Principle and structure of a multi-chamber piezoelectric pump with large flow rate integrated into printed circuit board

Parametric simulation of multi-chamber piezoelectric pump proposed by authors shows that its flow rate is positively correlated with chamber compression ratio when height of chamber wall is not less than central deflection of circular piezoelectric unimorph actuator (CPUA). Therefore, in this paper, principle and structure of multi-chamber piezoelectric pump with novel CPUAs with three-layer structure are proposed and realized, so as to improve its chamber compression ratio, and then improve its flow rate. Its processing technology compatible with PCB processing technology is studied and its flow rate model is established. Central deflection of CPUA with three-layer structure and the flow rate characteristics are tested. Experimental results show that when the central deflection of CPUA with three-layer structure reaches the maximum value of 106.8 μm, the chamber compression ratio and flow rate of multi-chamber piezoelectric pump reach the maximum value of 50% and 3.11 mL/min, respectively. The maximum flow rate is increased by 622% compared to unimproved pump. By comparing experimental results with numerical and finite element simulation results, the realized multi-chamber piezoelectric pump has large flow rate and the established flow rate model can predict its flow rate.

Numerical Modeling of Reinforced Concrete Slabs under Impact Loading

This paper aims to provide a numerical model able to represent the behavior of reinforced concrete slabs subjected to impact loads. The nonlinear finite element analysis adopted by ABAQUS/Explicit Software was used in this study. A parametric study was conducted to provide a comprehensive understanding of the behavior of reinforced concrete slabs subjected to impact load. Two parameters were varied amongst the slabs which classified in to two groups. In the first groups, the thickness of slabs is variable, which was equal to (75, 100, 150 mm). In the second group, the thickness of the slab is constant and the variable was the reinforcement ratio, which ranged from (0.58 to 1%), per layer. In dynamic analysis, the load-time history and deflection-time relation were investigated. For the first group, obviously, as the slab thickness increased, the maximum central deflection of the slabs decreased by (48 – 84 %). Also, the impact force of the slabs increased by (40 – 106%) as the thickness of the slab increased by (33 – 100%). For the second group, the maximum central deflection of the slabs decreased by (6.6 – 8.8 %) as the steel reinforcement increased by (0.58 – 1 %). It was observed in the second group that the change in the value of the impact force was very limited. This lead to a fact that the impact force was not affected by the change of the reinforcement ratio, but mainly affected by the change of the slab thickness.

Nonlinear flexural analysis of sandwich beam with multi walled carbon nanotube reinforced composite sheet under thermo-mechanical loading

Nonlinear flexural analysis of sandwich composite beam with multiwall carbon nanotube (MWCNT) reinforced composite face sheet and bottom sheet under the thermo-mechanically induced loading using finite element method is carried out. Solution of current bending analysis is performed using Newton’s Raphson approach by using higher order shear deformation theory (HSDT) and non-linearity with Von Kármán kinematics. The sandwich laminated composite beam is subjected to uniform, linear and nonlinear varying temperature distribution through thickness of the beam. The sandwich beam with MWCNT reinforced composite facesheet and bottom sheet is subjected to point, uniformly distributed (UDL), hydrostatic and sinusoidal loading. The two phase matrix is utilized with E-Glass fiber to form three phase composite face sheet and bottom sheet by Halpin-Tsai model. The static bending analysis is performed for evaluating the transverse central deflection of three and five layered sandwich composite beam. Transverse central deflection is measured by varying CNT volume fraction, uniformly distributed, linearly and nonlinear varying temperature distribution, thickness ratio, boundary condition, number of walls of carbon nanotube by using interactive MATLAB code.

ANALYSIS OF DAMAGE PREDICTION IN LAMINATED COMPOSITES SUBJECTED TO IMPACT LOADING

Fibre-reinforced laminated composites are susceptible to transverse impact, at low velocities causing significant damage, in terms of matrix cracks and delamination’s, which are very difficult to detect with the naked eye and can cause significant reductions in the strength and stiffness of the materials. This study aimed at analysing the transient dynamic response of laminated composites due to impact. The effect of fiber volume fraction, laminate thickness, plate boundary conditions, velocity and mass of impactor on the behaviour of composites during low velocity impact is analysed using ABAQUS software. For the analysis, a laminated composite panel made of graphite/epoxy fiber-reinforced laminates is subjected to transverse impact by projectile with a spherical nose. Hashin failure model was adopted for the analysis. The optimal fiber capacity fraction for extreme impact energy for T300/976 type of composite was determined. The velocity required to cause damage initiation was found out for different fiber volume fractions. The variation of contact force and central deflection with velocity and mass of impactor was determined and appropriate empirical models were developed to predict the maximum contact force and central deflection for particular values of impactor velocity and mass. The variation of resistance to failure with laminate thickness was found out and suitable boundary conditions of the plate were identified for different types of impact loading INDEX TERMS—Fiber Reinforced laminated Composite, impactor mass, contact force central deflection

Design, fabrication and experimental studies of compliant flexure diaphragm for micro pump

This study reports the performance of piezo actuated compliant flexure diaphragm for micropump and MEMS application. To achieve the high performance of diaphragm at the low operating voltage compliant flexure diaphragm design is introduced. Very limited work has done on the diaphragms of micropump. Large numbers of mechanical micropumps have used plane diaphragms. The central deflection of diaphragm plays an important role in defining the micropump performance. The flow rate of mechanical type micropump strongly depends on the central deflection of diaphragm. In this paper compliant flexure diaphragms are designed for micropump to achieve higher deflection at lower operating voltage. Finite element analysis of compliant flexure diaphragm with single layer PVDF (Polyvinylidene fluoride) actuator is simulated in COMSOL. Compliant flexure diaphragms with a different number of flexures are analyzed. The central deflection of compliant flexure diaphragms is measured for driving voltages of 90V to 140V in 10 steps. The deflection of the compliant flexure diaphragm mainly depends on flexure width and length, the number of flexures in the diaphragm, PVDF thickness, diaphragm thickness and driving voltage. Use of compliant flexure diaphragm for micropump will reduce the mass and driving voltage of micropump. An attempt is made to compare the results of compliant flexure diaphragms with plane diaphragms. From the experimental results it is noticed that the compliant flexure diaphragm deflection is twice that of the plane diaphragm at same driving voltage. Deflection of three flexure and four flexure compliant diaphragms is 10.5µm and 11.5µm respectively at 140V.

Multi-objective optimum design of ANFIS for modelling and prediction of deformation of thin plates subjected to hydrodynamic impact loading

Drop hammer impact experiments have been carried out to assess the dynamic plastic response of fully clamped circular and rectangular plates made of aluminum and steel subjected to hydrodynamic impact loading at various energy levels. Also, the effective parameters in forming process are proposed in non-dimensional forms for modeling and prediction of the central deflection of plates using adaptive neuro-fuzzy inference system in conjunction with genetic algorithm and singular value decomposition method. Genetic algorithm is used for optimal scheme of Gaussian membership function’s variables and multi-objective Pareto optimal design of adaptive neuro-fuzzy inference system model. Also, the singular value decomposition method is applied to compute the linear parameters of the adaptive neuro-fuzzy inference system method. The important conflicting objectives of developed adaptive neuro-fuzzy inference system, namely, training error and prediction error, are obtained by dividing date sets into two parts. Hence, various optimal choices of adaptive neuro-fuzzy inference system model are provided which are non-dominated states from each other. Moreover, optimal Pareto front of such model leads to trade-off between the conflicting pair of considered objectives for two series of experiments. The results of this work indicate that multi-objective Pareto optimal design of adaptive neuro-fuzzy inference system predicts central deflection of plates with a good accuracy. In addition, the comparison between the adaptive neuro-fuzzy inference system model and exiting one demonstrates superior performance of the present approach in simulating central deflection of plates.