Zeitschriftenartikel zum Thema „Gear Engagement Dynamics“

A numerical model is formulated to analyze the tooth contact dynamic load distribution and dynamic transmission error of a pair of spur gears under the influence of bearing elasticity and gearbox assembly errors. In the proposed model, the deformation of the tooth is computed by applying a combination of finite elements and contact mechanics. The elasticity of the bearings is represented with infinitesimal linear spring elements, while the shafts and gears except the teeth that are in engagement are assumed to be rigid bodies. Applying those assumptions, three sets of highly coupled governing equations representing the meshing teeth flexible behavior, gear-bearing assembly translation dynamics and gear rotation dynamics are derived. The resultant model is then used to predict the dynamical behaviors of the geared rotor system, tooth contact dynamic load, and dynamic transmission error. A set of parametric studies is also performed to analyze the gear dynamic response.

A control-oriented model of a typical four-speed automatic transmission is developed by using the bond graph modeling method. The planetary gear set model utilizes the Karnopp friction model for hydraulic and one-way clutches, in order to provide a favorable computing efficiency. The full gear set model is reduced for various phases of the park/reverse and park/drive engagements. The reduced gear set models and linearized torque converter model are used as a basis for an algebraic analysis of the engagement dynamics. The analysis is originally conducted for the basic case of fully applied brake, and it is then extended by an analysis of the influence of wheel dynamics in the brake-off case. The analysis results are verified by computer simulations and experiments.

Transient dynamic theory of the helical gear drive is investigated, and corresponding dynamics equations are derived. Based on parameterized language APDL of ANSYS, a parametric programming module for accurate modeling and automatic assembling of helical gear pair has been developed. The parametric modeling and transient dynamic analysis of a helical gear pair in a crane reducer are performed. Transient stresses and strains of the gear pair throughout the engagement process are obtained and the worst meshing location can be determined. Compared to the traditional static analysis, Simulation results of dynamic analysis are more accurate and reliable which provide the foundation for accurate estimation of the gear fatigue life.

Numerous dynamic models of spur gears, helical gears, bevel gears, and face gears can be found in various studies. However, studies that focus on the dynamic model of a double helical gear pair are quite limited. The author proposed a model of a double helical gear pair by only considering the axial vibration. The author did not consider the friction and multiple backlashes in the proposed model. The friction force of the tooth surface and backlash are important factors that can cause complex non-linear phenomena in gear pairs. Therefore, a dynamic model of a double helical gear pair that takes into consideration the axial vibration, friction and multiple backlashes is proposed. Firstly, based on the tooth contact analysis (TCA) of a double helical gear pair, the path of contact and meshing time from engagement to disengagement are obtained. The formula for determining the sliding friction coefficient is introduced. Based on TCA and the dynamic meshing force provided by the subsequent dynamics model of double helical gear pair, the sliding friction coefficient of the tooth surface is calculated. Secondly, the stiffness excitation, gear-into impact excitation and error excitation (including the axial displacement caused by the errors of manufacture and installation under low speed) are calculated according to the existing research results. Following this, a dynamic model of a double helical gear pair that takes into consideration the axial vibration, friction and multiple backlashes is both built and solved. Finally, an example is presented to verify the corresponding results.

Purpose. Development of a mathematical model of a heavy loaded gear transmission with a self-aligning drive gear; evaluation of the dynamic load on the gear transmission in the gear alignment process. Methodology. The calculation schematic and equations of the relative motion of the self-aligning drive gear are formed using the methods of rigid body dynamics. Analytical expressions for the gear self-alignment time, collision velocity during the alignment and dynamic load factor are obtained by integrating an ordinary differential equation. Methods of the linear theory for oscillations are used to determine the dynamic factor. Findings. The article investigates the state-of-art design and mathematical models of the self-aligning gear. An equation for the relative motion of the moving part of the gear has been formed using the methods of rigid body dynamics. It is shown that by using the proposed hypotheses, the movement of the gear can be reduced to rotation about the instantaneous axis. The influence of geometric and dynamic parameters of the ball mill drive on dynamic loads in the open gear transmission is investigated. The gear alignment speed dependences on the tooth mesh misalignment angle in the gear transmission and the inertial parameters of the gear have been obtained. The obtained dependencies were used to calculate the time and speed of the gear alignment in the open gear transmission of the ball mill 5.5 6.5 (central discharge ball mill). It is shown that in the real range of mesh misalignment angles and gear parameters, the time of the gear alignment is several orders of magnitude less than the time of teeth re-engagement. In the presence of the variable component of the mesh misalignment angle, the gear will constantly make a relative motion with strikes; depending on the current value of the mesh misalignment angle, the dynamic load on the gear transmission can be significant. It is shown that when assessing the efficacy of self-aligning gears, it is necessary to take into account a possible increase in dynamic loads. The dynamic factor and the load factor are calculated for the nominal value of the mesh misalignment angle in the open gear transmission of 5.5 6.5 ball mills. Originality. A mathematical model of the dynamics of a self-aligning gear transmission in heavy duty machine drives has been developed. A quantitative assessment of internal dynamic load factor in an open gear transmission of 5.5 6.5 ball mills has been carried out. Practical value. A method for determining the dynamic component of the load on a gear transmission containing a self-aligning drive gear has been developed.

With the respect of the phenomenon that gear teeth are broken in the gear-gear ring striking gear of un-connecting rod engine, this paper analyzes its movement rule, and applies the explicit integral finite element method to simulate its dynamics. It shows that the theory engagement of gear-gear ring conforms to the rule of epicyclic gear train, and the deviation of the phase angle caused by mismachining tolerance is the main reason why gear teeth are broken.

In gear applications where precipitous tooth failure mode such as scoring or scuffing has been avoided, “normal” wear becomes a life-determining factor. In this paper, sliding wear in spur gears, including the considerations of gear dynamics and rough-elastohydrodynamic lubrication, is analyzed. Formulas for equivalent wear rate and tooth wear profile along the line of action are derived. Results show that most materials are removed from both the addendum and dedendum tooth surfaces, and that the highest wear occurs at the beginning of an engagement. This high wear region corresponds to the root of the driving (pinion) teeth and the tip of the driven (gear) teeth. These analytical results correlate well with the practical evidences in AGMA documentation.

A significant number of failures, violation of smooth running, as well as exceeding the noise ranges raise the problem of the quality of engagement of the traction gear of the 2ES6 electric locomotive. The article presents an analysis of statistical data collected on planned and unplanned repairs of 2ES6 series electric locomotives operated on the Sverdlovsk railway. The positive dynamics of the growth of traction drive failures confirms the urgency of the problem. One of the main reasons for the loss of performance of the traction drive is the failure of the traction gear elements. The gearing quality is checked according to geometric parameters, which confirms an error in the design of the traction gear of the 2ES6 electric locomotive as an element of the traction drive. The recommended value of the overlap coefficient was exceeded, which leads to a violation of smoothness of the ride, exceeding the noise ranges, rapid wear and early failures. A method is proposed to reduce the number of failures in 2ES6 electric locomotives by increasing the displacement coefficients, at the initial stage, in order to reduce the quality of the gear ratio - the overlap coefficient.

In a modern vehicle design process, analytical tools are widely employed to complement experimental approaches for design evaluation. When effectively utilized, they lead to a reduced development time with improved vehicle performance. The development process of an automatic transmission (AT) system can benefit from an analytical representation which accurately captures AT shifting behaviours. In a typical AT system, friction components such as wet clutches and band brakes are utilized to alter planetary gear configurations for automatic shifting. Thus, an accurate representation of friction component dynamics is critical in predicting AT shifting behaviour. Engagement characteristics of friction components vary widely under different operating conditions. Although the basic engagement physics was identified in the 1970s, it is relatively recently that a predictive, yet computationally efficient model became available. This paper describes the first attempt to utilize a dynamic friction component model in drivetrain simulations. Specifically, a dynamic band brake model is implemented to predict the up-shift behaviour of a four-speed AT system under various operating conditions. Simulation results are qualitatively validated with experimental data obtained from a dynamometer test stand. The dynamic band brake model enhances the shift predictability of a drivetrain model and potentially allows analytical evaluation of shift quality and control strategy.

Wind turbine gearbox is the key component. Because of alternating loads caused by gear engagement, variations of wind speed and fluctuation of load, it is prone to get fatigue damage, which lead to the high failure rate and low life. In this paper, obtaining the stress time histories through multi-body dynamics simulation, then base on the simulation data, statistical processing load time histories by used rain flow counting method, the last is that estimating fatigue life of components, combined with P-S-N curves of parts material and linear cumulative damage law. The fatigue life prediction of each component in gearbox would be implemented by matlab programming. Through the fatigue analysis of a megawatt-class wind turbine gearbox transmission chain, the design was verified feasibility, but not economic, and it show that this method has certain reference value and potential for improvement.

Gear manufacturing error is one of the main sources of vibration and noise in gears; its influence on the dynamic transmission behaviour of gear systems is a research hotspot. In the current study on the effect of the manufacturing errors, the processing methods of the errors are mostly rough or hypothetical, so the analysis results cannot provide high reference value. This paper proposes a distinctive method to analyse the vibration response of helical gears in the presence of random manufacturing errors and modifications. The presented study performs tooth contact analysis (TCA) with the real tooth surface containing the random tooth profile error and the modification and performs loaded tooth contact analysis (LTCA) based on the superposition of the random pitch error and the initial gap between mating teeth obtained by TCA. Furthermore, the dynamic excitations, including time-varying mesh stiffness and meshing impact, are computed using the above-mentioned TCA and LTCA. The processing method for the manufacturing errors in this paper is reasonable and close to the actual situation of gear engagement. Using this proposed method, statistical analysis was carried out under machining accuracy grades 5, 6 and 7 to show the effect of the different distributions of random manufacturing errors on the gear vibration. The analysis results are of practical significance and provide references for the design and vibration control of gear drive systems.

This paper concentrates on modeling the gear transmission system using a three-dimensional finite-element approach for the acoustic radiation analysis and control. The combination of dynamic analysis and vibration response calculation for the gear engagement system can contribute to evaluate acoustic radiation. A case study of for gear engagement system internally excited with gear mesh fluctuation is presented in this research. Acoustic radiation quantity investigation has been carried out by Virtual.Lab Acoustics software. It can be concluded that numerical simulation is very important during gear system design and noise control.

The aim of the work is to create a computational and experimental method for the operational evaluation of the residual life of spur gears of technically complex products in the inter-repair period by conducting periodic vibration control. The proposed method is based on the main provisions of the theory of vibration-pulse diagnostics of gears developed in the Joint Institute of Mechanical Engineering of the National Academy of Sciences of Belarus. At the same time, the current value of the KV coefficient, which takes into account the internal dynamic load in the engagement of each gear, and its change during operation is determined based on the analysis of the time realizations of vibration accelerations. The main operation capacity criteria are the contact and bending strength of the teeth. An example of estimating the residual life of a gear pair is given that limits the reliability of a double-row planetary gear motor-wheel of a heavy-duty dump truck. The proposed method makes it possible at any stage of operation of a gear mechanism to assess the residual life of its gears, identify its most “weak” links, determine the probability of failure of the object, minimize the risk of accidents, optimize maintenance schedules, increase the inter-repair time. Thus, it is possible to organize highly effective monitoring of the reliability-limiting components of the technically complex products during operation and transition from planned preventive maintenance of machines to maintenance according to the actual condition.

A non-linear multi-rigid-body system dynamic modelling is developed for the automated clutch system in power transmission during clutch engagements, especially at sharp vehicle start-up, sudden engine flame-out, low driving speed and clutch plate overwearing. In order to guarantee an ideal dynamic performance of the clutch engagement, an adaptive optimal controller is designed by considering throttle angle, engine speed, gear ratio, vehicle acceleration and road condition. A non-linear model reference adaptive controller is utilized to prevent the engine from flame-out or fly-off effectively and the minimum value principle is also introduced to achieve an optimal dynamic performance of the non-linear system compromised in friction plate wear and vehicle drive quality. The optimal trajectory of the clutch engagement can be described in the form of explicit and analytical expressions and characterized by a deterministic and accurate control strategy instead of indeterministic and soft control techniques which need thousands of experiments. For validation of the controller, test work is carried out for the automated clutch engagements in a commercial car with a traditional mechanical transmission, a hydraulic actuator, a group of sensors and a portable computer system. It is shown through experiments that dynamic behaviours of the clutch engagement operated by the adaptive optimal control are more effective and efficient than those by a fuzzy PID control.

According to the principles of engagement and the mathematical model of non-circular gear tooth profile, the tooth profile of non-circular gear is draw. Then the three-dimensional model of the non-circular gear is created in Pro/E three-dimensional software to provide the basis for a non-circular gear motion analysis, dynamic analysis and finite element analysis.

The face gear drive is a gear meshing drive with cylindrical gear and bevel gear. Because of its small space, high contact ratio, large transmission torque, low vibration and noise, not sensitive to the axial phase error of the worm and so on, face gear transmission is widely applied. In the traditional gear transmission dynamic contact analysis (TCA), first, simulate the meshing equation; second, calculate the contact trajectory that is formed by the adherent point; last, solve each of the instantaneous contact areas and solve tooth contact region in meshing process. But it can’t solve the tail, diamond and other high contact defects. In the real mesh transmission, tooth meshing is very complex, including edges contact, multi-tooth engagement and many other issues. With the progress of the times, using finite element analysis software ANSYS, it will be able to simulate the dynamic contact analysis of the gear. In this paper, the offset face gear as the research object, with MATLAB program, Solidworks and ANSYS software, establish the mathematical model of the orthogonal offset face gear, simulate its geometric model in the three-dimensional software. Finally, implement the simulation of its dynamic contact meshing in the finite element analysis software.

In this paper, through generally using basic priniciple of heat transfer and gear, established the transient conduction differential equation and its definite conditions. On the basis of tribology and engagement theory, established the periodical boundary condition. Using ANSYS Programm, we analyzed temperature distribution of a spur gear operating under transient friction heat, and its periodical change. Simultaneously, we get the flash temperature distribution on the engaged surface of spur gear and its change curves. The basis for precisely studying its thermal deformation and profile modification is also established.

Automatic transmission gear shifts are handled by wet clutches, which determine the smoothness. The clutch face temperatures during the engagements are often an important parameter for the total clutch life. A wet clutch test rig has been used to evaluate how a wet clutch engagement can be improved in terms of smoothness and temperature. This was performed with control based upon knowledge about friction characteristics and dynamic performance. The parameters used for control were the drive torque and the normal force on the clutch. By drive torque shut-off and reduced normal force the torque variations were greatly reduced and the temperature rise was decreased by 37%. [S0742-4787(00)01601-5]

For a new type of bevel gear-logarithmic spiral bevel gear, which stress mechanical properties are studied during the meshing process. Three-dimensional meshing models of logarithmic spiral bevel gear are established by Pro/ E. Because its tooth trace is conical logarithmic spiral, the paper proposes a new modeling method and successfully constructs the engagement model. Based on this, the gear dynamic contact emulation analysis is operated with ANSYS/LS-DYNA software in order to obtain stress distribution in the process of tooth contact. The tooth contact stress and tooth root bending stress magnitude, stress distribution and variation of cloud are analyzed. Contacting engineering practice, the results are in-depth study. Thus it can provide the theory basis for design and the application of this kind of new bevel gear.

Coatings can significantly improve the load-carrying performance of a gear surface, but how they affect the vibration characteristic of the system is an urgent issue to be solved. Taking into account the nonlinear factors like the variable mesh stiffness, friction, backlash, and transmission error, a six-degree-of-freedom spur gear transmission system with coatings is presented. Meanwhile, the finite element method is applied to acquire the time-varying mesh stiffness of the coated gear pair in the engagement process. With the support of the time-history curve, phase curve, Poincare map, and fast Fourier transform spectrum, the dynamic characteristics and the effects of the coating elastic modulus on vibration behaviors of a gear transmission system are minutely dissected by using a numerical integration approach. Numerical cases illustrate that the dynamic characteristic of a gear transmission system tends toward a one-period state under the given operating condition. They also indicate that, compared with softer coatings, stiffer ones can properly enhance the transmission performance of the coated gear pair. Numerical results are also compared with previous studies, and can establish a theoretical basis for dynamic design and vibration control of the coated gear transmission system.

The meshing-stiffness of a helical gear pair is one of important parameters to study dynamic characteristics of gear transmission system. However, the equation to solve the meshing stiffness is very complex and difficult to get it. We put up with an improved method to quickly calculate the meshing stiffness through analyzing the meshing process and characteristics of the helical gear pair. The obtained time-variant meshing stiffness curve matches the theoretic stiffness curve very well. The result is shown that the method for calculating contact line based on the helical gear engagement process and characteristics, can be understand intuitively and easily.

According to the requirements of dynamic design for high-speed and heavy-loading marine gear, in view of slotting processing advantages, modification profile slotting cutter used to achieve modify high-speed and heavy-loading marine gear, and the modification profile of slotting cutter designed to the profile which consists of multiple segments of different profile shape profile angle, the modification profile angles of slotting cutter corresponding sections of involutes deduced using the profile angle error analysis theory, modification profile of slotting cutter precision designed based on engagement principle of slotting gear.

This paper describes a digital simulation of the vibration and impact in a dual drive branched gear system during the engagement and disengagement of the prime movers. A nonlinear transient response analysis is carried out to illustrate the influence of system inertia, the tooth backlash, rate of clutch engagement and disengagement, friction etc. on tooth separation and dynamic tooth loads. The simulation procedure which is based on the phase-plane-δ method provides a general and effective tool of analysis for this class of problems. The existence of an optimal backlash condition for the idle pinion, which minimizes the dynamic tooth load, is illustrated.

The mesh stiffness and contact ratio of gear drive are very important factors which have a great impact on the dynamic load. Contact ratio also affects the fluctuation and the mode of change of the mesh stiffness. In this research, a novel high contact ratio internal gear with a circular arc contact path is introduced. However, the irregular tooth profile of non-involute gear usually causes the numerical calculation to be more complex. To get the torsional mesh stiffness of a pair of internal spur gear, the two-dimensional finite element models of involute internal gear and high contact ratio internal gear are presented and compared. In addition, the influence of input torque on torsional mesh stiffness and contact ratio are analyzed. The mesh stiffness of a single tooth pair and the effect of different engagement positions on mesh stiffness are obtained and compared. Finally, experimental measurement of contact ratio is established by strain gauge technique. It is shown that the torsional mesh stiffness increases with the increase of input torque, and the greater the contact ratio, the smoother the gear drive.

Different from the common face gear pair fixed rotation motion between intersecting axes, the compound transmission of the curve-face gear is a new motion form, which can convert rotational motion into rotation and movement motion. To solve the contact fatigue life problem of this new motion form gear pair, a new contact fatigue life calculation method of the compound transmission curve-face gear pair was proposed. Based on the space gear engagement principle and the fracture mechanics theory, the theoretical contact fatigue model of the curve-face gear composite transmission was established. Considering that the contact load for every tooth is time-varying in the half-period of the curve-face gear, the contact fatigue life stage of the curve-face gear was divided into crack initiation and crack growth, and the crack growth fatigue life for each tooth was calculated using the finite element method. The curve-face gear pair was processed in the five-axis NC machining center and the compound transmission experiment platform of the curve-face gear was set up to measure the tooth surface dynamic contact stress, and the overall life of the curve-face gear was predicted. The comparison analysis between theoretical and experimental results verified the correctness of the theoretical contact fatigue calculation model.

An analytical investigation was undertaken of the dynamic loading and fatigue of the gear teeth of turbine generator turning gear mechanisms during engagement, using a nonlinear function of speed and load for the coefficient of friction, which was determined experimentally under stick-slip conditions and considering backlash. When heavy rotors are rotating on fluid bearings at low speeds, they are sometimes subject to stick-slip. The fatigue damage resulting in such systems due to the stick-slip self-excited vibrations developed on the bearings, and the backlash of the gear teeth can be predicted by a simulation procedure described in this paper. The effects of some design parameters on the fatigue life reduction and tooth loading are also investigated so that they may be used in design.

The harmonic gear cold rolling process is an effective method to solve mass production. However, tooth profile quality problems greatly hinder the development of the process. Based on engagement theory, the dynamic characteristics of the rolling process and flexible wheel rolling tooth profile errors caused by the changes of the number of contact points were analyzed and studied, and the process methods were put forward to eliminate or reduce tooth profile errors in this paper, which has an important significance in analysis of rolling tooth profile errors, modification shape of the rolling wheel, optimization of process parameters and improvement of gear rolling quality.

The paper presents the results of an experimental study aimed at assessing the correlation between the measurement of dynamic parameters (vibration, high-frequency vibration, and acoustic emission) and the analysis of friction mode and the state of lubrication of the contact surfaces of two gearboxes in the turbo-generator assembly (high-speed single-body steam turbine—gearbox—generator) with the transmission power of no more than 50 MW. The analysis confirmed the assumption of a significant correlation of the monitored high-frequency vibration signal with the unsatisfactory engagement of the gear teeth. Through vibration analysis, an increased level of the tooth vibration component and vibration multiples with increased acoustic emission were identified in gearbox operation. The gear oil of one of the gearboxes examined showed a loss of additive elements in the real operation of the contact surfaces of the teeth engagement. The trend analysis confirmed the complexity of the monitored transmission operation in terms of the friction mode and the influence of the oil quality on the state of the tooth flank microgeometry.

In planetary gear set, load sharing behavior determines the average amplitude of meshing force, so determines the tooth wear. Meanwhile, tooth wear accumulation increases the backlash, so affects the load sharing behavior. As a result, a “two-sides” coupling relation appears between load sharing behavior and tooth wear. In order to reveal this coupling relation, a static tooth wear prediction model for compound planetary gear set is employed to describe the wear distribution along tooth profile and backlash generated by tooth wear accumulation. Then, a “translational-rotational” lumped-parameter dynamic model of compound planetary gear set is built to calculate the eccentric load coefficient for each meshing pair, under the excitation from the backlash generated by tooth wear accumulation, transmission error, and other excitation. Based on the aforementioned two models, a dynamic tooth wear prediction model is put forward to reflect “two-sides” coupling relation between tooth wear accumulation and load sharing behavior in compound planetary gear set. Lastly, in order to improve the reliability, a 3D-diformable model is built to study the influence of tooth wear on load sharing. The results indicated that, with the system running and tooth wear increasing, under the condition of no-initial transmission error, tooth wear accumulation decreases the load sharing at meshing engagement and disengagement, and under the condition of initial transmission error, tooth wear accumulation improves load sharing behavior slightly.

The finite element analysis software Solidworks Simulation is used to the modal analysis of the dynamic disc of the new-type plate-rolling crusher, its natural frequency and main vibration modes of preceding five orders are obtained. The analysis results show that while the natural frequency of preceding two orders of the dynamic disc is closed to the engagement frequency of the gears of the reducer casing, resonance occurs. So corresponding measures of avoiding resonance are proposed, the study offers theoretical references for the dynamic design of the dynamic disc.

Hydromechanical continuously variable transmission (HMCVT) is capable of bearing large torque and has wide transmission range, which is suitable for high-power tractors. Dynamic characteristics could influence the tractor life, especially in a high-power tractor. Wet clutch is the crucial component in the HMCVT, which could smooth and soft power transmission. Therefore, it is important to study the dynamic characteristics and implement the wet clutch test of HMCVT. In this paper, AMESim is used to establish virtual models of gearbox, pump-controlled hydraulic motor system, and shifting hydraulic system. Then, a simulation study of tractor operation under working condition is carried out. The internal and external meshing forces of the planetary row are analyzed. Finally, the wet clutch engagement process of HMCVT in the high-power tractor is tested to verify the oil pressure. The simulation results show that the values of internal and external meshing force become larger as the throttle opening increases. At the moment of shifting change, the meshing forces of the planetary gear have great impact. The clutch test shows that the trend of the oil filling curve obtained from the bench test is similar to that obtained from the theoretical curve, which verifies the simulation results.

Rack and pinion drilling rig is a more advanced rigs, which canceled winch, wire rope and hook in the traditional rig, Down movement of the top drive through the mutual engagement of the gear with the rack. Dynamic characteristic of similar model prototype was established based on the similarity theory and design methods were researched. Similar model prototype with complete control and detection system was developed while maintaining main structure and functions of the drilling rig the same premise. Through the simulation platform, the drilling operation was simulated, and provides a theoretical basis and experimental data for the future development of rack and pinion drilling rig.

The joint simulation of Virtual Prototype Technology and Finite Element Method was utilized to perform the analysis of both strength and fatigue life of the input axis in a six-speed vehicle transmission with three axes. Firstly, the software Pro/E was used to establish a 3-D model of the input axis and its gear engagement, and the model was then imported into a software ADMAS of the virtual prototype technology to perform a dynamic simulation analysis. Secondly, the gear contact forces obtained by above-mentioned analysis were used as the loading condition of finite element analysis of the input axis to check its strength. Finally, the fatigue of meshing teeth on the input axis was analyzed to determine the fatigue life of the input axis. The results show that the static strength of input axis can meet the requirement of safe use under the working condition of input torque T=1.5kN·m, and the minimum fatigue life on the place where the stress is maximum at flexural root of a tooth is about 2 million times.

In this paper, a coordinated driving motor speed and shifting motor displacement control strategy is proposed for the integrated motor-transmission (IMT) system during the gearshift process. For active speed synchronization of IMT system, speed reference to driving motor is redesigned by using a polynomial speed trajectory. Compared with conventional step speed change reference, it can help improve the ride performance of IMT system. While in the gear release as well as engagement phase, a robust optimal preview controller is developed for the shifting motor to realize rapid and reliable position tracking of the sleeve in spite of load disturbance. Based on real time value of the driving motor speed and also sleeve axial position, proposed speed and position controllers are coordinated in plan during the whole gearshift process. Co-simulations with Matlab/Simulink and AMEsim are conducted to demonstrate dynamical characteristics of the IMT system during the whole gear shifting process, in which a two-layer switching logic is built by using Matlab/Stateflow. Comparative simulation tests are carried out to show the effectiveness as well as performance of proposed control strategies.

Vehicle drivelines are lightly damped non-linear systems possessing many degrees of freedom with dynamic interactions between the various subsystems. There are many sources of excitation such as torsional impact caused by the take-up of backlash in the power train system. Such sources of excitation exist in transmission backlash, in driveline splines and in pinion to ring gear contact in the differential. Abrupt application or release of the throttle in slowly moving traffic or rapid engagement of the clutch can be followed by noise and vibration responses referred to in the industry as ‘clonk’. This paper presents a method of modelling a vehicle driveline which can identify the phenomena known as ‘clonk’ and ‘shuffle’. This model is based on the assumption that vehicle drivelines can be considered as partially lumped and partially distributed, which for systems of this type is wholly appropriate. In doing this it is possible to derive an analytical solution to the governing equations, which has not been considered previously. The results from this model are compared with a totally lumped model of the vehicle driveline for comparison.

Primary cilia play a vital role in cellular sensing and signaling. An essential component of ciliogenesis is intraflagellar transport (IFT), which is involved in IFT protein recruitment, axonemal engagement of IFT protein complexes, and so on. The mechanistic understanding of these processes at the ciliary base was largely missing, because it is challenging to observe the motion of IFT proteins in this crowded region using conventional microscopy. Here, we report short-trajectory tracking of IFT proteins at the base of mammalian primary cilia by optimizing single-particle tracking photoactivated localization microscopy for IFT88-mEOS4b in live human retinal pigment epithelial cells. Intriguingly, we found that mobile IFT proteins “switched gears” multiple times from the distal appendages (DAPs) to the ciliary compartment (CC), moving slowly in the DAPs, relatively fast in the proximal transition zone (TZ), slowly again in the distal TZ, and then much faster in the CC. They could travel through the space between the DAPs and the axoneme without following DAP structures. We further revealed that BBS2 and IFT88 were highly populated at the distal TZ, a potential assembly site. Together, our live-cell single-particle tracking revealed region-dependent slowdown of IFT proteins at the ciliary base, shedding light on staged control of ciliary homeostasis.

Fire trucks should be maximally adapted to the elimination of emergency situations, in particular, to provide the necessary intensity of supply of extinguishing agents, that is, to be multifunctional. Special requirements are imposed on fire-fighting vehicles: high cross-country ability and speed, the ability to transport one compartment, transport tools and equipment for grabbing, backfilling with soil, filling the edge of the fire with water or chemical solutions, and the like. Scientific research is aimed at developing ways to assess the effectiveness of new models of fire and rescue vehicles for compliance with the requirements of the Ministry of Emergency Situations of Ukraine, in particular, through comparative analysis with alternative samples, to determine the factors affecting the operation of a fire truck, to develop a method for adapting vehicles for emergency response, to improve their level of operational excellence and operational efficiency. To realize the purpose of the assessment tests, a test procedure was developed and an experimental model of a fire-fighting vehicle for emergency response was created. The obtained relationship between the number of revolutions of the crankshaft of the engine and the value of the dynamic torque in the transmission of the test fire vehicle in the case of a sharp engagement of the clutch in the vehicle starting modes can be represented graphically. It is proposed to compare different variants of fire engine designs to take this characteristic as an efficiency criterion. Experimental studies were carried out: starting a car from a place on a steep rise, followed by an increase in gears; overcoming a roadside ditch with flat walls 0.2–0.6 m deep and at an angle of 45° to its axis; running over with wheels of one side of a fire engine on a curb 140–150 mm high; entering a turn from straight-line movement to the minimum possible turning radius on an asphalt surface in II and III gears at a constant speed of 10-12 km/h. To confirm the validity of the accepted assumptions of the mathematical model, the accuracy of applications and the reliability of the results obtained, the adequacy of mathematical modeling was checked by comparing the test problems of statics and dynamics of the movement of fire trucks for emergency response. A fire truck for liquidation of emergency situations, modeled on the basis of the proposed adaptation method of the base chassis for the needs of extinguishing forest fires and the formation of a container module, makes it possible to increase the efficiency of its use according to the selected criteria by 18%. The use of the longitudinal flexibility of the container modules in comparison with the conventional body mount provides a reduction in fuel consumption when driving a fire truck up to 4%.

he calculation of the dynamics of the planetary aircraft gearbox is proposed. The eigenfrequencies are determined and the vibrational behavior of the elastic multimass dynamic system of the reducer is studied. The possibility of reducing the level of vibration by using step difference in the area of two-pair engagement is shown. Keywords reducer, gearing, gear wheel, step difference, vibration ossialav@gmail.com

Synchronizer mechanisms play an important role in the selection and engagement of gears in manual, automated manual, and dual clutch transmissions (DCTs). These mechanisms rely heavily on the balancing of torque loads in cone clutches, dog gears, and from losses in the gearbox to ensure repeatable and reliable actuation, with excessive wear on friction and contact surfaces, leading to degradation of actuation and potential mechanism failure. DCTs, in particular, provide a unique operating environment for synchronizers, most notably is its actuation with the engine still driving the wheels during normal driving conditions. Thus, the consideration of increased transmitted vibrations through the powertrain must be evaluated to study the impact of these vibrations on the synchronizer. To conduct this investigation, this paper develops a detailed multibody dynamic model of a typical automotive powertrain equipped with a DCT. This includes engine models with torque harmonics that capture the instantaneous torque variations from piston firing in the engine. As the main consideration of this paper is the influence of engine harmonics, the semidefinite powertrain model is simplified to a fixed-free system and the response of the synchronizer mechanism to harmonic torque inputs is analyzed. Parametric analysis of the system is conducted to analyze the influence of variables—including gear ratio, torsional damper, system damping, and engine configuration—on the dynamic response of the mechanism. Results demonstrate the influence of each of these variables on synchronizer dynamics in the steady state, with stiffness of torsional damper having the strongest influence on forced vibration. Additionally, results vary significantly between single and dual lay-shaft transmissions.

The bearing internal load distribution and fatigue life estimation are accomplished based on the bearing static model at present, ignoring the gear engagement. Besides, bearings are modeled as a linear spring in gear dynamic models, failing to analyze bearing internal load. This article aims to study the bearing internal load fluctuation and corresponding bearing life in gear systems. A nonlinear dynamic model of the gear-bearing system is built, considering the time-varying mesh stiffness, the static transmission error, backlash, bearing clearance, and the nonlinear bearing force. The dynamic model is capable of calculating the bearing internal load. Based on the internal load, fatigue life is acquired using the linear damage theory. The numerical results show that the gear engagement has a significant influence on the bearing internal load analysis, in which periodic fluctuation is related to the mesh frequency and shaft frequency, resulting in the bearing life affected by gear meshing. Compared with the fatigue life predicted under the bearing static model, evident deviations are observed, pointing to the significant role of the gear engagement in the analysis of fatigue life estimation.

AbstractIn this paper, a computational model is proposed to predict the noise radiation of a planetary gear reducer. In addition, a system-level vibro-acoustic model of a two-stage planetary gear reducer is also established, and the dynamic contact equations of engagement are deduced to investigate the dynamic loads at the interface of bearing-housing and ring-housing in operation, using a large mining two-stage planetary reducer as a test mechanism. Moreover, the frequency response of the planetary transmission has been derived, the radiation noises from the two-stage planetary gear train are analyzed, the simulation results agree well with the experimental results. This research can be guide structural optimization of planetary gear mining reducer.

Tooth friction is unavoidable and changes periodically in gear engagement. Friction excitation is an important excitation source of a gear transmission system. They are different than the friction coefficients of any two points on the same contact line of a helical/herringbone gear. In order to obtain the influence of the friction excitation on the dynamic response of a helical/herringbone planetary gear system, a method that uses piecewise solution and then summing them to analyze the friction force and frictional torque of tooth surfaces is proposed. Then, the friction coefficient is obtained based on the mixed elastohydrodynamic lubrication (EHL) theory. A dynamic model of a herringbone planetary gear system is established considering the friction, mesh stiffness, and meshing error excitation by the node finite element method. The influence of friction excitation on the dynamic response of the herringbone planetary gear is studied under different working conditions. The results show that friction excitation has a great influence on the vibration acceleration of the sun and planetary gear. However, the effect on the radial and tangential vibration acceleration of a planetary gear is the opposite. In addition, the friction excitation has a slight effect on the meshing force.

This paper will use the popular television character, Dexter Morgan, to interrogate the relationship between self and persona, and unsettle the distinction between the two terms. This operation will enable me to raise a series of questions about the critical vocabulary and scholarly agenda of the nascent discipline of persona studies, which, I argue, needs to develop a critical genealogy of the term “persona.” This paper makes a modest contribution to such a project by drawing attention to some key questions regarding the discourse of authenticity in persona studies. For those not familiar with the show, Dexter portrays the life of a serial killer who only kills other serial killers. This is because Dexter, under the tutelage of his deceased father, develops a code that enables him to find a “socially useful” purpose for his homicidal impulses—by exclusively targeting other killers he rationalises his own deadly acts. Dexter necessarily leads a double life, which entails performing a series of normative social roles that conceal his true identity, and the murderous activities of his “dark passenger.” This apparent split between “true” self and “false” persona says a lot about popular conceptions of the performative nature of the self in contemporary culture, and provides a useful framework for unpacking some of the aporias generated by the concept of persona.My aim in the present context is to substantiate the argument that persona studies needs to engage with the philosophical discourse of “self” and “authenticity” if it is to provide a convincing account of the status and function of persona today. The term “persona” derives from the classical Latin word for mask, and has its roots in the theatre of ancient Greece. The Oxford English Dictionary defines the term thus:1. An Assumed character or role, especially one adopted by an author in his or her writing, or by a performer.2.a. as the aspect of a person’s character that is displayed to or perceived by others.b. Psychol. In Jungian psychology: the outer or assumed aspect of character; a set of attitudes adopted by an individual to fit his or her perceived social role. Contrasted with anima.For Jung the persona is “a complicated system of relations between individual consciousness and society, fittingly enough a kind of mask, designed on the one hand to make a definite impression upon others, and, on the other, to conceal the true nature of the individual” (305). We can see that all these usages share a theatrical or actorly dimension. Persona is something we adopt, display, or assume. Further, it is an external quality, which masks, presumably, that which is not assumed or displayed—the private self. Thus, persona is predicated on an opposition between inside and outside. Moreover, it is not a value neutral concept, but one, I will argue, that connotes a sense of “inauthenticity” through suggesting a division between self and role. The “self” is a complicated word with a wide range of usages and connotations. The OED notes that when used with reference to a person the word refers to an essential entity.3. Chiefly Philos. That which in a person is really and intrinsically he (in contradistinction to what is adventitious); the ego (often identified with the soul or mind as opposed to the body); a permanent subject of successive and varying states of consciousness.Of course both terms are further complicated by the way they function within specific specialised discourses. Jung’s use of the term “persona” is part of a complex psychological theory of personality, and the term “self” appears in a multitude of forms in a plethora of scholarly disciplines. The “self” is obviously a key concept in psychology and philosophy, where it is sometimes conflated with something called the subject, or discussed with reference to questions of personal identity. Michel Foucault’s project to track “the constitution of the subject across history which has led us up to the modern concept of the self” (202) is perhaps the most complex and rich body of work with which persona studies must reckon if it is to produce a distinctive account of the relationship between persona and self. In broad terms, this paper advocates a loosely Foucauldian approach to understanding the relationship between self and persona, but defers a detailed encounter with Foucault’s work on the subject (which requires a much larger canvas).For the moment I want to focus on the status of authenticity in the self/persona relationship with specific reference to world of Dexter, which provides an accessible forum for examining a contemporary manifestation of the self/persona relationship with specific reference to the question of authenticity. Dexter conveys the division between authentic inner self and persona through the use of a first person narrative voice that provides a running commentary on the character’s thoughts, and exposes the gap between Dexter’s various social roles and his real sociopathic self. Dexter Morgan is, of course, an unreliable narrator, yet he is acutely aware of how others perceive him, and his narrative voice-over functions as a device to bind the viewer to the character’s first-person perspective. This is important because Dexter is devoid of empathy—he lacks the ability to feel genuine emotion, and conform to the social conventions that govern everyday activities, yet he is focus of audience identification. This means the voice-over must perform the work of making Dexter sympathetic.The voice-over narration in Dexter is characterised by an obsession with the presentation of self, and the disparity between self and persona. In an early episode, Dexter’s narrative voice proclaims a love of Halloween because it is “the one time of year when everyone wears a mask—not just me. People think it's fun to pretend you're a monster. Me, I spend my life pretending I'm not. Brother, friend, boyfriend—all part of my costume collection” (Dexter “Let’s Give the Boy a Hand”).Dexter develops a series of social masks and routines to disguise his “real” self. He is compelled to develop a series of elaborate ruses to appear like a regular guy—a “normal” person who needs to perform a series of social roles. He thus becomes a studious observer of everyday life, and much of the show’s appeal lies in the way he dissects the minutiae of human behavior in order to learn how be normal. Indeed, because he does not comprehend emotion he must learn how to read the external signs that convey care, love, interest, concern and so on—“I just don't understand all that emotion, which makes it tough to fake,” he declares (Dexter, “Popping Cherry”). Each social role requires a considerable degree of actorly preparation, and Dexter demonstrates what we might call, with Erving Goffman, a dramaturgical approach to everyday life (2).For example, Dexter enters into a relationship with Rita, an ostensibly naïve, doe-eyed single mother of two children and a victim of domestic violence—he chooses her because he believes that she is as damaged as he is, and unlikely to challenge him too strongly—“Rita's ex-hubby, the crack addict, repeatedly raped her, knocked her around. Ever since then she's been completely uninterested in sex. That works for me!” (Dexter “Dexter”). Rita provides the perfect cover because she facilitates Dexter’s construction of himself as a normal, heterosexual family man. However, in order to play this most paradigmatic normative role, he must learn how to play with children, and feign affection and intimacy. J. M. Tyree observes that Dexter “employs a fake-it-till-you-make-it strategy for imitating normal life” (82). Of course, he cannot maintain the role too long before Rita becomes suspicious, and aware of Dexter’s repeated lies and evasions.In short, Dexter dramatises what Goffman calls impression management—the character of Dexter Morgan must consistently “give off” signs of normativity (80). Goffman argues that we are all compelled to perform social roles in the manner of Dexter, and this perhaps accounts for why the show appealed to such a wide audience. In many ways, Dexter exposes normative behavior as an “act” that nobody can sustain no matter how hard they try. Dexter’s struggle to decode the conventions that govern everyday life make him a sympathetic character despite his obviously sociopathic tendencies. In other words we are all a little bit like Dexter insofar we must all perform social roles we may not find comfortable. Of course, the whole question of impression management in Dexter becomes even more complex if one considers Michael C. Hall’s celebrity persona and his performance as the titular character, but I do not have the space to pursue this line of inquiry in the present context.So, Dexter is a consummate actor within his “everyday” world, and neatly, perhaps too neatly, confirms Goffman’s “dramaturgical” theory of the “self.” In his essay, “Letter to a Poor Actor” David E. R. George provides a fascinating critique of Goffman from the perspective of a theatre studies scholar. George provocatively claims that Goffman was attracted to theatrical metaphors because of the “anti-theatrical prejudice” embedded within the western tradition. George cites Jonash Barish’s authoritative tome on this topic, which argues “that with infrequent exceptions, terms borrowed from the theatre—theatrical, operatic, melodramatic, stagey, etc.—tend to be hostile or belittling” (1).Barish cites instances of this prejudice from Plato through to St Augustine and beyond, and George situates Goffman within this powerful tradition. He writes,the theatrum mundi metaphor has always been a recipe for paranoia, and in this respect Goffman appears merely to be continuing a long philosophical tradition: the actor-as-paranoiac puts on the maximum number of masks to protect a threatened and fragile self against the daily threat of intimacy, disrespect, deception. (353)It is hardly surprising, then, that Dexter, a paranoid sociopath, stands as an exemplary instance of Goffman’s dramaturgical conception of the self, for Dexter is a show that consistently presents narratives about the relationship between the need to protect the “fragile” self through the construction of various personae. George also argues, with Lyman and Scott, that a “dramatistic” approach to understanding the world produces a cynical perspective because drama is predicated on the split between appearance and reality, nothing is what it appears to be, and nobody is what they appear to be (7). The actor, traditionally, has always worn a mask in some form or another. From the literal masks worn by the actors in ancient Greece to the sophisticated make-up and prosthetic devices worn by today’s thespians, actors, even when they are supposedly playing themselves, expose the gap between self and persona. Arguably, the most challenging and provocative aspect of George’s theory of the actor for persona studies lies in his thesis about how the reviled art of the theatre, which has been pilloried for so many centuries, can function as a paradigm for authenticity. He cites Artaud and Grotowski as examples of two iconic figures that view the theatre as a sacred space that facilitates ‘close encounters of the authentic kind (George 361).George attempts to rescue an authentic core identity, which he perceives to be under siege from the likes of Goffman, who proffers an “onion” model of the self. In George’s reading, Goffman produces a self without an essential, authentic core. This is hardly surprising given Goffman’s background. As an advocate of symbolic interactionism, a school of sociology that proposes that the self is produced as a result of various acts of socialisation, Goffman’s dramaturgical account of the self reinforces George Herbert Mead’s belief that “when a self does appear it always involves an experience of another; there could not be an experience of the self simply by itself” (195).Dexter not only dramatises this self/other dynamic, but also underscores the extent to which we, to use the terminology of Benita Luckmann, inhabit a series of “small life-worlds.” In other words, we lead a series of part-time lives in part-time worlds—modern life, for Luckmann writing in 1970, unfolds on multiple stages that are not necessarily connected or operate according to the same regulatory principles. She writes,The multi-world existence of modern man requires frequent ‘gear-shifting.’ As he moves from one small world into the next, he is faced with at least marginally different expectations, requiring different role performances in concert with different sets of people. (590)Dexter must negotiate a variety of different social roles, each with different requirements and demands. He must, therefore, cultivate a professional persona as a blood-splatter analyst, and perform the personal roles of brother, lover, husband, and so on. Each of these roles occurs in a different “life world” and requires a different presentation of self. Luckmann’s analysis of modern life remains compelling despite being written more than 40 years ago, and she raises one of the most crucial questions for persona studies: what “self,” if any, functions as the executive “gear-shifter?” In Dexter, the narrative voice, the voice behind the masks implies such an essential entity—the true, authentic self, which is consistent with Jung’s account of the relationship between self and persona.Despite a welter of critical theory that debunks the possibility of an essential, self-identical, authentic self (from Adorno’s anti-Heideggerean argument in The Jargon of Authenticity to various post-structuralist theories of subjectivity, especially Judith Butler’s conception of performativity) the idea of sovereign self stubbornly persists in everyday discourse. One of the tasks of persona studies must be to examine these common notions of self and authenticity. On one level, most people experience the “self” as something that refers to what we might call a singular sense of being, and speak about when the feel “most like themselves.” For some, the self emerges within the private realm, the “backstage” areas to use Goffman’s terminology (3). Others speak of feeling most like themselves in executing a social role or some kind of professional occupation. For example, take this extract from a contemporary self-growth web site:Are you feeling like you don’t know who you are anymore? Or maybe you feel like you never really knew yourself. Perhaps you’ve gone through most of your life living by other people’s agendas or ideas of who you should be, and are just now realizing that you really don’t know yourself, your dreams, or your purpose. (Ewing 2013)From the Platonic exhortation to “know thyself” through to the advice dispensed by self-help gurus, the self emerges as a persistent, if elusive, trope in scholarly and everyday discourse. Persona studies needs to reckon with the scope and breadth of the deployment of the self. Indeed it is the very ubiquity of terms like self, authenticity, and persona that require genealogical analysis in the Foucauldian sense of the term. This task entails looking for and uncovering the conditions of possibility for talking about the self across a wide range of contexts.In summary, then, I contend that persona studies needs to carefully examine the relationship between various theories of self and the discourse of authenticity, and establish the extent to which Goffman’s apparently cynical account for the self challenges the assumed authenticity of the self in the Jungian paradigm. Of course, there are many other approaches one could take to this question. For example, Sartrean existentialism problematises any simple opposition between self and persona in its insistence that the self is the product of the others’ perceptions of the subject. This position is captured in his famous maxim that “hell is other people.” This is not because other people are inherently antagonistic or hostile, but that one’s sense of self is in the hands of others. Sartre dramatises this conundrum elegantly in his 1944 play, No Exit.Sartre’s philosophy also engages with the discourse of authenticity, which it borrows from Heidegger’s Being and Time. Existentialism, in its many guises, dominated continental philosophy up until the 1960s and popularised the idea of “authenticity” as an ideal, which enables one to avoid the tyranny of the “They” and avoid the pitfalls of living in bad faith. There is a possibility that the nascent discipline of Persona Studies, as articulated by P. David Marshall and others, risks ignoring the crucial relationship between the discourse of authenticity and the presentation of self by concentrating on the “presentational self” as a set of pragmatic, tactical techniques designed to maximise the impact of impression management within a variety of social and professional contexts (Marshall “Persona”; Barbour and Marshall “Academic”). A more detailed and direct engagement with Foucault’s account of the emergence and constitution of the modern subject, as well as with theories of performativity and authenticity that challenge the arguments and verities of Goffman, and Jung, can provide a richer account of how the concept of persona operates today with reference to, say, “the networked self” (Papacharissi; Barbour and Marshall).So, I would like to conclude by returning to Dexter and the question of authenticity. Dexter can never really manage to identify his authentic self—his “gear-changing” core.It’s there always, this Dark Passenger. And when he’s driving, I feel alive, half sick with the thrill of complete wrongness [...] lately there are these moments when I feel connected to something else... someone. It’s like the mask is slipping and things... people... who never mattered before are suddenly starting to matter. (Dexter, “An Inconvenient Lie”)In this speech, he paradoxically identifies his “dark passenger” as the driver (Luckmann’s “gear-changer”) but then feels “the mask” slipping. There is something beyond what he assumed to be his dark core—the innermost aspect of being that makes executive decisions. Moreover, the status of Dexter’s “dark passenger” is unclear in this speech—is he ‘”he self” or some external agent impelling Dexter to commit murder. Either way Dexter questions the motives and authenticity of this “dark passenger” and those of us with a stake in the nascent discipline of persona studies would do well to be equally skeptical about the status of our key terms.References Adorno, Theodor. The Jargon of Authenticity. Trans. Tarnowski, Knut and Will, Fredric. London and New York: Routledge, 2009.“An Inconvenient Lie.” Dexter. Season 2, Episode 3. DVD Showtime, 2007.Barbour K and Marshall P. D. “The Academic Online: Constructing Persona through the World Wide Web.” First Monday 17.9 (2012). 16 May 2014 http://firstmonday.org/ojs/index.php/fm/article/view/3969/3292.Barish, Jonas. The Anti-Theatrical Prejudice. University of California Press, 1981.Butler, Judith. Gender Trouble. London and New York: Routledge, 1990.“Dexter.” Dexter. Season 1, Episode 1. DVD Showtime, 2006.Ewing, Catherine. ‘Do You Feel Like a Stranger to Yourself?’ 17 April 2014 ‹ http://reawakenyourdreamer.com/2013/09/feel-like-stranger/ ›.Foucault, Michel. “About the Beginnings of the Hermeneutics of the Self: Two Lectures at Dartmouth.” Political Theory (1993): 198-227.George, David E.R. “Letter to a Poor Actor.” New Theatre Quarterly 2.8 (1986): 352-362.Goffman, Erving. 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Season 1, Episode 3. DVD Showtime, 2006.Sartre, Jean-Paul. No Exit and Three Other Plays. Trans. Stuart Gilbert. New York: Vintage, 1989.“self, pron., adj., and n.” OED Online. Oxford University Press, March 2014. 13 April 2014.Tyree, J.M. “Spatter Pattern.” Film Quarterly 62.1 (2008): 82-85.