Static deformation of a multilayered one-dimensional hexagonal quasicrystal plate with piezoelectric effect

Quasicrystals （QCs） are sensitive to the piezoelectric （PE） effect. This paper studies static deformation of a multilayered one-dimensional （1D） hexagonal QC plate with the PE effect. The exact closed-form solutions of the extended displacement and traction for a homogeneous piezoelectric quasicrystal （PQC）plate are derived from an eigensystem. The general solutions for multilayered PQC plates are then obtained using the propagator matrix method when mechanical and electrical loads are applied on the top surface of the plate. Numerical examples for several sandwich plates made up of PQC, PE, and QC materials are provided to show the effect of stacking sequence on phonon, phason, and electric fields under mechanical and electrical loads, which is useful in designing new composites for engineering structures.

Parameter Variations of Identified Model for Static Deformation Analysis of Arch Dam

The structural health monitoring of a dam is important for maintaining the safe operation and longevity of the dam system. The structural health of a large dam can be monitored from the measured static deformation. This paper presents an investigation of the parameter variations of the identified model of the measured long-term static deformation for the structural health monitoring of Fui-Tsui Dam, which is located in a very active seismic zone of Taiwan. The measured static deformation is characterized as a function of the measured physical parameters, including the effects of hydrostatic pressure and temperature variation. The identified parameters, associated with the effects of hydrostatic pressure and temperature variation, change with environmental factors, such as flooding, earthquake and foundation change.

Static-deformation based fault diagnosis for damping spring of large vibrating screen

Based on the statics theory, a novel and feasible twice-suspended-mass method(TSMM) was proposed to deal with the seldom-studied issue of fault diagnosis for damping springs of large vibrating screen(LVS). With the static balance characteristic of the screen body/surface as well as the deformation compatibility relation of springs considered, static model of the screen surface under a certain load was established to calculate compression deformation of each spring. Accuracy of the model was validated by both an experiment based on the suspended mass method and the properties of the 3D deformation space in a numerical simulation. Furthermore, by adopting the Taylor formula and the control variate method, quantitative relationship between the change of damping spring deformation and the change of spring stiffness, defined as the deformation sensitive coefficient(DSC), was derived mathematically, from which principle of the TSMM for spring fault diagnosis is clarified. In the end, an experiment was carried out and results show that the TSMM is applicable for diagnosing the fault of single spring in a LVS.

Nonlinearity analysis of piezoelectric micromachined ultrasonic transducers based on couple stress theory

This paper studies the static deformation behavior of a piezoelectric micromachined ultrasonic transducer （PMUT） actuated by a strong external electric field. The transducer membrane consists of a piezoelectric layer, a passive layer and two electrode layers. The nonlinearities of the piezoelectric layer caused by electrostriction under a strong electric field are analyzed. Because the thickness of the transducer membrane is on the microscale, the size dependence of the deformation behavior is evaluated using the couple stress theory. The results show that the optimal ratio of the top electrode diameter and the membrane diameter is around 0.674. It is also found that this optimal value does not depend on any other parameters if the thicknesses of the two electrodes are negligible compared with those of the piezo- electric and passive layers. In addition, the nonlinearities of the piezoelectric layer will become stronger along with the increase of the electric field, which means that softening of the membrane stiffness occurs when a strong external electric field is applied. Meanwhile, the optimal thickness ratio for the passive layer and the piezoelectric layer is not equal to 1.0 which is usually adopted by previous researchers. Because there exists size dependence of membrane deforma-tion, the optimal value of this thickness ratio needs to be greater than 1.0 on the microscale.

Static recrystallization behavior of 25CrMo4 mirror plate steel during two-pass hot deformation

The static recrystallization behavior of 25CrMo4 mirror plate steel has been determined by hot compression testing on a Gleeble 1500 thermal mechanical simulation tester. Compression tests were performed using double hit schedules at temperatures of 950-- 1 150 ~C, strain rates of 0.01--0.5 s-1 , and recrystallization time of 1--100 s. Results show that the kinetics of static recrystallization and the microstructural evolution were greatly influenced by the deformation parameters （deformation temperature, strain rate and pre strain） and the initial austenite grain size. Based on the experimental results, the kinetics model of static recrystallization has been generated and the comparison between the experimental results and the predicted results has been carried out. It is shown that the predicted results were in good agreement with the experimental results.

Manipulating a micro-cantilever between its optomechanical bistable states in a lever-based Fabry-Pérot cavity

In this paper, we demonstrate experimentally switching a cantilever between its optomechanical bistable states in a low finesse optical cavity. Our experiment shows that the deformation of cantilever can be manipulated by tuning the cavity resonance. When the laser power increases across the threshold value of 110 ?W, optomechanical bistability is induced by strong static photothermal backaction at room temperature. Numerical calculation revealed that the bistable effect originates from the multi-well potential created via the optomechanical interaction. Switching of the cantilever between the bistable states was achieved by tuning the cavity to the corresponding boundaries of the bistable region, where the barrier between the bistable states vanishes.