Active Vibration Control Analysis of Cantilever Pipe Conveying Fluid Using Smart Material

In this paper, experimental and simulation studies in active vibration of smart cantilever pipe conveying fluid have been presented to investigate the open and closed loop time responses. A program to simulate the active vibration reduction of stiffened pipe with piezoelectric sensors and actuators was written in the ANSYS workbench and  Parametric Design Language (APDL). This makes use of the finite element capability of ANSYS and incorporates an estimator based on optimal linear quadratic control (LQR) schemes to investigate the open and closed loop time responses. The procedures are tested by active control for free and forced vibrations of piezoelectric smart cantiliver pipe conveying fluid. Harmonic excitation is considered in the forced vibration. Experiments have been done to verify with simulations. Smart pipe consists of aluminum pipe surface glued piezoelectric patches of MIDÉ QuickPack QP20W transducers. An experimental result is acquired by LabVIEW programs. It is found the location of the piezoelectric actuator has in influence on the response of the cantilever pipe. The displacement increases when the actuators are moved closer to the clamped. This is due to the higher strain developed near the clamped . The control performance  decrease with increasing  the flow velocity due to increased  coriolis force.The better performance of control occur at minimum velocity(Q=10L/min) and location1 of actuator, the maximum reduced the displacement response from +8mm to 1mm. Keywords: Active vibration control, LQR, cantilever pipe, smart structure, Smart material, piezoelectric

An Analytical Investigation of Thermal Buckling Behavior of Composite Plates Reinforced by Carbon Nano Particles

The research used analytical and numerical methods to test thermal buckling activity for a composite plate structure with a range of Nano fractions. Experimental program with mechanical properties for the Nano composites were carried out and have been validated from previous work. In addition, both mechanical and thermal expansions were tested from previous work experimentally and used in numerical and analytical methods by the Nano composite. The general motion equation for thermal buckling load was derived and then, the results were compared with the numerical results. The analysis showed that the average outcome error was not greater (2.49%). Ultimately, the results showed that the thermal effect results in a buckling of Nano particle strengthening (1%) volume fraction for the adjusted structure of the plate leads to increase thermal buckling strength (63,4%). This achievement modified a high thermal buckling strength with low percentage of Nano volume fraction compared to the previous work in this field

BOUNDARY ELEMENTS MODELLING FOR SMALL/LARGE STRAIN ANALYSIS OF ELASTOMERIC MATERIALS

In this paper the boundary elements method is used as numerical techniques for solving elastomeric materials (rubber or rubber-like materials) under small and large strains analysis. Under small deformations, the formulations are based on assuming that the elastomer is linear elastic isotropic incompressible solid. While for the large deformation, the formulation is based on decomposing the 1st Piola-Kirchhoff stresses into linear and nonlinear parts. Thereafter, the final derived equations are composed of both boundary integral and non-linear domain integrals. The non-linear analyses were performed using an incremental procedure with an iterative algorithm. Solving some numerical examples and comparing the results with that obtained from some available results and ANSYS 10.0 showed that the boundary elements method is a good numerical technique for solving incompressible elastomeric materials. And the formulation used for the boundary elements derivations for large strain analysis gave satisfactory results as compared with that of ANSYS ver. 10.0

A Suggested Analytical Solution For Laminated Closed Cylindrical Shells Using General Third Shell Theory (G.T.T.)

Transient solutions will be developed for laminated simply supported closed cylindrical shells subjected to a uniform dynamic pressure at the outer surface of the cylinder. These solutions are obtained by using General Third Shell Theory (G.T.T.). Rectangular pulse, triangular pulse, sinusoidal ulse and (ramp-constant) load-time varying functions are studied and the required equilibrium equations are developed. The central deformation and principle stresses are investigated for different cross-ply laminates

Kinematic Analysis of Semi-Flexible Robot

In this work, a kinematic model of semi- flexible robot with two degrees of freedom based on the joint angles and arm’s deflections is presented with taking in consideration the small deflection parameter (exact model), and used experimental deformation results to make a comparison between the approximate model and the exact model. Due to the difficulties of using flexible robot in the real live, a two degrees semi-flexible robot was built; this robot will be used to get the experimental results for comparison. The comparison shows a small difference between the approximate model and the exact model, so with increasing the flexibility this difference will increase and in some applications of robot this difference will be significant and worth to take in consideration

FLUTTER SPEED LIMITS OF SUBSONIC WINGS

Flutter is a phenomenon resulting from the interaction between aerodynamic and structural dynamic forces and may lead to a destructive instability. The aerodynamic forces on an oscillating airfoil combination of two independent degrees of freedom have been determined. The problem resolves itself into the solution of certain definite integrals, which have been identified as Theodorsen functions. The theory, being based on potential flow and the Kutta condition, is fundamentally equivalent to the conventional wing-ection theory relating to the steady case. The mechanism of aerodynamic instability has been analyzed in detail. An exact solution, involving potential flow and the adoption of the Kutta condition, has been analyzed in detail. The solution is of a simple form and is expressed by means of an auxiliary parameter K. The use of finite element modeling technique and unsteady aerodynamic modeling with the V-G method for flutter speed prediction was used on a fixed rectangular and tapered wing to determine the flutter speed boundaries. To build the wing the Ansys 5.4 program was used and the extract values were substituted in the Matlab program which is designed to determine the flutter speed and then predicted the various effects on flutter speed. The program gave us approximately identical results to the results of the referred researches. The following wing design parameters were investigated skin shell thickness, material properties, cross section area for beams, and changing altitude. Results of these calculations indicate that structural mode shape variation plays a significant role in the determination of wing flutter boundary

Improving Fatigue Life of Bolt Adapter of Prosthetic SACH Foot

In this research an analysis for improving the fatigue behavior (safety factor of fatigue) of non- articular prosthetic foot (SACH) in the region (Bolt Adapter).The laser peening was carried to the fatigue specimens to improving the fatigue properties of bolt’s material. The tests of mechanical properties and fatigue behavior were carried for material that the bolt manufacture from it, a region where the failure occur and inserted of these properties to the program of engineering analysis (Ansys) to calculate the safety factor of fatigue. The results showed that the safety factor after hardening by laser is increased by 42.8%

THERMAL BUCKLING OF RECTANGULAR PLATES WITH DIFFERENT TEMPERATURE DISTRIBUTION USING STRAIN ENERGY METHOD

By using governing differential equation and the Rayleigh-Ritz method of minimizing the total potential energy of a thermoelastic structural system of isotropic thermoelastic thin plates, thermal buckling equations were established for rectangular plate with different fixing edge conditions and with different aspect ratio. The strain energy stored in a plate element due to bending, mid-plane thermal force and thermal bending was obtained. Three types of thermal distribution have been considered these are: uniform temperature, linear distribution and non-linear thermal distribution across thickness. It is observed that the buckling strength enhanced considerably by additional clamping of edges. Also, the thermal buckling temperatures and thermal buckling load have lowest values at first mode of buckling for all types of ends condition and with all values of aspect ratio

A STUDY OF THE EFFECT OF SEMI-ANGLE OF CONE ON THE VIBRATION CHARACTERISTICS OF CYLINDRICAL-CONICAL COUPLED SHELL STRUCTURE

In this work, the effect of variation of semi-angle of the conical part on the vibration characteristics of cylindrical-conical coupled structure is investigated. The shell is made of polyester resin reinforced by continuous E-glass fibers. The case is analyzed experimentally and numerically for orthotropic shell structures. The experimental program is conducted by exciting the fabricated structure by an impact hammer and monitoring the response using an attached accelerometer for different semi-angles of the conical part. Software named SIGVIEW is used to perform the signal processing on the acquired signal in order to measure the natural frequencies and the corresponding mode shapes. The numerical investigation is achieved using ANSYS (Finite Element software) which was verified by the experimental results. Good agreement is achieved when comparing the experimental and numerical results. The maximum deviation in results was found to be (5.9%). The maximum relative nodal rotational and translational amplitudes associated with the first normal mode of the orthotropic and isotropic shells are noted for the structure of semi-angle of cone of 45o

EXPERIMENTAL STUDY OF FATIGUE CHARACTERISTICS OF LAMINATED COMPOSITE PLATES

The fatigue damage is a dangerous and could be considered as the most unwanted failure in the materials that are used to construct the engineering components. As composites take an advanced position in the industry of aircraft, marine and many other high performance components, because of their high ability and their light weight and for their strength, this forces us to find the deformation and data to give a good expectation for the composite behavior under fatigue and other types of damage. In this study the material used is the glass fiber with a polyester resin; the experiment used a device to force the composite to be under a bending fatigue through specified deflection and then the force is measured. The results for different values of imposed deflection and different thicknesses are presented, as S-N curves and in a logarithmic way.nFractography has been used to characterize the fatigue damage in the composite, it is shown that the fatigue damage in the composite is a complex, interactive damage process and combines between several damage mechanisms such as delamination, fiber breakage, matrix cracking and fiber matrix debounding