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15 pages, 3118 KiB

Open AccessArticle

Non-Invasive Estimation of Machining Parameters during End-Milling Operations Based on Acoustic Emission

by Andrés Sio-Sever, Erardo Leal-Muñoz, Juan Manuel Lopez-Navarro, Ricardo Alzugaray-Franz, Antonio Vizan-Idoipe and Guillermo de Arcas-Castro

Sensors 2020, 20(18), 5326; https://doi.org/10.3390/s20185326 - 17 Sep 2020

Cited by 6 | Viewed by 2950

Abstract

This work presents a non-invasive and low-cost alternative to traditional methods for measuring the performance of machining processes directly on existing machine tools. A prototype measuring system has been developed based on non-contact microphones, a custom designed signal conditioning board and signal processing [...] Read more.

This work presents a non-invasive and low-cost alternative to traditional methods for measuring the performance of machining processes directly on existing machine tools. A prototype measuring system has been developed based on non-contact microphones, a custom designed signal conditioning board and signal processing techniques that take advantage of the underlying physics of the machining process. Experiments have been conducted to estimate the depth of cut during end-milling process by means of the measurement of the acoustic emission energy generated during operation. Moreover, the predicted values have been compared with well established methods based on cutting forces measured by dynamometers. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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18 pages, 7131 KiB

Open AccessArticle

Coaxial Thermocouples for Heat Transfer Measurements in Long-Duration High Enthalpy Flows

by Shizhong Zhang, Qiu Wang, Jinping Li, Xiaoyuan Zhang and Hong Chen

Sensors 2020, 20(18), 5254; https://doi.org/10.3390/s20185254 - 14 Sep 2020

Cited by 7 | Viewed by 4508

Abstract

Coaxial thermocouples have the advantages of fast response and good durability. They are widely used for heat transfer measurements in transient facilities, and researchers have also considered their use for long-duration heat transfer measurements. However, the model thickness, transverse heat transfer, and changes [...] Read more.

Coaxial thermocouples have the advantages of fast response and good durability. They are widely used for heat transfer measurements in transient facilities, and researchers have also considered their use for long-duration heat transfer measurements. However, the model thickness, transverse heat transfer, and changes in the physical parameters of the materials with increasing temperature influence the accuracy of heat transfer measurements. A numerical analysis of coaxial thermocouples is conducted to determine the above influences on the measurement deviation. The minimum deviation is obtained if the thermal effusivity of chromel that changes with the surface temperature is used to derive the heat flux from the surface temperature. The deviation of the heat flux is less than 5.5% when the Fourier number is smaller than 0.255 and 10% when the Fourier number is smaller than 0.520. The results provide guidance for the design of test models and coaxial thermocouples in long-duration heat transfer measurements. The numerical calculation results are verified by a laser radiation heating experiment, and heat transfer measurements using coaxial thermocouples in an arc tunnel with a test time of several seconds are performed. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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14 pages, 16773 KiB

Open AccessArticle

Development and Characterization of a Compact Device for Measuring the Braking Torque of a Vehicle

by Ester Olmeda, María Garrosa, Susana Sanz Sánchez and Vicente Díaz

Sensors 2020, 20(15), 4278; https://doi.org/10.3390/s20154278 - 31 Jul 2020

Cited by 3 | Viewed by 4633

Abstract

In this article, a new force transducer is designed, developed and built for the measurement of braking forces in the wheel rim of a motor vehicle. The parameters of the transducer design are justified using numerical simulation. In order to install it in [...] Read more.

In this article, a new force transducer is designed, developed and built for the measurement of braking forces in the wheel rim of a motor vehicle. The parameters of the transducer design are justified using numerical simulation. In order to install it in the vehicle in a simple and interference-free way, the metal base of the caliper rod is used. It is manufactured and installed in a vehicle in order to obtain the signals of the wheel braking torque, in real time, and at different speeds of circulation, carrying out several tests on the track. Subsequently, data are obtained from calculations of the disc brake system itself. The latter provides instantaneous adherence values between the brake pad and the disc. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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20 pages, 7489 KiB

Open AccessArticle

On the Role of Contact and System Stiffness in the Measurement of Principal Variables in Fretting Wear Testing

by Diego Infante-García, Miguel Marco, Alaitz Zabala, Farshad Abbasi, Eugenio Giner and Iñigo Llavori

Sensors 2020, 20(15), 4152; https://doi.org/10.3390/s20154152 - 26 Jul 2020

Cited by 9 | Viewed by 3399

Abstract

In this work, the role of the contact stiffness in the measurement of principal variables in fretting wear tests is assessed. Several fretting wear tribometers found in the literature, including one developed by the authors, are analysed and modelled using numerical methods. The [...] Read more.

In this work, the role of the contact stiffness in the measurement of principal variables in fretting wear tests is assessed. Several fretting wear tribometers found in the literature, including one developed by the authors, are analysed and modelled using numerical methods. The results show the importance of the tribosystem stiffness and tangential contact stiffness in the displacement sensor calibration and in the correct numerical modelling of fretting wear tests, especially for flat-to-flat contact configuration. The study highlights that, in most cases, direct comparisons between fretting results with severe wear obtained with different tribometers cannot be performed if the contact stiffness is not properly considered during the development of the experiments. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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18 pages, 7752 KiB

Open AccessArticle

An Experimental and Numerical Investigation to Characterize an Aerospace Composite Material with Open-Hole Using Non-Destructive Techniques

by Norberto Feito, José Vicente Calvo, Ricardo Belda and Eugenio Giner

Sensors 2020, 20(15), 4148; https://doi.org/10.3390/s20154148 - 26 Jul 2020

Cited by 12 | Viewed by 3166

Abstract

In this study, the open-hole quasi-static tensile and fatigue loading behavior of a multidirectional CFRP thick laminate, representative of laminates used in the aerospace industry, is studied. Non-destructive techniques such as infrared thermographic (IRT) and digital image correlation (DIC) are used to analyze [...] Read more.

In this study, the open-hole quasi-static tensile and fatigue loading behavior of a multidirectional CFRP thick laminate, representative of laminates used in the aerospace industry, is studied. Non-destructive techniques such as infrared thermographic (IRT) and digital image correlation (DIC) are used to analyze the behavior of this material. We aim at characterizing the influence of the manufacturing defects and the stress concentrator through the temperature variation and strain distribution during fatigue and quasi-static tests. On the one hand, the fatigue specimens were tested in two main perpendicular directions of the laminate. The results revealed that manufacturing defects such as fiber waviness can have a major impact than open-hole stress concentrator on raising the material temperature and causing fracture. In addition, the number of plies with fibers oriented in the load direction can drastically reduce the temperature increment in the laminate. On the other hand, the quasi-static tensile tests showed that the strain distribution around the hole is able to predict the crack initiation and progression in the external plies. Finally, the experimental quasi-static tests were numerically simulated using the finite element method showing good agreement between the numerical and experimental results. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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21 pages, 3345 KiB

Open AccessArticle

Some Practical Considerations for Compression Failure Characterization of Open-Cell Polyurethane Foams Using Digital Image Correlation

by Ricardo Belda, Raquel Megías, Norberto Feito, Ana Vercher-Martínez and Eugenio Giner

Sensors 2020, 20(15), 4141; https://doi.org/10.3390/s20154141 - 25 Jul 2020

Cited by 12 | Viewed by 3103

Abstract

(1) Background: Open-cell polyurethane foam mechanical behavior is highly influenced by microstructure. The determination of the failure mechanisms and the characterization of the deformation modes involved at the micro scale is relevant for accurate failure modeling. (2) Methods: We use digital image correlation [...] Read more.

(1) Background: Open-cell polyurethane foam mechanical behavior is highly influenced by microstructure. The determination of the failure mechanisms and the characterization of the deformation modes involved at the micro scale is relevant for accurate failure modeling. (2) Methods: We use digital image correlation (DIC) to investigate strain fields of open-cell polyurethane foams of three different densities submitted to compression testing. We analyze the effect of some DIC parameters on the failure pattern definition and the equivalent strain magnification at the apparent ultimate point. Moreover, we explore speckle versus non-speckle approaches and discuss the importance of determining the pattern quality to perform the displacement correlation. (3) Results: DIC accurately characterizes the failure patterns. A variation in the subset size has a relevant effect on the strain magnification values. Step size effect magnitude depends on the subset size. The pattern matching criterion presented little influence (3.5%) on the strain magnification. (4) Conclusion: The current work provides a comprehensive analysis of the influence of some DIC parameters on compression failure characterization of foamed structures. It highlights that changes of subset and step sizes have a significant effect on the failure pattern definition and the strain magnification values, while the pattern matching criterion and the use of speckle have a minor influence on the results. Moreover, this work stands out that the determination of the pattern quality has a major importance for texture analysis. The in-depth, detailed study carried out with samples of three different apparent densities is a useful guide for DIC users as regards texture correlation and foamed structures. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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14 pages, 2735 KiB

Open AccessArticle

Development of an Inverted Epifluorescence Microscope for Long-Term Monitoring of Bacteria in Multiplexed Microfluidic Devices

by Amaro Torres-Simón, María Henar Marino, Clara Gómez-Cruz, Marina Cañadas, Miguel Marco, Jorge Ripoll, Juan José Vaquero and Arrate Muñoz-Barrutia

Sensors 2020, 20(15), 4140; https://doi.org/10.3390/s20154140 - 25 Jul 2020

Cited by 5 | Viewed by 5238

Abstract

Developing more efficient methods for antibiotic susceptibility testing is a pressing issue in novel drug development as bacterial resistance to antibiotics becomes increasingly common. Microfluidic devices have been demonstrated to be powerful platforms that allow researchers to perform multiplexed antibiotic testing. However, the [...] Read more.

Developing more efficient methods for antibiotic susceptibility testing is a pressing issue in novel drug development as bacterial resistance to antibiotics becomes increasingly common. Microfluidic devices have been demonstrated to be powerful platforms that allow researchers to perform multiplexed antibiotic testing. However, the level of multiplexing within microdevices is limited, evidencing the need of creating simple, low-cost and high-resolution imaging systems that can be integrated in antibiotic development pipelines. This paper describes the design and development of an epifluorescence inverted microscope that enables long-term monitoring of bacteria inside multiplexed microfluidic devices. The goal of this work is to provide a simple microscope powerful enough to allow single-cell analysis of bacteria at a reduced cost. This facilitates increasing the number of microscopes that are simultaneously used for antibiotic testing. We prove that the designed system is able to accurately detect fluorescent beads of 100 nm, demonstrating comparable features to high-end commercial microscopes and effectively achieving the resolution required for single-cell analysis of bacteria. The proposed microscope could thus increase the efficiency in antibiotic testing while reducing cost, size, weight, and power requirements, contributing to the successful development of new antibiotic drugs. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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13 pages, 4270 KiB

Open AccessArticle

Grinding Wheel Loading Evaluation by Using Acoustic Emission Signals and Digital Image Processing

by Chien-Sheng Liu and Yang-Jiun Ou

Sensors 2020, 20(15), 4092; https://doi.org/10.3390/s20154092 - 22 Jul 2020

Cited by 15 | Viewed by 7554

Abstract

In the manufacturing industry, grinding is used as a major process for machining difficult-to-cut materials. Grinding is the most complicated and precise machining process. For grinding machines, continuous generating gear grinding machines are widely used to machine gears which are essential machine elements. [...] Read more.

In the manufacturing industry, grinding is used as a major process for machining difficult-to-cut materials. Grinding is the most complicated and precise machining process. For grinding machines, continuous generating gear grinding machines are widely used to machine gears which are essential machine elements. However, due to its complicated process, it is very difficult to design a reliable measurement method to identify the grinding wheel loading phenomena during the grinding process. Therefore, this paper proposes a measurement method to identify the grinding wheel loading phenomenon in the grinding process for continuous generating gear grinding machines. In the proposed approach, an acoustic emission (AE) sensor was embedded to monitor the grinding wheel conditions; an offline digital image processing technique was used to determine the loading areas over the surface of Al₂O₃ grinding wheels; and surface roughness of the ground workpiece was measured to quantify its machining quality. Then these three data were analyzed to find their correlation. The experimental results have shown that there are two stages of grinding in the grinding process and the proposed measurement method can provide a quantitative grinding wheel loading evaluation from the AE signals online. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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11 pages, 3656 KiB

Open AccessArticle

Estimation of Stresses in Concrete by Using Coda Wave Interferometry to Establish an Acoustoelastic Modulus Database

by Hanyu Zhan, Hanwan Jiang, Chenxu Zhuang, Jinquan Zhang and Ruinian Jiang

Sensors 2020, 20(14), 4031; https://doi.org/10.3390/s20144031 - 20 Jul 2020

Cited by 18 | Viewed by 2421

Abstract

This article presents an experimental study of estimating stresses in concrete by applications of coda wave interferometry to establish an acoustoelastic modulus database. Under well-controlled laboratory conditions, uniaxial load cycles were performed on three groups of 15 × 15 × 35-cm concrete prisms, [...] Read more.

This article presents an experimental study of estimating stresses in concrete by applications of coda wave interferometry to establish an acoustoelastic modulus database. Under well-controlled laboratory conditions, uniaxial load cycles were performed on three groups of 15 × 15 × 35-cm concrete prisms, with ultrasonic signals being collected continuously. Then, the coda wave interferometry technique, together with acoustoelastic and Kaiser theories, are utilized to analyze the stress-velocity relations for the distinct ranges before and after historical maximum loads, forming an acoustoelastic modulus database. When applied to different concrete samples, their stresses are estimated with a high degree of accuracy. This study could be used to promote the development of novel nondestructive techniques that aid in structural stress monitoring. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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12 pages, 2252 KiB

Open AccessArticle

Repeatability of High-Pressure Measurement in a Diesel Engine Test Bed

by Tomasz Skrzek, Mirosław Rucki, Krzysztof Górski, Jonas Matijošius, Dalibor Barta, Jacek Caban and Janusz Zarajczyk

Sensors 2020, 20(12), 3478; https://doi.org/10.3390/s20123478 - 19 Jun 2020

Cited by 13 | Viewed by 3152

Abstract

This paper addresses the issue of metrological accuracy of instantaneous in-cylinder pressure measurement in a diesel engine test bed. In studies, the central unit has been the single-cylinder AVL 5402 engine. The pressure measurement was performed with a sensor designed for thermodynamic analysis, [...] Read more.

This paper addresses the issue of metrological accuracy of instantaneous in-cylinder pressure measurement in a diesel engine test bed. In studies, the central unit has been the single-cylinder AVL 5402 engine. The pressure measurement was performed with a sensor designed for thermodynamic analysis, and the results were related to the crank angle, where two rotations corresponding to the four-stroke working cycle were denoted as angles between −360° and +360°. The novelty of this paper is the proposition of how to perform a type A uncertainty estimation of the in-cylinder pressure measurement and to assess its repeatability. It was demonstrated that repeatability of the measurement during the ignition process was difficult to estimate because of the phenomena that cannot ensure the repeatability conditions. To solve the problem, two methods were proposed. In one method, the pressure was measured in the subsequent cycles immediately after the ignition was turned off, and in another method, the engine was driven by a starter. The latter method provided maximal pressure values much lower than during usual tests. The obtained repeatability of measured pressure was %EV = 0.4%, which proved high capability of the evaluated measurement system. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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16 pages, 7262 KiB

Open AccessArticle

Postmortem Analysis Using Different Sensors and Technologies on Aramid Composites Samples after Ballistic Impact

by Ignacio Rubio, Antonio Díaz-Álvarez, Richard Bernier, Alexis Rusinek, Jose Antonio Loya, Maria Henar Miguelez and Marcos Rodríguez-Millán

Sensors 2020, 20(10), 2853; https://doi.org/10.3390/s20102853 - 17 May 2020

Cited by 16 | Viewed by 3732

Abstract

This work focuses on the combination of two complementary non-destructive techniques to analyse the final deformation and internal damage induced in aramid composite plates subjected to ballistic impact. The first analysis device, a 3D scanner, allows digitalising the surface of the tested specimen. [...] Read more.

This work focuses on the combination of two complementary non-destructive techniques to analyse the final deformation and internal damage induced in aramid composite plates subjected to ballistic impact. The first analysis device, a 3D scanner, allows digitalising the surface of the tested specimen. Comparing with the initial geometry, the permanent residual deformation (PBFD) can be obtained according to the impact characteristics. This is a significant parameter in armours and shielding design. The second inspection technique is based on computed tomography (CT). It allows analysing the internal state of the impacted sample, being able to detect possible delamination and fibre failure through the specimen thickness. The proposed methodology has been validated with two projectile geometries at different impact velocities, being the reaction force history on the specimen determined with piezoelectric sensors. Different loading states and induced damages were observed according to the projectile type and impact velocity. In order to validate the use of the 3D scanner, a correlation between impact velocity and damage induced in terms of permanent back face deformation has been realised for both projectiles studied. In addition, a comparison of the results obtained through this measurement method and those obtained in similar works, has been performed in the same range of impact energy. The results showed that CT is needed to analyse the internal damage of the aramid sample; however, this is a highly expensive and time-consuming method. The use of 3D scanner and piezoelectric sensors is perfectly complementary with CT and could be relevant to develop numerical models or design armours. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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20 pages, 9227 KiB

Open AccessArticle

Vibration Control of Scanning Electron Microscopes with Experimental Approaches for Performance Enhancement

by Yun-Ho Shin, Seok-Jun Moon, Yong-Ju Kim and Ki-Yong Oh

Sensors 2020, 20(8), 2277; https://doi.org/10.3390/s20082277 - 17 Apr 2020

Cited by 7 | Viewed by 3923

Abstract

A vibration isolator embedded in precision equipment, such as a scanning electron microscope (SEM), wafer inspection equipment, and nanoimprint lithography equipment, play a critical role in achieving the maximum performance of the equipment during the fabrication of nano/micro-electro-mechanical systems. In this study, the [...] Read more.

A vibration isolator embedded in precision equipment, such as a scanning electron microscope (SEM), wafer inspection equipment, and nanoimprint lithography equipment, play a critical role in achieving the maximum performance of the equipment during the fabrication of nano/micro-electro-mechanical systems. In this study, the factors that degrade the performance of SEM equipment with isolation devices are classified and discussed, and improvement measures are proposed from the viewpoints of the measured image patterns and vibrations in comparison with the relevant vibration criteria. In particular, this study quantifies the image patterns measured using SEMs, and the results are discussed along with the measured vibration. A guide for the selection of mounting equipment is presented by performing vibration analysis on the lower mount of the dual elastic mount configuration applied to the SEM, as well as the image patterns analyzed with that configuration. In addition, design modifications for the mount and its arrangement are suggested based on impact tests and numerical simulations. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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23 pages, 3658 KiB

Open AccessArticle

Smart Sensors for Smart Grid Reliability

by Monica Alonso, Hortensia Amaris, Daniel Alcala and Diana M. Florez R.

Sensors 2020, 20(8), 2187; https://doi.org/10.3390/s20082187 - 13 Apr 2020

Cited by 36 | Viewed by 10894

Abstract

Sensors for monitoring electrical parameters over an entire electricity network infrastructure play a fundamental role in protecting smart grids and improving the network’s energy efficiency. When a short circuit takes place in a smart grid it has to be sensed as soon as [...] Read more.

Sensors for monitoring electrical parameters over an entire electricity network infrastructure play a fundamental role in protecting smart grids and improving the network’s energy efficiency. When a short circuit takes place in a smart grid it has to be sensed as soon as possible to reduce its fault duration along the network and to reduce damage to the electricity infrastructure as well as personal injuries. Existing protection devices, which are used to sense the fault, range from classic analog electro-mechanics relays to modern intelligent electronic devices (IEDs). However, both types of devices have fixed adjustment settings (offline stage) and do not provide any coordination among them under real-time operation. In this paper, a new smart sensor is developed that offers the capability to update its adjustment settings during real-time operation, in coordination with the rest of the smart sensors spread over the network. The proposed sensor and the coordinated protection scheme were tested in a standard smart grid (IEEE 34-bus test system) under different short circuit scenarios and renewable energy penetration. Results suggest that the short-circuit fault sensed by the smart sensor is improved up to 80% and up to 64% compared with analog electromechanics relays and IEDs, respectively. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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27 pages, 9884 KiB

Open AccessArticle

Validation and Improvement of a Bicycle Crank Arm Based in Numerical Simulation and Uncertainty Quantification

by R. Gutiérrez-Moizant, M. Ramírez-Berasategui, José A. Calvo and Carolina Álvarez-Caldas

Sensors 2020, 20(7), 1814; https://doi.org/10.3390/s20071814 - 25 Mar 2020

Cited by 6 | Viewed by 4412

Abstract

In this study, a finite element model of a bicycle crank arm are compared to experimental results. The structural integrity of the crank arm was analyzed in a universal dynamic test bench. The instrumentation used has allowed us to know the fatigue behavior [...] Read more.

In this study, a finite element model of a bicycle crank arm are compared to experimental results. The structural integrity of the crank arm was analyzed in a universal dynamic test bench. The instrumentation used has allowed us to know the fatigue behavior of the component tested. For this, the prototype was instrumented with three rectangular strain gauge rosettes bonded in areas where failure was expected. With the measurements made by strain gauges and the forces registers from the load cell used, it has been possible to determine the state of the stresses for different loads and boundary conditions, which has subsequently been compared with a finite element model. The simulations show a good agreement with the experimental results, when the potential sources of uncertainties are considered in the validation process. This analysis allowed us to improve the original design, reducing its weight by 15%. The study allows us to identify the manufacturing process that requires the best metrological control to avoid premature crank failure. Finally, the numerical fatigue analysis carried out allows us to conclude that the new crank arm can satisfy the structural performance demanded by the international bicycle standard. Additionally, it can be suggested to the standard to include the verification that no permanent deformations have occurred in the crank arm during the fatigue test. It has been observed that, in some cases this bicycle component fulfils the minimum safety requirements, but presents areas with plastic strains, which if not taken into account can increase the risk of injury for the cyclist due to unexpected failure of the component. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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24 pages, 5722 KiB

Open AccessArticle

A Strain-Based Intelligent Tire to Detect Contact Patch Features for Complex Maneuvers

by Mª Fernanda Mendoza-Petit, Daniel García-Pozuelo, Vicente Díaz and Oluremi Olatunbosun

Sensors 2020, 20(6), 1750; https://doi.org/10.3390/s20061750 - 21 Mar 2020

Cited by 23 | Viewed by 5856

Abstract

Tires are essential components of vehicles and are able to transmit traction and braking forces to the contact patch, contribute to directional stability, and also help to absorb shocks. If these components can provide information related to the tire–road interaction, vehicle safety can [...] Read more.

Tires are essential components of vehicles and are able to transmit traction and braking forces to the contact patch, contribute to directional stability, and also help to absorb shocks. If these components can provide information related to the tire–road interaction, vehicle safety can be increased. This research is focused on developing the tire as an active sensor capable to provide its functional parameters. Therefore, in this work, we studied strain-based measurements on the contact patch to develop an algorithm to compute the wheel velocity at the contact point, the effective rolling radius and the contact length on dynamic situations. These parameters directly influence the dynamics of wheel behavior which nowadays is not clearly defined. Herein, hypotheses have been assumed based on previous studies to develop the algorithm. The results expose to view an experimental test regarding influence of the tire operational condition (slip angle, vertical load, and rolling velocity) onto the computed parameters. This information is used to feed a fuzzy logic system capable of estimating the effective radius and contact length. Furthermore, a verification process has been carried out using CarSim simulation software to get the inputs for the fuzzy logic system at complex maneuvers. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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15 pages, 3670 KiB

Open AccessArticle

Heat Source Forecast of Ball Screw Drive System Under Actual Working Conditions Based on On-Line Measurement of Temperature Sensors

by Zhenjun Li, Zechen Lu, Chunyu Zhao, Fangchen Liu and Ye Chen

Sensors 2019, 19(21), 4694; https://doi.org/10.3390/s19214694 - 29 Oct 2019

Cited by 7 | Viewed by 3307

Abstract

In view of the time-varying complexity of the heat source for the ball screw feed system, this paper proposes an adaptive inverse problem-solving method to estimate the time-varying heat source and temperature field of the feed system under working conditions. The feed system [...] Read more.

In view of the time-varying complexity of the heat source for the ball screw feed system, this paper proposes an adaptive inverse problem-solving method to estimate the time-varying heat source and temperature field of the feed system under working conditions. The feed system includes multiple heat sources, and the rapid change of the moving heat source increases the difficulty of its identification. This paper attempts to develop a numerical calculation method for identifying the heat source by combining the experiment with the optimization algorithm. Firstly, based on the theory of heat transfer, a new dynamic thermal network model was proposed. The temperature data signal and the position signal of the moving nut captured by the sensors are used as input to optimize the solution of the time-varying heat source. Then, based on the data obtained from the experiment, finite element software parametric programming was used to optimize the estimate of the heat source, and the results of the two heat source prediction methods are compared and verified. The other measured temperature points obtained by the experiment were used to compare and verify the inverse method of this numerical calculation, which illustrates the reliability and advantages of the dynamic thermal network combined with the genetic algorithm for the inverse method. The method based on the on-line monitoring of temperature sensors proposed in this paper has a strong application value for heat source and temperature field estimation of complex mechanical structures. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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16 pages, 6244 KiB

Open AccessArticle

A Hybrid Two-Axis Force Sensor for the Mesoscopic Structural Superlubricity Studies

by Taotao Sun, Zhanghui Wu, Zhihong Li, Quanshui Zheng and Li Lin

Sensors 2019, 19(15), 3431; https://doi.org/10.3390/s19153431 - 5 Aug 2019

Cited by 2 | Viewed by 4376

Abstract

Structural superlubricity (SSL) is a state of nearly zero friction and zero wear between two directly contacted solid surfaces. Recently, SSL was achieved in mesoscale and thus opened the SSL technology which promises great applications in Micro-electromechanical Systems (MEMS), sensors, storage technologies, etc. [...] Read more.

Structural superlubricity (SSL) is a state of nearly zero friction and zero wear between two directly contacted solid surfaces. Recently, SSL was achieved in mesoscale and thus opened the SSL technology which promises great applications in Micro-electromechanical Systems (MEMS), sensors, storage technologies, etc. However, load issues in current mesoscale SSL studies are still not clear. The great challenge is to simultaneously measure both the ultralow shear forces and the much larger normal forces, although the widely used frictional force microscopes (FFM) and micro tribometers can satisfy the shear forces and normal forces requirements, respectively. Here we propose a hybrid two-axis force sensor that can well fill the blank between the capabilities of FFM and micro tribometers for the mesoscopic SSL studies. The proposed sensor can afford 1mN normal load with 10 nN lateral resolution. Moreover, the probe of the sensor is designed at the edge of the structure for the convenience of real-time optical observation. Calibrations and preliminary experiments are conducted to validate the performance of the design. Full article

(This article belongs to the Special Issue Sensors in Experimental Mechanics)

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