In order to understand the brake judder of a passenger car, the brake judder test of a passenger car was performed with initial speeds of 90, 120, and 150 km/h, end speed of 20 km/h, and pedal forces of 25, 30, 35, and 40 N on a roller dynamometer in a semi-anechoic chamber. The pressure fluctuation of the brake fluid pipe was presented. The accelerations of the steering wheel were recorded at vertical, lateral, and radial directions respectively, and the frequency analysis of the brake judder was also performed. The frequency response functions of the steering system were measured in order to understand the cause of the brake judder. Meanwhile, the multibody system dynamics model of the test vehicle was created with a flexible body and steering system. The brake torque calculated with the brake fluid pressure of the brake pipe in the brake judder test was exerted on the brake systems. The simulated accelerations of the steering wheel were calculated at three different directions, and the frequency analysis of the brake judder was also presented. The design of experiment was presented in order to reduce the brake judder and improve the comfort of the vehicle. An orthogonal array table was designed with 13 factors and 3 levels. The optimum combination was confirmed. The brake judder was also simulated, and the accelerations of the steering wheel were also calculated. Furthermore, the optimization results were verified by the brake judder test. The verification of the optimization indicates that the optimization results are correct and effective.

Microfluidic chips made by traditional materials (glass and silicon) are still important for fluorescence tests, biocompatible experiments, and high temperature applications. However, the majority of the present bonding methods suffer from ultra-clean requirement, complicated fabrication process, and low production efficiency. In the present work, an Electrohydrodynamic printing assist bonding method was proposed. By this method, the ultraviolet-cured-glue dots were printed onto the silicon substrate, and then the patterned glass and silicon substrate can be bonded together at room temperature. The influence of printing condition (nozzle inner-diameter, applied voltage, printing height, and flow rate) on the diameter of printed dot was analyzed by experiments. By the optimized printing condition, the glass-silicon microfluidic chip can be well bonded. The bonding strength and leakage test demonstrated the high bonding quality of the microfluidic chip (bonding strength of 28 MPa and leakage pressure of 3.5 MPa).