COMPOSITE AND SMART STRUCTURES GROUP (CSSG)

School of Aerospace, Mechanical and Mechatronic Engineering,
Building J07 University of Sydney,
Sydney, NSW, Australia, 2006.
Tel: 61-2-9351 2338 Fax: 61-2-9351 4841

RESEARCH PROJECTS

  1. Failure Analysis of Adhesively Bonded and Stitched Joints
  2. Damage Tolerance of Adhesively Bonded Composite Joints
  3. Modeling of 3D Woven Composite Materials
  4. Shape and Vibration Control of Laminated Beams/Plates Based on Higher Order Theories
    5. .... More Details
  5. Damage Detection of Laminated Composites Using Built-in Sensors/Actuators
  6. Buckling and Vibration of Laminated Plates and Shells




1. Failure Analysis of Adhesively Bonded and Stitched Joints

DAJOINT software
A demonstration version of the DAJOINT programs is NOW available running under MS Windows. For information view the READ.ME file. For further details please contact [email protected]

2. Damage Tolerance of Adhesively Bonded Composite Joints

3. Modeling of 3D Woven Composite Materials

Fiber reinforced woven fabric has been widely used in aerospace structures. To effectively utilize this material, it is necessary to evaluate its mechanical and thermomechanical properties for a wide range of weave architecture parameters and to tailor the composite to the specified requirements of its role in practical structures. Measurements of these properties are difficult and can be very expensive when investigating the effects of some manufacturing and geometrical parameters. Fortunately, theoretical and FEA modeling provide a cost-effective alternative for determining these properties. The aim of this Ph.D project is to develop analytical and FEA models for investigating the mechanical and thermomechanical behavior for three-dimensional (3D) fiber reinforced woven fabric composites.
Goals
  1. To develop the theoretical and FEA models for predicting the mechanical and thermomechanical properties for opened-packing plain woven fabric composites, closed-packing plain weaves, 3D orthogonal and angle interlock woven composite materials.

  2. To investigate the effect of some geometrical parameters on the mechanical and thermomechanical properties for the 3D orthogonal and angle interlock woven composites

  3. To conduct the experimental tests for validating the models developed.
Significance The theoretical models and FEA modeling technique proposed here can be used to design satisfactory woven fabric structures for the practical application. This can be achieved by choosing the suitable fiber volume fractions, geometrical parameters, mechanical and thermomechanical properties of the composite constituents, then using the relevant FEA and theoretical models and carrying on the numerical study until the results are satisfactory.

 

Fig. 1 FEA model for 3D orthogonal woven fabric interior unit cell

 

 

4. Shape and Vibration Control of Laminated Beams/Plates Based on Higher Order Theories - More Details

A theoretical formulation is being developed for laminated composite smart structures using higher order theories. The active material will be piezoelectric materials. This formulation will be particularly suited to laminated composites and also applicable to simple non-laminated structures. This method will be able to analyse additional effects and characteristics of the smart composite that earlier models have neglected.
So far, a beam model has been developed and current work focusses on using plate elements using finite element analysis. The FE code has to be developed from scratch since existing FE codes differs in the fundamental formulation. Applications that could be examined from this model would include activating some of the piezoelectric in the structure as sensors or actuators. A further step is to consider the application in shape control (the inverse problem of finding what is needed to generate a given shape) and feedback vibration control.

 

Fig. 2 Shape Control: Deformation due to mechanical load is countered by piezoelectric actuators

 

 

5. Damage Detection of Laminated Composites Using Built-in Sensors/Actuators

Due to their high specific stiffness and strength, the use of composite materials has been increasing consistently in aerospace and automotive applications. However, mechanical properties of composite materials may degrade severely in the presence of damage. Failures of structures, particularly aircraft structures, often have tragic consequences. While the available non-destructive evaluation techniques are expensive, cause a great amount of down-time for the structure, and are impractical in many cases such as in-service aircraft testing, space structure. Smart structures will be able to identify structural damage on line and greatly reduce the maintenance cost.
A smart structure / intelligent materials system contains a network of sensors and actuators, real-time control capabilities, computational capabilities and a host structural material. The structure/system can inspect the health conditions of the structure automatically and continuously by itself. Therefore, the structures/systems could be able to detect damage as it occurs, determine the location and extent of the damage, predict if and when catastrophic failure of the structure will occur, and alert the operator as to how the performance of the structure is affected so that appropriate steps can be made to remedy the situation.
This research will investigate a Model-Based On Line Damage Detection Technique for Delamination in Composite Materials. It aims to develop a technique that will identify delamination when it occurs, and will indicate the location and the extent of delamination, The actuator and sensor will use piezoelectric material.

6. Buckling and Vibration of Laminated Plates and Shells

For structures with well defined curvatures, then the analysis will need to include shell theory. Once again, by incorporating the piezoelectric material into the formulation, one can obtain a model that accurately describes the behaviour of the composite smart structure. The controlling mechanism will be piezoelectric actuators that are activated by the application of electric voltages. Piezoelectric material used as sensors will collect information (in voltages) and the control unit will decide on the next actuation configuration based on sensor information. Such a model will be extremely useful in various applications and can incorporate buckling control and vibration control. Real applications could be found in bridges, buildings, airframes, large space structures, etc...

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Last updated 15 June 2000
(Background: Negative Image of Carbon Fibre Composite)
This page is maintained by Q.Nguyen & C.Chee with the help of CSSG members
Suggestions and comments can be sent to: [email protected]