UV-Activated Frequency Control of Beams and Plates Based on Isogeometric Analysis

2017 ◽  
Author(s):  
Yujie Guo ◽  
Hornsen Tzou
Keyword(s):  
Isogeometric Analysis ◽  
Uv Light ◽  
Frequency Control ◽  
Dynamic Stiffness ◽  
Frequency Variation ◽  
Frequency Change ◽  
Engineering Structures ◽  
Plate Structures ◽  
C1 Continuity ◽  
Euler Bernoulli Beam

A new LaSMP smart material exhibits shape memory behaviors and stiffness variation via UV light exposures. This dynamic stiffness provides a new noncontact actuation mechanism for engineering structures. Isogeometric analysis utilizes high order and high continuity NURBS as basis functions which naturally fulfills C1-continuity requirement of Euler-Bernoulli beam and Kirchhoff plate theories. The UV light-activated frequency control of LaSMP laminated beam and plate structures based on the isogeometric analysis is presented in this study. The accuracy and efficiency of the proposed isogeometric approach are demonstrated via several numerical examples in frequency control. The results show that, with LaSMPs, broadband frequency control of beam and plate structures can be realized. Furthermore, the length of LaSMP patches on beams is varied, which further broadens its frequency variation ranges. Studies suggest that 1) the newly developed IGA is an effective numerical tool and 2) the maximum frequency change ratio of beam and plate structures respectively reach 24.30% and 6.37%, which demonstrates the feasibility of LaSMPs induced vibration control of structures.

Ultraviolet-Activated Frequency Control of Beams and Plates Based on Isogeometric Analysis

2018 ◽  
Vol 140 (3) ◽  
Author(s):  
Yujie Guo ◽  
Hornsen Tzou
Keyword(s):  
Shape Memory ◽  
Isogeometric Analysis ◽  
Uv Light ◽  
Frequency Control ◽  
Dynamic Stiffness ◽  
Shape Memory Polymer ◽  
Laminated Plates ◽  
Engineering Structures ◽  
Plate Structures ◽  
Finite Cell

A new light-activated shape memory polymer (LaSMP) smart material exhibits shape memory behaviors and stiffness variation via ultraviolet (UV) light exposures. This dynamic stiffness provides a new noncontact actuation mechanism for engineering structures. Isogeometric analysis (IGA) utilizes high order and high continuity nonuniform rational B-spline (NURBS) as basis functions which naturally fulfills C1-continuity requirement of Euler–Bernoulli beam and Kirchhoff plate theories. Compared with the traditional finite elements of beams and plates, IGA does not need extra rotational degrees-of-freedom while providing accurate results. The UV light-activated frequency control of LaSMP fully and partially laminated beam and plate structures based on the IGA is presented in this study. For the analysis of LaSMP partially laminated plates, the finite cell approach in the framework of IGA is proposed to handle NURBS geometries containing trimming features. The accuracy and efficiency of the proposed isogeometric approach are demonstrated via several numerical examples in frequency control. The results show that, with LaSMPs, broadband frequency control of beam and plate structures can be realized. Furthermore, changing LaSMP patch sizes on beams and plates further broadens its frequency control ranges. Studies suggest that: (1) the newly developed IGA combining finite cell approach is an effective numerical tool and (2) the maximum frequency manipulation ratios of beam and plate structures, respectively, reach 24.30% and 16.75%, which demonstrates the feasibility of LaSMPs-induced vibration control of structures.

Frequency Control of Beams and Cylindrical Shells With Light-Activated Shape Memory Polymers

2015 ◽  
Vol 137 (1) ◽  
Author(s):  
Huiyu Li ◽  
Hua Li ◽  
Hornsen Tzou
Keyword(s):  
Shape Memory ◽  
Frequency Control ◽  
Memory Function ◽  
Shape Memory Polymer ◽  
Cylindrical Shells ◽  
Shape Memory Polymers ◽  
Frequency Variation ◽  
Frequency Change ◽  
Variation Range ◽  
A New Technique

Light activated shape memory polymer (LaSMP) is a novel smart material. It realizes the shape memory function under the exposure of laser lights with two different wavelengths. During the exposure process, the stiffness of LaSMPs also changes. With this noncontact actuation feature, this study presents a new technique to manipulate frequencies of beams and cylindrical shells. Fundamental LaSMP mechanism and its stiffness manipulation are presented first. The LaSMP/elastic coupled dynamic equations of cylindrical shells coupled with LaSMPs are established first and then simplified to the governing equation of beams. In case studies, the natural frequency of a cantilever beam laminated with LaSMP patches is studied. Furthermore, the length of LaSMP patches is varied to broaden its frequency variation range. Results show that the maximum frequency change ratio reaches to about 24.5% on beams. A simply supported cylindrical shell laminated with LaSMPs on both the inner and outer surfaces is also analyzed and its frequency varies about 6% for the lowest (1,4) mode. Thus, adopting LaSMPs to manipulate the structural frequencies is a new noncontact actuation technique in vibration controls.

scholarly journals Control of Oscillations in Second-Order Differential Equation

2014 ◽  
Vol 22 (35) ◽  
pp. 57-62
Author(s):  
Zuzana Šutová ◽  
Róbert Vrábeľ ◽  
Bohuslava Juhásová ◽  
Martin Juhás
Keyword(s):  
Oscillation Frequency ◽  
Order Differential Equation ◽  
Frequency Control ◽  
Nonlinear Dynamical System ◽  
Perturbation Parameter ◽  
Second Order ◽  
Frequency Change ◽  
Nonlinear Dynamical ◽  
Second Order Differential Equations ◽  
Control Of Oscillations

Abstract The article deals with the control of oscillations in a specific type of second-order differential equations. The purpose of the research is to prove the possibility of oscillation frequency control based on a change in the value of a singular perturbation parameter placed into a mathematical model of a nonlinear dynamical system at the highest derivative. The oscillation frequency change caused by a different value of the parameter is verified by numerically modelling the system.

scholarly journals Stiffness and Cavity Test of Concrete Face Based on Non-Destructive Elastic Investigation

2018 ◽  
Vol 10 (12) ◽  
pp. 4389 ◽  
Author(s):  
Jinpyo Hong ◽  
Seokhoon Oh ◽  
Eunsang Im
Keyword(s):  
Electrical Resistivity ◽  
Dynamic Stiffness ◽  
Poor Quality ◽  
High Resistivity ◽  
Destructive Testing ◽  
Plate Structures ◽  
Cavity Detection ◽  
Concrete Face ◽  
Concrete Face Rockfill Dam ◽  
Non Destructive

A non-destructive testing (NDT) method was used in a concrete face rockfill dam (CFRD) to identify the condition of the concrete face slab and detect any existing cavities between the concrete face slab and the underlying support layer. The NDT for the concrete face slab was conducted using the impulse response (IR) method and the electrical resistivity tomography (ERT) method with the application of non-destructive electrodes. Information regarding the dynamic stiffness and average mobility of the concrete was obtained based on the mobility-frequency of the IR method, and cavity detection under the plate structures was analyzed using the two-dimensional (2D) electrical resistivity section of the ERT method. The results of the IR method showed that zones with low dynamic stiffness and high average mobility were expected to be found in concrete of poor quality and in cavities beneath the concrete face slab. The results of the ERT method showed that zones with high resistivity were expected to be cavities between the concrete face slab and the underlying support layer. As a result, the tendency toward low dynamic stiffness, high average mobility, and high resistivity in both methods implies unstable concrete conditions and the possible occurrence of a cavity. The results of the two methods also showed a good correlation, and it was confirmed that the NDT method was reliable in terms of cavity estimation.

Vibration of Plate Structures Solved by DQEM Using EDQ

2003 ◽  
Author(s):  
Chang-New Chen
Keyword(s):  
Numerical Algorithms ◽  
Element Model ◽  
Equation System ◽  
Solution Procedure ◽  
Analysis Model ◽  
Engineering Structures ◽  
Discrete Eigenvalue ◽  
Plate Structures ◽  
Wide Range ◽  
Structural Boundary

The vibration of plate structures is solved by DQEM using EDQ. In the DQEM discretization, EDQ is used to define the discrete element model. Discrete eigenvalue equations defined at interior discrete points in all elements, transition conditions defined on the inter-element boundary of two adjacent elements and boundary conditions at the structural boundary form the overall discrete eigenvalue equation system. Numerical results obtained by the developed numerical algorithms are presented. They demonstrate the developed numerical solution procedure. This vibration analysis model can be used to solve wide range of offshore engineering structures.

The Experimental Study on Fracture and Damage Mechanism of RC T-Beam

2010 ◽  
Vol 452-453 ◽  
pp. 661-664
Author(s):  
Mi Zhou ◽  
Yue Zhang
Keyword(s):  
Degradation Mechanism ◽  
Dynamic Stiffness ◽  
Load Ratio ◽  
Damage Mechanism ◽  
Frequency Variation ◽  
Static Stiffness ◽  
Element Analysis ◽  
Single Beam ◽  
Functional Relationships ◽  
T Beam

In order to research the stiffness degradation mechanism of RC T-beam under the condition of different damage and get the influence law of damage degree on dynamic characteristics of single beam, the dilapidated static and dynamic test on four pieces of RC simple T-beams is explained in the paper. Under different degree of damage these parameters of four pieces of RC simple T-beams with two kinds of reinforcement ratio, such as crack, mid-span deflection, basic frequency, dynamic stiffness, static stiffness are measured. The frequency and stiffness variation of RC T-beam is obtained. The functional relationships of T-beam between ratio of static stiffness to dynamic stiffness and load ratio , the frequency ratio and load ratio were established. Furthermore the numerical simulation calculation on test results is made by the finite element analysis. According to the above research, the damage mechanism and frequency variation of RC T-beam under vertical load are summarized.

Paper 22: Metal Surfaces in Contact under Normal Forces: Some Dynamic Stiffness and Damping Characteristics

1967 ◽  
Vol 182 (11) ◽  
pp. 92-100 ◽  
Author(s):  
C. Andrew ◽  
J. A. Cockburn ◽  
A. E. Waring
Keyword(s):  
Surface Finish ◽  
Dynamic Stiffness ◽  
Joint Interface ◽  
Force Frequency ◽  
Oil Viscosity ◽  
Engineering Structures ◽  
Oil Film ◽  
Good Surface ◽  
Joint Area ◽  
Surface Finishes

This paper describes an experimental investigation into the dynamic stiffness characteristics of flat joints subjected to an alternating force superimposed on a steady pre-load. The joints consist of the interfaces between mild-steel discs arranged in a column, in sets with surfaces either turned or lapped together. The influences of pre-load and of alternating force frequency were investigated for both dry and oiled joints, for different values of surface finish, apparent joint area and oil viscosity. The ranges of the conditions considered are compatible with those existing in typical machine tool structures. It was found that the dynamic stiffness of dry joints is independent of frequency and no energy dissipation is measurable. The stiffness is primarily a function of pre-load and surface finish, with apparent joint area becoming important only for very good surface finishes. If oil is introduced into the joint interface, a quadrature stiffness component arises and is accompanied by an increase in the ‘in-phase’ stiffness component. The magnitudes of the oil film stiffness components decrease sharply with an increase in the effective oil film thickness, which is governed primarily by the surface roughness. They increase with oil viscosity, the apparent joint area and the frequency of vibration, and represent a potentially valuable source of vibration damping in engineering structures.

scholarly journals Design of Fractional Order PID (FOPID)for Load Frequency Control Via IMC & Grey Wolf Algorithm (GWO), for a Non-Reheated Power System by Comparing with the Big Bang Big Crunch (BBBC) Optimization

2020 ◽  
Vol 9 (1) ◽  
pp. 1253-1260
Keyword(s):  
Fractional Order ◽  
Frequency Control ◽  
Big Bang ◽  
Load Frequency Control ◽  
Frequency Variation ◽  
Grey Wolf Optimizer ◽  
Grey Wolf ◽  
Electrical System ◽  
Load Frequency ◽  
Fractional Order Pid

In this paper work deals about the application of Grey Wolf Optimizer (GWO) for optimization of fractional order PID (FOPID) controlling device to the frequency disturbance, of system load in the one (or) single area non re-heated electrical system and also comparison to the non re-heated BBBC optimization outputs. In this BBBC optimization we have the two bounding cases (low & upper), they are before and after the perturbation cases. And also we observed that the BBBC output responses. After finding the BBBC outputs we observed that the settling time value of load frequency of BBBC is more when compared with the GWO. This problem is resolved by designing of FOPID via GWO algorithm. The Grey Wolf Optimization is well known meta-heuristic algorithm and has been previously used for optimization of various conventional PID and FOPID controllers. In this paper the GWO is used for optimization of FOPID controller to the load frequency variation in the electrical system for non reheated turbine electrical system .the execution outputs of the proposed controlled method also validated to the other existing techniques

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