Applications of ENF criterion in forensic audio, video, computer and The sensor design structure, divided into protective layer, piezoresistive layer, support layer. the time each file type required to fail under cyclic flexural fatigue testing. In this study, the flexural behavior of ultra-high-performance fiber- reinforced. Several alternative application of Reed’s terrestrial-passage foundation to The sensor design structure, divided into protective layer, piezoresistive layer, support layer. The analytes were separated and quantified by ultra performance liquid .. the time each file type required to fail under cyclic flexural fatigue testing. The general theory is formulated in view of application to graphene, The sensor design structure, divided into protective layer, piezoresistive layer, support layer. the time each file type required to fail under cyclic flexural fatigue testing. .. Albuquerque, Cibele Gonçalves de; Correr, Américo Bortolazzo; Venezian.
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Plate equations for piezoelectrically actuated flexural mode ultrasound transducers. This paper considers variational methods to derive two-dimensional plate equations for piezoelectrically actuated flexural mode ultrasound transducers. In the absence of analytical expressions for the equivalent circuit parameters of a flexural mode transducer, it is difficult to calculate its optimal parameters ameeico dimensions, and to choose suitable materials.
The influence of coupling between flexural and aplpication deformation, and coupling between the structure and the acoustic volume on the dynamic response of piezoelectrically actuated flexural mode transducer is analyzed using variational methods.
Variational methods are applied to derive two-dimensional plate equations for the transducer, and to calculate the coupled electromechanical field variables. In these methods, the variations across the thickness direction vanish by using the stress resultants.
Thus, two-dimensional plate equations for a stepwise laminated circular plate are obtained. Flexural strength and failure modes of layered ceramic structures.
For bi-layered design, the specimens were tested in both conditions: Fracture surfaces were analyzed using stereomicroscope and scanning electron microscopy SEM. Two types of fracture mode were identified: The mechanical performance of the specimens was determined by the amercio under tension during testing, confirming the study hypothesis.
Published by Elsevier Ltd. This reporting period marked a change in the funding configuration from a combination of a grant and a contract from two different National Aeronautics and Space Administration NASA sections to one single contract.
We chose this reporting period as a transition from the previous reporting period of 1 April to 31 March, to the current reporting period of 18 November to 17 November. To compliment our new mission, we have a new name, the Alaska Satellite Facility ASFdeeply rooted in the University environment and focused on satellite data products, services, and science support.
We have the opportunity to reshape and rebuild ASF ; we will continue to honor our heritage and Serve the science community. Our long-term goals include the commitment to continued first-rate service to our user community. Modeling and analysis of circular flexural-vibration-mode piezoelectric transformer. We propose a circular flexural-vibration-mode piezoelectric transformer and perform a theoretical analysis of the transformer.
An equivalent circuit is derived from the equations of piezoelectricity and the Hamilton’s principle. With this equivalent circuit, the voltage gain ratio, input impedance, and the efficiency of the circular flexural-vibration-mode piezoelectric transformer can be determined.
The basic behavior of the transformer is shown by numerical results. Cooling flexural modes of a mechanical oscillator by magnetically trapped Bose-Einstein-condensate atoms.
We theoretically study cooling of flexural modes of a mechanical oscillator by Bose-Einstein-condensate BEC atoms Rb87 trapped in a magnetic trap. The mechanical oscillator with a tiny magnet attached on one of its free ends produces an oscillating magnetic field.
When its oscillating frequency matches certain hyperfine Zeeman energy of Rb87 atoms, the trapped BEC atoms are coupled out of the magnetic trap by the mechanical oscillator, flying away from the trap with stolen energy from the mechanical oscillator.
Thus the mode temperature of the mechanical oscillator is reduced. The mode temperature of the steady state of mechanical oscillator, measured by the mean steady-state phonon number in the flexural mode of the mechanical oscillator, is analyzed. It is found that ground state phonon number less than 1 may be accessible with optimal parameters of the hybrid system of mechanical oscillator and trapped BEC atoms. Comparing contribution of flexural and planar modes to thermodynamic properties.
Graphene, the most studied and explored 2D structure has unusual thermal properties such as negative thermal expansion, high thermal conductivity etc.
We have already studied the thermal expansion behavior and various thermodynamic properties of pure graphene like heat capacity, entropy and free energy. The results of thermal expansion and various thermodynamic properties match well with available theoretical studies. For a deeper understanding of these properties, we analyzed the contribution of each phonon branch towards the total value of the individual property. To compute these properties, the dynamical matrix was calculated using VASP code where the density functional perturbation theory DFPT is employed under quasi-harmonic approximation in interface with phonopy code.
It is noticed that transverse mode has major contribution to negative thermal expansion and all branches have almost same contribution towards the various thermodynamic properties with the contribution of ZA mode being the highest. Experimental and simulation characterisation of flexural vibration modes in unimorph ultrasound transducers. A unimorph flexural transducer design is proposed and tested with regard to mode shapes and frequencies.
The transducers consist of a passive metal cap structure, and a thin piezoelectric disc, rigidly bonded to the inside. Extensive finite element FE modelling, and experimental 2D, time-resolved displacement measurements were done to characterise the transducers flexural properties, and to compare them to the analytical solutions of thin vibrating plates.
Emphasis was put on characterising the passive layer of the unimorph structure, before bonding the piezoelectric element, to understand how the active element affects the behaviour of the flexing plate. A high power Nd: YAG laser was used to actuate the metal plate non-contactand the frequency content of the resulting displacement signal was analysed to identify the flexural modes.
The non-axisymmetric modeswhich are conventionally disregarded because of their unfavourable acoustic properties, were also taken into account. There was excellent agreement between the experimental results and the FE simulation data. There was good agreement with the analytical edge clamped plate model, but with some notable deviations, which have not previously been identified or commented upon.
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Specifically, the second axisymmetric mode is split into three separate modeswhich is not explained by the traditional theory of vibrating plates.
Published by Elsevier B. Rapid repair of severely earthquake-damaged bridge piers with flexural -shear failure mode.
An experimental study was conducted to investigate the feasibility of a proposed rapid repair technique for severely earthquake-damaged bridge piers with flexural -shear failure mode. Six circular pier specimens were first tested to severe damage in flexural -shear mode and repaired using early-strength concrete with high-fluidity and carbon fiber reinforced polymers Ametico.
After about four days, the repaired specimens were tested to failure again. The seismic behavior of the repaired specimens was evaluated and compared to the original specimens. Test results indicate that the proposed repair technique is highly effective. Both shear strength and lateral displacement of the repaired piers increased when compared to the original specimens, and the failure mechanism of the piers shifted from flexural -shear failure to ductile flexural failure.
Finally, a simple design model based on the Seible formulation for post-earthquake repair design was compared to the experimental results. It is concluded that the design equation for bridge pier strengthening before an earthquake could be applicable to seismic repairs after an earthquake if the shear strength contribution of the spiral bars in the repaired piers is disregarded and 1.
Sound waves and flexural mode dynamics in a,erico crystals.
Starting from a Hamiltonian with anharmonic coupling between in-plane acoustic displacements and out-of-plane flexural modeswe derived coupled applicaation of motion for in-plane displacements correlations and flexural mode density fluctuations. Linear response theory and time-dependent thermal Green’s functions techniques americco applied in order to obtain different response fildtype.
As external perturbations we allow for stresses and thermal heat sources. The displacement correlations are described by a Dyson equation where the flexural density distribution enters as an additional perturbation. The flexural density distribution satisfies a a;plication equation where the in-plane lattice displacements act as a perturbation.
In the hydrodynamic limit this system of coupled equations is at the basis of a unified description of elastic and thermal phenomena, such as isothermal versus adiabatic sound motion and thermal proetctor versus second sound. The general theory is formulated in view of application to graphene, two-dimensional h-BN, and 2H-transition metal dichalcogenides and oxides. It has been documented that AE signals propagate in thin plates as extensional and flexural plate modes. A typical signal from a pencil lead break source which identifies these two modes is shown.
Smith showed that crack growth events in thin aluminum plates under spectrum fatigue loading produced signals that propagated as plate modes. Additionally, Prosser et al. Experimental study on slow flexural waves around the defect modes in a phononic crystal beam using fiber Bragg gratings. This work experimentally studies influences of the point defect modes on the group velocity of flexural waves in a phononic crystal Timoshenko beam.
Using the transfer matrix method with a supercell technique, the band structures and the group velocities around the defect modes are theoretically obtained.
Particularly, to demonstrate the existence of the localized defect modes inside the band gaps, a high-sensitivity fiber Bragg grating protecror system is set up and the displacement transmittance is measured. Slow propagation of flexural waves via defect coupling in the phononic crystal beam is then experimentally demonstrated with Hanning windowed tone burst excitations. Modeling and experimental study on near-field acoustic levitation by flexural mode.
Near-field acoustic levitation NFAL has been used in noncontact handling and transportation of small objects to avoid contamination. We have performed a theoretical analysis based on nonuniform vibrating surface to quantify the levitation force produced by the air film and also conducted experimental tests to verify our model. Modal analysis was performed using ANSYS on the flexural proector radiator to obtain its natural frequency of desired modewhich aoplication used aamerico design the measurement system.
Then, the levitation force was calculated as a function of levitation distance based on squeeze gas film theory using measured amplitude and phase distributions on the vibrator surface.
Compared with previous fluid-structural analyses using a uniform piston motion, our model based on the nonuniform radiating surface of the vibrator is more realistic and fits better with experimentally measured levitation force. Methods to calculate fluid density and viscosity using a micro-cantilever and based on the resonance principle were paplication forward.
Their measuring mechanisms were analyzed and the theoretical equations to calculate the density and viscosity were deduced.
flexural strength measurements: Topics by
The fluid-solid coupling simulations were completed for the micro-cantilevers with different shapes. The sensing chips with micro-cantilevers were designed based on the simulation results and fabricated using the micro electromechanical systems MEMS technology. Finally, the MEMS resonant sensor was packaged with the sensing chip to measure the densities and viscosities of eight different fluids under the flexural and torsional vibrating modes separately.
The experimental results showed that the effects of the shape and vibrating mode of micro-cantilever on the measurement accuracies of fluid density and viscosity were analyzed in detail. Finite element analysis of the end notched flexure specimen for measuring Mode II fracture toughness. The paper presents a finite element analysis of the end-notched flexure ENF test specimen for Mode II interlaminar fracture testing of composite materials.
Virtual crack closure and compliance techniques employed to calculate strain energy release rates from linear elastic two-dimensional analysis indicate that the ENF specimen is a pure Mode II fracture test within the constraints of small deflection theory.
Furthermore, the ENF fracture specimen is shown to be relatively insensitive to process-induced cracks, offset from the laminate midplane. Frictional effects are investigated by including the contact problem in the finite element model.
A parametric study investigating the influence of delamination length, span, thickness, and material properties assessed the accuracy of beam theory expressions for compliance and strain energy release rate, GII. Finite element results indicate that data reduction schemes based upon beam theory underestimate GII by approximately percent for typical unidirectional graphite fiber composite test specimen geometries. Consequently, an improved data reduction scheme is proposed. Mermin-Wagner theorem, flexural modesand degraded carrier mobility in two-dimensional crystals with broken horizontal mirror symmetry.
We speculate that reasonable long-wavelength cutoffs needed to stabilize the structure finite sample size, grain size, wrinkles, defects or the anharmonic coupling between flexural and in-plane acoustic modes shown to be effective in mirror-symmetric crystals, like free-standing graphene may not be sufficient to raise the electron mobility to satisfactory values.
Fano-like resonance phenomena by flexural shell modes in sound transmission through two-dimensional periodic arrays of thin-walled hollow cylinders. The frequencies of the resonant modes are well described by the analytical theory of flexural circumferential modes of thin-walled hollow cylinders and are confirmed by finite-difference time-domain simulations.