Evaluation of Hardtop Roof Mounting Schemes for High Speed Performance and Noise

Customer comfort has been at the core of any vehicle design. A segment of vehicle wherein the provision given for roof to be removed to enhance the customer experience. A similar vehicle is the subject matter for the evaluation here. The vehicle being off-roader, customer buying such vehicles are passionate about these lifestyle vehicle’s performance aspects. The roof components are plastic and are bolted with the BIW structure with sealing in place at the interface. The windshield angle being close to vertical, there is a tendency for flow separation at the front tip of roof, while vehicle driven at speed. This creates significant pressure difference across the roof surface, leading to vertical deformation of roof between the bolted mounts. In case the magnitude of deformations not controlled, the reduced sealing effectiveness lets air gushing in the cabin and make noise which can be audible to customer. It becomes top priority to analyze the roof top for structural deformation in early stage of program using pressure generated by the CFD analysis for high speed and optimize the number mountings and locations as well. The final optimized design has been tested for allowable deformation with the proto vehicle.