Modal properties of a two-stage planetary gear system with a Timoshenko beam as the intermediate shaft model

This study investigates the mode properties of a two-stage planetary gear (TSPG) system with short intermediate shafts. For this purpose, the rotating intermediate shafts in this system are considered Timoshenko beams and compared with the Euler-Bernoulli beam model. The gyroscopic effect is also considered in the TSPG model. The natural frequencies are given, and mode energy analysis is applied to quantify the importance of intermediate shafts in the total TSPG system. The vibration modes are speed dependent, and three mode types exist. The influence of the rotational speed, length of intermediate shafts and number of planets is evaluated.

Numerical Solution of Bending of the Beam with Given Friction

We are interested in a contact problem for a thin fixed beam with an internal point obstacle with possible rotation and shift depending on a given swivel and sliding friction. This problem belongs to the most basic practical problems in, for instance, the contact mechanics in the sustainable building construction design. The analysis and the practical solution plays a crucial role in the process and cannot be ignored. In this paper, we consider the classical Euler–Bernoulli beam model, which we formulate, analyze, and numerically solve. The objective function of the corresponding optimization problem for finding the coefficients in the finite element basis combines a quadratic function and an additional non-differentiable part with absolute values representing the influence of considered friction. We present two basic algorithms for the solution: the regularized primal solution, where the non-differentiable part is approximated, and the dual formulation. We discuss the disadvantages of the methods on the solution of the academic benchmarks.

Optimization of a Bioinspired Piezocomposite Pump Based on an Electromechanical Model

This paper presents the mechanical design and modeling of an active segment of a bioinspired piezocomposite aquatic pump. The design and analysis is based on an electromechanical Euler-Bernoulli beam model. The self-contained propulsion/pumping system is composed of a series of piezo-active soft cymbal-like segments that are connected by passive soft films. By applying coordinated excitations for expansion and contraction to different active segments, the design creates a traveling wave along the pump axis, which in return propels the fluid to generate a unidirectional thrust force. In the model, the insulation and mechanical properties of the waterproofing sealant layer are considered. Using the proposed electromechanical model, a parametric analysis is conducted to understand the effectiveness of the cymbal-like piezocomposite active segment. Two performance metrics are considered, including the area change of the enclosed by the cymbal-like segment, and the work done by the actuators. The optimal structural parameters of the piezocomposite pump are decided by these performance metrics.

Model-driven fault diagnosis of slant cracks in aero-hydraulic straight pipes

A model-driven fault diagnosis method for slant cracks in aero-hydraulic straight pipes is presented in this paper. First, fracture mechanics theory and the principle of strain energy release are used to derive an expression for the local flexibility coefficient of straight pipes with slant cracks. The inverse method of total flexibility is used to calculate the stiffness matrix of straight pipe elements with slant cracks. Second, the Euler-Bernoulli beam model theory is used in conjunction with the finite element method to construct a dynamic model of the cracked pipe. Finally, a contour map method is used to diagnose the slant crack fault and quantitatively determine the crack position and depth. Experimental results show that the proposed method can accurately and effectively identify a slant crack fault in aero-hydraulic pipelines.