JournalTOCs

Experimental Techniques
Journal Prestige (SJR): 0.296

Citation Impact (citeScore): 1
Number of Followers: 51

Hybrid journal (It can contain Open Access articles)
ISSN (Print) 0732-8818 - ISSN (Online) 1747-1567
Published by Springer-Verlag

[2469 journals]

Correction: Investigation of High Temperature Performance and Viscosity
Characteristics of Modified and Unmodified Color Asphalt
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  PubDate: 2022-06-01
Correction to: Effect of Anodizing Process on Inter Laminar Shear Strength
of GLARE Composite through T-Peel Test: Experimental and Numerical
Approach
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  Abstract: A Correction to this paper has been published: https://doi.org/10.1007/s40799-021-00450-8
  PubDate: 2022-06-01
Circular Tracking Performance of a Flexure-Based Micro-Motion Stage
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  Abstract: Abstract This paper presents the circular tracking performance of a flexure-based micro-motion stage. The mechanical design and prototype development are first illustrated. A double closed-loop control strategy, including the inner and outer feedback controllers, is then employed. Subsequently, main factors affecting its circular tracking performance are further analyzed. Experimental results show that the actual circular trajectory can be enlarged by increasing KP and KI. The circular tracking performance is improved when the sampling period decreases within a certain range. By contrast, it deteriorates as the amplitudes of input sinusoid signals increase. In addition, tracking errors cannot be decreased through exchanging input signals. It demonstrates that there are four parts in a certain cycle where the circular tracking performance is poor. The reason is that these parts are peak and valley points of input signals, and they are influenced by dynamic characteristics of this stage.
  PubDate: 2022-06-01
J-integral Analysis of the Simulated Heat-affected Zone of the
Elevated-temperature Martensitic Steel
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  Abstract: Abstract Due to its superior strength at high temperatures P/T91 steel is often applied in the chemical, petrochemical and fossil-fired power generation industries. The high strength is achieved by a suitable martensitic microstructure after appropriate heat treatment procedure. Welding is the most important process of joining the components in such plants, and the heat-affected zone is often the weakest part of these structures. Having in mind that the welded joint is the weakest area, it is necessary to know its properties and assess the level of its degradation. It was found that the life-limiting factor in case of P/T91 steel welded structures are the cracks located in the heat affected zones, more precisely in its intercritical region. In present paper the results of the fracture toughness measurement carried out on simulated P91 steel ICHAZ specimens produced using a weld simulator has been presented. The tests were done on two types of simulated specimens, those subjected to the subsequent PWHT and with those left untreated (without PWHT), at room temperature and 600 °C. For the J-integral estimation pin-loaded SEN(T) specimens were tested in plane stress conditions using the unloading compliance method of deriving a single specimen resistance curve and the η-method.
  PubDate: 2022-06-01
Investigation of the Transiting Test Method for the Aerodynamic
Performance of Vertical Axis Wind Turbine Using Wind Generated by a Moving
Vehicle
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  Abstract: Abstract With the continuous consumption of fossil energy, environmental pollution problems have become increasingly prominent, and clean energy forms, such as wind energy, have become the focus of research in various countries. The main form of wind energy utilization is wind turbines. However, the single wind tunnel experiment method limits the experimental research on wind turbine aerodynamic performance. The proposed transiting test method using wind generated by a moving vehicle to test the aerodynamic performance of a vertical axis wind turbine (VAWT), provides a new idea for experimental research. This study uses the transiting test method to investigate the static torque and power coefficients of VAWT. Results show that under the limited conditions of the transiting test, the static torque coefficient of VAWT measured by the transiting test coincides with the wind tunnel test measurement results. The error between the static torque coefficient and the wind tunnel test results is basically less than 15%, and the error is within a reasonable range. The power coefficient of VAWT obtained through the transiting test is similar to previous research results, and the error from the wind tunnel test result is within an acceptable range. The transiting test can reproduce the research results of VAWT in the wind tunnel test and can meet the needs of the aerodynamic performance research of VAWT, which is a novel test approach for research on the aerodynamic performance of VAWT.
  PubDate: 2022-06-01
Development of an Integrated Load Testing Device for a Substructure Hybrid
Test of a Curved Bridge
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  Abstract: Abstract A substructure hybrid test is an effective approach to reproduce the seismic behavior of engineering structures. The structure is partitioned into several substructures; those with complex behavior are analyzed experimentally, whereas the others are analyzed numerically, combining the merits of physical experiments and numerical simulations. Previous studies often loaded physical substructures in two or three translational directions. Simultaneous rotational loading in three Cartesian axes is difficult because the load testing device has to be configured spatially, resulting in control problems due to strong coupling. Special expertise in mechanical engineering is necessary to solve this problem. To this end, this study proposes an integrated load testing device suitable for physical loading in all six degrees-of-freedom simultaneously. The device is based on a Stewart platform and can provide a large axial force required by most gravity-bearing components. It also has a large inherent stiffness necessary to obtain the force-displacement curve from damage through complete failure. This paper describes the force-displacement mixed control based on the Stewart configuration, which is necessary for testing engineering structures. Control software is developed and interfaced with the mid-ware OpenFresco to coordinate the numerical substructure. A hybrid test is conducted using a small-scale, electronic-driven load testing device. The test ran smoothly without any malfunctions, demonstrating the excellent performance of the testing system.
  PubDate: 2022-06-01
Low-cost Solutions for Velocimetry in Rotating and Opaque Fluid
Experiments using Ultrasonic Time of Flight
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  Abstract: Abstract Many common techniques for flow measurement, such as Particle Image Velocimetry (PIV) or Ultrasonic Doppler Velocimetry (UDV), rely on the presence of reflectors in the fluid. These methods fail to operate when e.g centrifugal or gravitational acceleration leads to a rarefaction of scatterers in the fluid, as for instance in rapidly rotating experiments. In this article we present two low-cost implementations for flow measurement based on the transit time (or Time of Flight) of acoustic waves, that do not require the presence of scatterers in the fluid. We compare our two implementations against UDV in a well controlled experiment with a simple oscillating flow and show we can achieve measurements in the sub-centimeter per second velocity range with an accuracy of \(\sim 5-10\%\) . We also perform measurements in a rotating experiment with a complex flow structure from which we extract the mean zonal flow, which is in good agreement with theoretical predictions.
  PubDate: 2022-06-01
Multi-Level Stator Winding Failure Analysis on the Insulation Material for
Industrial Induction Motor
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  Abstract: Abstract Multi-level stator winding failure investigation on the insulation material for industrial induction motor at its incipient stage can achieve tremendous energy savings, minimize maintenance costs, and enhance the operational life. Early detection has the main advantage of preventing motor failure, which gradually leads to catastrophic or complete shutdown. In this paper, the multi-level stator winding failure of an industrial induction motor in the numerical model was designed and implemented using Finite-Element Analysis (FEA). Since multi-level stator winding failure constitutes substantial time and frequency domains, the signature from the motor is analysed employing a time-frequency-based technique using wavelets. Early detection of the multi-level stator winding failures uses signatures from the experimental setup of both healthy and faulty motors by combining both modular and virtual instruments. FEA results were then validated under the same operating conditions using an experimental setup. It has been observed that the results obtained from the FEA are in good agreement with the experimental setup. The frequency component variation in the sensor frequency response for fault conditions at various severity levels suggests multiple frequency bands. When the motor was under the influence of a 50% stator turn-turn fault, a similar frequency band between 700-800 Hz was observed. As a result, the proposed research was accurate, with a correlation factor of 0.96.
  PubDate: 2022-06-01
A Lightweight DFT-Based Approach to the Optical Measurement of
Displacements Using an Open-Source Python Code
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  Abstract: Abstract Commonly available digital image correlation (DIC) tools are designed to evaluate displacement/deformation fields using well-optimized correlation functions and computational procedures. However, real-time monitoring at high sampling rates or tracking motion at predefined locations from large sequence images can be hardly accomplished due to extreme computational costs. As shown in this paper, a lightweight approach based on the registration of subpixel subset shifts using discrete Fourier transform (DFT) can easily tackle large sets of images if the measurement is limited to discrete locations. A simple open-source python software designed for evaluation of displacements using virtual extensometers is described in this paper, along with the analysis of its performance. It is shown that the DFT-based algorithms outperform a commonly used DIC package in terms of computational efficiency and required user interactions, without sacrificing precision and accuracy.
  PubDate: 2022-06-01
The Effect of Load Phase Angle on Roof Components of Electric Driven Bus
Fatigue Damage
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  Abstract: Abstract In this study, the effect of phase shift under multiaxial excitation on fatigue damage was investigated for the roof components of electrical driven bus. The experiments were performed using a servo-hydraulic controlled multiaxial shaker. Firstly, phase degree and concurrence of servo-hydraulic actuators were calculated and compared for in-phase and out-of-phase loading cases. Following response signals of both loadings were acquired to investigate the dynamic response of the structure and roof components. Both test loadings were compared by level crossing counting and damage calculations in the frequency domain. The results indicate that the out-of-phase loading can reduce the acceleration and strain values on the flaps induced damage significantly compared to in-phase loading. Furthermore, the out-of-phase loading of bench testing corresponds well to the experimental results of rough road, which represent customer drive conditions.
  PubDate: 2022-06-01
Dynamic Characteristics Monitoring Changes of Damaged and Retrofitted RC
Buildings
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  Abstract: Abstract This paper presents results of an experimental study that focuses on monitoring changes in dynamic characteristics of a damaged and retrofitted two-story reinforced concrete (RC) building model with poor detailing. In the study, ambient vibration tests are performed via four test setup protocols in order to monitor changes in dynamic characteristics before and after such setups. The four main test setups are: (i) undamaged (as-built) case (Setup # 1), (ii) damaged cases with different degrees of damages (Setup # 2), (iii) repaired case with different types of repair methods (Setup # 3), and (iv) strengthened case with externally bonded CFRP composite laminates (Setup # 4). In addition, a total of eight ambient vibration tests are conducted in order to assess the effects of degree of damage and associated retrofit systems on building’s dynamic characteristics such as natural frequencies, mode shapes, and damping ratios. The Stochastic Subspace Identification (SSI) Method is used to identify the dynamic characteristics. Experimentally identified dynamic characteristics obtained from all setups are compared with each other in order to detect the effect of damage and repair applications on the structure’s dynamic characteristics. Moreover, Modal Assurance Criterion (MAC) and Coordinate Modal Assurance Criterion (COMAC) are determined to examine the changes of stiffness of each RC building model.
  PubDate: 2022-06-01
Analysis of Out-of-Plane Hail Impact Resistance of Steel Roof Panels
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  Abstract: Abstract Residential and commercial buildings often use metal roof panels. In contrast, the dent resistance of steel panel subjected to impact of hailstone is insufficiently studied. The analysis of the whole experimental setup has been carried out using a finite element model (FEM). Artificial hailstones were launched at different steel sheets based on their size at different terminal velocities for comparison with natural hailstones that remained intact after impact. Based on comparisons between experimental results and the FE model, the simulation approach and material properties are evaluated. Additionally, an equation to predict dent depth using kinetic energy and stress is presented. The results of this study provide an understanding of both hail and roof panel failure modes and their effect on dent resistance. Experimental observations and numerical simulations in this study were well matched with results obtained using analytical models. In addition, the proposed equation overestimates dent depths compared with those found in the tested steel sheets, while underestimating the ones determined by finite element models.
  PubDate: 2022-06-01
Numerical Simulations of Modal Tests on Yingzhou Bridge Using a Passing
Vehicle as the Excitation
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  Abstract: Abstract Modal tests using ambient excitations might lead to inaccurate results for bridges with the fundamental natural frequencies greater than 1 Hz. Modal tests using passing vehicles as the excitations are proposed for use in this regard. For effective modal tests using passing vehicles as the excitations to take place on full-scale arch bridges, two matters of science should be clarified, i.e., the effects of the measuring point placement and the influences of the vehicle excitation parameters (the vehicle speed and the vehicle weight). In this article, thorough studies are given to the two scientific issues based on the numerical simulations of modal tests on Yingzhou Bridge (a 120 m-span special-shaped steel arch bridge). It is found that both the accelerometer placement based on the genetic algorithm and the vehicle excitation parameters selected using the response surface method can help experiment personnel get more accurate modal test results. Therefore, the field modal test carried out on Yingzhou Bridge employs optimized accelerometer arrangement and vehicle excitation parameters. It is found that the modal parameters measured on the full-scale Yingzhou Bridge agree well with the results calculated by modal analysis.
  PubDate: 2022-06-01
Creep and Hysteresis Testing of Unfilled Natural Rubber Using
Scanner-based Digital Image Correlation
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  Abstract: Abstract The conventional digital image correlation (DIC) method is not readily applicable for testing creep and hysteresis in high strain polymeric materials at temperatures above room conditions due to the limited field-of-view of the camera and the difficulty associated with heating the specimen during loading. In this work, the previously developed scanner-based digital correlation (SB-DIC) method for in-plane displacement and strain measurement was extended to investigate creep and hysteresis in unfilled natural rubber at temperatures up to 65 °C. An enclosed loading rig was designed to load the rubber specimens both mechanically and thermally. Two cylindrical quartz heaters were used to apply constant heat to the rubber specimen at controlled temperatures during loading. Speckle patterns on the specimens were created artificially and images were acquired by scanning using a flatbed scanner at regular time intervals. The zero-normalized cross correlation criterion in the DIC algorithm was used to map strains up to 400 % due to creep and hysteresis. A series of creep experiments from 25 to 65 °C and hysteresis experiments from 25 to 55 °C were carried out to investigate the effect of temperature on creep and hysteresis in rubber. The full-field displacement vectors showed a rapid increase in creep strain above 35 °C. The hysteresis loops were also found to increase with temperature.
  PubDate: 2022-06-01
Design of a Shake Table with Moderate Cost
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  Abstract: Abstract Shake table testing is a very efficient tool in earthquake engineering that may be used to enhance construction methods and the overall safety of structures. Shake tables permit investigation of the dynamic behaviour of civil engineering structures. This paper details the development of a uniaxial shake table that was designed and built with the objective of limiting its cost to a moderate amount, bellow 250 k€. The technical specifications of the shake table are presented as well as the evaluation of its performance and its validation. It is shown that it is possible to build an operational shake table capable of generating real seismic motion for the assessment of structural behaviour at a moderate cost.
  PubDate: 2022-06-01
Experimental Stress Analysis of Spherical Roller Bearing for High-Speed
Trains Using Photoelasticity
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  Abstract: Abstract Most studies on bearing stress analysis have considered single row rolling elements. In this study, the stress behavior of a spherical roller bearing with two rows of rolling elements is investigated. Photoelastic experimental hybrid method, is applied to investigate the interior and contact stresses of high-speed train bearings under combined axial and radial loads. The experimental results show that the bearing under investigation has the capability of sustaining high loads. The sharing of the loads between the two rows of rollers was found to contribute to excellent load bearing capabilities. It is also shown that the barrel-shaped roller has an influence on the stress concentrations and their distributions on the bearing races. At low radial and axial loads, the stresses on the races result from the bulging out section of the roller. As load is increased, the roller deforms and race stress occur at the ends of the roller, which now act like a punch. Only half of the bearing structure was found to be highly stressed. At position 3, the few isochromatic fringes on rollers and inner race shows that low stress concentrations occur on them. A comparison of the results from spherical roller bearing (SRB) and tapered roller bearing (TRB) showed that the stresses induced at the bearing races of the TRB bearing have higher magnitudes than those of SRB. This observation can be attributed to the two rows of rollers in SRB. High stress concentrations often lead to crack initiation and spall growth. Therefore, the low stresses on the SRB makes them more suitable for applications involving heavy loads.
  PubDate: 2022-05-13
Characterising Multiaxial Fatigue Random Strain Time Domain in Assessing
the Durability of a Suspension Coil Spring
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  Abstract: Abstract The aim of this study is to characterise the fatigue life data of multiaxial strain signals of an automobile suspension coil spring under various road load condition. The automobile coil spring experiences cyclic load due to the variation of road conditions, resulting in compression-tension loads, and providing a direct shear force and a torsion in the coil spring’s internal tension. Currently, the uniaxial analysis overestimates the component’s fatigue life because the uniaxial fatigue excludes complex stress and strain states relating to the fatigue life. Therefore, multiaxial analysis was proposed in order to determine the variance in the magnitude of main stress effects. The critical or hotspot region of a quarter car model was determined using finite element analysis. The rosette strain gauge was located at the critical region in order to capture the maximum strain signals on various roads, i.e. highway, rural and campus road during data measurement analysis in time-domain. Global statistic features of kurtosis and root mean square were analysed to obtain random signals classification. Brown-Miller, Fatemi–Socie, and Wang-Brown models were proposed to predict the multiaxial fatigue life where these models include strain criteria. Multiaxial fatigue models were proposed when evaluating fatigue life due to the complex geometries and torsional effect on coil spring. The results indicated that multiaxial strain life from Brown-Miller model possessed the highest fatigue lives. Probability distribution function for fatigue lives from Brown-Miller, Fatemi–Socie and Wang-Brown model is plotted to characterise the distribution of fatigue lives under the time domain. In order to determine the acceptability of the data, the conservative fatigue life 1:2 and 2:1 data scattering approach is proposed. Hence, the proposed life models can be used to characterise multiaxial fatigue under random strain signals for the automobile coil spring.
  PubDate: 2022-05-09
Study on Cutting Force and Surface Topography of Peripheral Milling CFRP
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  Abstract: Abstract When constant parameters are used for peripheral milling CFRP, it is difficult to meet the requirement of high quality, so variable parameters machining is proposed. First, the response surface method was used to explore the effect of changing cutting conditions on the interaction of spindle speed, cutting depth and feed speed on radial force. The surface topography and roughness after the test were observed and analyzed. The results show that defects are more likely to occur at the entrance and the exit area than the central area. Taking the minimum radial force as the experimental goal, the optimal parameters combination was obtained and used for finite element and experimental verification. Second, the variable parameters milling were used the cemented carbide tool and PCD tool. The radial force, surface topography and roughness were analyzed and the optimized variable parameters combination was obtained. The results show that the high spindle speed, low feed speed and low cutting depth are beneficial to improve the surface quality at the entrance and the exit area when the machining parameters at the centra area remain unchanged. Meanwhile, when the parameters change abruptly, the fluctuation of the radial force at the variable parameters area is decreased. The variable parameters compared to constant parameters, the surface roughness of the machining with the cemented carbide tool at the entrance area by 29.7% and 7.4%, respectively and the machining with PCD tool at the exit and the entrance area decreased by 60.5%, 43.5% and 38.8%, 51.9%, respectively. Compared with the cemented carbide tool, the radial force of the PCD tool is more stable and the surface quality is further improved.
  PubDate: 2022-05-03
Multi-Axis 3D Printing Defect Detecting by Machine Vision with
Convolutional Neural Networks
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  Abstract: Abstract Part quality inspection is playing a critical role in Fused Deposition Modeling (FDM). It produces a part quality analysis report which can be adopted to further improve the overall part quality. However, the part quality inspection process puts heavy reliance on the engineer’s background and experience. This manual process suffers from both low efficiency and potential errors. The purpose of the paper is to look into a deep neural network towards a robust method for montoring of 3D priting Parts. However, there is little research on the detection of multi-axis FDM printing. Aiming at FDM printing defects, an offline detection method of multi-axis FDM printing based on machine vision and convolutional neural network (CNN) is proposed. The CCD (Charge Coupled Device) camera is used to capture the current layer, and the self-constructed CNN network is used to classify the defects. The interlayer stripping defect is taken as an example to verify the detection method’s feasibility. The data set of the defect is established, used as CNN’s input. The network’s structure is continuously improved through training and testing. Finally, the CNN with excellent performance is constructed. The classification results show that the CNN network’s classification accuracy for interlayer stripping and normal state is 83.1%, the sensitivity is 85.6% and 80.5% and the ROC curve area is 0.824, which proves the feasibility of the detection method. Moreover, the method can be extended to other print defect detection. It provides a new method to ensure the quality of FDM prints.
  PubDate: 2022-04-29
Correction to: Modeling and Sensitivity Analysis of Thermal Conductivity
of Ethylene Glycol–Water Based Nanofuids with Alumina Nanoparticles
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  PubDate: 2022-04-18