This paper discusses the development of a methodology for multi-scale multi-domain predictive simulation of structural sensing. Tools are provided to extend the modeling capacities and improve quality and reliability of 1-D and 2-D guided wave propagation models using commercially available finite element method (FEM) packages. Predictive simulation of ultrasonic nondestructive evaluation (NDE) and structural health monitoring (SHM) in realistic structures is challenging. Analytical methods that can perform efficient modeling of wave propagation are limited to simple geometries. Realistic structures with complicated geometries are usually modeled with the FEM. However, the accuracy of the FEM models needs to be carefully assessed before they can be used to simulate the minute changes induced by structural damage. The modeling of the interaction between piezoelectric wafer active sensor (PWAS) and structural waves is addressed. Two main issues are discussed: (a) modeling of pitch-catch ultrasonic waves betwwen a PWAS transmitter and a PWAS receiver by comparison exact Lamb wave solutions, various FEM results, and experimental results; (b) nonlinear FEM models for localized structural sensing. The paper ends with summary and conclusions followed by recommendations for further work.