Dynamic Characteristics of Fluid-Conveying Pipes with Piecewise Linear Support

2016 ◽  
Vol 16 (06) ◽  
pp. 1550025 ◽  
Author(s):  
Zhan-Ying Li ◽  
Jian-Jun Wang ◽  
Ming-Xing Qiu
Keyword(s):  
Dynamic Characteristics ◽  
Piecewise Linear ◽  
Time Integration ◽  
Measurement Data ◽  
Element Model ◽  
Harmonic Excitation ◽  
Dynamic Responses ◽  
Fluid Structure ◽  
Pipe System ◽  
Fluid Conveying Pipes

For the analysis of dynamic characteristics of fluid-conveying pipes with piecewise linear support, a fluid–structure coupling dynamic model based on the finite element method is proposed. A user-defined pipe element based on Euler–Bernoulli beam is developed for modeling the pipes, considering the dynamic flow conditions. A nonlinear spring element is utilized to model the clamp between the pipe and the base. The dynamic responses of the system are obtained through the direct time integration. The stiffness of the clamp support is investigated by the analytical method and the experimental method, in which it is found that the clamp stiffness is piecewise linear. For different pipe geometries the user-defined element model, analytical model and measurement data are compared. The results show high quality of the element developed in this paper. Finally, the dynamic characteristics of the pipe system with piecewise linear support subjected to base harmonic excitation are calculated and the effects of the system parameters on pipe behaviors have also been studied. As a consequence, the model proposed in this paper can represent the piecewise linear nonlinearity of the clamp support and be used conveniently to investigate the effects of the fluid–structure coupling on the system behaviors.

Evaluation of the CSR-H Sloshing Criterion Using Direct Fluid Structure Calculation

2015 ◽  
Author(s):  
Po-Wen Wang ◽  
Chi-Fang Lee ◽  
Yann Quéméner ◽  
Chien-Hua Huang
Keyword(s):  
Finite Element ◽  
Fluid Dynamic ◽  
Plate Thickness ◽  
Structural Response ◽  
Element Model ◽  
Dynamic Responses ◽  
Interaction Technique ◽  
Time Step ◽  
Fluid Structure ◽  
Structural Rules

The objective of this study was to clarify the theoretical basis of sloshing loads and required plate thickness formulations in the harmonized common structural rules. This study used computational fluid dynamic (CFD) to calculate sloshing loads and used finite element analyses (FEA) to evaluate structural response. The sensitivity of the CFD predictions to the time step and grid size was also investigated. Cargo oil tanks were then selected in a handy size oil tanker and a very large crude carrier to evaluate the longitudinal and transverse sloshing loads on the tank boundaries. The results showed that the sloshing pressures computed at four filling levels were mostly consistent with CSR-H. Afterward, the sloshing pressure produced by CFD was applied to the finite element model by using a fluid-structure interaction technique to obtain the dynamic response of the structure. The dynamic responses were investigated to validate the quasistatic approach for sloshing assessment.

Inflight Deicing of Self-Actuating Aircraft Wing Structures With Piezoelectric Actuators

2002 ◽  
Author(s):  
Y. J. Lin ◽  
Suresh V. Venna
Keyword(s):  
Finite Element ◽  
Natural Frequencies ◽  
Laminated Composite ◽  
Piezoelectric Actuators ◽  
Element Model ◽  
Harmonic Excitation ◽  
Dynamic Responses ◽  
Underlying Structure ◽  
Shear Stresses ◽  
Modeling And Analysis

Self-actuating aircraft wings for in-flight deicing with minimal power requirements are proposed. Lightweight piezoelectric actuators are utilized to excite the wing structure to its natural frequencies to induce shear stresses on the surface of the wing. The shears are generated in such a way that they are sufficient to break the weak bond between the ice layer and the wing surface. A laminated composite cantilever plate is used for the modeling and analysis. Analytical model is developed to predict the natural frequencies and shear stresses on the surface of the plate and finite element modal analysis is carried out to verify the results. In addition, finite element model involving the ice deposited on the underlying structure is built. The dynamic responses of the structure to harmonic excitation to its first five natural frequencies are investigated. It is observed that significant amount of ice de-bonding from the substrate occurs in the third mode, or the second symmetric mode. Moreover, the energy requirements of the piezoelectric actuators to actuate an adaptive composite structure with given weight are evaluated.

Dynamic Characteristics Analysis of a Seal-Rotor System with Rub-Impact Fault

2021 ◽  
Author(s):  
Yuegang Luo ◽  
Pengfei Wang ◽  
Haifeng Jia ◽  
Fengchao Huang
Keyword(s):  
Dynamic Characteristics ◽  
Element Model ◽  
Rolling Bearing ◽  
Rotor System ◽  
Dynamic Responses ◽  
Force Model ◽  
Nonlinear Phenomena ◽  
Combination Frequency ◽  
Labyrinth Seals ◽  
Frequency Locking

Abstract Labyrinth seals are widely used to prevent fluid leakage in high-low pressure areas of the rotating machinery. However, the rub-impact fault easily occurs in labyrinth seals. Considering the influence of gyroscopic effect, a finite element model of seal-rubbing rotor system is established in this study based on the Muszynska seal force model, the rolling bearing force model and the nonlinear rubbing force model. The vibration characteristics under the coupling faults of airflow excitation and rub-impact are analyzed. Firstly, the response of the system without rub-impact fault is numerically simulated and verified by experiments. Subsequently, the dynamic characteristics of the rotor under the conditions of slight rub-impact and severe rub-impact faults are analyzed. Finally, the influence of the rub-impact parameters is further studied. The results indicate that when the rub-impact fault is absent, airflow excitation occurs at a certain speed, which exhibits the characteristics of frequency locking and combination frequency. The coupling dynamic responses of airflow-induced vibration and rub-impact fault show a rich spectrum of nonlinear phenomena, which is closely related to the degree of rub-impact. This study may provide a theoretical basis for the detection and diagnosis of fluid-induced rub-impact fault in labyrinth seal-rotor systems.

Dynamic Characteristics of a Horizontal Milling Machine with Hybrid Guideway Systems

2013 ◽  
Vol 423-426 ◽  
pp. 2127-2131
Author(s):  
Jui Pin Hung ◽  
Wei Chu Lin ◽  
Tzou Lung Luo ◽  
Yu Sheng Lai
Keyword(s):  
Finite Element ◽  
Dynamic Characteristics ◽  
Contact Stiffness ◽  
Dynamic Performance ◽  
Dynamic Compliance ◽  
Element Model ◽  
Dynamic Responses ◽  
Milling Machine ◽  
Feeding Mechanism ◽  
Axis Direction

This study was aimed to investigate dynamic characteristics of a milling machine with horizontal spindle tooling system, which was feed through the linear feeding mechanism combined with the sliding guides and linear roller guide modulus. To predict the dynamic characteristics, we created finite element model of the milling machine with the introduction of the contact stiffness defined at the sliding and rolling interface, respectively. The results of the finite element simulations reveal that linear guides with different preloads greatly affect the dynamic responses of the horizontal spindle tool. The maximum dynamic compliance can be increased by 7.4 % in X-axis direction and increased by 12 % in Y-axis direction, respectively when the linear guides are changed from low to high preload. Overall, current results clearly illustrate that the proposed modeling approach of feeding mechanism can quantify the preload effect of the guideway system on the dynamic performance of a milling machine.

Test and Finite Element Analysis on Dynamic Characteristics of Trestle Wharf

2012 ◽  
Vol 594-597 ◽  
pp. 908-913
Author(s):  
Xi Ping Sun ◽  
Zhen Yu Zhu ◽  
Bing Hao Zhao
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Comparative Analysis ◽  
Finite Element Model ◽  
Modal Analysis ◽  
Dynamic Characteristics ◽  
Element Model ◽  
Dynamic Responses ◽  
Steel Pipe ◽  
Element Analysis

The project intends to construct steel pipe piles on both sides of trestle wharf, and the soil vibrations caused by piling construction might have an important effect on the safe service of wharf. In this paper, the dynamic signals during piling construction were recorded and recognized by NExT-ERA. Meanwhile, modal analysis through finite element model of wharf was performed. Through a comparative analysis of the two results, the first two orders of frequency for wharf were obtained. The results would lay foundation for further analysis of dynamic responses of wharf when pile locations close to wharf.

Analysis of Dynamic Responses of Pipe Vibration in Chemical Ship

2012 ◽  
Vol 472-475 ◽  
pp. 226-230
Author(s):  
Xiao Min Shi ◽  
Hai Zhou Ni
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Element Model ◽  
Exciting Force ◽  
Dynamic Responses ◽  
Pipe System ◽  
Calculation Results ◽  
Vibration Mechanism ◽  
The Finite Element Model ◽  
Pipe Vibration

Abstract. Above all, it is discussed about vibration mechanism of the pipe system in a chemical ship, according to layout feature of pipes, the finite element model of the pipe system is constructed by means of CAESARⅡ software, through analyzing internal characteristics of pipes, exciting force and valves of dynamic responses are deduced, displacement responses are tested after the pipe system is applied by exciting force, damping projects of pipes are put forward to after measuring results are compared with calculation results.

Dynamic Responses of Frame Structures Solved Using DQEM and EDQ Based Time Integration Method

2004 ◽  
Author(s):  
Chang-New Chen
Keyword(s):  
Dynamic Equilibrium ◽  
Time Integration ◽  
Element Model ◽  
Equation System ◽  
Dynamic Responses ◽  
Frame Structures ◽  
Equilibrium Equations ◽  
Integration Schemes ◽  
Time Element ◽  
Time Integration Schemes

The dynamic response of frame structures is solved by using the DQEM to the spacial discretization and EDQ to the temporal discretization. In the DQEM discretization, EDQ is also used to define the discrete element model. Discrete dynamic equilibrium equations defined at interior nodes in all elements, transition conditions defined on the inter-element boundary of two adjacent elements and boundary conditions at the structural boundary form a dynamic equation system at a specified time stage. The dynamic equilibrium equation system can be solved by the direct time integration schemes of time-element by time-element method and stages by stages method which are developed by using EDQ and DQ. Numerical procedures and numerical results are presented.

Transient Resonance Passage With Respect to Friction

2012 ◽  
Author(s):  
Marius Bonhage ◽  
Lars Panning-von Scheidt ◽  
Jörg Wallaschek ◽  
Christoph Richter
Keyword(s):  
Power Plants ◽  
Piecewise Linear ◽  
Linear Equations ◽  
Time Integration ◽  
Equation Of Motion ◽  
Harmonic Excitation ◽  
Friction Contact ◽  
Friction Damping ◽  
Tangential Stiffness ◽  
Multi Body

Gas and steam turbine applications are exposed to high vibration amplitudes. Friction damping elements are commonly used to prevent blades from fatigue failure. Most of the work done so far in this field is dealing with steady state vibration occurring due to harmonic excitation. Regarding the growing importance of renewable energy, the number of run-ups and rundowns in power plants is increasing continuously. Furthermore, also the speed of jet engines is changed regularly during operation. To give an analytical approach on how to calculate and create most effective friction damping during instationary excitation, this paper discusses the computation of transient nonlinear vibration. Following the description of a single-degree-of-freedom system comprising a friction contact, it is shown how to assemble the equation of motion using piecewise linear equations. An analytical ansatz is illustrated to solve the ODEs of the system. In the next step, two simple multi-body-systems are created that are coupled by a friction contact. To validate the analytical computation of the vibration response of the system, a numeric time integration of the system is done. The calculations are compared, and it is shown that the analytical ansatz is valid to compute the vibration of the system. Using the solution of the equation of motion of the multi-body-system, it is shown how the optimal friction damping of the system can be determined while varying important parameters like e.g. the normal force of the friction contact and the tangential stiffness of the contact model.

scholarly journals Mechanical Stability of Hybrid Corrugated Sandwich Plates under Fluid-Structure-Thermal Coupling for Novel Thermal Protection Systems

2020 ◽  
Vol 10 (8) ◽  
pp. 2790
Author(s):  
Wenzheng Zhuang ◽  
Chao Yang ◽  
Zhigang Wu
Keyword(s):  
Mechanical Stability ◽  
Thermal Protection ◽  
Element Model ◽  
Parameter Study ◽  
The Novel ◽  
Thermal Coupling ◽  
Mechanical Instability ◽  
Fluid Structure ◽  
Thermal Protection Systems ◽  
Protection Systems

Hybrid corrugated sandwich (HCS) plates have become a promising candidate for novel thermal protection systems (TPS) due to their multi-functionality of load bearing and thermal protection. For hypersonic vehicles, the novel TPS that performs some structural functions is a potential method of saving weight, which is significant in reducing expensive design/manufacture cost. Considering the novel TPS exposed to severe thermal and aerodynamic environments, the mechanical stability of the HCS plates under fluid-structure-thermal coupling is crucial for preliminary design of the TPS. In this paper, an innovative layerwise finite element model of the HCS plates is presented, and coupled fluid-structure-thermal analysis is performed with a parameter study. The proposed method is validated to be accurate and efficient against commercial software simulation. Results have shown that the mechanical instability of the HCS plates can be induced by fluid-structure coupling and further accelerated by thermal effect. The influences of geometric parameters on thermal buckling and dynamic stability present opposite tendencies, indicating a tradeoff is required for the TPS design. The present analytical model and numerical results provide design guidance in the practical application of the novel TPS.

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