Figure 4.
The contour plots comprise panel a and panel b. A contour scale indicates element densities from 0.01 to 1.00, with an additional category for no result. Coordinate axes indicate X and Z directions. Panel a contains a dense network of interconnected structural members across the central span, roof, sides, and lower frame, with concentrated members around the end support regions. Panel b presents a simplified structural arrangement with fewer members, larger open regions, and continuous diagonal and horizontal load paths connecting the end support regions through the central structure.Topology optimisation (a) without and (b) with module frame of the middle coach