Research of dynamics analysis and active control of suspension smart structure

2012 ◽  
Author(s):  
Qingmin Wang ◽  
Mubiao Su ◽  
Yaoen Yang ◽  
Zhentao Li
Keyword(s):  
Active Control ◽  
Smart Structure ◽  
Dynamics Analysis

Analysis of Hybrid Programming Simulation Based on the Variable Stiffness Ring With Expanding Loop SMA Actuator

2017 ◽  
Author(s):  
Lei Wang ◽  
Zong-quan Deng ◽  
Hao-di Wang ◽  
Hong-hao Yue
Keyword(s):  
Thermal Stress ◽  
Elastic Modulus ◽  
Active Control ◽  
Driving Force ◽  
Structure Design ◽  
Smart Structure ◽  
Space Craft ◽  
Stiffness Variation ◽  
Sma Actuator ◽  
Driving Source

In the development of space craft design index, the requirements of hypersonic space craft control accuracy has been increasingly rigorous. Thin-walled structure is often employed in hypersonic craft to reduce the weight of the load and to save the room. During the flight of the craft, temperature field is produced along the surface and the dynamic properties of the craft structure are obviously changed. The decreasing elastic modulus of the structure material and the appearance of thermal stress lead to the decrease of integral rigidity and stability of the structure, then the thermal flutter appears and control difficulties increase. Shape Memory Alloy (SMA) has the advantages of the considerable driving force in the compact volume and the simple driving method. By the combination of actuator structure design and stiffness control, the smart structure is able to make active control to the thermal stiffness variation. In this paper, the apex high-temperature area is equivalent to a ring structure. Finite difference method is employed firstly to transform the governing partial differential equation into discrete finite difference equations. Then the elastic modulus change, thermal stress and tension along the circumference are considered comprehensively to propose the calculation formulas of equivalent young’s modulus. The discrete dynamic matrix model is obtained containing the control terms of SMA. To solve the big-matrix calculation and multiple iterated large data problem, hybrid program is developed with C++ and MATLAB. Finite element software is employed to make optimization analysis to design an expanding loop actuator containing SMA as driving source, variable thickness loops of spring steel as expanding units, and universal-ball pre-loading units. On the basis of that, the thermal stiffness variation active control system with smart structure is developed based on expanding loop SMA actuator. After the analysis of examples, the variation law of the needed SMA driving force is obtained. The distribution position and quantity of the driving source is optimized. This research provides reference for the Theoretical Analysis and Simulation of structure stiffness active control and adaptive control of the aircraft employing smart material. The research results have guiding significance for the smart structure design of hypersonic aircraft in the future.

Active Vibration Attenuation of Smart Shell Structure Instrumented With Piezoelectric Layers

2018 ◽  
pp. 22-49 ◽  
Author(s):  
Anshul Sharma
Keyword(s):  
Finite Element ◽  
Fuzzy Logic ◽  
Spherical Shell ◽  
Active Control ◽  
Degrees Of Freedom ◽  
Fuzzy Logic Controller ◽  
Equations Of Motion ◽  
Piezoelectric Sensor ◽  
Smart Structure ◽  
Fuzzy Logic Approach

The active control of vibration of piezoelectric flexible smart structure is an important issue in engineering. Reducing vibration may improve the user's comfort and safety. This chapter presents a fuzzy logic approach for active control of vibration of a smart composite laminated spherical shell. The spherical shell is in the form of a layered composite shell having collocated piezoelectric sensor/actuator pair. The vibratory response of the shell is modeled using finite element method. There are five mechanical degrees of freedom per node and the potential difference across the piezoelectric layer is introduced as an additional electrical degree of freedom on an element level. The mode superposition method has been used to transform the coupled finite element equations of motion in the physical coordinates into a set of reduced uncoupled equations in the modal coordinates. The simulation results illustrate that the superiority of designed nonconventional fuzzy logic controller over conventional controllers.

Smart Structure for Improving Crashworthiness in Vehicle Frontal Collisions

1999 ◽  
Author(s):  
Saad A. Jawad ◽  
Hikmat F. Mahmood ◽  
Mohamed R. Baccouche
Keyword(s):  
Active Control ◽  
High Speed ◽  
Smart Structures ◽  
Smart Structure ◽  
High Mass ◽  
Zone Length ◽  
Acceleration Pulse ◽  
Front End ◽  
Hydraulic Cylinders ◽  
The Impact

Abstract Traditional passive front-end structure is limited by its fixed characteristics. The implication is that it performs well under given crash conditions only. Design compromise is a necessity to cope with both full Frontal and Offset crashes. A trade off between pulse requirements and intrusion injury requirements is also necessary in short front-end design. Energy management in passive structures is thus constrained by the fixed length and stiffness of the structure. Ideally it is required to make the structure longer and stiffer for high speed-high mass crashes, and softer for low speed-low mass crashes. Offset crashes ideally require stiffer structure on the impact side and softer structure on the other side. The way out of this impasse is to introduce the concept “Smart Structures” where the characteristics (length and stiffness) may be intelligently adjusted according to suit the particular crash circumstances. This research is attempting to improve vehicle crashworthiness by introducing a novel system of “Smart Structures” to support the function of the existing passive structure. A ten-degrees of freedom, two-dimensional spring-mass-damper simulation model has been developed to study the dynamics of crash between two vehicles in head-on collisions. The model inputs mass and speed of both colliding vehicles as well as offset overlap ratio of the crash. Masses and stiffness of various parts of the front end are calculated according to the vehicle total mass. The model was shown to be capable of capturing deformation displacement of the front and backup rail separately. For offset crashes the model was shown to capture the rotation of the structure as well as the deformation of the LHS and RHS rails independently. The model assumes that the two colliding structures geometrically interact with each other. Two injury risk criteria have been considered in this study; average dynamic acceleration sustained by the passenger compartment throughout impact (shock injuries), and length of back up deformation (intrusion injuries). The proposed “Smart Structures” consist of two independently controlled hydraulic cylinders integrated with the front-end rails. By applying active control strategy, this structure is characterised by variable crash zone length, variable Stiffness and independent or asymmetric characteristics of the left/right rails in offset crashes. This paper attempts to analyse the performance of “Smart Structures” applying active control to the crash process for the purpose collision mitigation and improvement of compatibility between vehicles of different masses. It is shown that “Smart Structures” employing two hydraulic cylinders, that extend up to 0.35 meter, prior to collision, is capable of absorbing most impact energy at 30mph. The sustained average dynamic acceleration pulse is 15g. The main improvement is in reducing intrusion injuries at high impact speeds and offset crashes. At low impact speed lower acceleration pulse and lower delta V index are obtained. Deployment of “Smart Structures” in heavy vehicles was shown to have considerable improvement in the compatibility of frontal crashes with smaller vehicles. The intrusion injury index was nearly halved upon deploying the “Smart Structures” in a head-on collision with mass ratio of 10.

scholarly journals Improvement of Transmission Loss Using Active Control with Virtual Modal Mass

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
V. Lhuillier ◽  
L. Gaudiller ◽  
C. Pezerat ◽  
S. Chesne
Keyword(s):  
Active Control ◽  
Transmission Loss ◽  
Smart Structure ◽  
Virtual Mass ◽  
Frequency Range ◽  
Control Approach ◽  
Large Bandwidth ◽  
Damping Control ◽  
Modal Damping ◽  
Modal Mass

This paper deals with an alternative modal active control approach to reduce sound transmission through a structure excited by an acoustic wave. Active control makes it possible to conserve lightness while improving acoustic performances. “Modal mass damping control” is proposed for light and small structures having slight modal overlap. The aim of this control is to modify the modal distribution of high radiation efficiency modes with active modal virtual mass and active modal damping. The active virtual mass effects lower eigen frequencies to less audible frequency range while reducing vibration amplitudes in a broad frequency range. An application of this concept is presented in a simple smart structure. It is harmonically excited on large bandwidth by a normal acoustic plane wave. Results obtained by active modal virtual mass and damping control are compared to other modal control approaches.

Experimental active control results from the SPICES smart structure demonstrations

1996 ◽  
Author(s):  
David S. Flamm ◽  
G. K. Toth ◽  
Kenneth C. Chou ◽  
Larry P. Heck ◽  
William C. Nowlin ◽  
...  
Keyword(s):  
Active Control ◽  
Smart Structure
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