Optimizing Body Panels for NVH Performance 2015-01-2265
Automotive manufacturers are being challenged to come up with radical solutions to achieve substantial (30-35%) vehicle weight reductions without compromising Safety, Durability, Handling, Aero-thermal or Noise, Vibration and Harshness (NVH) performance. Developing light weight vehicle enablers have assumed foremost priority amongst vehicle engineering teams in order to address the stringent Fuel Economy Performance (FEP) targets while facilitating lower CO2 emissions, downsizing of engines, lower battery capacities etc. Body sheet metal panels have become prime targets for weight reductions via gage reduction, high strength steel replacement, lighter material applications, lightening holes etc. Many of these panel weight reduction solutions are in sharp conflict with NVH performance requirements. The main challenge for NVH engineers is to recover panel stiffness and mitigate the potentially increased air-borne as well as structure-borne noise transmissibility thru these lighter panels. This is achievable with a systematic approach to optimizing panel geometry and damping treatment upfront during the body structure development process while also incorporating innovative new light weight solutions for acoustic insulation.
This paper describes generic FE based methods to virtually engineer body panels starting with optimization of geometry features followed by efficient damping treatment to meet weight and stiffness targets upfront in the design process. Panel geometry study parameters include panel features such as curvature, form geometry and beads in combination. Mesh morphing to vary panel curvatures coupled with topography methods to optimize features such as bead pattern are used to achieve panel frequencies and FRF targets. Further, a new methodology is introduced to assess panel sensitivities to mid-frequency structure borne noise which is then used to fine tune the panel features for stiffness as well as identification of target panel areas for efficient damping treatment. Also, innovative concepts for weight effective acoustic insulation are referenced.