, is widely used as a predictor of injury risk. The National Automotive Sampling System/Crashworthiness Data System (NASS-CDS) uses the WinSMASH computer code to reconstruct ΔV based on postcrash vehicle deformation. WinSMASH, a direct descendant of CRASH3, first uses vehicle damage to estimate absorbed energy and then applies momentum conservation to estimate ΔV. This study aims to determine the accuracy of WinSMASH ΔV reconstructions for NHTSA side crash tests.
This study is based upon 168 dynamic side impact tests conducted by the National Highway Traffic Safety Administration (NHTSA). For each crash test the actual ΔV for the struck vehicle was first determined from test instrumentation. WinSMASH was then used to reconstruct the struck vehicle ΔV for each test. WinSMASH-reconstructed ΔVs were compared to measured ΔVs for each test to assess reconstruction accuracy.
WinSMASH predicts ΔV at maximum crush, before restitution occurs. WinSMASH predictions of struck vehicle ΔV at maximum crush were 20 percent high on average when using vehicle specific stiffnesses, with a great deal of inter-case variability in the error. When compared to the total struck vehicle ΔV at separation (including restitution), WinSMASH overpredicted ΔV by 11 percent. WinSMASH overpredicted the amount of energy absorbed in collisions by 40 percent, which is consistent with overprediction of ΔV. When forced to reconstruct tests using the amount of absorbed energy calculated from the test data, error in WinSMASH ΔV effectively disappeared.
When reconstructing NHTSA side crash tests, WinSMASH overpredicts maximum crush ΔV by about 20 percent on average. The primary factors determining the amount of ΔV overprediction appear to be overprediction of absorbed energy and the assumption of zero restitution. WinSMASH vehicle side stiffness parameters are calculated based on artificially high energies; this may explain the overprediction of absorbed energy. WinSMASH's assumption of zero restitution partially masks the effect of energy overprediction. When given accurate reconstruction inputs and energy estimates, WinSMASH is capable of accurately reconstructing maximum crush ΔV in NHTSA side crash tests but cannot compensate for restitution.
Delta-V（ΔV）是车辆在碰撞过程中经历的速度变化量，被广泛用作伤害风险的预测指标。国家汽车抽样系统/耐撞性数据系统（NASS-CDS）使用 WinSMASH 计算机代码根据碰撞后车辆变形来重建ΔV。WinSMASH 是 CRASH3 的直接后代，首先使用车辆损坏来估计吸收的能量，然后应用动量守恒来估计ΔV。本研究旨在确定 WinSMASHΔV 重建用于 NHTSA 侧面碰撞测试的准确性。
本研究基于美国国家公路交通安全管理局（NHTSA）进行的 168 次动态侧面冲击测试。对于每一次碰撞测试，首先从测试仪器中确定了被撞车辆的实际ΔV。然后，为每个测试使用 WinSMASH 重建被撞车辆的ΔV。将 WinSMASH 重建的ΔVs 与每个测试的实测ΔVs 进行比较，以评估重建准确性。
WinSMASH 在发生恢复之前预测最大压缩时的ΔV。当使用车辆特定刚度时，WinSMASH 对被撞车辆最大压缩时的ΔV 预测平均高出 20%，并且在误差方面存在很大的个案间可变性。当与分离时（包括恢复）的总被撞车辆ΔV 相比，WinSMASH 高估了 11%的ΔV。WinSMASH 高估了碰撞中吸收的能量，高估了 40%，这与高估ΔV 一致。当被迫使用从测试数据中计算得出的吸收能量来重建测试时，WinSMASHΔV 的误差实际上消失了。
在重建 NHTSA 侧面碰撞测试时，WinSMASH 平均高估了最大压缩时的ΔV 约 20%。确定ΔV 高估量的主要因素似乎是高估了吸收的能量和零恢复的假设。WinSMASH 车辆侧面刚度参数是根据人为较高的能量计算得出的，这可能解释了高估吸收的能量。WinSMASH 对零恢复的假设部分掩盖了能量高估的影响。当给出准确的重建输入和能量估计时，WinSMASH 能够准确重建 NHTSA 侧面碰撞测试中的最大压缩ΔV，但无法补偿恢复。
