Incommensurate vibro-acoustic performance due to in-process blank holder force variation during deep drawing process

Single-stage forming is widely used in the automobile industry due to less cycle times, cost-effectiveness and ease of implementation. The continuously adaptable blank holder force (BHF) systems help produce defect-free components during the deep drawing process. However, this manufacturing process induces a significant amount of variability both at geometry and functional performance of the component. A systematic investigation of the effect of small geometrical changes on the vibro-acoustic properties is carried out using a combination of simulations and experiments. The influence of BHF and friction coefficient on vibro-acoustic properties is investigated through forming simulations. The forming analysis results-geometry prole and thinning- are used as an input to predict the vibro-acoustic behaviour of the formed component. The small geometric prole and thickness variations are significant and affect radiated noise-directivity pattern and sound power levels by 1.4 dB, as shown by simulation results. Two physical components are manufactured using a single-stage deep drawing process. The natural frequencies and mode shapes obtained in free-free boundary conditions vary between the two components up to 20% for the first six flexible modes. The sound intensity measurements are carried out using a pressure and particle velocity (P-u) probe, and it is found that the sound power is varied by 2 dB(A) between the two components. Finally, it is demonstrated that the frequency and amplitude variations between the components are higher at higher frequenciesstatus: accepte