  Shock response spectrum (SRS) is a widely accepted method for shock testing
specification. However, SRS, as a supremum, is over-conservative and cannot
fully describe the relative severity for various shock environments. This study
introduces shock response matrix, from which shock severity infimum (SSI) can
be extracted using singular value decomposition method. Based on SRS and SSI,
dual spectra are introduced to determine the range of shock severity between
its supremum and infimum. The evaluation of the relative severity of various
shock signals is discussed and validated by finite element simulations.
