NVH and structural analysis of shift cable holder bracket

NVH (Noise, Vibration and Harshness) fundamental defines undesirable sound, tactile sensation and subjective impression from particular characteristics of the noise/vibration. Due to legislation and customers' noise sensitiveness increasing with design of more quiet vehicles (increased sound quality) NVH studies became a very significant goal day by day. Confliction of development time, cost etc. and the design of vehicle with good sound quality is major engineering problem. In example of important engineering working for powertrain NVH engineers is not only check the good sound quality but also perception of sound from driveline should be met with customer expectation. In this NVH study, the produced test vehicle will check for focusing of powertrain NVH side especially to transmission and external control system. Data collection from test vehicle will be described with field test and tool specifications. After subjective evaluation "Knocking noise happens especially between 1100 - 1500 rpm" reported and to solve this issue the source identification will be performed from objective data that shows the source of abnormal noise is shift cable holder bracket. Transfer path can be described as shifter cable bracket (source), shifter cable, shifter box and shifter arm. To understand NVH characteristic of shift cable holder bracket experimental modal analysis (hammer excitation test) has been performed to two production brackets from different production batch. Mode frequencies are reviewed different at two brackets hypothesis has been done according to connection stiffness of the bracket mode shapes can be reviewed at different frequencies. Thus computational modal analysis accoplished with Altair Hypermesh and ABAQUS softwares to compare of experimental modals and computation modal, and it is verified experimental modal and computation modal is matched with good connection stiffness. In addition, hypothesis is also verified with lack of connection stiffness can affect mode shape frequencies at computational analysis. NVH solution is also suggested with reinforced bracket design and it is verified with computational analysis and prototype part at vehicle. Furthermore, structural durability analysis performed with comparasion of baseline and reinfored bracket design to double check that proposed design is better than in aspect of the sound quality and structuraly. Structural durability analysis is done with ABAQUS software with data that data mesh and connection stiffness verified computational modal analysis and it is carried out according to fatigue life criteria of Von Mises.