As storage data density in hard-disk drives (HDDs) increases for constant or miniaturizing sizes, precision positioning
of HDD heads becomes a more relevant issue to ensure enormous amounts of data to be properly written
and read. Since the traditional single-stage voice coil motor (VCM) cannot satisfy the positioning requirement of
high-density tracks per inch (TPI) HDDs, dual-stage servo systems have been proposed to overcome this matter,
by using VCMs to coarsely move the HDD head while piezoelectric actuators provides fine and fast positioning.
Thus, the aim of this work is to apply topology optimization method (TOM) to design novel piezoelectric HDD
heads, by finding optimal placement of base-plate and piezoelectric material to high precision positioning HDD
heads. Topology optimization method is a structural optimization technique that combines the finite element
method (FEM) with optimization algorithms. The laminated finite element employs the MITC (mixed interpolation
of tensorial components) formulation to provide accurate and reliable results. The topology optimization
uses a rational approximation of material properties to vary the material properties between 'void' and 'filled' portions. The design problem consists in generating optimal structures that provide maximal displacements, appropriate structural stiffness and resonance phenomena avoidance. The requirements are achieved by applying formulations to maximize displacements, minimize structural compliance and maximize resonance frequencies. This paper presents the implementation of the algorithms and show results to confirm the feasibility of this approach.
The advances in miniaturization techniques over the last decades has made the widespread of electronic devices greater than ever and the rate of growth increases each day. Research has been carried out all over the world aiming at developing devices capable of capturing ambient energy and converting it into useable energy in this very promissing field of energy harvesting. Piezoelectric laminates have been used in the design of energy harvesting systems. While most of current research considers traditional assemblies with bimorph transducers and proof masses, this work involves the design of novel energy harvesting devices and other laminate piezoelectric structures by applying topology optimization, which combines Finite Element Method with optimization algorithms. The finite element employs a robust formulation capable of representing both direct and converse piezoelectric effects, based on the MITC formulation. The topology optimization uses the PEMAP-P model (Piezoelectric Material with Penalization and Polarization) combined with the RAMP model (Rational Approximation of Material Properties), where the design variables are the pseudo-densities that describe the amount of piezoelectric material at each finite element. A multi-objective function is defined for the optimization problem, which aims at designing eigenvalues and eigenvectors and maximizing the electromechanical coupling of a specific mode. This paper presents the implementation of the finite element and optimization software and shows results achieved.
Sensors and actuators based on piezoelectric plates have shown increasing demand in the field of smart structures,
including the development of actuators for cooling and fluid pumping applications and transducers for novel energy
harvesting devices. This project involves the development of a finite element and topology optimization
software to design piezoelectric sensors, actuators and energy harvesting devices by distributing piezoelectric material
over a metallic plate in order to achieve a desired dynamic behavior with specified vibration frequencies.
The finite element employs a general formulation capable of representing both direct and converse piezoelectric
effects. It is based on the MITC formulation, which is reliable, efficient and avoids the shear locking problem. The
topology optimization formulation is based on the PEMAP-P model (Piezoelectric Material with Penalization
and Polarization), where the design variables are the pseudo-densities that describe the amount of piezoelectric
material at each finite element. The optimization problem has a multi-objective function, which can be subdivided
into three distinct problems: maximization of mean transduction, minimization of mean compliance and
optimization of Eigenvalues. The first one is responsible for maximizing the amount of electric energy converted
into elastic energy, the second one guarantees that the structure does not become excessively flexible and the
third one tunes the structure for a given frequency. This paper presents the implementation of the finite element
and optimization software and shows preliminary results achieved.
The microchips inside modern electronic equipment generate heat and demand, each day, the use of more
advanced cooling techniques as water cooling systems, for instance. These systems combined with piezoelectric
flow pumps present some advantages such as higher thermal capacity, lower noise generation and miniaturization
potential. The present work aims at the development of a water cooling system based on a piezoelectric flow
pump for a head light system based on LEDs. The cooling system development consists in design, manufacturing
and experimental characterization steps. In the design step, computational models of the pump, as well as the
heat exchanger were built to perform sensitivity studies using ANSYS finite element software. This allowed us
to achieve desired flow and heat exchange rates by varying the frequency and amplitude of the applied voltage.
Other activities included the design of the heat exchanger and the dissipation module. The experimental tests of
the cooling system consisted in measuring the temperature difference between the heat exchanger inlet and outlet
to evaluate its thermal cooling capacity for different values of the flow rate. Comparisons between numerical and
experimental results were also made.
Precision flow pumps have been widely studied over the last three decades. They have been applied in the areas of
Biology, Pharmacy and Medicine in applications usually related to the dosage of medicine and chemical reagents.
In addition, thermal management solutions for electronic devices have also been recently developed using these
kinds of pumps offering better performance with low noise and low power consumption. In a previous work, the
working principle of a pump based on the use of a bimorph piezoelectric actuator inserted in a fluid channel to
generate flow was presented. In this work, a novel configuration of this piezoelectric flow pump that consists
of a flow pump using two bimorph piezoelectric actuators in parallel configuration has been studied and it is
presented. This configuration was inspired on fish swimming modes. The complete cycle of pump development
was conducted, consisting in designing, manufacturing, and experimental characterization steps. Load-loss and
flow rate characterization experimental tests were conducted, generating data that allows us to analyze the
influence of geometric parameters in the pump performance. Comparisons among numerical and experimental
results were made to validate the computational results and improve the accuracy of the implemented models.
Precision flow pumps have been widely studied over the last three
decades. They have been applied as essential components in thermal
management solutions for cooling electronic devices offering better
performance with low noise and low power consumption. In this work,
a novel configuration of a miniature piezoelectrically actuated flow
pump with the purpose of cooling a LED set inside a head light
system for medical applications has been studied and it will be
presented. The complete cycle of pump development was conducted. In
the design step, the ANSYS finite element analysis software
has been applied to simulate and study the fluid-structure
interaction inside the pump, as well as the bimorph piezoelectric
actuator behavior. In addition, an optimization process was carried
out through Altair Hyperstudy software to find a set of
parameter values that maximizes the pump performance measured in
terms of flow rate. The prototype manufacturing was guided based on
computational simulations. Flow characterization experimental tests
were conducted, generating data that allows us to analyze the
influence of frequency and amplitude parameters in the pump
performance. Comparisons between numerical and experimental results
were also made.