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This paper presents an analytical approach to determine the singular stress fields near sharp corners in anisotropic notched plate subjected to bending. The first-order shear deformation plate theory (FSDPT) is used and the material anisotropy is modeled by the Stroh formalism. Based on the Mellin transform method, the stress singularity orders as well as the stress intensities are determined analytically. The results presented in this paper give us the singular behaviors for various plate angle α, material orientation angles ϕ and the anisotropic parameters e. These new findings are helpful in reducing or even eliminating the singularities near the sharp corner.

This paper aims at the stress singularities in a sectorial plate based on Reissner–Mindlin plate theory. The Mellin transform is applied to solve the governing equations of the plate. Both the bending stress singularities due to concentrated moments at boundaries and transverse shear stress singularities due to concentrated transverse shear forces at boundaries are investigated. The application of inverse Mellin transform gives the exact forms of singular stress fields near the corner, including the stress singularity orders and the generalized stress intensity factors. For various plate angles and loading conditions, the singular stress parameters are computed by finite element models and the results are compared to the analytical solutions. The comparisons reveal that the stresses obtained by the analytical procedure proposed in this paper are correct.

The objective of this study is to develop and analyze a nonlinear suspended energy harvester (NSEH) that can be mounted on a rotating wheel. The device comprises a permanent magnet as a mass in the kinetic system, two springs, and two coil sets. The mass vibrates along the transverse direction because of the variations in gravitational force. This research establishes nonlinear vibration equations based on the resonance frequency variation of the energy harvester, these equations are used for analyzing the power generation and vibration of the harvester. The kinetic behaviors can be determined according to the stiffness in the two directions of the two suspended springs. Electromagnetic damping is examined to estimate the power output and effect of the kinematic behaviors on NSEH. The power output of the NSEH with a 52 Ω resistor connected in series ranged from approximately 30 to 4200 μW at wheel speeds that ranged from nearly 200 to 900 rpm.

In this paper, a compact synthetic jet actuator comprising a primary jet actuator and a synthetic jet chamber was proposed. This synthetic jet actuator can enhance the total airflow rate by combining the primary, and secondary flows synthesized by the synthetic jet. The oscillating diaphragm and valve parts of the synthetic jet actuator were designed as a closed magnetic flux loop to enhance the magnetic flux density in the coils. The primary jet actuator was designed with a separate inlet and outlet to serve as a heat-dissipation application and prevent the re-ingesting of heated air. Thus, a dynamic model of a synthetic jet actuator was constructed, and motion equations were subsequently derived using plate theory, the Lorentz law, and magnetic flux simulation. The behavior in association with the displacement of the oscillating diaphragm, oscillation frequency, and driving current is discussed in this paper. Finally, an experimental rig was constructed to verify the correctness of the airflow simulations. The synthetic jet actuator was integrated with flow channels, and achieved an airflow rate of 9.23 L/min at a 1.5 V driving voltage.

A novel natural frequency self-tuning energy harvester is presented, which utilizes the presence of the nonlinearity model and the well-weighted swing disk to maximize the power output and the frequency bandwidth for a wheel rotating at any speed. Kinetic energy harvesters are frequency selective, meaning that they have high power transmission efficiency only when they are excited at their natural frequency. The well-weighted swing disk with nonlinear effects can render the energy harvester more broadband, that is, it has a more steady power generation at various wheel speeds than the ill-weighted swing disk has. We integrate magnets in a novel circular Halbach array and coils into the design to augment the magnetic strength on one side of the array where the coils are placed. Therefore, the gradient of the average magnetic flux density for the circular Halbach array disk is larger than that of the multipolar magnetic disk. The dynamic models with electromechanical couplings have been established and are analyzed. In the experiments, the power output of the prototype at an optimum external resistance was approximately 300–550 µW at about 200–500 rpm and precisely matches the numerical results.

This study designed a well-weighted pendulum to harvest energy from a rotating wheel, which consisted of a pendulum and one or more weights. In general, a pendulum cannot oscillate with a large angle at any wheel speed. In this study, three well-designed weights helped the pendulum to adjust its natural frequency to meet the wheel rotation frequency. Therefore, the well-weighted pendulum is able to oscillate at various wheel speeds with a large angle and a high velocity. The kinetic energy produced was converted into electrical energy by electromagnetic induction, and a numerical study revealed that the well-weighted pendulum generated a power of several milli-Watts. The numerical results obtained using the analytical model of the well-weighted pendulum were in good agreement with the experimental results. The swing angle of the weighted pendulum was close to 43° at a wheel rotation speed of 350 rpm, 8 times that of the ill-weighted pendulum, verifying that the well-weighted pendulum oscillated at larger angles.

Based on stochastic crack growth model, the effects of material variations on aircraft inspection schedules are investigated in this paper. Fatigue tests are performed to obtain the log standard deviation of fatigue lives due to material variations. The test materials are 7475-T7351, 7050-T7451, 2024-T851 and 2124-T851. The effects of material variation on inspection schedule are significant. For a large material variation, the inspection schedule should be shortened for conservative consideration. The effects of sample size on the material variation under 50% and 95% confidence levels are investigated numerically. The results of this study provide a guideline to allocate resources of fleet planning more realistically by compromising between the cost (or time) of fatigue experiments and aircraft inspections.

This technical note deals with two special topics from our previous paper (Chue and Chen in Arch Appl Mech 72 673–685, 2003) in Archive of Applied Mechanics: the effects of electrical conditions imposed on the edges and bonded interfaces of piezoelectric–dielectric and piezoelectric–conductor wedges on antiplane problems. After employing relatively realistic electrical conditions, we found that stress and electric displacement singularities are altered when boundary conditions and/or continuity conditions are changed, and we compared the results with those of previous studies.

In this paper, the eigen-equations governing antiplane stress singularities in a bonded piezoelectric wedge are derived analytically. Boundary conditions are set as various combinations of traction-free, clamped, electrically open and electrically closed ones. Application of the Mellin transform to the stress/electric displacement function or displacement/electric potential function and particular boundary and continuity conditions yields identical eigen-equations. All of the analytical results are tabulated. It is found that the singularity orders of a bonded bimaterial piezoelectric wedge may be complex, as opposed to those of the antiplane elastic bonded wedge, which are always real. For a single piezoelectric wedge, the eigen-equations are independent of material constants, and the eigenvalues are all real, except in the case of the combination C–D. In this special case, C–D, the real part of the complex eigenvalues is not dependent on material constants, while the imaginary part is.

A prototype of a stylus probe with an interferometric transducer for surface profiling and roughness measurement was recently developed for surface texture, form error, radius, inclination and dimension measurement. A reflective cylindrical holographic diffraction grating fabricated into cylindrical shape, referred to as the `length master', acts as the moving part governing the path length of light. The surface profile information was transformed into electrical signals using a laser diode grating interferometer to measure the rotational motion of the measuring lever. To precisely define the performance capability of the system, error analysis was performed in order to assess the potential measuring error due to imperfections in manufacturing and assembly of the system's mechanical components. The uncertainty relating to the construction of the device, geometrical features, operating environment and optical characteristics is also presented.

This study presents a novel design for a two-axis scanning device driven by lead-zirconate-titanate (PZT) ceramic. The proposed device consists of a scanning mirror and a Y-shaped piezoelectric actuator. The scanning mirror was fabricated using an MEMS process involving three masks. Experimental results show that the fast and slow frequencies at resonance are 25.0 kHz and 0.56 kHz, respectively. The optical scanning angles are 27.6° and 39.9°. The power consumption of the device is 13.4 mW at a driving voltage of 10 V. This study also develops a laser projection module integrated with the scanning device. The module can project a 2-D image at a resolution of 640 x 480.

This study presents the design and analysis of a two-axis scanner driven by lead-zirconate-titanate (PZT) ceramic. The proposed device consists of a silicon-based MEMS scanning mirror and a bulk-type piezoelectric actuator. The MEMS process involves three masks. The experimental results showed that the fast and slow frequencies at resonance are 29.6 kHz and 4.8 kHz, respectively. For the fast scan, the scanning angle is 46.9 degrees at a driving voltage of 10 V. For the slow scan, the scanning angle is 22.6 degrees at a driving voltage of 20 V. A multi-DOF vibration model was developed to analyze the scanning characteristics of the device. The numerical simulations, including the resonance frequency, scanning angle and the mode coupling phenomenon, were validated with the experimental observations. This study also develops a laser projection module integrated with the scanning device. The module can receive a video content with a resolution of 720 p and project a 16:9 image that is 19 inches in diagonal at a projection distance of 600 mm.

This paper presents the development of a wheel-mounted eccentric ring energy harvester that is driven by centripetal and gravitational forces during wheel rotation. The natural frequency of the eccentric ring matches the wheel rotation frequency at any car speed because its character length is designed equal to the wheel radius. Consequently, the eccentric ring oscillates with a relatively large swing angle at the wheel speed to generate high levels of power. The nonlinear dynamic behavior of the eccentric ring is investigated to ensure that the proposed design produces steady swing angles, especially at high wheel speeds. Herein, the jump phenomenon of the dynamic motion of the eccentric ring is analyzed by using the Duffing equation and the linearization process. The discriminant value obtained from the analysis confirms that no jump phenomenon occurs at all wheel speeds if the eccentric ring is properly designed. In the experiment, the eccentric ring is integrated with magnets and a coil set to generate 318?442??W at constant wheel speeds between 300 and 500?rpm. This shows that the proposed device is a potential power source for low-power wheel-mounted electronics, such as pressure sensors, accelerometers, and thermometers.