Experimental Test Setup Research Articles

Strain distribution at the transition from bent to unbent regions in tube rotary draw bending: an in-situ, real-time measurement study

In tube bending processes, accurate control of springback is of crucial importance as this affects the dimensional accuracy of the final product and overall equipment efficiency. The distribution of stress and strain during bending is one of the most fundamental issues determining the springback magnitude of the product. In conventional analyses of rotary draw bending, the deformation behaviour along the bending direction is normally assumed to be uniform for constant-radius bends, following the contour of the die configuration. In practice, however, the stress-strain distribution is non-uniform, particularly at the transition between the bent and unbent regions of the formed component. The distribution makes a significant contribution to springback and its variations, especially for low bend-angle components. This research focuses on exploring the strain distribution at the end transition of the bend of aluminium tubes in rotary draw bending. An experimental test setup for strain measurements with a strain gauge glued to the unbent area has been designed and conducted to measure the strain distribution during bending. The characteristics of non-uniform strain distribution during tube bending, including the evolving transition behaviour at the transition between bent and unbent areas, are studied. The results enhance the understanding of deformation characteristics of bent tubes, and contribute to improved physically-based models and springback control routines in industrial practice.

Investigations of Hydrodynamic Force Generated on the Rotating Cylinder Implemented as a Bow Rudder on a Large-Scale Ship Model

This paper presents experimental studies of the force generated on the rotating cylinder implemented as a bow rudder on a large-scale ship model. The research focused on the maneuverability of the unit equipped with a rotating cylinder (RC) in the front part of the model and its future use as a steering device on small draft river barges. The study presented in this paper is a continuation of the research carried out using the small physical model of a river push train in 1:20 geometric scale equipped with two bow RCs and open water tests of separated rotating cylinders carried out in a flume tank. The experimental test setup with RC installed on the model in 1:24 geometric scale allowed to compare the parameters of standard maneuvers performed with the use of RC and without it. The proposed method based on the measurement of the ship model trajectory during maneuvers allowed to compare the hydrodynamic steering force generated by RC with the steering force generated by the conventional stern spade rudder. The results of the experiments compared with empirical models show a similar trend. RC dynamics was tested for rotational speeds up to 570 RPM (revolutions per minute) and ship model velocity up to 1 m/s. The rotating cylinder generated velocity field is presented and phenomena influencing the generated hydrodynamic force are discussed.

Using Numerical Models to Accelerate Electrolyte Transport Parameter Identification

A new electrolyte transport parameter identification methodology, based on the numerical solution of a symmetric Li–Li cell model, is presented. In contrast to available techniques in the literature, where small concentration perturbations are generated in testing setups and linearization is assumed to identify transport properties for the initial salt concentration, large currents are used here to excite nonlinear dynamics able to reveal concentration dependent transport properties. This approach allows a significant reduction in the experimental effort. The proposed methodology is applied to two synthetic experiments. Firstly, an ideal case (where all difficulties associated to stripping and plating dynamics on Li metal surface are neglected) is considered in order to show both the details of the proposed methodology and its performance (specially its robustness, including the effect of the noise level in the voltage measurements in the experiment). A second case considers the effect of complex stripping and plating dynamics to show that, provided (macroscopic) modelling/identification of this dynamics is carried out, the proposed methodology is still able to accurately identify electrolyte transport properties using a simple experimental test setup.

Simulation Model for Digital Twins of Pneumatic Vacuum Ejectors

AbstractIncreasing productivity, as well as flexibility, is required for the industrial production sector. To meet these challenges, concepts in the field of “Industry 4.0” are arising, such as the concept of Digital Twins. Vacuum handling systems are a widespread technology for material handling in industry and face the same challenges and opportunities. In this field, a key issue is the lack of Digital Twins containing behavior models for vacuum handling systems and their components in different applications and use cases. A novel concept for modeling and simulating the fluidic behavior of pneumatic vacuum ejectors as key components of vacuum handling systems is proposed. In order to increase the simulation accuracy, the concept can access instance‐specific data of the used asset instead of object‐specific data. The model and the data are part of the Digital Twins of pneumatic vacuum ejectors, which shall be able to be combined with other components to represent a Digital Twin of entire vacuum handling systems. The proposed model is validated in an experimental test setup and in an industrial application delivering sufficiently accurate results.

Non-condensable gas in the refrigerant of air-source heat pumps: Interactions between detection features, charge level, and temperature

Non-condensable gas (NC) can be introduced into a vapor compression refrigeration cycle through improper installation or service, and decrease system efficiency, increase burden on the compressor, and reduce the compressor life span. Therefore, detecting this fault early can prevent energy waste and prolong the operating life of the system. However, diagnostic methods are not widely available, and neither are methods to quantify NC amounts based on easily measured variables. Therefore, an experimental test apparatus was built to provide data to improve understanding of NC-refrigerant interactions. Two NC fault intensities (50%, 100%), each at four charge levels (70%, 80%, 100%, 120%), were tested under five different ambient temperatures (0-40°C). Dry nitrogen gas was used for the NC. The results showed that the theoretical estimation method is inaccurate. The trends of the results from experimental tests are consistent with those from theoretical calculations, but the thresholds obtained from experimental tests are larger than those from theoretical calculations. This paper explains these differences, and provides a model to quantify the NC fault intensity using easily-measured variables. The specific model is applicable to typical residential air-conditioner and heat pump systems that use R410A refrigerant, but the general findings are applicable to other refrigerants.

Experimental Investigation on the Thermal Performance of a Conical Solar Water Heater Using Mixed Asphalt Absorber Plate

Abstract In the present research, an investigational study on thermal performance of a mixed asphalt conical solar water heater (MACSWH) was analyzed under field conditions. The key target of the present research is to evaluate the dynamics of heat and performance of a conical solar collector with an attached mixed asphalt as an absorber plate. In the current experimental test setup, the mixed asphalt as an absorber plate with a diameter of 0.20 m and thickness of 0.05 m was set in the middle of the focal area for accumulating the solar radiation, reflecting from a polished zinc conical reflector. The aperture diameter of the MACSWH was 0.45 m with a concentration ratio of 2.20. The copper pipe had a total length of 2 m, and the inclination angle of the conical was fixed at 15 deg. The experimental results provide evidence that the mixed asphalt set as an absorber plate at the center of the focal area was an effective practical approach to improve the performance of a conical solar collector. This method raises the maximum percentage difference between inlet water temperature and outlet water temperature by approximately 47.27%, while the maximum temperatures of absorber plate, copper pipe, and efficacy are at 82 °C, 62 °C, and 72%, respectively.

Fluorometric setup and method for studying the functional activity of corneal endotheliocytes

Subject of study. Experimental methods for investigating the state of preservation and functionality of the corneal endothelium, which is determined by the water permeability of the cells and activity of ion pumps, mainly by sodium–potassium adenosine triphosphatase, were considered. Aim of study. The aim of this study was to identify significant measurable parameters such as the fluorescence intensity integrated over the entire cornea preparation and the temporal dynamic of this fluorescence. Additionally, a specialized experimental fluorometric setup was designed based on fiber optics. Method. Modifications were introduced to the composition and design of a universal experimental setup for the measurement of cell functions that enabled implementation of a fluorescence-based method for determination of the intracellular sodium concentration without processing the digital image of the cornea preparation. Main results. The specialized experimental setup and method were developed for investigating functions of the corneal endothelial cells and the intracellular signaling mechanisms whose activation or disfunction under conditions of a traumatic inflammation and after a hypothermic preservation can be related to the development of a corneal edema and a corneal graft disease. Practical significance. The specialized experimental setup and methods for functional testing of the corneal endothelial cells developed in this study can be applied to determine the degree of suitability of the cornea as a transplantation material. They can also be used as a system of tests for determining the effectiveness of the cornea preservation methods.

Numerical model for solar drying mechanism of grapes using double glazed cabinet type solar dryer

AbstractA development of an integrated mathematical model based on heat and mass transfer process was used to predict the shrinkage, moisture content, and thermal properties of grapes under different climatic conditions. A lab‐scale experimental test setup has also been developed, and tests are performed. The results obtained from the mathematical model are compared with experimental results and found to be in agreement with a maximum error of 14%. The moisture content evaluated from the model showed a fair agreement with the experimental results. An energy balance equation is used to obtain the cabinet temperature. A time‐dependent radiation flux density (I(t)) at a certain day is obtained through meteorological records. The effective moisture diffusivity (Deff) is obtained using Fick's diffusion equation for all the investigated conditions. The model is also validated with the results reported in the literature. Moisture is reduced from the initial moisture content of 4.88 kg of water per kg of dry matter to the final moisture content of approximately 0.38 kg of water per kg dry matter. The average radius of the grape decreased by 34.67% at the end of drying process (moisture content ~13%). The maximum water activity is 0.37 for the highest moisture content. The maximum radius change was found 4.9 mm from 7.5 mm for 50°C case. The maximum temperature increase of grapes with respect to drying time is 18°C. The results obtained using the proposed mathematical model can be used to predict product temperature, moisture content, and drying time for cylindrical‐shaped products.

Experimental Setup for Fatigue Testing of Additively Manufactured Specimens

Poor fatigue life is a huge issue of additively manufactured parts, despite the unique qualities characterizing this manufacturing process (such as low waste of material and geometry freedom). Fatigue life is strongly affected by both surface defects and internal defects, metal AM is characterized by extremely poor surface quality, internal porosities and lack of fusions. For this reason, many researchers investigated methods to improve manufacts quality. The most promising methods are surface finishing treatments and thermal treatments which provide an enhancement of fatigue behavior. A focal point of the research should be evaluating the respective contribution of surface treatments and thermal treatments. In order to evaluate the effectiveness of surface treatment, it is necessary to highlight the surface quality contribution in terms of fatigue life thus a specific testing method is necessary. Rotating beam fatigue test fits this requirement because each point of the specimen’s surface is subjected to the maximum stress. The aim of this work is to present the experimental setup for rotating beam fatigue testing that has been used to evaluate the fatigue behavior of AM SLM IN718 specimens.

Multiscale Shear Properties and Flow Performance of Milled Woody Biomass

One dominant challenge facing the development of biorefineries is achieving consistent system throughput with highly variant biomass feedstock quality and handling performance. Current handling unit operations are adapted from other sectors (primarily agriculture), where some simplifying assumptions about granular mechanics and flow performance do not translate well to a highly compressible and anisotropic material with nonlinear time- and stress-dependent properties. This work explores the shear and frictional properties of loblolly pine at multiple experimental test apparatus and particle scales to elucidate a property window that defines the shear behavior over a range of material attributes (particle size, size distribution, moisture content, etc.). In general, it was observed that the bulk internal friction and apparent cohesion depend strongly on both the stress state of the sample in granular shear testers and the overall particle size and distribution span. For equipment designed to characterize the quasi-static shear stress failure of bulk materials ranging from 50 to 1,000 ml in test volume, similar test results were observed for finely milled particles (50% passing size of 1.4 mm) with a narrow size distribution (span between 10 and 90% passing size of 0.9 mm), while stress chaining and over-torque issues persisted for the bench-scale test apparatus for larger particle sizes or widely dispersed sample sizes. Measurement of the anisotropic particle–particle friction ranged from coefficients of approximately 0.20 to 0.45 and resulted in significantly higher and more variable friction measurements for larger particle sizes and in perpendicular alignment orientations. To supplement these laboratory-scale properties, this work explores the flow of loblolly pine and Douglas fir through a pilot-scale wedge-shaped hopper and a screw feeder. For the gravity-driven hopper flow, the critical arching distance and mass discharge rate ranged from approximately 10 to 30 mm and 2 to 16 tons/hour, respectively, for both materials, where the arching distance depends strongly on the overall particle size and depends less on the hopper inclination angle. Comparatively, the auger feeder was found to be much more impacted by the size of the particles, where smaller particles had a more consistent and stable flow while consuming less power.

Failure analysis of POM ternary nanocomposites for gear applications: Experimental and finite element study

The main purpose of the present study is to assess the failure behavior of polyoxymethylene/carbon black/CaCO3 ternary nanocomposite gears by employing an experimental gear test setup and a gear renewal technique. The failure-related factors including surface temperature, tooth wear, and failure analysis at macro- and micro-scales were studied. The tooth surface temperature was measured continuously based on an online-measuring approach. The tooth wear was calculated using microscopic images and software analysis. The maximum contact stress on meshing teeth surfaces was specified by finite element analysis. According to SEM micrographs, the application of both nanostructures contributed to a more uniform distribution of each nanophase within the POM matrix. The gear test results indicated an enhanced tooth resistance and service life of up to 58% and 125%, respectively, for ternary nanocomposites relative to neat POM gears. The tooth surface temperature was reduced for nanocomposite gears due to the promoted heat transfer and thermal stability. The tooth deformation and cracking were highly suppressed for ternary nanocomposite gears at failure. The evaluation of teeth surface damages at micro-scale revealed the suppression of plastic flow and material adhesion for ternary nanocomposites.

Experimental analysis of steering wheel vibrations of an agriculture tractor for reduction of hand-arm vibrations

Steering wheel vibration is one of the most important factors in determining the operator comfort in agricultural tractors. It is important to investigate steering wheel vibrations in an agricultural tractor in order to improve the operator’s comfort and decrease the negative health impacts on the operator’s hand. The Mahindra 575 DI tractor was selected for further investigation and development as the maximum vibration acceleration was found in the Mahindra 575 DI tractor while measuring the amplitude of vibration on various tractors. The experimental test setup was designed with a solution to reduce steering wheel vibrations. The experimental analysis of steering wheel vibration of an agriculture tractor for the reduction of Hand-Arm Vibration Syndrome (HAVS) is presented in this research article. The vibration level was decreased effectively after establishing a tuned mass damper between the steering gearbox and the vibration exciter.

Heat transfer analysis of air-mist evaporative cooling in heat sink

This paper investigates heat transfer enhancement of evaporative air-mist cooling in heat sinks. Heat transfer in heat sink is studied through the development of theoretical equations of mass, momentum, energy, and water droplets evaporation. The flow domain consists of air and water droplets entrained in the primary air phase. An experimental testing setup is built and used to examine the validity of the numerical modeling of the air-mist cooling approach. The influence of mist droplets on heat transfer and the thermal performance of the heat sink is analyzed numerically and experimentally. Investigation is carried out for Reynolds number ranging between 100 and 1500, mist volume fraction ranging between 1 and 10%, and mist droplets diameter of 10 µm. It is found that increasing the inlet mist fraction from 1% to 6% increases the heat transfer coefficient by approximately 158%. Moreover, it is found that increasing Reynolds number from 100 to 1000 increases the heat transfer coefficient by approximately 100%. This numerical investigation illustrates the effectiveness of using two-phase air-mist flow cooling of heat sinks in comparison with a single-phase air flow. This study highlights the importance of using two-phase flow for enhanced heat transfer and it contributes to the development of advanced microelectronic cooling systems.

Experimental study of a liquid metal film flow in a streamwise magnetic field

Continuous wetting of a surface with liquid metal is indispensable in many applications, such as in fusion reactors. In the present study, we provide data on the suppression of free-surface instabilities of liquid metal film flows under the action of strong streamwise magnetic fields in analogy to the poloidal fields used in application. We have designed and built up an experimental test setup which allows studying the influence of magnetohydrodynamics on the dynamic behaviour of liquid metal GaInSn film flows in laminar, transient, and turbulent regimes. While the width and the length of the film are adjusted at w = 23 mm and l = 120 mm, respectively, we are able to apply strong uniform magnetic fields up to B = 5 T over the entire fluid-flow volume. Moreover, the setup allows to vary the Reynolds number within the range 200 ≤ Re ≤ 1700. The corresponding Hartmann and Stuart numbers are Ha ≤ 180 and N ≤ 40, respectively. This study shows that a streamwise magnetic field is capable of suppressing free-surface instabilities even in the turbulent regime of the film flow by dampening any motion perpendicular to the applied magnetic field. Plans for future studies include the quantitative investigation of the parameter space. Figs 4, Refs 8.

A six degree-of-freedom set-up for wind tunnel testing of floating wind turbines

In this paper we present a six-degree-of-freedom (DoF) experimental set-up for wind tunnel testing of floating offshore wind turbines (FOWTs). The system is composed of a 6-DoF Stewart platform that can be used to mimic realistically the motions of a floating turbine at laboratory scale. The platform is specifically made for the Model Wind Turbine Oldenburg 0.6 (MoWiTO 0.6). First, the methodology followed to design the system as well as the scaling issues are depicted. Then, the characterisation of the platform is presented. Finally, limitations of the set-up are discussed.

Data-driven model-based calibration for optimizing electrically boosted diesel engine performance

Engine calibration is a process of optimizing its control variables, which is a crucial step to achieve the desired performance from the engine system. However, its complexity has increased dramatically due to the constant evolution of the engine architecture with multiple control variables interacting with each other, making it difficult to calibrate its control variables with significantly increased experimental costs. System complexity also affects the physics-based modeling process as it makes the system model highly non-linear and difficult to capture system dynamics under all engine operating conditions. To overcome these challenges, the current work proposes a machine learning-based framework to reduce the required calibration effort. The work implements a stochastic surrogate assisted optimization approach on an actual engine experimental test setup, which efficiently looks for the global optimal solution based on only the input-output data set. This work performs a steady-state calibration of a turbocharged diesel engine with an additional external electric-assisted boosting system (eBoost). Three control parameters are considered for this study: Variable Geometry Turbocharger (VGT) vane position, Exhaust Gas Recirculation (EGR) valve position, and eBoost speed to identify the optimal trade-off between engine efficiency (Brake Specific Fuel Consumption) and emissions ( NO x). The addition of eBoost makes the calibration problem difficult because the two control parameters, VGT and EGR, also depend on eBoost speed. Using the proposed data-driven calibration approach, the experimental results showed enhanced engine performance in terms of efficiency and emissions using the eBoost compared with the case without eBoost. At the same time, the experimental cost was reduced significantly due to the reduced number of testing points required to achieve the optimum.

Mass Removal of Botnet Attacks Using Heterogeneous Ensemble Stacking PROSIMA classifier in IoT

In an Internet of Things (IoT) environment, any object, which is equipped with sensor node and other electronic devices can involve in the communication over wireless network. Hence, this environment is highly vulnerable to Botnet attack. Botnet attack degrades the system performance in a manner difficult to get identified by the IoT network users. The Botnet attack is incredibly difficult to observe and take away in restricted time. there are challenges prevailed in the detection of Botnet attack due to number of reasons such as its unique structurally repetitive nature, performing non uniform and dissimilar activities and invisible nature followed by deleting the record of history. Even though existing mechanisms have taken action against the Botnet attack proactively, it has been observed failing to capture the frequent abnormal activities of Botnet attackers .When number of devices in the IoT environment increases, the existing mechanisms have missed more number of Botnet due to its functional complexity. So this type of attack is very complex in nature and difficult to identify. In order to detect Botnet attack, Heterogeneous Ensemble Stacking PROSIMA classifier is proposed. This takes advantage of cluster sampling in place of conventional random sampling for higher accuracy of prediction. The proposed classifier is tested on an experimental test setup with 20 nodes. The proposed approach enables mass removal of Botnet attack detection with higher accuracy that helps in the IoT environment to maintain the reliability of the entire network.

Increasing the accuracy of clinching process simulations by modeling the friction as a function of local joining process parameters

In this study, an innovative friction model is used to improve the quality of clinching process simulations. Consequently, the future over dimensioning can be reduced. Furthermore, the improved prediction quality of the joining process simulation leads to an improvement in the simulation of load-bearing capacity as well. In this way, the entire sampling process can be performed virtually without any experimental investigations. This will contribute to the advancement of lightweight construction in the automotive industry. In this work, the frictional behavior is studied in dependence on the local joining process parameters. As a reference for the numerical investigations, clinch joints by means of a die with fixed geometry are joined. Additionally, a hardness mapping is performed on the microsection of the clinch joints. It shows the local strain hardening, which correlates with the forming degree in the simulation. Based on the occurring contacts and the local joining process parameters in the joining process simulation, the test matrix for the experimental friction tests is defined. The friction tests are carried out on a compression-torsion-tribometer. This type of tribometer is able to apply high interface pressures above the initial yield stress due to the specimen encapsulation. Besides, the pure joining part contact, the contact between the joining part and joining tool can be tested as well. The experimental test setup offers the possibility to evaluate the influences of temperature, relative velocity, interface pressure, and frictional stroke independently. Based on the results of the experimental friction tests, a friction model is created. The resulting friction model is integrated into the numerical joining process simulation via a subroutine. To validate the quality of the new friction modeling, the results of simulations are compared with the experiments in terms of load-stroke diagrams, joint geometry, and hardness mappings on the microsection.

Radar Interferometric Experimental Reconstruction of Three-Dimensional Displacement Vectors and Mode Shapes for Masonry Constructions

Abstract Radar interferometry is an innovative measurement technique capable of remotely measuring vibrations in terms of displacement history. It apparently allows overcoming some major drawbacks of the plodding and time-consuming conventional accelerometric experimental setup for vibration testing. Indeed, radar interferometry does not require any access to the structure; moreover, its use is simpler and faster. Therefore, this technique appears very appealing for ambient vibration testing on structures, and in particular on architectural heritage masonry constructions. However, radar interferometry is still affected by some relevant limitations, that currently outweigh the advantages. One of the most important limitations is that displacements are measured only along the line-of-sight; therefore, it is not possible to determine the whole three-dimensional displacement vector for moving structural points and, consequently, to reconstruct three-dimensional mode shapes of structures, whose knowledge is crucial for characterizing the dynamic behavior of structures and for detecting eventual damages. In this paper, a theoretical and experimental approach for reconstructing both three-dimensional displacement vectors and mode shapes of masonry constructions is proposed. This approach is based on the simultaneous use of two synchronized radar interferometers, and on the application of a theoretical model assuming a specific kinematical constraint, which is generally plausible in the case of masonry constructions. The proposed approach has been validated through in-situ experimental tests on a masonry bell tower.

Non-invasive internal pressure measurement of 18650 format lithium ion batteries during thermal runaway

The dynamics of 18650 format lithium ion battery pressure build-up during thermal runaway is investigated to inform understanding of the subsequent pressure-driven venting flow. Battery case strain and temperature were measured on cells under thermal abuse which was used to calculate internal pressure via hoop and longitudinal stress relations. Strain measurement is a non-invasive approach with no impact on the chemical decomposition within batteries that leads to thermal runaway. The experimental methodology and test apparatus were developed and validated through predictable, representative test specimens of open cases and pressurized gas cylinders. Live battery experiments reliably captured the final pressure rise before venting onset. The pressure build up was observed to coincide with the beginning of thermal runaway.