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Bolt connection is an important component in mechanical structure which significantly affects the dynamic property of the whole structure. In this paper, a three-dimensional transition interface model which contains geometric and physical parameters is proposed to model the bolted joint based on the contact analysis. The geometric parameters and the physical parameters are used to characterize the influence of contact area and contact pressure which are related to connection parameters such as material, roughness, connection thickness, and tightening force, respectively. After that, the geometric parameter identification method is proposed, and the geometric parameter database of bolt joints for machine tools is constructed based on the Kriging interpolation method. Then, the model updating method based on the combination of modal parameters and frequency response function is proposed to identify the physical parameters and thickness of the three-dimensional transition interface model. The database of the transition interface model is constructed after verifying the validity of the proposed model. Finally, an engineering example of an engraving machine tool is used to check the practicability of the proposed transition interface model and the usage of the constructed parameter database.

To overcome the problem of frequency consistency and simplify the design process of linear ultrasonic motor, a novel traveling wave linear ultrasonic motor with a ring-type stator is proposed in this paper. The combination of two orthogonal bending vibration modes with the same order is selected as the operating mode of the motor. A traveling wave along the side of the stator is utilized to drive the slider to move linearly. The stator adopts a ring symmetrical structure, which can effectively ensure that the resonance frequencies of the two vibration modes are consistent. Thus, we do not need to tune the frequencies of the two vibrations by constantly adjusting the shape of the stator or designing complex clamping parts to fix the stator without making any influence on the vibrations. Meanwhile, a three-dimensional finite element model of the motor is built. Using the model, we obtain the elliptical motion trajectories of the stator driving surface, the output performance of the motor, the sticking-slipping-separation contact characteristic between the stator and the slider and fabricate and measure a prototype of the proposed motor.

The precise mathematical model for the tooth surface and transition surface of spiral bevel gears is derived. Taking a pair of spiral bevel gears of a heavy vehicle as an example of calculation and analysis, a finite element model of spiral bevel gears transmission system is established. Through the finite element tooth contact analysis under quasi-static loading and high loading condition, the influences of torque on the root stress distribution, contact stress, and transmission error are discussed, and the results are compared with the empirical formula results. Finally, a contact performance test bench of spiral bevel gear pair is developed, then the root bending stress, contact pattern, and transmission error tests are carried out. These experiment results are compared with analyzed ones, which showed a good agreement.