• Journal of the Korean Society for Nondestructive Testing
• /
• v.19 no.3
• /
• pp.207-216
• /
• 1999

A phased array is a multi-element piezoelectric device whose elements are individually excited by electric pulses at programmed delay time. One of the advantages of using phased array in nondestructive evaluation (NDE) application over conventional ultrasonic transducers is their great maneuverability of ultrasonic beam. There are some parameters such as the number and the size of the piezoelectric elements and the inter-element spacing of the elements to design phased array transducer. In this study, the characteristic of ultrasonic beam for phased array transducer due to the variation of the number of elements has been simulated for ultrasonic SH-wave on the basis of Huygen's principle. Ultrasonic beam directivity and focusing due to the change of time delay of each element were discussed due to the change of the number of piezoelectric elements. It was found that ultrasonic beam was much more spreaded and hence its sound pressure was decreased as steering angle of ultrasonic beam was increased. In addition, the ability of ultrasonic bean focusing decreased gradually with the increase of focal length at the same piezoelectric elements. However, the ability of beam focusing was improved as the number of consisting elements was increased.

• Journal of the Korean Ceramic Society
• /
• v.32 no.8
• /
• pp.945-949
• /
• 1995

In order to investigate the performance of compression-type accelerometer on piezoelectric properties, PZT materials have been studied. The ring-shaped piezoelectric elements were prepared using commercial PZT powders by conventional ceramic process. Their estimated relative dielectric constant, piezoelectric charge constant (d33) and voltage constant (g33) values showed 390∼3400, (90∼593)×10-12 C/N and (19.5∼40.5)×10-3 V-m/N, respectively. The charge sensitivity of accelerometer is proportional to the piezoelectric charge constant value (d33) of PZT, but its voltage sensitivity is related with the piezoelectric voltage constant (g33). Since the mounted resonance frequency and sensitivity are dependent on the seismic mass as well as physical charateristics and size of PZT elements, the suitable considerations between two components are required for accelerometer's design.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2003.06a
• /
• pp.742-745
• /
• 2003

Piezoelectric elements driven ultra-precision stages have been used for high accuracy, fast response and high load rapacity. which are allowable to apply the stages to AFMs. Most of the piezoelectric driven stages are guided by flexure hinges for force transmission and mechanical amplification. However the flexure hinge mechanisms cause lack of position accuracy due to coupled and parasitic motions. Hence it is important that the mechanism design of the stage is focused on the stiffness of the flexure hinges to accomplish fast response and hish accuracy without the coupled and parasitic motions. In this study, some constraints for optimal design of a piezoelectric elements driven stage and a design method are proposed. Next, an optimal design is carried out using mathematical calculation. Finally the designed results are verified by FEM.

• Journal of the Korean Society for Precision Engineering
• /
• v.12 no.12
• /
• pp.45-52
• /
• 1995

A prototype of a linear piezoelectric actuator is developed and its dynamic behaviors are investigated. The actuator consists of a driving tip with two stacked piezoelectric elements and a slider. Dynamic characteristics of slider over various vibration lici of the driving tip and changes of normal force acting on the vibratory tip are examined through experiments. The moving direction of slider can be controlled by changing a phase angle between input signals applied to piezoelectric elements. A change of phase difference between input signals also have a great influence on the vibration locus of driving tip. Changes of slider motion due to different vibration loci are examined by experiments.

• Journal of the Korean Society for Precision Engineering
• /
• v.27 no.1
• /
• pp.49-57
• /
• 2010

This paper describes the design, construction, and fundamental testing of a precision rotational device that utilizes piezoelectric elements as a source of driving force and impact drive mechanism as a driving principle. A novel device structure is designed and the numerical simulations about the static displacement, stress distribution, and mode shape of the designed structure are performed. A fabricated rotational device has been rotated successfully by applying saw-shaped voltages to the piezoelectric elements. The one-step rotational angle was $0.44{\times}10^{-3}$ rad at the applied voltages of 80V. The angular velocities of the device were revealed to be increased as the driving frequency and voltage were respectively increased and the preload was decreased. The device has a feature that it can be translated as well as rotated. An experimental result shows that the device was translated by ${\pm}4.56{\mu}m$ maximum when the 120V sinusoidal voltages with a phase difference of $180^{\circ}$ were respectively supplied to two piezoelectric elements.

• Smart Structures and Systems
• /
• v.20 no.6
• /
• pp.729-737
• /
• 2017

Piezoelectric composite laminates are a powerful material system that offers vast options to improve structural behavior. Successful design of piezoelectric adaptive structures and testing of control laws call for highly accurate, reliable and numerically efficient numerical tools. This paper puts focus onto linear and geometrically nonlinear static and dynamic analysis of smart structures made of such a material system. For this purpose, highly efficient linear 3-node and 4-node finite shell elements are proposed. Both elements employ the Mindlin-Reissner kinematics. The shear locking effect is treated by the discrete shear gap (DSG) technique with the 3-node element and by the assumed natural strain (ANS) approach with the 4-node element. Geometrically nonlinear effects are considered using the co-rotational approach. Static and dynamic examples involving actuator and sensor function of piezoelectric layers are considered.

• Korean Journal of Materials Research
• /
• v.25 no.10
• /
• pp.523-530
• /
• 2015

Electricity generation through fossil fuels has caused environmental pollution. To solve this problem, research on new renewable energy (solar, wind, geothermal heat, etc.) to replace fossil fuels is in progress. These devices are able to consistently generate power. However, they have many drawbacks, such as high installation costs and limitations in possible set-up environments. Thus, piezoelectric harvesting technology, which is able to overcome the limitations of existing energy technologies, is actively being studied. Piezoelectric harvesting technology uses the piezoelectric effect which occurs in crystals that generate voltage when stress is applied. Therefore, it has advantages such as a wider installation base and lower technological cost. In this study, a piezoelectric energy harvesting device based on constant wave motion was investigated. This device can regenerate electricity in a constant turbulent flow in the middle of the sea. The components of the device are circuitry, a steel bar, an bimorph piezoelectric element and buoyancy elements. In addition, a multiphysical analysis coupled with the structure and piezoelectric elements was conducted to estimate the performance of the device. With this piezoelectric energy harvesting device, the displacement and electric power were analyzed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.19 no.10
• /
• pp.87-97
• /
• 2020

In general, tires require various sensors and power supply devices, such as batteries, to obtain information such as pressure, temperature, acceleration, and the friction coefficient between the tire and the road in real time. However, these sensors have a size limitation because they are mounted on a tire, and their batteries have limited usability due to short replacement cycles, leading to additional replacement costs. Therefore, vibration energy harvesting technology, which converts the dynamic strain energy generated from the tire into electrical energy and then stores the energy in a power supply, is advantageous. In this study, the output voltage and power generated from piezoelectric elements are predicted through finite element analysis under static state and transient state conditions, taking into account the dynamic characteristics of tires. First, the tire and piezoelectric elements are created as a finite element model and then the natural frequency and mode shapes are identified through modal analysis. Next, in the static state, with the piezoelectric element attached to the inside of the tire, the voltage distribution at the contact surface between the tire and the road is examined. Lastly, in the transient state, with the tire rotating at the speeds of 30 km/h and 50 km/h, the output voltage and power characteristics of the piezoelectric elements attached to four locations inside the tire are evaluated.

• The Journal of the Acoustical Society of Korea
• /
• v.27 no.5
• /
• pp.215-220
• /
• 2008

The kerfs between arrayed piezoelectric elements in a medical ultrasonic transducer or a piezoelectric composite transducer are generally filled by polymeric materials. The boundary condition of the elements for lateral mode vibration is changed according to the kerf-filling materials, so that the resonance frequency for longitudinal mode of the transducer is also varied. In this study, to investigate the resonance frequency variation for an arrayed transducer experimentally, the piezoelectric vibration elements of $14mm{\times}0.22mm{\times}0.44mm$ were fabricated and those were linearly arrayed. And, the resonance frequencies were measured for three cases of kerf-filling condition, non-filling and two different kinds of epoxy filling. Conclusively, it is confirmed that the resonant frequency variation shows the similar tendency with the theoretical one for the longitudinal mode.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.9 no.1
• /
• pp.69-76
• /
• 1989

Piezoelectric elements, backing and shoe material are the important components of the ultrasonic transducer. In this study, characteristic constants in the domestic and the foreign PZT ceramic elements are investigated, The acoustic properties of the domestic and the foreign backing and shoes are characterized. The effects of components characteristics, the kinds of the piezoelectric elements and the thickness of the wear plates are investigated for the manufactured normal beam ultrasonic transducers.