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

2020 ◽  
Vol 12 (9) ◽  
pp. 168781402095497
Author(s):  
Dou Jinxin ◽  
Yang Tongguang ◽  
Yu Xiaoguang ◽  
Xue Zhengkun ◽  
Liu Zhongxin ◽  
...  
Keyword(s):  
Fault Diagnosis ◽  
Strain Energy Release ◽  
Beam Model ◽  
Model Driven ◽  
Local Flexibility ◽  
Slant Crack ◽  
Diagnosis Method ◽  
Flexibility Coefficient ◽  
Euler Bernoulli Beam ◽  
Bernoulli Beam Model

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.

scholarly journals Numerical Solution of Bending of the Beam with Given Friction

Mathematics ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 898
Author(s):  
Michaela Bobková ◽  
Lukáš Pospíšil
Keyword(s):  
Sliding Friction ◽  
Quadratic Function ◽  
Building Construction ◽  
Beam Model ◽  
Bernoulli Beam ◽  
Sustainable Building ◽  
Construction Design ◽  
Euler Bernoulli Beam ◽  
Bernoulli Beam Model ◽  
Fixed Beam

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.

scholarly journals Solution of Contact Problems for Nonlinear Gao Beam and Obstacle

2015 ◽  
Vol 2015 ◽  
pp. 1-12 ◽  
Author(s):  
J. Machalová ◽  
H. Netuka
Keyword(s):  
Solution Method ◽  
Mixed Finite Element ◽  
Mixed Finite Element Method ◽  
Contact Problems ◽  
Beam Model ◽  
Contact Conditions ◽  
Beam Elements ◽  
Solution Methods ◽  
Euler Bernoulli Beam ◽  
Bernoulli Beam Model

Contact problem for a large deformed beam with an elastic obstacle is formulated, analyzed, and numerically solved. The beam model is governed by a nonlinear fourth-order differential equation developed by Gao, while the obstacle is considered as the elastic foundation of Winkler’s type in some distance under the beam. The problem is static without a friction and modeled either using Signorini conditions or by means of normal compliance contact conditions. The problems are then reformulated as optimal control problems which is useful both for theoretical aspects and for solution methods. Discretization is based on using the mixed finite element method with independent discretization and interpolations for foundation and beam elements. Numerical examples demonstrate usefulness of the presented solution method. Results for the nonlinear Gao beam are compared with results for the classical Euler-Bernoulli beam model.

Optimization of a Bioinspired Piezocomposite Pump Based on an Electromechanical Model

2020 ◽  
Author(s):  
Xin Shan ◽  
Onur Bilgen
Keyword(s):  
Performance Metrics ◽  
Mechanical Design ◽  
Structural Parameters ◽  
Beam Model ◽  
Electromechanical Model ◽  
Pumping System ◽  
Active Segment ◽  
Work Done ◽  
Euler Bernoulli Beam ◽  
Bernoulli Beam Model

Abstract 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.

Vibration Analysis of Drug Delivery CNTs Using Transfer Matrix Method

2011 ◽  
Author(s):  
Anooshiravan Farshidianfar ◽  
Ali A. Ghassabi ◽  
Mohammad H. Farshidianfar ◽  
Mohammad Hoseinzadeh
Keyword(s):  
Boundary Conditions ◽  
Transfer Matrix ◽  
Transfer Matrix Method ◽  
Matrix Method ◽  
Equation Of Motion ◽  
Beam Model ◽  
Multi Wall Carbon Nanotubes ◽  
Resonance Frequencies ◽  
Euler Bernoulli Beam ◽  
Bernoulli Beam Model

The free vibration and instability of fluid-conveying multi-wall carbon nanotubes (MWCNTs) are studied based on an Euler-Bernoulli beam model. A theory based on the transfer matrix method (TMM) is presented. The validity of the theory was confirmed for MWCNTs with different boundary conditions. The effects of the fluid flow velocity were studied on MWCNTs with simply-supported and clamped boundary conditions. Furthermore, the effects of the CNTs’ thickness, radius and length were investigated on resonance frequencies. The CNT was found to posses certain frequency behaviors at different geometries. The effect of the damping corriolis term was studied in the equation of motion. Finally, a useful simplification is introduced in the equation of motion.

Nonlinear Dynamics of Electrically-Actuated Carbon Nanotube Resonator

2008 ◽  
Author(s):  
Hassen M. Ouakad ◽  
Mohammad I. Younis
Keyword(s):  
Nonlinear Dynamics ◽  
Carbon Nanotube ◽  
Natural Frequency ◽  
Primary Resonance ◽  
Beam Model ◽  
Harmonic Load ◽  
Shooting Technique ◽  
The Galerkin Method ◽  
Euler Bernoulli Beam ◽  
Bernoulli Beam Model

This paper presents an investigation into the nonlinear dynamics of a carbon nanotube (CNT) actuated electrically by a DC force and an AC harmonic load. The CNT is described by an Euler Bernoulli beam model that accounts for the system nonlinearities due to mid-plane stretching and electrostatic forcing. A reduced-order model based on the Galerkin method is developed and utilized to simulate the static and dynamic response of the CNT. The static deflection of the CNT and its pull-in voltage are calculated and validated by comparing them to published results. It was found that mid-plane stretching has a major impact on the pull-in prediction of CNT. Dynamic analysis is conducted to explore the nonlinear oscillation of the CNT near its fundamental natural frequency (primary resonance) and near one half, twice, and three times its natural frequency (secondary resonances). The nonlinear analysis is carried out using a shooting technique combined with the Floquet theory to capture periodic orbits and analyze their stability. The results show that these resonances can lead to complex nonlinear dynamics phenomena such as hysteresis, dynamic pull-in, hardening and softening behaviors, and frequencies bands with an inevitable escape from a potential well.

Bidirectional actuation of buckled bistable beam using twisted string actuator

2018 ◽  
Vol 30 (4) ◽  
pp. 506-516 ◽  
Author(s):  
Reynolds Addo-Akoto ◽  
Jae-Hung Han
Keyword(s):  
Response Time ◽  
Input Voltage ◽  
Beam Model ◽  
Output Displacement ◽  
Actuation Mechanism ◽  
Buckled Beam ◽  
Voltage Signal ◽  
Twisted String ◽  
Euler Bernoulli Beam ◽  
Bernoulli Beam Model

A new actuation mechanism using the twisted string concept to trigger the snap-through of a bistable buckled beam to produce an effective on/off bistable actuator is proposed. The twisted string concept combined with a pin utilizes actuation moment to actuate a bistable beam. The required actuation loads are analytically formulated using the Euler–Bernoulli beam model and solved with the proposed solution algorithm. The actuation mechanism is fabricated to meet the 24.3 N mm actuation requirements. A prototype of the actuator was built, and its performance was evaluated. In a unidirectional actuation, an actuator response time of 104 ms was achieved. The overall response time of the actuator is affected by the length of the string. The twisted string mechanism was also placed in an antagonistic configuration to enable bidirectional actuation. The shape of the input voltage signal also affected the bidirectional performance of the actuator. The actuator produced an actuation bandwidth of 2 and 5 Hz with sine and square input voltages, respectively, while generating 10 mm output displacement.

Sign in / Sign up

Export Citation Format

Share Document