This study proposed a multidisciplinary design of the inner belt weatherstrip of automobiles for the simultaneous reduction of wind noise and squeak of the glass window. The conclusions drawn from this study are as follows.
Considering both the manufacturing deviation and deformation of the glass when stalled, we proposed the minimum overlap amount of the inner belt weatherstrip that maintains contact even in the event of permanent deformation. In addition, the value of the minimum contact load to maintain the wind noise when the CLD is reduced was proposed after experimental analysis. This value was proposed considering the degree of permanent deformation according to the viscoelastic characteristics of the TPV elastomer.
Through the TPV material characterization, it was found that an increase in the loss factor was attributed to the higher ratio of EPDM. The lower PP ratio also decreased the compression set value because the amount of PP permanently deformed per unit area decreased. The loss factor tends to increase owing to the influence of the crosslinked network formed in the EPDM particles. SEM analysis revealed that the size of the EPDM particles decreased as the crosslinking density of the EPDM increased. This caused the increased interfacial area of EPDM particles with PP, thereby increasing the energy loss by intermolecular friction at the interface. Based on this study, it was possible to synthesize a new TPV compound, namely ENB #3, with a high loss factor (0.11 at 24 C, 10 Hz) and a low compression set (27.55). 
Through the flocking coating material characterization, it was established that the coefficient of friction of flocking tends to increase as the normal load decreases, and flocking without coating of dμ/dv has a negative slope at speeds higher than 40 mm/s under a normal load of 2 N. When amino-modified silicone is applied to the flocking surface, because dμ/dv has a positive value under all conditions, it leads to a positive and increased ζ, which stabilizes the vibration. In addition, the coefficient of friction is reduced by more than 70%, confirming that it helps to counter sprag slip. Moreover, the difference between the friction coefficient in the dry and wet states tends to decrease as the amount of coating solution increases. This effectively reduces squeak that occurs frequently on rainy days.
To predict frictional vibration, the CAE methodology was devised by simulating the VDA 230-206 test, including not only the hyperelasticity of the TPV and flocking materials, but also the viscoelasticity and the change in the friction coefficient with respect to speed on the flocking surface. The CAE results were validated with the test results showing the same tendency of the magnitude of the acceleration and frequency with respect to different TPV materials. 
Based on the study of the TPV material damping and lip angle design, a new material and structural design of the inner belt weatherstrip was established and the actual parts were fabricated for further evaluation. In the component-level test, both permanent deformation and CLD satisfied the guide. Moreover, the enhanced damping of the TPV material with coating on the flocking surface (5 g/m2) significantly reduced the magnitude of acceleration from 0.42 g to 0.24 g (43% reduction) in the friction induced vibration test. Through the vehicle level performance tests, the newly developed inner belt weatherstrip exhibited better performances in both the wind noise (1.0 dB(A) and 1.2 dB(A) reduction for the cabin noise and proximity noise, respectively) and squeaking noise (periodic noise in the frequency range of 0.1 and 1 kHz was disappeared).
This study demonstrated a multidisciplinary design for simultaneous reduction in wind noise and squeak of the inner belt weatherstrip, which can be applied to next-generation vehicles such as autonomous EVs and urban air mobility.