Customized Test Rig Research Articles

Enhancing the Elastohydrodynamic Lubrication and Vibration Behavior of Rolling Bearings Using a Hybrid Bio-Grease Blended with Activated Carbon Nanoparticles

In recent years, bio-lubricants have received a growing interest for industrial applications. Still, a full-scale implementation in machinery lubrication requires a thorough evaluation of their performance through tribological and operational tests to stand upon their performance. Additionally, the promising outcomes achieved by nanoadditives in improving the performance of synthetic lubricants have prompted research efforts to identify suitable nanoadditives for bio-grease. This paper introduces a bio-grease from a hybrid vegetable oil and glycerol monostearate as a thickener for the lubrication of rolling bearings. Activated carbon nanoparticles (ACNPs) as nanoadditives were synthesized, characterized, and incorporated into the bio-grease at concentrations of 0.5, 1, and 2% by weight. Tribo-tests were conducted on these bio-grease blends, and running tests were carried out using 6006 ball bearings on a custom test rig. Throughout a 30-min test run under a radial load of 10% of the bearing’s dynamic load rating, mechanical vibrations and power consumption were measured and analyzed for each bearing. The bio-grease with ACNPs exhibited a substantial reduction in wear scar diameter (WSD) and coefficient of friction (COF), achieving improvements of up to 73.6 and 65%, respectively, in comparison to lithium grease. Furthermore, the load carrying capacity was enhanced by 200%. The study revealed a strong correlation between measured vibration amplitudes and the viscosity of the bio-grease. The absence of high frequency resonant bands in vibration spectra indicated that the test grease samples satisfied the conditions of elastohydrodynamic lubrication, and these findings were corroborated through calculations of the minimum oil film thickness.

Developing a sustainable grease from jojoba oil with plant waste based nanoadditives for enhancement of rolling bearing performance

This paper presents a novel grease from jojoba oil and activated carbon nanoparticles (ACNPs) extracted from banana peel waste. The raw jojoba oil and ACNPs are first characterized for structural properties. Samples of jojoba grease blended with 0.5 and 1.5 wt. % ACNPs are prepared and tested for physicochemical and tribological properties as compared to plain jojoba grease. Adding ACNPs to jojoba grease improves corrosion resistance from grade 2c to 1a while increasing the dropping point from 100 to 109 °C. ACNPs enhanced the viscosity of jojoba oil by up to 33% for testing temperature range of 40–100 °C. The load-carrying capacity of jojoba grease is increased by about 60% when blended with 1.5 wt.% ACNPs. The same blending decreased both the coefficient of friction and the wear scar diameter by 38% and 24%, respectively. A customized test rig is used to test the effectiveness of the grease samples in rolling bearing lubrication in terms of vibration levels and power consumption. The novel jojoba grease proved to show exceptional reductions power consumption reaching 25%. The vibration spectra show the absence of resonant peaks at high frequencies suggesting the capability of jojoba grease to form a stable full film lubrication.

Novel performance enhancement of straight blade vertical axis wind turbines through cross-flow fan integration

In this study, a novel technique for enhancing the output power of Vertical Axis Wind Turbines (VAWTs) is introduced through the integration of a cross-flow fan (CFF) for active flow control, a first-of-its-kind approach. The CFF, positioned on the airfoil's trailing edge, employs suction to regulate flow separation. A thick airfoil with a 35% thickness-to-chord ratio is utilized to accommodate the CFF. A VAWT, featuring a diameter of 1 m and a height of 0.5 m, is designed, fabricated, and subjected to experimental testing in a wind tunnel. Additionally, a standard NACA 0018 wind turbine with identical dimensions and solidity is manufactured for performance comparison purposes. A custom test rig is developed to measure turbine output, encompassing a fixation mechanism, torque measurement system, and a mechanical brake mechanism for load variation. The impact of the CFF on the wind turbine performance is investigated by measuring turbine static torque due to the fan, fan motor power consumption, turbine torque, and rotational speed across various wind speeds. Power assessments are conducted to estimate the real turbine power increase, taking into account the power consumed by the fans. A fan map is generated to determine the optimal conditions and rotational speeds for fan operation.

ANALYSIS OF THERMAL CRACK FORMATION IN WATER-CHARGED AIR-COOLED HEAT EXCHANGERS FOR HEAVY-DUTY VEHICLES

The non-uniform flow distribution at the inlet severely affects the thermal cycling loading of the water-charged air-cooled (WCAC) systems resulting in crack formation after periods and hence leakage in the internal coolant. WCAC cracks are serious since having crucial effects on performance and durability. The thermal crack can be identified by testing the WCAC for various fatigue boundary conditions. The present study developed a custom thermal fatigue test rig to precisely determine the crack formation's location and cycle time in WCACs. The test rig was designed to reflect the vehicle's situation by simultaneously controlling the air and waterside of the WCAC continuously. Accordingly, the thermal fatigue tests of the WCAC parts were performed through the developed custom thermal fatigue test rig. The formation crack was observed periodically by carrying out tests with different critical cycles on the test rig, and the thermal cycling profile was generated. It was seen that the crack formation in the WCAC can be predicted at the same cycle time and exact location with the developed custom test rig compared to the vehicle tests. Moreover, the total cost, time, and man-hours per test increased by 80 %,75 %, and 60, % respectively, compared to traditional vehicle tests. Subsequently, the modified WCAC design was proposed to prevent non-uniform flow distribution at the inlet of the WCAC. The thermal fatigue tests of the modified WCAC design were performed using the developed test rig for stressful operating conditions. The results showed that the modified WCAC design is more robust to thermal fatigue than the old design. There was no crack formation in the modified WCAC design under various stressful operating conditions.

Design and Fabrication of Micro Saw Enabling Root-Side Cutting of Bone

A novel micro saw was fabricated using a combination of photolithography and electroplating techniques, resembling a miniature timing belt with sideways blades. The rotation or oscillation direction of the micro saw is designed to be perpendicular to the cutting direction so that transverse cutting of the bone is attainable to extract a preoperatively planned bone-cartilage donor for osteochondral auto-graft transplantation. The mechanical property of the fabricated micro saw obtained using the nanoindentation test shows that the mechanical properties of the micro saw are almost an order of magnitude higher than bone, which indicates its potential bone-cutting application. To demonstrate the cutting capability of the fabricated micro saw, an in vitro animal bone cutting was performed using a custom test rig consisting of a microcontroller, 3D printer, and other readily available parts.

Fault diagnosis of rolling element bearing using continuous wavelet transform and K- nearest neighbour

Rotating machines are a common class for machineries in industries and one of the root cause of failure of these machines are faults in rolling element bearing (REB). Therefore, to prevent machinery performance degradation and malfunctioning, an effective bearing fault diagnosis technique is vital. So, the use of different machine learning techniques proposes a new method of diagnosing REB defects. Machine learning (ML) method namely K-nearest neighbour (KNN) is used to classify different types of REB faults. In this article, vibration signals are acquired from a customized test rig for three conditions of deep groove ball bearings: Normal (N), defect on Inner Race (IR) and defect on Outer Race (OR) at different loads and maximum speed. Continuous Wavelet Transform (CWT) has been applied to the acquired signal and Seventeen Time Frequency Domain (TFD) statistical features were extracted from CWT coefficients. KNN classifier is trained using these TFD. The classification accuracy on test data i.e., 83.3% reveals that KNN can be effectively used to classify different conditions of REB.

MEMS Vibrometer for Structural Health Monitoring Using Guided Ultrasonic Waves

Structural health monitoring of lightweight constructions made of composite materials can be performed using guided ultrasonic waves. If modern fiber metal laminates are used, this requires integrated sensors that can record the inner displacement oscillations caused by the propagating guided ultrasonic waves. Therefore, we developed a robust MEMS vibrometer that can be integrated while maintaining the structural and functional compliance of the laminate. This vibrometer is directly sensitive to the high-frequency displacements from structure-borne ultrasound when excited in a frequency range between its first and second eigenfrequency. The vibrometer is mostly realized by processes earlier developed for a pressure sensor but with additional femtosecond laser ablation and encapsulation. The piezoresistive transducer, made from silicon, is encapsulated between top and bottom glass lids. The eigenfrequencies are experimentally determined using an optical micro vibrometer setup. The MEMS vibrometer functionality and usability for structural health monitoring are demonstrated on a customized test rig by recording application-relevant guided ultrasonic wave packages with a central frequency of 100 kHz at a distance of 0.2 m from the exciting ultrasound transducer.

A custom designed modular, scalable test system for an efficient performance evaluation of thermoelectric devices

• A modular, scalable test rig capable of evaluating unicouple, devices and modules. • Ability to handle most thermoelectric (TE) performance evaluation criterion’s including real-world endurance high temperature thermal cycling, thermal soaking and identifying defective devices is demonstrated. • Evaluated three different TE systems viz. Bismuth Telluride, Skutterudites and Half Heusler alloys across different temperature gradients. • Single software platform interacting with DAQ with special features like automatic temperature stability control, high vacuum control, inert gas purging to minimize high temperature oxidation/sublimation of TE device. Reliable and efficient performance evaluation of thermoelectric (TE) elements and devices is critical for developing high performance and robust thermoelectric generator. Due to the inherent thermomechanical coupling, testing thermometric devices is a challenge and requires design of customized test rigs for a thorough evaluation. This article discusses design and development of a modular, scalable customized test rig for performance evaluation of TE devices of different proportions. Various standard TE specifications like harvested power, specific power, instantaneous device resistance, power–current relationships, device efficiency/competence measured against time/temperature difference can be readily evaluated. Further, the test rig is also employed for mimicking real-world endurance thermal cycling tests, high temperature thermal soaking and using measured data to potentially identifying defective devices which have not been addressed in detail before. All these test results together can help determine the effectiveness of TE materials in an actual real world application setting. The scalability and robustness aspects of the proposed test rig is demonstrated by evaluating three different classes of TE systems viz. Bismuth Telluride, Skutterudites and Half Heusler alloys across different temperature gradients and various TE material/legs, devices or modules. The test is capable of handling other TE material systems, geometric configurations and temperature gradients that are not discussed in this work.

A methodology to assess mixer performance for selective catalyst reduction application in hot air gas burner

The active SCR aftertreatment system is one of the most crucial technology for the NOx reduction of diesel engines. One of the essential parameters of this technology is the urea spray performance on the catalyst. This study presents an experimental and numerical investigation of urea spray behavior used in the heavy-duty diesel engine's selective catalytic reduction (SCR) aftertreatment systems.The custom test rig is designed and built to simulate exhaust aftertreatment systems of heavy-duty diesel vehicles. Urea injector parameters were observed in this test rig with optic windows for spray and flow visualization. This test rig is available to simulate diesel engines in the sense of exhaust mass flow rate, temperature and spray control unit. The discussion is made about the effects of droplet size of spray and velocity distribution upon flow characterization.A detailed assessment of the numerical model was presented, and validation was carried out for different interest measurement locations. The predicted droplet size distributions, breakup performance, and velocities are numerically and correlated with the experimental data. The validated model is subsequently used to study the urea-flow mixing dynamics to develop a urea mixer numerically. Test results show that smaller droplets enhance the mixing and thus catalyst efficiency. Mixer design performance can be assessed numerically in the droplet size break up based on the developed criteria called mixer performance criteria. Upstream and downstream of the mixer, droplet size can be extracted from the simulation, and different mixer designs can be compared in terms of the breakup performance.

INTEGRATION OF THE SIMULATION AND TEST METHODOLOGIES TO DESIGN NOVEL EXHAUST MANIFOLD RIG

Computer Aided Engineering is an effective tool utilized to drive an exhaust manifold design by early assessment within the engine program development phase. However, in the end, for exhaust manifold design verification, various tests must be performed in engine dynamometer cells under severe operating conditions. The test running durations are up to 2500 hours for the heavy-duty (HD) exhaust manifold. Therefore, the validation tests are expensive and time-consuming. Alternative ways are sought to replace these expensive tests for cost reduction purposes and more efficient dynamometer cells. Thus, the custom test rig is designed and built. This system contains the burner system supplying hot gas at a similar temperature and mass flow ranges with the engine. The drawback of the burner system is, it runs in steady-state mode, so very challenging to replicate the engine's pulsating flow effect exactly. Therefore, with the coupling of Star-CCM+ and Modefrontier, the CAE study is carried out to assess the feasibility of obtaining similar manifold skin temperature distribution in the burner test cell with engine conditions. It is aimed to determine the correct valve opening positions regulating the mass flow rate through the runners. This innovative methodology reduces the trial-and-error count in the experiment phase.

Force attenuation capacity of weft-knitted spacer fabric in low-velocity impact

PurposeThis study aimed to determine the peak impact force and force attenuation capacity of weft-knitted spacer fabrics intended for padding that can be used for human body protection against impact.Design/methodology/approachA total of five weft-knitted spacer fabrics were fabricated with four different diameters of nylon monofilament yarns and one doubled monofilament yarns, respectively. The impact performances of the weft-knitted spacer fabrics were tested using a drop test method with a customized test rig to simulate falling. Impact tests were conducted on single- and multilayered experimental spacer fabrics to investigate the peak impact force and force attenuation capacity.FindingsIt was found that weft-knitted spacer fabric with a coarser or larger diameter of monofilament spacer yarn generated lower impact force and higher force attenuation capacity, thus resulting in better impact performance. Greater force attenuation can be achieved by utilizing a higher number of spacer fabric layers. However, the increase in thickness must be considered with the spacer fabric end use.Originality/valueThis study employed relatively coarse nylon monofilament yarn as spacer yarns to gain knowledge on the impact performance of weft-knitted spacer fabrics compared to warp-knitted spacer fabrics which are more common. The results showed that the diameter of spacer yarn significantly influenced the impact performance of the experimental weft-knitted spacer fabrics. These results could be useful for designing and engineering textile-based impact protectors.

Utilization of Bracing Arms as Additional Reinforcement in Pultruded Glass Fiber-Reinforced Polymer Composite Cross-Arms: Creep Experimental and Numerical Analyses.

The application of pultruded glass fiber-reinforced polymer composites (PGFRPCs) as a replacement for conventional wooden cross-arms in transmission towers is relatively new. Although numerous studies have conducted creep tests on coupon-scale PGFRPC cross-arms, none had performed creep analyses on full-scale PGFRPC cross-arms under actual working load conditions. Thus, this work proposed to study the influence of an additional bracing system on the creep responses of PGFRPC cross-arms in a 132 kV transmission tower. The creep behaviors and responses of the main members in current and braced PGFRPC cross-arm designs were compared and evaluated in a transmission tower under actual working conditions. These PGFRPC cross-arms were subjected to actual working loads mimicking the actual weight of electrical cables and insulators for a duration of 1000 h. The cross-arms were installed on a custom test rig in an open area to simulate the actual environment of tropical climate conditions. Further creep analysis was performed by using Findley and Burger models on the basis of experimental data to link instantaneous and extended (transient and viscoelastic) creep strains. The addition of braced arms to the structure reduced the total strain of a cross-arm’s main member beams and improved elastic and viscous moduli. The addition of bracing arms improved the structural integrity and stiffness of the cross-arm structure. The findings of this study suggested that the use of a bracing system in cross-arm structures could prolong the structures’ service life and subsequently reduce maintenance effort and cost for long-term applications in transmission towers.

Acoustic response of high-speed deep groove ball bearing by modifying the internal geometry

In this paper, a mathematical model to predict acoustic responses of high-speed bearing has been developed and demonstrated in an application of Induction motors. Effect on the acoustic behaviour of bearing has studied by modifying the internal geometry, such as the number of rotating elements, curvature ratio, rotating speed with the oval shape of the track raceway due to pre-operational damage. The mathematical model predicts the contact stress, elliptical contact area, noise level dB and Frequencies of waviness pattern. High-speed bearing is tested at four different speeds to monitor acoustic behaviour. This drive end bearing undergoes different rotational speeds; however, the author has simulated the results at a majorly driven constant speed. The author has incorporated application-level testing at the customized test rig. The mathematical model has simulated using coupled governing equations with the help of the Ranga-Kutta method. The simulation and experimental results presented in this paper in the form of a waterfall diagram, FFT spectrum and colour pressure plots. Acoustic characteristics during measurements of the rolling bearing have shown systematically to correlate the mathematical model with an experimental result. Results indicate the remarkable influence of raceway nonconformities of bearing on the noise level. The novelty of research study is to estimate the amplitude of noise level due to waviness generated on rings of bearing after pre-operation damage which is the realistic scenario that occurred after a complaint recorded by the motor manufacturer. The authors believe that this technique enables the bearing designer to choose the appropriate diametric ratio of the ball and track curvature for elliptical contact stress as well as acoustic level. This method is developed specifically for an application of drive-end position ball bearing. Practical use of this method is to determine the Noise level of an electric motor (up to 60 kW capacities) due to improper handling and inappropriate installation of bearing which cause inherent waviness on components.

Low-cycle Fatigue Fracture of Stranded Ropes in Pantographs for Electrically Driven Trucks

AbstractFractured wire ropes of a pantograph actuator system for electrical trucks were received from the client. They failed by low cycle fatigue (LCF) fracture during service in a customized test rig. The client reported wide scatter of the number of testing cycles to failure. A laboratory order was placed for a metallurgical failure analysis of the subject stranded ropes, this to derive recommendations for design improvements, so that the minimum number of cycles to failure could be increased, and the scatter decreased.

Macro-Scale Tread Patterns for Traction in the Intestine.

Tread patterns are widely used to increase traction on different substrates, with the tread scale, geometry and material being tailored to the application. This work explores the efficacy of using macro-scale tread patterns for a medical application involving a colon substrate - renowned for its low friction characteristics. Current literature was first summarized before an experimental approach was used, based on a custom test rig with ex vivo porcine colon, to assess different macro-scale tread patterns. Performance was based on increasing traction while avoiding significant trauma. Repeated testing (n = 16) was used to obtain robust results. A macro-scale tread pattern can increase the traction coefficient significantly, with a static traction coefficient of 0.74 ± 0.22 and a dynamic traction coefficient of 0.35 ± 0.04 compared to a smooth (on the macro-scale) Control (0.132 ± 0.055 and 0.054 ± 0.015, respectively). Decreasing the scale and spacing between the tread features reduced apparent trauma but also reduced the traction coefficient. Significant traction can be achieved on colon tissue using a macro-scale tread but a compromise between traction (large feature sizes) and trauma (small feature sizes) may have to be made. This work provides greater insight into the complex frictional mechanisms of the intestine and gives suggestions for developing functional tread surfaces for a wide range of clinical applications.

Experiment to Investigate the Relationship Between the Third-Body Layer and the Occurrence of Squeals in Dry Sliding Contact

Braking is an energy dissipation mechanism used to restrict the movement of vehicles. Friction brakes may induce vibrations and noise. These effects constitute a major shortcoming related to the functioning of friction braking systems. Known as brake squeal, this phenomenon involves unstable vibrations induced by coupling modes between components in frictional contact leading to large amplitude vibrations. Despite significant progress in experimental techniques and numerical modeling, the origin of squeal occurrence remains misunderstood and is still a matter of debate. It is, however, commonly admitted that squeal is affected by many different factors on both micro and macro scales. In addition, a close correlation between wear and squeal occurrence in braking system has been reported. This study examines linking the change in the third-body layer with the occurrence of squeals in sliding dry contact. A simplified customized test rig was used with a transparent glass disc and an artificial alumina third-body. Results show that squeal occurrence is strongly linked to the densification and redistribution of the third-body, as well as internal flows in the interface.

Machine Learning Driven Image Analysis of Fine Grinded Knife Blade Surface Topographies

The optical perception of high precision, fine grinded surfaces plays a major role, especially in various consumer goods. The very complex manufacturing process of cutlery consists of a variety of parameters such as feed rate, cutting speed, grinding disc, cutting fluid, contact force or process time. The change of a parameter setting has a direct effect on the surface topography. Therefore, a standardized and optimized configuration of process parameters enables a desired quality of a product.In this study, the image analysis of the fine grinded surface is performed. For this reason, a customized test rig is designed in the first step. Here, constant boundary conditions such as defined light, specified camera settings, and a fixation ensuring the proper positioning of the samples are considered and determined for the further, computational analysis. The gathered image material serves as the training data for the machine learning analysis.The image of each grinded sample is analyzed concerning the measured roughness (Ra and Rz) and gloss value subjected to the corresponding production parameters based on Computer Vision (CV) techniques. Above all, Neural Networks as well as inductive methods are used for the image analysis. Additionally, the color data (L*a*b color space) is extracted using CV and serves as additional information for the further analysis.The application of the methodology is shown within the real case study.

Sliding friction and wear behavior of winding hoisting rope in ultra-deep coal mine under different conditions

Wear problems exist in multi-layer windings of ultra-deep coal mine hoisting ropes that are wound around drums. Wear decreases the life of such hoisting ropes directly, and that in turn threatens mine safety. An investigation of winding hoisting ropes was conducted using a custom test rig to study the effects of different contact loads, crossing angles and displacement amplitudes on rope friction and wear. Results show that the coefficient of friction (COF) in the steady-state period changes very little with an increase in contact load and that it stabilizes at about 0.61. Additionally, the COF slightly decreases with an increase of crossing angle. As the amplitude of sliding motion increases to 30mm and 50mm, the COF increases linearly. Using thermal imaging, the temperature rise in the steady-state period increases with the contact load and crossing angle. Moreover, the maximum wear depth increases linearly with an increase of contact load. Nevertheless, the wear depth changed very little when the amplitude is less than 30 mm, but it increases rapidly until an amplitude of 70mm. The major wear mechanisms of ropes without lubrication include adhesive wear, abrasive wear and fatigue wear.

Brush Seal Structural Analysis and Correlation With Tests for Turbine Conditions

Bristle tip contact forces and resulting stress levels under engine conditions are critical for optimizing brush seal performance as well as for achieving operational safety. Literature survey reveals the lack of test data and analysis methods for evaluating seal stiffness and stress levels under operating conditions. In an attempt to meet this need, a custom test rig design and methodology have been developed to perform stiffness tests under pressure and rotor speed of 3000 rpm. Finite element (FE) simulations have been performed for brush seals and results have been correlated with the test data of this study. Considering the critical importance of contact loads on brush seal overall performance and system health, and due to the complicated structure of brush seals, where bristles are contacting with each other as well as with the backing plate and the rotor, computer-aided engineering (CAE) analyses with high fidelity is required to simulate the test and turbine operating conditions. For this purpose, FE methodology has been developed for structural analyses of brush seals. Three-dimensional FE models of brush seals have been constructed and simulations have been performed for pressurized rotor-rub conditions. CAE model of brush seals includes rotor–bristle, bristle pack–backing plate, and interbristle contacts with friction. Simulations with nonrotating rotor and transient analyses with rotating rotor have been conducted, and the extracted bristle tip force (BTF) levels are correlated with the test results. Inertial effects during dynamic tests have also been simulated through transient analyses and results show good agreement with the dynamic test data. Displacement and stress profiles obtained from correlated FE models give better understanding of brush seal behavior under turbine operating conditions.

An Experimental Investigation into the Onset of Smearing Damage in Nonconformal Contacts with Application to Roller Bearings

The onset of smearing damage was studied under controlled conditions in a custom test rig that simulates the passage of a rolling element through loaded and unloaded zones of a rolling bearing. The setup includes a spherical roller that is intermittently loaded between two bearing raceways driven at a prescribed speed. The roller is free to accelerate during the loading phase. Contact load, roller speed and acceleration, and electrical contact resistance are recorded during the test. Contact shear stress, friction coefficient, frictional power intensity, and elastohydrodynamic film thickness are calculated from the recorded kinematics data. Results suggest that the first onset of smearing occurs early in the loading phase where the roller is near stationary and the frictional power intensity is high. The raceway speed at the onset of damage decreases with increasing load and increasing lubricant supply temperature. The maximum frictional power intensity is found to be relatively constant at all contact conditions that led to smearing. An existing thermomechanical contact model is used to estimate the contact temperature distribution under smearing conditions and the potential for elastohydrodynamic lubrication (EHL) film thickness reduction due to forward heat conduction.