Suresh Kaluvan

Design of current sensor using a magnetorheological fluid in shear mode

A new approach to measure the direct current (dc) using magnetorheological (MR) fluids with a resonance concept is proposed in this work. The current measurement system is designed using a piezolaminated cantilever beam coupled with an electromagnetic coil-based MR fluid shearing set-up. The cantilever beam is maintained at resonance using simple closed-loop electronics. The current-induced magnetic field produced by the coil changes the viscosity of the MR fluids and produces an additional stiffness to the resonating cantilever beam. The shift in resonant frequency due to the change in viscosity of the MR fluid is measured, and the shift in frequency is related to the input electrical current to the coil. The analytical model of the current measurement system is derived, and the results are compared with the experimental results. The resonance-based current measurement system is evaluated for the input current range of 0 to 1 A.

A new resonant based measurement method for squeeze mode yield stress of magnetorheological fluids

A new approach to measure the field-dependent yield stress of magnetorheological (MR) fluids in squeeze mode using the resonance concept is proposed. The measurement system is designed using the piezolaminated cantilever beam coupled with an electromagnetic coil based MR fluid squeezing setup. The cantilever beam is maintained at resonance using simple closed-loop electronics. The magnetic field produced by the coil changes the viscosity of MR fluids and produces an additional stiffness to the resonating cantilever beam. The shift in resonant frequency due to the change in viscosity of the MR fluid is measured, and the shift in frequency is analytically related to the yield stress. Two types of MR fluids based on sphere and plate iron particles are used to demonstrate the effectiveness of the proposed measurement system.

Bio-inspired device: a novel smart MR spring featuring tendril structure

Smart materials such as piezoelectric patches, shape memory alloy, electro and magneto rheological fluid, magnetostrictive materials, etc are involved by far to design intelligent and high performance smart devices like injectors, dental braces, dampers, actuators and sensors. In this paper, an interesting smart device is proposed by inspiring on the structure of the bio climber plant. The key enabling concept of this proposed work is to design the smart spring damper as a helical shaped tendril structure using magneto-rheological (MR) fluid. The proposed smart spring consists of a hollow helical structure filled with MR fluid. The viscosity of the MR fluid decides the damping force of helical shaped smart spring, while the fluid intensity in the vine decides the strength of the tendril in the climber plant. Thus, the proposed smart spring can provide a new concept design of the damper which can be applicable to various damping system industries with tuneable damping force. The proposed smart spring damper has several advantageous such as cost effective, easy implementation compared with the conventional damper. In addition, the proposed spring damper can be easily designed to adapt different damping force levels without any alteration.

Design, Modeling, and Experiment of a Piezoelectric Pressure Sensor Based on a Thickness-Shear-Mode Crystal Resonator

This paper presents the design, modeling, and experimental demonstration of a novel pressure sensor using an AT-cut quartz crystal resonator with beat frequency analysis-based temperature compensation technique. The combination of a compact design of the proposed pie-zoelectric crystal resonator structure and temperature compensation technique has advantages such as high accuracy, low cost, and good performance attributes. The sensor measures pressure and temperature simultaneously with a single AT-cut quartz resonator, thus avoiding the thermal lag problem in the commercial multiresonator-based pressure sensors. The pressure sensor is designed using computer-aided design software and CAE software (COMSOL Multiphysics). Finite-element analysis (FEA) of the pressure sensor is performed to analyze the stress–strain of the sensors mechanical structure. A 3-D-printing prototype of the sensor was fabricated, and the sensing principle was verified using a force–frequency analysis apparatus. Subsequently, a full-up pressure sensor was fabricated with a stainless steel housing and a built-in crystal oscillator circuit. Based on the FEA and experimental results, we have determined that the maximum pressure the sensor can safely measure is 45 psi. Test results performed on the stainless steel product show a good linear relationship between the input (pressure) and the output (frequency).

A novel magnetorheological actuator for micro-motion control: identification of actuating characteristics

A novel actuator using magnetorheological (MR) fluid sandwiched between two electrode type coils is proposed in this research work. The key enabling concept of the proposed actuator is to enhance the force due to the magnetic field produced by the electrode coil using the magnetorheological fluid. The direction and amount of current input to the top and bottom electrode coils decide the characteristics such as contraction, extension and the force generated by the actuator, respectively. To obtain the required displacement and actuation force, the viscosity of the MR fluid sandwiched between the two electrode coils is precisely varied by the input current. In this work, the MR fluid is operated in one of the most powerful modes, called squeeze mode, and hence the designed magnetorheological actuator is more powerful and precise. The experimental results shown in this paper show that it has a great advantage in micron-level displacement and vibration control applications. The main contribution of this innovative magnetorheological actuator design is that it can also behave like a damper. This technology will lead to a new dimension in the design of self-actuation and damping devices. In addition, the proposed magnetorheological actuator has additional advantages such as cost effectiveness and easy implementation.

A Novel DC Current Sensor Using SMA Controlled Piezoelectric Bimorph Cantilever

A new approach to measure direct current (DC) using shape memory alloy (SMA) tuning piezo cantilever resonant frequency technique is proposed in this work. The proposed current sensor system is designed using an electrically insulated SMA wire surface mounted on the cantilever beam with piezoelectric actuator. The cantilever beam is maintained at resonance using a closed loop piezo resonator circuit and the current ‘I’ to be measured is given to the SMA wire. The current induced temperature change of the SMA wire produces a mechanical shape change and produces a stiffness change to the resonating cantilever beam. The shift in resonant frequency due to the stiffness change is measured, which is related to the input electrical current ‘I’ to the SMA wire. The key enabling concept of this proposed work is to alter the cantilever resonant frequency using the shape changing property of SMA wire with input unknown electric current. The analytical model of the current sensor system is derived and the results are compared with the experimental results. The SMA coupled with piezo actuator based resonant current sensing system is evaluated for the input current range of 0 to 0.5A. The proposed current sensing concept is simple and completely novel and it is found that it has very high sensitivity to current and result is piecewise linear.Copyright

A new measurement method for operation mode dependent dynamic behavior of magnetorheological fluid

This paper presents a new measurement method to investigate the operational mode dependent dynamic behavior of magnetorheological fluid. The proposed measurement system is designed using an electromagnetically actuating cylindrical rod coupled with the magnetorheological fluid squeezing setup. The cylindrical rod is clamped to base at one end and the other end is free to move in the z- and y-axis. A disc-type permanent magnet is attached to the free end of the cantilever rod and an electromagnetic actuator is placed nearer to the permanent magnet. The magnetorheological fluid squeezing setup is mounted nearer to the fixed end. The magnetorheological squeezing setup is designed using two electromagnetic coils placed face to face in z-axis with the gap of “d”. The magnetorheological fluid is placed between the gap “d” to form the squeezing effect. The direction of vibration of the cantilever rod to bottom surface is determined by the angular position of electromagnetic actuator. The actuator position is fixed to the desired angle with the help of stepper motor setup. The horizontal direction of vibration of cantilever rod produces the shear mode operation of the magnetorheological fluid in the magnetorheological fluid squeezing setup. Similarly, the vertical and intermediate direction of vibration of rod produces the squeeze and coupled mode operation of the magnetorheological fluid, respectively. The analytical and experiment analyses to determine the dynamic damping behavior of the magnetorheological particles for various directions of actuation angle is undertaken using the proposed measurement system. The analytical model of the proposed measurement system is firstly derived and the experimental setup is then developed in real-time laboratory environment. The analytical and experimental results show that the dynamic damping behavior of squeeze mode operation of the magnetorheological fluid is superior to the shear and coupled mode operation of the magnetorheological fluid. The effectiveness and novelty of the proposed measurement system is demonstrated by presenting dynamic force variation and vibration amplitude reduction at different modes like squeeze, shear, and intermediate mode operation of the magnetorheological fluid.

Measurement of mechanical properties of metallic glass at elevated temperature using sonic resonance method

Bulk metallic glasses are fully amorphous multi-component alloys with homogeneous and isotropic structure down to the atomic scale. Some attractive attributes of bulk metallic glasses include high strength and hardness as well as excellent corrosion and wear resistance. However, there are few reports and limited understanding of their mechanical properties at elevated temperatures. We used a nondestructive sonic resonance method to measure the Young’s modulus and Shear modulus of a bulk metallic glass, Zr41.2Ti13.8Cu12.5Ni10Be22.5, at elevated temperatures. The measurement system was designed using a laser displacement sensor to detect the sonic vibration produced by a speaker on the specimen in high-temperature furnace. The OMICRON Bode-100 Vector Network Analyzer was used to sweep the frequency and its output was connected to the speaker which vibrated the material in its flexural mode and torsional modes. A Polytec OFV-505 laser vibrometer sensor was used to capture the vibration of the material at various frequencies. The flexural and torsional mode frequency shift due to the temperature variation was used to determine the Young’s modulus and Shear modulus. The temperature range of measurement was from 50°C to 350°C. The Young’s modulus was found to reduce from 100GPa to 94GPa for the 300°C temperature span. Similarly, the Shear modulus decreased from 38.5GPa at 50°C to 36GPa at 350°C.

Design of an oscillator circuit for Langasite (LGS) based resonant pressure — Temperature sensor

A closed loop frequency tracking electronics circuit has been proposed for the measurement of pressure and temperature using a newly developed Langasite (LGS) piezo crystals. The ambient force and heat applied on the LGS crystal produces the shift in its resonant frequency. The proposed closed loop electronics tracks the shift in resonant frequency and measures the pressure and temperature by relating to the difference in frequency shift. The steady state oscillation condition of the resonator circuit is analytically derived and experimentally verified. The experimental setup consists of an operational amplifier based resonator circuit connected to the langasite piezo crystal placed between a double side diametric forces loading device with temperature controller bath. The diametric force applied on the LGS crystal produces the frequency shift in its fundamental mechanical vibration mode (C-mode). Similarly, the change in temperature produces the frequency shift in its second mechanical vibrational mode (B-mode). The frequency shifts are measured using two separate closed loop resonator electronics for two different measurand. Whenever the force on the LGS crystal is changed by the external unknown pressure, an additional intrinsic material property change is added to the piezo and changes the fundamental oscillating resonant frequency. The closed loop resonant circuit tracks the change in resonance frequency and vibrates the LGS with the new resonance frequency depends on the external pressure strength. Similar procedure is followed for temperature induce frequency tracking measurement also. The proposed frequency tracking electronics concept is simple and it is found that it has high sensitivity and linearity.

Design of an electronic oscillator for resonant pressure sensor with non-collocated sensor and actuator

This paper presents a simple closed loop circuit (oscillator) design for producing sustained, oscillations required to continuously vibrate the resonance based pressure sensor at its resonant frequency. For each variation in applied input pressure, the sensor’s resonant frequency varies and the circuit makes the sensor to vibrate at its new resonant frequency, thereby enabling the measurement of change in resonant frequency shift due to corresponding pressure. The resonant condition is achieved by automatic tuning of phase angle required to satisfy Barkhausen criteria. The proposed circuit is evaluated analytically and verified experimentally for different pressure sensors fabricated using various grades of Stainless Steel material.