affaissement plastique

CONT: About half of the cars with large breaches were clustered toward the end of the derailment. These cars would have encountered more severe derailment conditions than the conditions experienced by the cars located toward the front of the train, due to the large pileup ahead of them. This pileup likely acted as a wall for the cars derailing toward the end of the train. These highly constrained derailment conditions caused large-scale buckling and extreme tank deformations (that is, plastic collapse), which resulted in large shell ruptures.