Gear Effect Research Articles

Microstructural evolution and mechanical behavior of Mg/Al laminated composite sheet by novel corrugated rolling and flat rolling

AZ31B Mg/5052 Al laminated composite sheet with superior mechanical property and good sheet shape was fabricated by novel corrugated roll/flat roll corrugating rolling and flat roll/flat roll flat rolling (CFR) at elevated temperatures. The microstructural evolution and mechanical behavior variation of the composite sheet under CFR hot rolling condition were investigated by experimental and numerical simulation methods. The results show that first-pass corrugated rolling induces relatively high and inhomogeneous shear strain in the Mg side and various corrugated interface positions at a low reduction of 35%. It leads to significant grain refinement, outstanding basal texture modification as well as tensile twin activation Mg alloy, which perfectly coordinates the plastic deformation between hard-to-deform Mg and ductile Al and achieve the strong interface metallurgy bonding in Mg/Al sheet and also significantly improves the mechanical properties of Mg/Al composite sheet. The annealing before second-pass flat rolling causes the pronounced static recrystallization and grain growth of Mg alloy in corrugated-rolling Mg/Al sheet, and the formation of ~25 μm thick interfacial compound layer consisted of Mg17Al12 and Al3Mg2 two sublayers. Second-pass flat rolling with a reduction of 30% further imposes severe inhomogeneous shear deformation on the composite sheet, which results in the formation of a wave-shape three-dimensional bonding interface, and the interface compound layers cracking at peak and waist interface positions or fragmenting into well-aligned discrete particles to the bonding interface, in addition to substantial matrix microstructure refinement, texture modification and twin activation in Mg alloy. Such interface structure greatly enhances the interface bonding force of the Mg/Al composite sheet by the larger interface contact area, mechanical gearing effect as well as particle pinning effect. Hence the significant microstructural refinement, strong interface bonding and low residual stress induced by CFR process account for the excellent performance of the Mg/Al laminated composite sheet.

Effect of installation errors on beveloid gears’ precision ground by cone-shape worm wheel

Both the mathematical model of a cone-shape worm wheel and the mathematical model of cone-shape worm wheel grinding beveloid gears with installation errors of a gear workpiece and a cone-shape worm wheel are developed. The effect of the installation errors including gears’ incline error, eccentric error, mounting angle error of a cone-shape worm wheel and coupling error of installation errors mentioned on gears’ surface deviation is investigated. The sensitivity of tooth surface deviation to installation errors mentioned is analyzed. The results show that the helix slope deviation, helix total deviation and tooth cumulative pitch deviation are more sensitive to gears’ incline error. The tooth cumulative pitch deviation, profile total deviation, profile slope deviation are more sensitive to gears’ eccentric error. The effect of gears’ incline error and eccentric error on cumulative pitch deviation and individual cumulative pitch deviation is inverse which lead that coupling error including gears’ incline error and eccentric error causes smaller cumulative pitch deviation and individual cumulative pitch deviation compared to gears’ incline error or eccentric error. Moreover Effect of the mounting angle error of cone-shape worm wheel on gears’ surface deviation is very limited.

Design and Analysis of a Novel Dual-Stator Cylindrical Linear Vernier Machine With LTS Field Windings

The cylindrical linear vernier machine (CLVM), in which the magnetic gearing effect is adopted, is a specific kind of the linear vernier machines (LVMs) and is suitable for the direct-drive applications that both low speed and high thrust are demanded at the same time. In order to further improve the thrust density of the LVMs, a novel dual-stator CLVM with low-temperature superconducting field windings (DCLVM-LTS) is proposed and analyzed in this paper. The operation principles of the DCLVM-LTS will be introduced in the paper by the analysis of the air-gap flux density. The superiorities of the proposed DCLVM-LTS are calculated by the finite element method. Compared to a DCLVM with PM arrays, the thrust density of the proposed DCLVM-LTS exhibits a considerable improvement in terms of thrust density, power factor, and economy efficiency.

A Novel HTS Claw-Pole Vernier Machine Using Single Excitation Unit With Stationary Seal

This paper proposes a novel high-temperature super-conducting (HTS) claw-pole vernier machine, which combines the merits of stator HTS-excitation machine with the “magnetic gearing effect” designed for direct-drive applications. The key is to adopt claw-pole stator structure to realize the multi-pole pattern using single HTS-excitation unit with stationary seal, thus greatly simplifying the cooling Dewar architecture as well as improving the structural compactness. Moreover, the armature windings are wound around the split-teeth which are set on the surface of claw poles to achieve the physical separation from the HTS-excitation coil, thus reducing their space conflicts and impact with each other. The operation principle analysis and the initial machine design are conducted in details. By using the three-dimensional finite element analysis, the machine performances are evaluated, and its validity is verified.

Gear junctions between chiral boron nitride nanotubes

A gear effect is demonstrated at parallel and cross junctions between boron nitride nanotubes (BNNTs) via atomistic simulations. The atoms of neighboring BNNTs are meshed together at the junctions like gear teeth through long-range non-covalent interaction, which are shown to be able to transmit motion and power. The sliding motion of a BNNT can be spontaneously translated to rotating motion of an adjoining one or viceversa at a well-defined speed ratio. The transmittable motion and force strongly depend on the helical lattice structure of BNNTs represented by a chiral angle. The motion transmission efficiency of the parallel junctions increases up to a maximum for certain BNNTs depending on displacement rates. It then decreases with increasing chiral angles. For cross junctions, the angular motion transmission ratio increases with decreasing chiral angles of the driven BNNTs, while the translational one exhibits the opposite trend.

Different blends of biodiesel, bioethanol, diesel and noise pollution emitted by stationary and moving MF285 tractor.

Given the significance of the relationships between human beings, environment, machines and ergonomics as well as the necessity of using renewable fuels, the present study aimed to investigate the effects of different blends of biodiesel, bioethanol and diesel on noise pollution emitted by a MF285 tractor in stationary and moving modes by the aid of statistical methods. In this respect, the emitted noise was measured using the noise dosimeters and sound level meters in the driver and the bystander's positions, at 1000, 1600 and 2000 RPM in both stationary and moving modes. Then, nine fuel blends of biodiesel, bioethanol and diesel with different volumetric percentages as well as pure diesel were studied. To study the effects of key factors on noise pollution, the factorial experiment was conducted in the form of a completely randomized design, followed by the application of the SPSS Statistics Software Version 19.0. The fuel type nearly affected the noise pollution at the level of 5%, and other factors such as engine rotational speed and the fuel type-engine rotational speed interaction influenced it at the level of 1%. In both the driver and bystander's positions, the minimum and maximum noise pollution occurred at 1000 and 2000 RPM, respectively. The effects of gears along with their twofold and threefold interaction with other factors were not significant. Finally, the results of the present study demonstrated that the B25E4D71 fuel, composed of 25% biodiesel and 4% bioethanol, had the lowest noise pollution.

Durability and design parameters of a Steel/PEEK gear pair

The parameters necessary for the reliable design of PEEK gears were determined. The effect of a steel gear's surface on the polymer gear's wear was investigated. Values for the wear coefficient of a steel/PEEK gear pair in dry and lubricated conditions are proposed. Testing showed that, on average, grease lubrication extends the lifespan of PEEK gears by a factor of 1.23, while the additional treatment of steel gears with trovalisation and lubrication extends the lifespan by a factor of 2.54. Temperature measurements were used to determine the coefficient of friction that is required to compute the operating temperature of a steel/PEEK gear pair. Using numerical simulations it was found that a proper tooth tip relief can improve the meshing and results in a further extension of the gear's lifespan.

A Consequent-Pole PM Magnetic-Geared Double-Rotor Machine With Flux-Weakening Ability for Hybrid Electric Vehicle Application

Electric continuously variable transmission (e-CVT) device is a key component in hybrid electric vehicles (HEVs), which serves to perform the energy transmission among the initial combustion engine, battery, and output shaft. This paper presents a novel consequent-pole PM magnetic-geared double-rotor machine (CPDRM) that utilizes the magnetic gearing effect to transmit the power with a high efficiency. The artistry of CPDRM is to insert a dc winding within the center of the stator on the circumferential direction. Therefore, the machine can extend the constant-power region by changing the current direction and amplitude of dc windings. Meanwhile, the flux density within the air gap is changed accordingly. Then, the working principle of CPDRM and the flux change process are illustrated by employing the magnetic circuit method. Finally, a finite-element method model is constructed to verify the performances of the CPDRM under different operating modes. The result shows that the proposed machine has an excellent flux-weakening ability, and it can serve as a suitable candidate as an e-CVT component for HEVs.

The effect of aquaculture gear on the growth and shape of the oyster Crassostrea virginica during a “finishing period” in Chesapeake Bay, USA

Growth of the oyster aquaculture industry on the US east coast has accelerated in recent decades due to advances in breeding technologies and grow-out methods. As the industry grows, competition in the market place is likely to increase attention to product quality, for example, shell conformation and meat content. This study investigated how gear type and tidal zone location influenced shell shape and product quality of Crassostrea virginica during a four month “finishing” period at an oyster farm on Fishing Creek MD on the eastern shore of Chesapeake Bay. For these experiments, a mix of sub-market sized, triploid oysters from two local farms were deployed in four gear treatments that varied in water column location and exposure to wave action: OysterGro™ floats, a rack and bag system, a bottom cage placed in the intertidal, and a bottom cage placed subtidally, which represents the ‘control’ treatment (no change of gear type for finishing). Shell height, length, width, and weight (total and wet meat) were measured each month from August to December 2015 and an index of shell shape relative to an idealized 3-2-1 ratio of height to length to width was calculated. Overall, oysters grew well in all gear types (3.0–-4.8 mm increase in shell height per month) and experienced relatively low mortality (4–8% across treatments) – mean height of oysters from each gear treatment exceeded market size by the end of the experiment. Gear treatment had a significant effect on oyster height and weight at the end of the experiment (P < 2.0e–05) and the OysterGro™ treatment produced the largest gains in growth compared to all other treatments (2.3-2.5 fold– increase in wet or total weight). Gear type also affected shell shape (P = 0.023), with significantly lower mean 3-2-1 ratio deviations (more ideal, rounded shells) in the OysterGro™ compared to subtidal bottom cage or rack and bag gear. Shell shape improved the most between initial and final time points for the OysterGro™ treatment, while the rack and bag and bottom cage subtidal treatments showed no improvement. This study provides some of the first data on growth performance and shell shape using the OysterGro™ system in Chesapeake Bay and overall, results indicate that floating gear such as the OysterGro™ system may be a valuable method to finish oysters, facilitating good growth, and improving shape over a relatively short period of time.

Analysis of Stator/Rotor Pole Combinations in Variable Flux Reluctance Machines Using Magnetic Gearing Effect

The torque production of variable flux reluctance machines (VFRMs) is explained by the “magnetic gearing effect” in recent research. Based on this theory, this paper concludes the general principles for feasible stator/rotor pole selection and corresponding winding configuration for VFRMs. The influence of stator/rotor pole combination on torque performance is comprehensively investigated not only in terms of average torque and torque ripple, but also in terms of each single torque component. It is found that the synchronous torque is proportional to the fundamental rotor radial permeance component and has the dominant contribution in average torque for all the VFRMs. The stator slot number and rotor pole number should be close to each other to achieve the highest output torque. Meanwhile, the 6-stator-slot/(6 i ± 2)-rotor-pole (6s/(6 i ± 2)r) and their multiples are large torque ripple origins for VFRMs due to the large reluctance torque ripple. Also, it is proved that a lower stator slot number is preferable choice to obtain higher torque/copper loss ratio, whereas a higher stator slot number is more suitable for large machine scale scenario. Finally, the analyses and conclusions are verified by finite element analysis on the 6-, 12-, 18-, and 24-stator-slot VFRMs and by experimental tests on a 6s/7r and 6s/8r VFRMs.

Comparative Analysis of Variable Flux Reluctance Machines With Double- and Single-Layer Concentrated Armature Windings

In this paper, the variable flux reluctance machines (VFRMs) with double- and single-layer concentrated armature windings are comparatively analyzed. First, the single-layer winding is found to have an identical winding factor as a double-layer winding, but significantly larger peak value of magneto-motive force, which will result in severe local saturation in cores of VFRMs with single-layer winding. Then, based on the magnetic gearing effect and finite-element analysis, the electromagnetic performances of VFRMs with both winding types are compared. The VFRMs with single-layer winding are proved to be always lower in average torque, higher in torque ripple, larger in iron loss, and lower in efficiency than those with double-layer winding. Nevertheless, better fault-tolerance capability is achieved for a single-layer winding due to its physical separation between phases and larger phase self-inductance. Overall, the double-layer armature winding is the preferable choice for the VFRMs. Finally, a 6-stator-slot/4-rotor-pole VFRM with both double- and single-layer windings is prototyped for verification.

Permanent magnet vernier machine: a review

Permanent magnet vernier machines (PMVMs) gained a lot of interest over the past couple of decades. This is mainly due to their high torque density enabled by the magnetic gearing effect. This study will provide a thorough review of recent advances in PMVMs. This review will cover the principle of operation and nature of magnetic gearing in PMVMs, and a better understanding of novel PMVM topologies using different winding configuration as well as different modulation poles and rotor structures. Detailed discussions on the choice of gear ratio, slot–pole combinations, design optimisation and role of advanced materials in PMVMs will be presented. This will provide an update on the current state-of-the art as well as future areas of research. Furthermore, the power factor issue, fault tolerance as well as cost reduction will be discussed highlighting the gap between the current state-of-the art and what is needed in practical applications.

Effects of Detailed Aircraft Geometry on Wake Vortex Dynamics During Landing

The final approach and touchdown of a landing aircraft is studied numerically with different hybrid Reynolds-averaged Navier–Stokes (RANS)/large-eddy simulations (LES) approaches. Particular emphasis is put on the ground effect and the wake vortex evolution before and after touchdown. Additionally, the effect of the landing gear on the aircraft’s aerodynamics during landing is analyzed. The near field around the landing aircraft is generated using two different RANS methods. In a number of steady-state simulations the altitude of the aircraft above ground was varied in fixed steps. Furthermore, a simplified continuous landing maneuver was simulated by applying unsteady RANS simulations. The resulting RANS fields are then coupled with an LES simulation using three different approaches. The computed vortex circulation is compared with aircraft measurements. As a result it can be seen that the new transient hybrid approach provides physically reasonable results. The landing gears have a notable effect on the aircraft’s drag, as well as on the wake footprint. However, the effect on the wake vortex circulation evolution is moderate. Remarkably, the simulations with landing gear show a strong coherent vortex, merging late with the main vortex. A particular emphasis is put on the comparison with light detection and ranging (LIDAR) measurement data collected in a recent campaign at Vienna airport. The vortex structures predicted by the simulations are clearly visible in those measurements. Simulated tangential velocity profiles are compared with vortex model profiles. It is observed that standard vortex models fail to capture the complex vortex structures emerging during the landing process but can be improved including mirror vortices.

Noise reduction effect of molded plastic gears with crowning tooth profile

Noise reduction effect of molded plastic gears with crowning tooth profile

Investigation of Dual-Stator Spoke-Type Vernier Machine for EV Application

Recently, vernier machines have been nominated for EV applications numerously [1]–[3]. The attractive features of vernier machine for EV applications are a reduction of volume due to the removal of gearbox [4], and high power density owing to magnetic gear effect, also called as vernier effect. However, one of the critical issues for vernier machine on EV application is the low power factor. To enhance power factor of vernier machine, various methods and topologies were suggested continuously [5]. Especially, one stator-spoke type vernier machine was suggested to increase power factor with the use of flux focusing effect. However, it had flux bypass issue that reduced vernier effect [6]. To solve the issue, dual stator spoke type vernier machine (DSSTVM) uses dual stator to permit flux as additional flux path [7]. DSSTVM eventually realized flux focusing effect to boost torque thus high power factor. However, the study of DSSTVM had been limited to the combination of 12 slots and 20 poles [8]. In this paper, the comparative study of different slot/pole combination DSSTVMs with different winding configurations to find a suitable model for the EV application is done. Power density per volume and weight is a critical feature for light weighted EV. Additionally, good flux weakening capability for wide speed range and high efficiency for less energy usage is required for future EV application. Hence, comparisons of different models of DSSTVM with the aspect of back-emf, torque, power density, power factor, loss, and efficiency are done. The top priority of the work was to find the best model for EV application in overall performance and to discover various trade-off relationships for each machine with differences they are given. Finite element method (FEM) analysis is utilized for the overall performance comparison.

Characteristics Analysis of Doubly Fed Magnetic Geared Motor Considering Winding Frequency Conditions

The magnetic geared motor, which has improved torque density because of the magnetic gearing effect, has been researched. However, its narrow operating region due to the operating mechanism by the magnetic gearing effect and field flux by the PM is a challenge that needs to be overcome. Whereas, the doubly fed magnetic geared motor (DFMGM) can extend the operating region because of the double stator and double winding structure with the individual frequency control of the current fed to the inner and outer windings. However, two rotating magnetic fields, which are produced by the inner and outer winding flux, exist at the air-gap, and the large numbers of space harmonic components of the modulated flux density are produced at the air-gaps. These space harmonic components, which are produced by the winding MMF, influence not only the back-EMF of the winding but also the performances of the operating torque. Besides, the inner and outer windings affect each other in the back-EMF, and its characteristics appears differently in the inner and outer windings. Thus, in this paper, the structure, operating strategy, and basic characteristics according to the frequency condition in the inner and outer windings are presented.

Impacts of a multi-trap line on benthic habitat containing emergent epifauna within the Mid-Atlantic Bight

Abstract Alteration and degradation of benthic structure by fishing gear can impede efforts to manage fish stock sustainably. Although the impacts of mobile gear are well known, effects of passive gear (e.g. fish traps) upon structure have been little studied. We modified commercial traps for American lobster Homarus americanus and black sea bass Centropristis striata by attaching GoPro® cameras to ascertain the degree and nature of impacts to seafloor habitats. Customized traps were included within a line of 20 traps, deployed and retrieved according to standard commercial fishing practice. Less than 5% of traps landed directly on bedforms when deployed. However, during retrieval traps dragged along the ocean floor, increasing trap–habitat contact rate to 50%, and causing traps to collide with corals, bryozoans, and other epifauna. Drag time of traps depended on the position in the trap line. Experimentally extending the trap line reduced drag time during retrieval for traps near the distal end of the line. Our results show that impacts of commercial trap fishing can be substantial during trap retrieval, and that the impact depends on their location on a trap line. Fishing practices should be developed that minimize effects of trap retrieval on structural benthic habitat.

Magnetic Gearing as a Functional Principle in Electric Drives

The partitioned stator flux reversal machine (PS-FRPM) is a novel stator PM machine topology, which exhibits a higher torque capability than its single stator counterpart and the conventional permanent magnet synchronous machine (PMSM). The PS-FRPM consists of two stators, one which carries the armature winding, and one which is equipped with surface mounted permanent magnets. The rotor is sandwiched between the two stators. The separation of the stator allows a better utilization of the machine volume which results in a higher torque density. Furthermore, because the magnets are placed on a stationary component, they can be cooled effectively. Consequently, critical rare-earth materials can be saved.The structure of the PS-FRPM is very similar to that of magnetic gears. In this paper the torque production of a PS-FRPM is described by means of the magnetic gearing effect. First the magnetic gearing effect is introduced and then the corresponding analytics is transferred to the PS-FRPM. Based on Maxwell's stress tensor, the torque contributions of the individual space harmonics are determined. In contrast to conventional machines, the torque in PS-FRPM is produced by several space harmonics in both air gaps.

Otter Trawl Gear Effects On Estuary Ecosystems

Otter Trawl Gear Effects On Estuary Ecosystems

Reconstructing global marine fishing gear use: Catches and landed values by gear type and sector

The interaction between fishing gears and the marine environment define ‘fisheries,’ and the effect of gears on marine ecosystems and fish stocks has been the source of much debate. Here, we present the first summary of globally reconstructed fisheries catches by major gear categories for 1950–2014. We used the Sea Around Us reconstructed global catch database that accounts for reported and unreported fisheries catches, and associated all catches to a fishing gear category. We assigned all industrial (i.e., large-scale) fisheries catches to industrial gear categories by fishing country, taxon, year and the area of fishing. Additionally, we derived catches by individual small-scale gear types for the most-important small-scale fishing countries in each of nine regions around the world, and applied their gear use to similar countries in each of the regions, to serve as a preliminary small-scale catch-by-gear assignment that can be improved upon over time. The combination of these account for gear use for all marine fisheries globally. We found that two industrial gear types, bottom trawling and purse seining, jointly account for over 53% of all catches, while bottom trawling alone dominated discarded catches. In the small-scale sector, over 60% of catches were caught by gillnets, various line gear, and encircling nets. Small-scale fisheries contributed most to the value of landed catches, while industrial bottom trawlers were responsible for discarding large amounts of potentially valuable catches. Catches by purse seines fluctuated over time, mainly due to variability of the underlying species, e.g., anchovies and sardines. The distribution and scale of use of different fishing gears, combined with knowledge of their divergent environmental impacts should allow a new wave of research into the global impacts of fisheries.