Standard Rolling Research Articles

Load Capacity Estimation of Elliptical Contact Rolling Bearings

Bearing affiliation load capacity is one of the most important aspect while designing the bearings or while selecting it for applications. It has high influence on fatigue life prediction. Various international standards are normally used to calculate bearing load capacity; however, these standards are with predefined approaches only for the bearings with standard rolling elements and do not support for bearings with non-standard shape of rolling elements. To achieve higher load carrying capacity from elliptical contact bearing, a new bearing with concave rolling element geometry has been conceptualized and designed by the first author. The study in this paper explores different methods available for arriving at the load ratings and develops a numerical calculation; finite element analysis approach; for estimating the static and dynamic load ratings of new bearing design - high capacity elliptical contact concave roller bearing, which also called as deep groove roller bearing. The methodology is validated with the bearings that has standard shape of rolling element and known the load rating i.e. deep groove ball bearings. The numerical approach accounts the Hertzian contact pressure and orthogonal shear stresses for load rating estimation. Predicted load ratings are evaluated and compared across the results estimated from different tools

Understanding the short-term aging of warm mix asphalt using rolling thin film oven

Standard Rolling thin film oven (RTFO) test at 163°C for 85 minutes has been investigated and revised to represent the short-term aging of the warm mix asphalt (WMA) binder which is mixed and aged at lower temperature. Because of wide mixing temperature and variation in duration of storage and paving time, field short-term aging differs significantly. To simulate the reduced aging of WMA binders in the laboratory, series of RTFO tests were conducted on two binders at three different temperatures and for four aging periods. Short-term oven aging (STOA) of mix was performed for the same time duration at those three RTFO aging temperatures. A RTFO aging model was developed correlating the rheological properties of STOA mix. Following the aging model developed in this study aging temperature and duration can be selected for RTFO testing to simulate aging effect that a binder experiences in STOA of mix. It is observed that the change in aging index of binder follows a linear relationship with aging time, and the rate of change of the aging index changes linearly with temperature. This study also affirms that STOA of mix exhibits more sensitivity to temperature than that of RTFO aging of binder. Investigation of plant and laboratory mix depicts that very small portion of mix aging occurs during mixing phase however, main portion of short-term aging occur during the storage of plant mix or oven aging of laboratory mix. Because of wide mixing temperature RTFO aging test protocol need to be adjusted.

Numerical and experimental investigation on material flow in gear forced throughfeed rolling process

The cylindrical die forced throughfeed rolling process for gears was proposed to overcome an end-effect behavior of the standard radial-feed gear rolling process which can result in pitch variation and excessive axial end-flow. In the rolling process, the workpieces are pushed through the gap of the rolling tools to form the gear teeth. Understanding of material flow is important for grasping the cause of defect formation and improving the quality of formed gears. In this paper, the material flow behavior of the gear forced throughfeed rolling process was studied on the flow velocity and displacement of key locations by using finite element analysis (FEA). The experiment was also conducted and its blank was sliced to thin pieces, and the grid pattern (GP) was utilized to track the trajectory of flowing materials. The results show that the end-flow is located at the root rather than the tooth crest of the formed workpiece, because the compressive forces from rolling tool mainly take effect at the root of the formed workpiece. The asymmetry of circumferential flow displacements with respect to the gear teeth results in the asymmetrical flanks defect, and this is due to the meshing between teeth of rolling tool and workpiece. The local displacement in the radial direction is larger than that in the circumferential direction.

(149) What Exercise Interventions Might Combat Pain and Flexibility after Sedentary Activity in College Students?

Sedentary activity is a concern for students and can decrease lumbar range of motion (LROM) and increase lower back pain (LBP). Standard foam rolling is a popular intervention to increase ROM; however, vibrating foam rollers are relatively unexplored for their potential to combat pain and inflexibility after sedentary time. This study compares 3 interventions (self-paced walking [W], foam rolling [R], or vibrating foam rolling [VR]) on pain and flexibility in college students after sedentary activity. Healthy students (18-26 years) were recruited for 1 session. Participants sat x 50 minutes and completed the International Physical Activity Questionnaire [IPAQ]) and homework. Post-Sedentary self-reported pain (Visual Analog Scale [VAS]), LROM for flexion (F) and extension (E) via Modified-Modified Schober Test (MMST), and hip ROM for extension (EXT), internal rotation (IR), and external rotation (ER) were measured. Participants were randomly assigned to a 15-minute intervention of either W, R, or VR with 1-on-1 instruction. Post-Intervention and final pain, LROM and hip ROM were measured. Changes in pain, LROM and hip ROM were compared via ANOVA and post-hoc Bonferroni (p

A model for hybrid bearing life with surface and subsurface survival

Hybrid bearings have rings made of steel and rolling elements made of bearings grade silicon nitride ceramic. Due to the higher modulus of elasticity of ceramic compared to steel, the ellipse of the Hertzian contact is slightly smaller than that in a conventional bearing. This results in about a 12% increase in the contact pressure between the ceramic ball and the raceway. Following the standard Rolling Contact Fatigue theory, a higher contact pressure leads to a reduction of the dynamic load-carrying capacity and service life of the bearing. However, long experience in the use of hybrid bearings shows that, in most applications, hybrid bearings clearly outperform traditional bearings made entirely out of steel.This paper addresses this issue by applying a novel approach to Rolling Contact Fatigue. Central to the new method is the survival probability of the raceway surface which is explicitly formulated into the basic life equations of the rolling contact. This allows tailoring the contribution of the stress system close to the rolling surface to better represent the ceramic-steel interaction, which has been proven to be substantially more favourable in the case of a hybrid ceramic-steel contact. The comparison between experimentally obtained hybrid bearings fatigue lives and lives predicted using the new calculation model indicates good agreement.It is found that an increase of the fatigue resistance of the raceway surface of hybrid bearings can, in most cases, compensate for the additional stress present in the subsurface region of the rolling contact. The new methodology, by providing a direct account of the survival probability of the ceramic-steel interface gives a better representation of the expected performance of hybrid bearings, opening new opportunities for the reliable use of this type of bearing in modern machinery.

A Phase 2 Study of Ruxolitinib with Chemotherapy in Children with Philadelphia Chromosome-like Acute Lymphoblastic Leukemia (INCB18424-269/AALL1521): Dose-Finding Results from the Part 1 Safety Phase

Background: Philadelphia chromosome-like acute lymphoblastic leukemia (Ph-like ALL) is a high-risk subtype occurring in 15-30% of older children and adolescents/young adults (AYAs) with B-ALL. Ph-like ALL is associated with high relapse rates and poor survival despite intensive multi-agent cytotoxic chemotherapy. Development of successful treatment strategies to decrease relapse and improve cure rates in patients with Ph-like ALL remains a major therapeutic gap.Rearrangements of cytokine receptor-like factor 2 (CRLF2-R) with frequent concomitant JAK2 point mutations occur in 50% of Ph-like ALL cases and induce constitutive JAK/STAT and other kinase signaling. An additional 15-20% of Ph-like ALL harbors other JAK pathway alterations, such as JAK2 or EPOR rearrangements, that similarly activate JAK/STAT signaling. Ruxolitinib is a potent, selective JAK1/JAK2 inhibitor with demonstrated activity in preclinical Ph-like ALL models and clinical safety as monotherapy in children with relapsed/refractory cancers. We report the initial safety of ruxolitinib in combination with post-induction chemotherapy in children and AYAs with newly-diagnosed high-risk (HR) Ph-like ALL with CRLF2-R or other JAK pathway alterations treated on the non-randomized, 2-part phase 2 study INCB18424-269 (AALL1521; NCT02723994).Methods: Patients aged 1-21 years at time of diagnosis with HR B-ALL and eligible Ph-like genetic lesions who had completed 4-drug induction chemotherapy as per the Children's Oncology Group (COG) AALL1131 study (NCT02883049) were eligible to participate. Patients were stratified into 4 cohorts by genetic alterations and end-induction flow cytometric minimal residual disease (MRD) status: cohort A = CRLF2-R JAK-mutant, MRD+; B = CRLF2-R JAK-wild-type, MRD+; C = other JAK pathway alterations, MRD+, D = any CRLF2-R or JAK pathway alteration, MRD-. Patients commenced treatment on the INCB18424-269/AALL1521 study at consolidation with ruxolitinib orally twice daily in combination with augmented Berlin-Frankfurt-Münster (aBFM) post-induction chemotherapy as per AALL1131. Five discontinuous dose levels (10-50 mg/m2/dose 14-days-on/14-days-off per cycle [DL-2 to DL2]) and one continuous DL1b (40 mg/m2/dose × 28 days per cycle) of ruxolitinib with aBFM chemotherapy were explored via a standard rolling 6 design. Dose-limiting toxicities (DLTs) were assessed through Day 29 of delayed intensification (DI) and defined as hematologic and non-hematologic toxicity with higher grade or more prolonged duration than observed in children with treated with identical chemotherapy (without ruxolitinib) on other COG HR B-ALL trials. Pharmacokinetic (PK) and pharmacodynamic (PD) analyses were conducted using serial blood samples obtained from patients during consolidation therapy.Results: Forty patients (pts) were enrolled in Part 1 (cohort A, n=10; B, n=9; C, n=5; D, n=16). Four patients discontinued study treatment before the Day 29 DI timepoint, 3 of whom were replaced. Patients had a median age of 14 years, and 67.5% were male. Treatment-emergent adverse events occurred in all patients and included anemia (75%), platelet count decrease and/or thrombocytopenia (65%), febrile neutropenia (72.5%), and AST or ALT increase (57.5%). Thirty-three patients had Grade 3/4 events deemed possibly related to ruxolitinib without identified DLTs. Eleven patients in Part 1 (27.5%) discontinued study therapy for various reasons: CNS relapse (2 pts), end-consolidation MRD+ (4 pts), multi-system organ dysfunction (MSOD; 2 pts), elective MRD- stem cell transplantation (1 pt), psychosocial/compliance issues (2 pts). One patient died of septic shock and MSOD not attributed to ruxolitinib. Preliminary analysis of plasma drug levels at 4 hours post-dose was consistent with the known PK profile of ruxolitinib. PD studies demonstrated dose-dependent inhibition of target phosphoproteins and, importantly, sustained inhibition of phosphorylated STAT5 with continuous ruxolitinib dosing at DL1b.Discussion: These findings demonstrate safety and tolerability of ruxolitinib in combination with intensive multi-agent chemotherapy in children and AYAs with newly-diagnosed HR CRLF2-R/JAK pathway-mutant Ph-like ALL and support continued investigation of treatment efficacy in Part 2 of this trial. DisclosuresTasian:Aleta Biopharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Research Funding; Incyte Corporation: Research Funding. Assad:Incyte Corporation: Employment, Equity Ownership. Hunter:Incyte Corporation: Employment. Du:Incyte Corporation: Employment.

Comparing in- and out-of-sample approaches to variance decomposition-based estimates of network connectedness an application to the Italian banking system

We use methods that exploit variance decompositions from standard (rolling window) estimates of VAR(p) models to obtain estimates of network connectedness and perform an empirical comparison of the results derived under two alternative approaches: To base the decompositions on in-sample forecast errors vs. out-of-sample forecast errors derived from a separation between estimation and forecast evaluation window. Using the intraday realized variance of bank stock return, we derive novel empirical results on the systemic risk of the Italian banking system, whose network connectedness turns out to be generally high, increasing over time especially during the Great Financial and the European sovereign debt crises. However, whether a few net exporters of systemic risk may be reliably estimated turns out to depend on the methodology adopted when computing rolling window variance decompositions.

Quasi-LPV modelling of a projectile’s behaviour in flight

The behaviour of a projectile in flight is usually described by the Newton-Euler equations of motion, through a nonlinear model structure. Its transformation into a quasi-LPV form often requires the model to be simplified, or analysed only as a set of locally linearized approximations of the system. Consequently, the region of validity of the model is reduced. In this paper, the aim is to develop a less restrictive modelling approach, based on two main steps. Firstly, the nonlinear model is described w.r.t. a so-called non-rolling reference frame, which allows to reduce the model complexity while preserving its accuracy. Then, a quasi-LPV model is developed using an analytical function substitution method, where the scheduling variables correspond to the values which are measurable or observable during real-world experiments. Consequently, a model whose validity is not restricted to an equilibrium manifold is created. The validation of the quasi-LPV model developed in a non-rolling frame, w.r.t. the nonlinear one developed in a standard rolling frame, is performed through a series of simulations.

Ceramic Bearings for Electric Motors: Eliminating Damage with New Materials

Since the advent of variable frequency drive motors, standard rolling element bearings have been failing from electrical arcing because of stray electrical currents in the motors. This article will explore the damage mechanism in the bearings and introduce the use of ceramic rolling element bearings to eliminate this issue. Case histories will be provided.

A Bending Test for Determining the Atterberg Plastic Limit in Soils.

The thread rolling test is the most commonly used method to determine the plastic limit (PL) in soils. It has been widely criticized, because a considerable subjective judgment from the operator that carries out the test is involved during its performance, which may affect the final result significantly. Different alternative methods have been put forward, but they cannot compete with the standard rolling test in speed, simplicity and cost. In an earlier study by the authors, a simple method with a simple device to determine the PL was presented (the "thread bending test" or simply "bending test"); this method allowed the PL to be obtained with minimal operator interference. In the present paper a version of the original bending test is shown. The experimental basis is the same as the original bending test: soil threads which are 3 mm in diameter and 52 mm long are bent until they start to crack, so that both the bending produced and its related moisture content are determined. However, this new version enables the calculation of PL from an equation, so it is not necessary to plot any curve or straight line to obtain this parameter and, in fact, the PL can be achieved with only one experimental point (but two experimental points are recommended). The PL results obtained with this new version are very similar to those obtained through the original bending test and the standard rolling test by a highly experienced operator. Only in particular cases of high plasticity cohesive soils, there is a greater difference in the result. Despite this, the bending test works very well for all types of soil, both cohesive and very low plasticity soils, where the latter are the most difficult to test via the standard thread rolling method.

Investigation of two Warm Mix Asphalt additives

In order to address pertinent issues in relation to the use of Warm Mix Asphalt (WMA) in pavement construction, it is imperative to understand the effects that such additives have on rheological and failure properties in service. In this study, two commercial WMA additives, a proprietary siloxane-based compound and an oxidized polyethylene wax, were added to a soft Roofing Asphalt Flux (RAF), a soft Recycled Engine Oil Bottom (REOB) tainted binder, and a somewhat harder binder containing 20% oxidized asphalt derived from Recycled Asphalt Pavement (RAP). Binders were aged according to standard Rolling Thin Film Oven (RTFO) and Pressure Aging Vessel (PAV) protocols. Selected compositions were subjected to a period of extended PAV aging for 40h. Standard and advanced rheological and failure tests were used to predict the performance of these binders in service. Dynamic Shear Rheometer (DSR) and Bending Beam Rheometer (BBR) tests according to Superpave™ protocols were done to determine performance grades. Extended BBR (EBBR) and Double-Edge-Notched Tension (DENT) tests were done to provide further insights into durability and strain tolerance, properties of utmost importance to assure long term pavement performance. The findings of this study show that the addition of the oxidized polyethylene wax WMA additive to REOB and/or RAP tainted systems can provide binders that are unstable and likely prone to premature and excessive low temperature failure in service. In contrast, the siloxane-based WMA additive appears to be a better choice to avoid premature low temperature and fatigue cracking distress.

Estimating Security Betas Using Prior Information Based on Firm Fundamentals

We propose a hybrid approach for estimating beta that shrinks rolling window estimates toward firm-specific priors motivated by economic theory. Our method yields superior forecasts of beta that have important practical implications. First, unlike standard rolling window betas, hybrid betas carry a significant price of risk in the cross-section even after controlling for characteristics. Second, the hybrid approach offers statistically and economically significant out-of-sample benefits for investors who use factor models to construct optimal portfolios. We show that the hybrid estimator outperforms existing estimators because shrinkage toward a fundamentals-based prior is effective in reducing measurement noise in extreme beta estimates.

Molecular Beacon Enables Combination of Highly Processive and Highly Sensitive Rolling Circle Amplification Readouts for Detection of DNA-Modifying Enzymes

Here we present an optimized readout format for detection of the circularized products from a DNA-based sensor for measurement of DNA-modifying enzymes including DNA Topoisomerase I. The basic design of the DNA-sensor relies on the use of a substrate that can be circularized by the activity of DNA-modifying enzymes like type IB Topoisomerases and subsequently amplified by a rolling circle amplification (RCA) mechanism. The RCA process can be followed in real-time by the addition of a molecular beacon with a fluorophore/quencher pair. Upon hybridization to the amplified product, the fluorophore/quencher pair is separated, giving rise to a fluorescent signal, measurable in pseudo real-time using a qPCR machine or in a fluorimeter. The RCA products in complex with the molecular beacon can subsequently be moved to microscopic slides and analyzed in a fluorescence microscope. We describe the proof of the principle of this molecular beacon-based method combining the qPCR readout format with the standard Rolling circle Enhanced Enzymatic Assay previously reported. Although the qPCR setup is less sensitive, it allows easy, fast, and high-throughput measurement of enzyme activities. Human Topoisomerase IB (TopIB) is a well-known target for the clinically used anticancer drugs of the camptothecin family. The cytotoxic effect of camptothecins correlates directly with the intracellular TopIB activity affecting reversibly the Topoisomerase/DNA cleavage complexes. Therefore, we envisioned that the presented method may find use for the prediction of cellular drug response and for drug screening to discover novel molecules that specifically inhibit TopIB or other DNA-modifying enzymes.

Vibro-acoustic propagation of gear dynamics in a gear-bearing-housing system

This work developed a computational process to predict noise radiation from gearboxes. It developed a system-level vibro-acoustic model of an actual gearbox, including gears, bearings, shafts, and housing structure, and compared the results to experiments. The meshing action of gear teeth causes vibrations to propagate through shafts and bearings to the housing radiating noise. The vibration excitation from the gear mesh and the system response were predicted using finite element and lumped-parameter models. From these results, the radiated noise was calculated using a boundary element model of the housing. Experimental vibration and noise measurements from the gearbox confirmed the computational predictions. The developed tool was used to investigate the influence of standard rolling element and modified journal bearings on gearbox radiated noise.

Understanding white etching cracks in rolling element bearings: The effect of hydrogen charging on the formation mechanisms

Among prevalent tribological failures, notably in rolling element bearings for wind turbines, an unusual rolling/sliding contact fatigue failure mode has been identified as white etching cracks. White etching cracks are broad subsurface three-dimensional branching crack networks bordered by white etching microstructure, eventually leading to flaking. Reproduction of the failure mode on standard rolling element bearings test rigs has not been mastered yet except with artificial hydrogen charging. Even though these failures have been reported for several decades, there is no evident common denominator in different occurrences. Hence, initiation and propagation mechanisms are not yet fully understood in application. Analyses of the contact conditions of a standard rolling element bearings test rig reproducing white etching cracks on standard and hydrogen precharged inner rings reveal that hydrogen charging seems to modify the white etching cracks initiation mechanism. Based on fractographs, serial sectioning, and scanning electron microscopic analyses, surface initiation and propagation mechanisms are proposed, including influent drivers and possible preventive techniques.

Effect of Waste Engine Oil Residue on Quality and Durability of SHRP Materials Reference Library Binders

This paper discusses the effects of widely used waste engine oil (WEO) residue on asphalt binder properties. Five SHRP Materials Reference Library binders and one commercial material from Ontario, Canada, were modified with 15% WEO. Materials were aged according to a standard rolling thin film oven protocol followed by 20 and 40 h of pressure aging vessel (PAV). Binder quality was determined according to AASHTO specification M 320 as well as dynamic shear characterization. Durability was assessed after additional conditioning at high temperature in the PAV and at low temperature in the bending beam rheometer. All but one of the WEO-modified materials transitioned to a gel-type state more readily upon chemical and physical conditioning; this result explains the poor thermal cracking performance seen for such binders on Ontario roads.

A Computationally Efficient and Adaptive Approach for Online Embedded Machinery Diagnosis in Harsh Environments

Condition-based monitoring (CBM) has advanced to the stage where industry is now demanding machinery that possesses self-diagnosis ability. This need has spurred the CBM research to be applicable in more expanded areas over the past decades. There are two critical issues in implementing CBM in harsh environments using embedded systems: computational efficiency and adaptability. In this paper, a computationally efficient and adaptive approach including simple principal component analysis (SPCA) for feature dimensionality reduction and K-means clustering for classification is proposed for online embedded machinery diagnosis. Compared with the standard principal component analysis (PCA) and kernel principal component analysis (KPCA), SPCA is adaptive in nature and has lower algorithm complexity when dealing with a large amount of data. The effectiveness of the proposed approach is firstly validated using a standard rolling element bearing test dataset on a personal computer. It is then deployed on an embedded real-time controller and used to monitor a rotating shaft. It was found that the proposed approach scaled well, whereas the standard PCA-based approach broke down when data quantity increased to a certain level. Furthermore, the proposed approach achieved 90% accuracy when diagnosing an induced fault compared to 59% accuracy obtained using the standard PCA-based approach.

Effect of rolling with shear technology on structure, properties, and plasticity of low-carbon steel

In this study, the authors have proposed and developed a new forming process—rolling with shear (RS-technology) characterized by volume stressed state with severe plastic deformation. A hereditary effect of the rod structure on the physical–mechanical properties and structure of wire made by RS-technology has been investigated and compared with the standard technology used at OJSC ArcelorMittal Kryviy Rih. It has been shown that RS-technology allows us to improve the quality of the wires and reduce power consumption. It is possible because of increased plasticity, after deformation, by RS-technology instead of standard rolling processes.

Numerical Modelling of the Microstructure during Rolling of Flat Bars

This paper presents theoretical analysis of microstructure changes in the material during standard rolling and normalizing rolling of the 35x20 mm flat bars. The analysis was carried out by means of computer software Forge 2007® that is based on finite element method. Two cases of accelerated cooling during rolling process were considered. Numerical results of 35x20 mm flat bars rolling process allowed to determine the average recrystallized austenite diameter as well as basis energy and force parameters. Proposed modification of the 35x20 mm flat bar rolling technology with accelerated cooling results in the reduction of average austenite diameter, which could improve the strength of the final product.

Fatigue life of double row slewing ball bearing with irregular geometry

Standard procedure for bearing life calculation, as described in standard ISO281:2008, was developed for standard, rather small axial or thrust rolling bearings. Since the geometry and manufacturing procedures of large rolling slewing bearings are considerably different from those of standard rolling bearings, different calculation procedures have to be used. The paper describes a computational procedure, where the geometry of the bearing is described with vectors, which enables modelling of irregular shapes of the bearing rings. These can be a result of the manufacturing procedure or of the deformations caused by the operating conditions. The calculation procedure consists of calculation of the maximum contact force on the rolling element, which is done by the in-house developed program, and detailed finite element analysis of the contact between the ball and the raceway. The finite element analysis also takes into account depth-dependent material parameters of a raceway. Different calculation theories are then used for the calculation of fatigue life, and a comparison of the results is made at the end.