Finite element methods (FEM) are capable of incorporating complex variations in material stresses in the time varying response. While these methods are widely available, they are quite complex and in many cases, their use is not warranted due to uncertainties in blast load prediction. The dynamic material properties presented in this section can be used in FEM calculations; however, the simplified response limits in the next section may not be suitable. Most FEM codes contain complex failure models which are better indicators of acceptable. see chapter 6, dynamic analysis methods, for additional information