## 3 New Zonal Concept and Mesh Interfacing  
One of the main concerns for the conventional simulation techniques is how to represent changes of mesh and domain boundaries for the dynamic systems (e.g., moving  
Figure 1: **(a)** Finite element (FE) numerical mesh for a gantry boom and (b) its typical stress contour results. objects, extension of domain, and cracking) to define the consequences of these changes on the solutions. The concepts of dynamic and evolving domain (internal and external) and its discretization techniques have been developed recently [19; 20; 21] to overcome numerical problems related to the continuous evolution of numerical domains. The transient nature of some numerical domains (e.g., moving vehicle under road structure) and its continuous changes/expansion have conventionally been handled using either element birth and death approach or the splitting of element layer at the stationary-moving interface. However, the newly proposed approach would treat the changing/evolved parts of the domain as a dynamic zone that can move/evolve in a predefined or calculated manner (e.g., movement of a truck under a gantry on a slow lane). These generated dynamic zones would be attached to the main domain through smart overlapping boundaries. As the generated zones (or sub-domains) are interfaced into the main domain, a comprehensive mapping procedure (including nodal condensation, energy transfer or propagation interface, and so on) would be applied to the hybrid domain to handle the new material/energy input. The dynamic single/multiple zones can be stationary or moving depends on requirement of numerical model for the design process (e.g., passing of HSV or trains under a gantry structure). Figure 2 shows a digital model of a truck within a moving zone along with a portal gantry model and its meshing setup, as well as buffeting of HSVs' fatigue-scenario arrangement under a gantry structure. As the numerical solution is performed on a full parallel-processing machine, multiple instances of the same solver (or alternatively different solvers) can be employed for the main domain and multiple zones, independently. The generated zones can gradually join the main domain (and become a part of main domain) or stay independent for further processing as the changes within the zones (i.e., movement, nonlinearities) come to an end. As shown in Figure 2a, the virtual porotype of a typical HSV can be placed with a dynamic moving zone for passage under a gantry model (defined as stationary high-resolution zone) and the HSVs' fatigue passage scenario can be performed using three vehicle zones and a single stationary zone. New zones and their associated mesh/grid are generated and moved during the simulation within the main numerical domain to capture the dynamic nature of the engineering system. As the generation of new material/energy within the dynamic domain produces numerical instabilities, it is essential to distribute the physical effects of new entries through  
Figure 2: (**a**) CAD models for a typical high sided vehicle (HSV); (**b**) gantry structure (stationary zone); (**c**) overlapped discretized numerical domain; and (**d**) HSVs’ arrangement for fatigue assessment scenarios with three moving zones. balancing schemes [19]. Different types of material/energy evolution within the numerical domain can be perceived for dynamic engineering systems; namely, internal moving (e.g., vehicle movement) and evolving zones with different sources of energy sink/sourcing within the domain (kinetic energy during passage). The new concepts of dynamic zoning and finite local/global zonal systems can promote new generation of simulation techniques for dynamic engineering systems. It can also have an effect on reducing the field study costs as well as CPU (Central Processing Unit) time for the design of complex systems within mobility applications.