Critical assessment of operational path analysis: mathematical problems of transmissibility estimation

Abstract

Classical transfer path analysis(TPA) is a widely used and reliable method for tackling noise and vibration problems. But due to its complexity and time‐consuming measurement procedure there is an ongoing research for simpler and faster methods. One such method, most often referred to as operational path analysis(OPA), was presented two years ago and has quickly gained popularity in the NVH field for its speed and ease of use. To estimate path contributions transmissibilities are calculated from the measured operational reference and target accelerations and sound pressures. This new method is now critically examined and compared to a reliable classical TPAmeasurement. The results of this examination reveal three significant weaknesses. This paper focuses on the problems related to the estimation of transmissibilities which mostly arise from the limited amount of orders present in the signal and the coherence between inputs. It is shown that despite the advantages of the method, it is not applicable in many situations and has to be used with care for it can easily give misleading results.