1. A method of analyzing the durability of a structure, the method comprising: for each of one or more materials of the structure, performing load-controlled testing on one or more samples of the material to relate each of a plurality of critical strain invariants of the material to cyclic rates of strain invariant accumulation and frequencies associated with the cyclic rates; characterizing each material based on effective properties of the material, the properties including the cyclic rates; using laminate properties of the one or more materials and a geometrical definition of the structure to obtain a parametric model including a plurality of elements; applying load conditions to the model; using the material characterizations to determine frequency responses of the elements to the load conditions, and for each element, using the determined frequency responses and the critical strain invariants to determine whether damage is indicated at the element.