Modeling of a Dynamic Mirror Actuator

2010 ◽  
Author(s):  
James A. Mynderse ◽  
George T. C. Chiu
Keyword(s):  
Experimental Data ◽  
Laser Beam ◽  
Linear Model ◽  
Natural Frequency ◽  
Beam Steering ◽  
Constitutive Models ◽  
Higher Order ◽  
Piezoelectric Stacks

A novel dual-actuated dynamic mirror actuator (DMA) is presented for laser beam steering. The DMA is driven by a pair of piezoelectric stack actuaors (PESAs). The piezoelectric stacks are modeled using a linear model and five variations of constitutive models from literature. The resulting DMA models are simulated. While the constitutive models capture some higher order dynamics, the linear model provides the best combination of accuracy to experimental data and simplicty of model between DC and the first natural frequency of the DMA. For control of the DMA up to the first natural frequency of the DMA, a linear model should be adequate.

Improved Modeling of a Dynamic Mirror With Antagonistic Piezoelectric Stack Actuation

2011 ◽  
Author(s):  
James A. Mynderse ◽  
Ann M. Whitney ◽  
George T. C. Chiu
Keyword(s):  
Experimental Data ◽  
Laser Beam ◽  
Natural Frequency ◽  
Natural Frequencies ◽  
Beam Steering ◽  
Proposed Model ◽  
Mechanical Compliance ◽  
Charging Dynamics ◽  
Good Agreement ◽  
Shunt Circuit

An enhanced model of a dynamic mirror actuator (DMA) for laser beam steering is presented. The DMA is driven by an antagonistic pair of piezoelectric stack actuators (PESA). The proposed model of the DMA employs explicit PESA charging dynamics and an adjustable PESA shunt circuit to address the frequency-dependent effective mechanical compliance term in several previous models from literature. The proposed DMA model with shunt circuit accurately predicts the first damped natural frequency of the DMA with a shunt circuit across each PESA. Simulation and experimental data are presented. Good agreement is shown between the predicted and measured damped first natural frequencies.

scholarly journals Influence of the Porosity of Polymer Foams on the Performances of Capacitive Flexible Pressure Sensors

Sensors ◽  
2019 ◽  
Vol 19 (9) ◽  
pp. 1968 ◽  
Author(s):  
Sylvie Bilent ◽  
Thi Hong Nhung Dinh ◽  
Emile Martincic ◽  
Pierre-Yves Joubert
Keyword(s):  
Experimental Data ◽  
Linear Model ◽  
Dielectric Material ◽  
Pressure Sensors ◽  
Volume Ratio ◽  
Measurement Range ◽  
Polymer Foams ◽  
First Order ◽  
Non Linear ◽  
Flexible Pressure Sensors

This paper reports on the study of microporous polydimethylsiloxane (PDMS) foams as a highly deformable dielectric material used in the composition of flexible capacitive pressure sensors dedicated to wearable use. A fabrication process allowing the porosity of the foams to be adjusted was proposed and the fabricated foams were characterized. Then, elementary capacitive pressure sensors (15 × 15 mm2 square shaped electrodes) were elaborated with fabricated foams (5 mm or 10 mm thick) and were electromechanically characterized. Since the sensor responses under load are strongly non-linear, a behavioral non-linear model (first order exponential) was proposed, adjusted to the experimental data, and used to objectively estimate the sensor performances in terms of sensitivity and measurement range. The main conclusions of this study are that the porosity of the PDMS foams can be adjusted through the sugar:PDMS volume ratio and the size of sugar crystals used to fabricate the foams. Additionally, the porosity of the foams significantly modified the sensor performances. Indeed, compared to bulk PDMS sensors of the same size, the sensitivity of porous PDMS sensors could be multiplied by a factor up to 100 (the sensitivity is 0.14 %.kPa−1 for a bulk PDMS sensor and up to 13.7 %.kPa−1 for a porous PDMS sensor of the same dimensions), while the measurement range was reduced from a factor of 2 to 3 (from 594 kPa for a bulk PDMS sensor down to between 255 and 177 kPa for a PDMS foam sensor of the same dimensions, according to the porosity). This study opens the way to the design and fabrication of wearable flexible pressure sensors with adjustable performances through the control of the porosity of the fabricated PDMS foams.

Control of a Flexible Continuum Manipulator for Laser Beam Steering

2021 ◽  
Vol 6 (2) ◽  
pp. 1074-1081
Author(s):  
Hangjie Mo ◽  
Ruofeng Wei ◽  
Bo Ouyang ◽  
Liuxi Xing ◽  
Yanhu Shan ◽  
...  
Keyword(s):  
Laser Beam ◽  
Beam Steering ◽  
Continuum Manipulator

scholarly journals Ability of Constitutive Models to Characterize the Temperature Dependence of Rubber Hyperelasticity and to Predict the Stress-Strain Behavior of Filled Rubber under Different Defor Mation States

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 369
Author(s):  
Xintao Fu ◽  
Zepeng Wang ◽  
Lianxiang Ma
Keyword(s):  
Experimental Data ◽  
Temperature Dependence ◽  
Mechanical Response ◽  
Constitutive Models ◽  
Uniaxial Tensile ◽  
Uniaxial Tensile Test ◽  
Chain Model ◽  
Stress Strain ◽  
Filled Rubber ◽  
Yeoh Model

In this paper, some representative hyperelastic constitutive models of rubber materials were reviewed from the perspectives of molecular chain network statistical mechanics and continuum mechanics. Based on the advantages of existing models, an improved constitutive model was developed, and the stress–strain relationship was derived. Uniaxial tensile tests were performed on two types of filled tire compounds at different temperatures. The physical phenomena related to rubber deformation were analyzed, and the temperature dependence of the mechanical behavior of filled rubber in a larger deformation range (150% strain) was revealed from multiple angles. Based on the experimental data, the ability of several models to describe the stress–strain mechanical response of carbon black filled compound was studied, and the application limitations of some constitutive models were revealed. Combined with the experimental data, the ability of Yeoh model, Ogden model (n = 3), and improved eight-chain model to characterize the temperature dependence was studied, and the laws of temperature dependence of their parameters were revealed. By fitting the uniaxial tensile test data and comparing it with the Yeoh model, the improved eight-chain model was proved to have a better ability to predict the hyperelastic behavior of rubber materials under different deformation states. Finally, the improved eight-chain model was successfully applied to finite element analysis (FEA) and compared with the experimental data. It was found that the improved eight-chain model can accurately describe the stress–strain characteristics of filled rubber.

Laser Beam Steering Along Three-Dimensional Paths

2018 ◽  
Vol 23 (3) ◽  
pp. 1148-1158 ◽  
Author(s):  
Brahim Tamadazte ◽  
Rupert Renevier ◽  
Jean-Antoine Seon ◽  
Andrey V. Kudryavtsev ◽  
Nicolas Andreff
Keyword(s):  
Laser Beam ◽  
Beam Steering ◽  
Three Dimensional

A Dynamic Test of Fully Prestressed Concrete Beams

2011 ◽  
Vol 368-373 ◽  
pp. 2483-2490
Author(s):  
Yao Ting Zhang ◽  
Yi Zheng ◽  
Hong Jian Li
Keyword(s):  
Experimental Data ◽  
Elastic Modulus ◽  
Theoretical Analysis ◽  
Natural Frequency ◽  
Axial Force ◽  
Prestressed Concrete ◽  
Concrete Beams ◽  
Dynamic Test ◽  
Modified Formula

A dynamic test of two unbonded fully prestressed concrete beams has been conducted. The results indicate that the natural frequency of beams increases with the prestress force, which is opposite to the analytical arguments for homogeneous and isotropic beams subject to axial force. This paper explains the change in frequencies by discussing the change in the elastic modulus. A modified formula is also proposed, and the experimental data agree well with the theoretical analysis.

Optical GNSS Receiver for the ESA's NGGM-MAGIC Mission and for LEO Satellites with the Highest Orbit Accuracy

2021 ◽  
Author(s):  
Drazen Svehla
Keyword(s):  
Laser Beam ◽  
Gravity Field ◽  
Carrier Phase ◽  
Beam Steering ◽  
Precise Orbit Determination ◽  
Optical Carrier ◽  
Gnss Receiver ◽  
Cw Laser ◽  
Leo Satellites ◽  
Leo Satellite

<p>Precise orbit determination (POD) of LEO satellites is done with a geodetic grade GPS receiver measuring carrier-phase between a LEO and GPS satellites, and in some cases this is supported with a DORIS instrument measuring Doppler between LEO and ground DORIS stations. Over the last 20 years we have demonstrated 1-2 cm accurate LEO POD and about 1 mm for inter-satellite distance. In order to increase the accuracy of the single satellite POD or satellites in LEO formation we propose an “optical GNSS receiver”, a cw-laser on a LEO satellite to measure Doppler between a LEO and GNSS satellite(s) equipped with SLR arrays and to develop it for the next gravity field mission.      </p><p>The objective of the ESA mission NGGM-MAGIC (Next Generation Gravity Mission - Mass-change and Geosciences International Constellation) is the long-term monitoring of the temporal variations of Earth’s gravity field at high resolution in time (3 days) and space (100 km), complementing the GRACE-FO mission from NASA at 45° orbit inclination. Currently, the GRACE-type mission design is based on optical carrier-phase measurements between two LEO satellites flying in a formation and separated by 200 km.</p><p>We propose an extension of the GRACE-type LEO-LEO concept by the “optical GNSS receiver” to provide Doppler measurements between a LEO satellite and GNSS satellite(s) equipped with SLR corner cubes by means of a cw-laser onboard a LEO satellite. Such a “vertical” LEO-GNSS observable is missing in the classical GRACE-type LEO-LEO concept. If Doppler measurements are carried out from the two GRACE-type satellites in the LEO orbit to the same GNSS satellite and by forming single-differences to that GNSS satellite one can remove any GNSS-orbit related error in the measured LEO-GNSS Doppler. In this way, radial orbit difference can be obtained between the two GRACE-type satellites (free of all GNSS orbit errors) and complement “horizontal” LEO-LEO measurements between the two GRACE-type satellites in the LEO orbit.</p><p>The non-mechanical laser beam steering has been developed for an angle window of -40° to +40° and it does not require a rotating and a big telescope in LEO (no clouds and atmosphere turbulences in LEO). Therefore, in such a beam-steering window, one could always observe with a fiber cw-laser one GNSS satellite close to the zenith from both GRACE-type satellites. The non-mechanical beam steering concept in zenith direction can be supported by a small 10-cm like (fixed) Ritchey-Chrétien telescope (COTS), a Cassegrain reflector design widely used for LEO satellites, e.g., for James Webb Space Telescope or for an optical Earth imaging with Cubesats with the 50 cm resolution.</p><p>Considering that several GNSS satellites in the field of view could be observed from a LEO satellite with this approach (including LAGEOS-1/2 and Etalon satellites) and the non-mechanical laser beam steering could be extended towards the LEO horizon, an “optical” GNSS receiver is a new concept for POD of LEO satellites. Here, we provide simulations of this new concept for LEO POD with GNSS/SLR constellations equipped with SLR arrays and discuss all new applications this new concept could bring.</p>

Experimental and Numerical Investigations on Hot Deformation Behavior and Processing Maps for ASS 304 and ASS 316

2018 ◽  
Vol 37 (9-10) ◽  
pp. 873-888 ◽  
Author(s):  
Nitin Kotkunde ◽  
Hansoge Nitin Krishnamurthy ◽  
Swadesh Kumar Singh ◽  
Gangadhar Jella
Keyword(s):  
Experimental Data ◽  
Strain Rate ◽  
Hot Deformation ◽  
Deformation Behavior ◽  
Constitutive Models ◽  
Tensile Tests ◽  
Uniaxial Tensile ◽  
Processing Maps ◽  
Hot Deformation Behavior ◽  
Statistical Measures

AbstractA thorough understanding of hot deformation behavior plays a vital role in determining process parameters of hot working processes. Firstly, uniaxial tensile tests have been performed in the temperature ranges of 150 °C–600 °C and strain rate ranges of 0.0001–0.01s−1 for analyzing the deformation behavior of ASS 304 and ASS 316. The phenomenological-based constitutive models namely modified Fields–Backofen (m-FB) and Khan–Huang–Liang (KHL) have been developed. The prediction capability of these models has been verified with experimental data using various statistical measures. Analysis of statistical measures revealed KHL model has good agreement with experimental flow stress data. Through the flow stresses behavior, the processing maps are established and analyzed according to the dynamic materials model (DMM). In the processing map, the variation of the efficiency of the power dissipation is plotted as a function of temperature and strain rate. The processing maps results have been validated with experimental data.

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