中文摘要：

基于对层裂问题的理解和相关文献，就自由面速度剖面解读层裂问题的局限性提出了一些看法。指出：自由面速度剖面测量给出的层裂破坏过程是间接信息，而不是直接信息，用它确定的理论模型和数值模拟参数，也许并没有真实地反映层裂过程的物理本质；层裂强度常被人们用来表征材料在高应变率下的抗拉伸能力，但是在目前的层裂强度计算公式中没有考虑损伤介质对波剖面传播的影响，使得计算结果明显偏低；传统的单点测量得到的结果有很大的局限性，对于层裂问题，采用概率评估或者置信度评估，也许更符合真实情况。建议：为了全面真实地评价层裂问题中的物理、力学过程，应该加快发展更多的实验探测和诊断技术，尤其是对内部损伤状态的观测。

英文摘要：

A few questions on the spallation behavior resolved by the measurement of free-surface velocity profile have been discussed. Firstly, the way from the measured free-surface velocity profile to infer the dynamic damage behavior of the target is an ＂Inverse Problem＂ and the theoretical model and simulation parameters determined by such a solution maybe not represent the real physical nature of spall fracture inside the target. Secondly, how to calculate the spall strength？ Due to the attenuation effect of micro-voids or damage on the wave propagation, the spall strength computed from the freesurface velocity profile is apparently lower than the tensile strength suffered by the shocked material. Thirdly,limitation of the traditional single-point measurement on the free-surface velocity profile is briefly reviewed. Given that the shocked target is inhomogeneous, the amplitude of the measured velocity profile is varied from point to point. According to these discussions, future research suggestions have been proposed in order to clearly understand the spallation behavior.