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Viewing 1 to 30 of 40838
2015-06-15
Technical Paper
2015-01-2134
Tom Currie, Dan Fuleki
There is significant recent evidence that ice crystals ingested by a jet engine at high altitude can partially melt and then accrete within the forward stages of the compressor, potentially producing a loss of performance, rollback, combustor flameout, compressor damage, etc. Several studies of this ice crystal icing (ICI) phenomenon have been conducted in the past 5 years using the RATFac (Research Altitude Test Facility) altitude chamber at the National Research Council of Canada (NRCC), which includes an icing wind tunnel capable at operating at Mach numbers (M), total pressures (po) and temperatures (To) pertinent to ICI. Humidity can also be controlled and ice particles are generated with a grinder. The ice particles are entrained in a jet of sub-freezing air blowing into the tunnel inlet. Warm air from the altitude cell also enters the tunnel, where it mixes with the cold ice-laden jet, increasing the wet-bulb temperature (Twb) and inducing particle melting.
2015-06-15
Technical Paper
2015-01-2114
Jeanne G. Mason, Melissa Bravin
Ice crystal icing has now been established as the cause of a number of jet engine powerloss and damage events(1). Solid water particles in the atmosphere can melt inside the heated engine, cool surfaces, leading to conditions where ice can form. This paper will show that the current statistics indicate ice accretion caused powerloss and damage events are more prevalent at cruise power than in other flight phases, and introduce data which establishes that commercial flights are regularly traversing areas of cloud similar to those which cause engine events, yet the rate of events is much less than the encounter rate. Not every cruise flight through a cloud containing high concentrations of ice crystals results in an event. The Boeing event database also indicates that for a given engine type with cruise power events, the altitudes where events occur is limited to altitudes above 26,000ft, even though at 26000 ft, the atmospheric total water content is thought to be a maximum(3).
2015-06-15
Technical Paper
2015-01-2144
James MacLeod, Michael Clarke, Doug Marsh
The GLACIER Icing Facility – Lessons Learnt in the first Five Years of Operation J.D. MacLeod M. Clarke National Research Council of Canada Rolls-Royce plc Gas Turbine Laboratory Civil Aerospace Ottawa, ON Derby, UK Abstract The Global Aerospace Centre for Icing and Environmental Research Inc. (GLACIER) facility is located in Thompson, Manitoba, Canada. This facility provides icing certification tests for large gas turbine engines, as well as performance, endurance and other gas turbine engine qualification testing. This globally unique outdoor engine test and certification facility was officially opened back in 2010. The prime purpose of this facility is for icing certification of aero gas turbines. The facility provides the aviation industry with the required environmental conditions (by virtue of its location), and the capability to meet the growing demands for icing certifications and other adverse cold weather conditions.
2015-06-15
Technical Paper
2015-01-2174
Yuanfeng Xia, Jian Pang, Cui Zhou, Hongcheng Li, Wenjuan Li
Study on the Bending Vibration of a Two-Piece Propeller Shaft for 4WD Driveline Yuanfeng Xia1, 2, Jian Pang1, 2,*, Cui Zhou1, 2, Hongcheng Li1, 2, Wenjuan Li1, 2 1 Changan Auto Global R&D Center, Chongqing, China, 401120 2. State Key Laboratory of Vehicle NVH and Safety Technology, Chongqing, China, 401120 * Correspondence author, e-mail address: pangjian@changan.com.cn Currently, the four wheel drive (4WD) system is widely used in Sports Utility Vehicle (SUV) due to the increasing demand of fuel efficiency and dynamic performance by customers. However, propeller shaft consisting of different universal joints and tubes on 4WD vehicle easily induces low frequency bending vibration. This paper analyzes the characteristics of driveline bending vibration of a 4WD vehicle and provides control methods to reduce the low frequency vibration caused by propeller shaft bending resonances.
2015-06-15
Technical Paper
2015-01-2176
Rajkumar Bhagate, Ajinkya Badkas, Kiran Mohan
Gear rattle is an annoying noise and vibrations phenomena of the automotive driveline, which is mainly controlled by the engine’s torque variations creating the source for torsional fluctuations. In the current work, torsional vibrations are analyzed for improving comfort of the drivetrains. A 6 DOF, 1-D multibody mathematical model for the torsional vibrations of front wheel drive automotive drivetrain is developed and utilized for the optimization of sensitive system parameters for reducing the driveline rattle. Second order differential equations of the mathematical model are solved by using MATLAB and the output response is validated with the testing data. The model is further utilized for optimizing the flywheel inertia and clutch stiffness which are considered to be most sensitive parameters for reducing the input excitations to transmission.
2015-06-15
Technical Paper
2015-01-2175
Jason Ley, Zhaohui Sun, William Braun, Jeffrey Nyquist
Vehicle driveline integration has long been recognized as a key element to vehicle NVH performance. As competition keeps rising, the consumer has also become more demanding of vehicle performance, especially in the NVH realm. However, regulations are pushing OEMs to develop lighter and more efficient vehicles; which can make traditional NVH integration solutions such as torsional or linear dampers, or propshaft tube size change both weight and cost prohibitive. In addition, the mass reduction trends at the OEM level have had the secondary consequence of creating vehicles which can be more sensitive and susceptible to modal alignment. These problems have led to an increased need for targeted, light weight, cost effective solutions that can be quickly adjusted to meet vehicle demands. This paper presents the propshaft liner development that is expanded from previously published SAE technical paper and US patents.
2015-06-15
Technical Paper
2015-01-2178
Mohamed El Morsy, Gabriela Achtenova
When localized fault occurs in a bearing, the periodic impulsive feature of the vibration signal appears in time domain, and the Corresponding bearing characteristic frequencies (BCFs) emerge in frequency domain. However, one limitation of frequency-domain analysis is its inability to handle non-stationary waveform signals, which are very common when machinery faults occur. The common technique of Fast Fourier Transforms (FFT) and Envelope Detection (ED) are always used to identify faults occurring at the BCFs. In the early stage of bearing failures, the BCFs contain very little energy and are often overwhelmed by noise and higher-level macro-structural vibrations. In order to extract the weak fault information submerged in strong background noise of the gearbox vibration signal, an effective signal processing method would be necessary to remove such corrupting noise and interference. Optimal Morlet Wavelet Filter and Envelope Detection (ED) are applied in this paper.
2015-06-15
Technical Paper
2015-01-2180
Almahdi Saleh, Michael Krak, Jason Dreyer
This study examines clutch damper subsystem dynamics under transient excitation and validates predictions using a new laboratory experiment (subject of a companion paper). The proposed models include multi-staged stiffness and hysteresis elements as well as spline nonlinearities. Several example cases, such as two high (or low) hysteresis clutches in series with a pre-damper, are considered. First, detailed multi-degree of freedom nonlinear models are constructed, and their time domain predictions are validated by analogous measurements. Second, key damping sources that affect transient events are identified, and appropriate models or parameters are selected or justified. Finally, torque impulses are evaluated using metrics, their effects on driveline dynamics are quantified, and dynamic interactions between clutch damper and spline backlash nonlinearities are briefly discussed.
2015-06-15
Technical Paper
2015-01-2179
Laihang Li, Rajendra Singh
The transient vibration phenomenon in a vehicle powertrain system during the start-up (or shut-down) process is studied with focus on the properties of multi-staged clutch damper. First, a four-degree-of-freedom torsional model with multiple discontinuous nonlinearities, under flywheel motion input, is developed, and the transient event is validated with a vehicle start-up experiment. Second, the role of the nonlinear clutch damper on the transient event is investigated in time and time-frequency domains; interactions between the clutch damper and the transmission transients are estimated. Third, a semi-analytical method is applied to a simplified and validated single-degree-of-freedom powertrain system model to examine the nonlinear characteristics of clutch damper during a slowly varying non-stationary process. Finally, analytical formulas are successfully verified to approximate the nonlinear amplification level for a rapidly varying process.
2015-06-15
Technical Paper
2015-01-2182
Yawen Wang, Junyi Yang, Teik Lim
Due to the design of lightweight, high speed driveline system, the large displacement of shaft rotation and rotor dynamics must be considered to predict vibratory responses more realistically. In the current analysis, a lumped parameter model of the propeller shaft is developed with Timoshenko beam elements, which includes the effect of rotary inertia and shear deformation. The propeller shaft model is then coupled with a hypoid gear pair representation using the component mode synthesis approach. In the proposed formulation, the gyroscopic effect of both the gear and propeller shaft is considered. The simulation results show that the interaction between gear gyroscopic effect and propeller shaft bending flexibility has considerable influence on the gear dynamic mesh responses around bending resonances, whereas the torsional modes still dominate in the overall frequency spectrum.
2015-06-15
Technical Paper
2015-01-2181
Dong Guo, Yawen Wang, Teik Lim, Peng Yi
A combined lumped parameter, finite element (FE) and boundary element (BE) model is developed to predict the whine noise from rear axle. The hypoid geared rotor system, including the gear pair, shafts, bearings, engine and load, is represented by a lumped parameter model, in which the dynamic coupling between the engaging gear pair is represented by a gear mesh model condensed from the loaded tooth contact analysis results. The lumped parameter model gives the dynamic bearing forces, and the noise radiated by the gearbox housing vibration due to the dynamic bearing force excitations is calculated using a coupled FE-BE approach. Based on the predicted noise, a new procedure is proposed to tune basic rear axle design parameters for better sound quality purpose. To illustrate the salient features of the proposed method, the whine noise from an example rear axle is predicted and tuned.
2015-06-15
Technical Paper
2015-01-2184
Syeda Mahmud, Shahjada Pahlovy
Fuel efficiency can be improved by reducing the energy loss of power train and it’s components. Some estimates shows that about 14%–30% of the energy from the fuel gets used to move a car down the road and 5-6% energy is lost due to drive train. Therefore, a potential improvement of power train components can lower the fuel consumption significantly. Due to the engagement and disengagement process of transmission clutches, a frictional heat is generated which leads to some damage to clutches. Therefore, it is necessary to cool down the disks to increase the service life of clutch. An automatic transmission fluid (ATF) is delivered in between the friction disks and separator plate to cool them. Since the friction plates and separator plates are always in relative motion to each other, a shear force is generated on the fluid in the gap between the disks. This shear force generates a drag torque which is considered as a loss.
2015-06-15
Technical Paper
2015-01-2183
Thomas Wellmann, Kiran Govindswamy, Jeff Orzechowski, Sudharsan Srinivasan
Integration of automatic engine start/stop systems in “conventional” drivetrains with 12V starters is a relatively cost effective measure to reduce fuel consumption. Therefore, automatic engine start/stop systems are becoming more prevalent and increasing market share of such systems is predicted. A quick, reliable and consistent engine start behavior is essential for customer ac-ceptance of these systems. The launch of the vehicle should not be compromised by the start/stop system, which implies that the engine start time and transmission readiness for transmitting torque should occur within the time the customer releases the brake pedal and de-presses the accelerator pedal. Comfort and NVH aspects will continue to play an important role for customer acceptance of these systems. Hence, the engine stop and re-start behavior should be imperceptible to the driver from both a tactile and acoustic standpoint.
2015-06-15
Technical Paper
2015-01-2188
Zhaohui Sun, Glen Steyer, Chih Hung Chung
With the high competitiveness in the automotive industry and the pressure of CAFE regulation, the trend of using lightweight and mass optimized structures becomes one of the key factors for future success of an auto company. Utilizing alternative metals such as aluminum to replace traditional cast iron or steel have become more common. Aluminum carrier drive axles pose new challenges to engineers, particularly for product NVH performance. This is largely due to the significantly higher thermal expansion rate and lower elastic modulus of aluminum compared with cast iron and steel. This paper discusses approaches to properly design aluminum axles for optimized NVH characteristics. By effectively using well established and validated FEA and other CAE tools, key factors that are particularly associated with aluminum axles are analyzed and discussed.
2015-06-15
Technical Paper
2015-01-2192
Manchi Venkateswara Rao, Jos Frank, Prasath Raghavendran
Meeting various customer(s) requirements with the given automotive product portfolio within the stipulated time period is a challenge. Design of product configuration matrix is an intelligent task and it requires information about vehicle performance for different configurations which helps in deciding the level of new development. Most often the situation arises, particularly in the field of NVH, to strike the right balance between engine power and structural parameters of the body. The sensitivity of engine power on the overall NVH behavior is the key information necessary to take major business decisions. In this paper, the effect of change in torsional fluctuation of the engine on the NVH behavior of the rear wheel drive vehicle is experimentally studied. The torsional fluctuation of the driveline are given as input with the help of electric motor to the existing test vehicle at its differential end and the current NVH levels are measured.
2015-06-15
Technical Paper
2015-01-2191
Peng Yu, Tong Zhang, Shiyang Chen, Jing Li, Rong Guo
In view of the problem of low-frequency longitudinal vibration exists in a pure electric vehicle, modeling methods of driveline torsion vibration system are conducted. Firstly, dynamometer test is performed, signals of motor speed and seat rail acceleration are obtained, the frequency characteristics of flutter is determined using the order analysis and time frequency analysis. Then four types of modeling and analysis are investigated facing the driveline torsion vibration problem, including single model without electromagnetic stiffness, branch model without electromagnetic stiffness, single model considering electromagnetic stiffness and branch model considering electromagnetic stiffness. The results show that, modeling taking into account the electromagnetic stiffness and branches can reflect more low-frequency characteristics, helps to reveal the low-frequency longitudinal flutter of electric vehicle.
2015-06-15
Technical Paper
2015-01-2190
Manchi Venkateswara Rao
Mount development and optimization plays a significant role in vehicle NVH refinement as they significantly influence overall driving experience. Dynamic stiffness is a key parameter that directly affects the mount performance. Conventional dynamic stiffness evaluation techniques are cumbersome and time consuming. The dynamic stiffness of mount depends on the load, frequency of application and the displacement. The above parameters would be far different in the test conditions under which the mounts are normally tested when compared to operating conditions. Hence there is need to find the dynamic stiffness of mounts in actual vehicle operating conditions. In this paper, the dynamic stiffness of elastomeric mounts is estimated by using a modified matrix inversion technique popularly termed as operational path analysis with exogenous inputs (OPAX).
2015-06-15
Technical Paper
2015-01-2228
Drivelines used in modern pickup trucks commonly employ universal joints. This type of joint is responsible for second driveshaft order vibrations in the vehicle. Large displacements of the joint connecting the driveline and the rear axle have a detrimental effect on vehicle NVH. As leaf springs are critical energy absorbing elements that connect to the powertrain, they are used to restrain large axle windup angles. One of the most common types of leaf springs in use today is the multi-stage parabolic leaf spring. A simple SAE 3-link approximation is adequate for preliminary studies but it has been found to be inadequate to study axle windup. A vast body of literature exists on modeling leaf springs using nonlinear FEA and multibody simulations. However, these methods require significant amount of component level detail and measured data. As such, these techniques are not applicable for quick sensitivity studies at design conception stage.
2015-06-15
Technical Paper
2015-01-2252
Haixin Dai PhD, Weikang Jiang, Yuanyi Huang cEng
Engine mounting plays an important role to interior noise of automobiles. Decoupling optimal design of mounting has been researched for long, but vibration power into body transmitted from engine can be a more intuitive way to improve NVH performance. Some approach for minimizing transfer power through engine mount based on finite element model was reported, whose disadvantages are lack of data and inaccuracy at high frequency in some cases. To get an analytic formula of transmitted power, a model considering coupled vibration between bodywork and engine is presented here. In this model, the engine is modeled as a rigid body, the rubber mounts are modeled as springs and dampers, and the bodywork is modeled as flexible. An impedance function matrix is used to describe the dynamic relationship between the mounting points on the body.
2015-06-15
Technical Paper
2015-01-2256
Colin Troth
This paper considers some aspects of rigid body dynamics of power trains with respect to noise and vibration (by definition a power train (PT) term here is an engine plus transmission). Rigid body concepts are very important in helping assess unwanted levels of flexibility of PT’s and attached ancillaries e.g. mounting brackets. Using rigid body concepts it is possible to define vibration and noise ‘entitlement’ to what can theoretically be achieved. Targets can then be to set based upon these entitlements. This can then lead to better more robust designs to achieve higher levels of refinement. Dedicated software and the use of generic 3 and 4 cylinder one litre in-line PT’s are used to aid this study which can be shown to adhere more to rigid body behaviour due to their compact designs and lower (frequency) dominant orders of excitation.
2015-06-15
Technical Paper
2015-01-2255
Jun Kokaji, Masashi Komada, Masayuki Takei, Masaya Takeda
This paper describes mechanism of idling vibration specific to V6 engine rear wheel drive hybrid vehicles. The mechanism depends on unique torsional vibration characteristics of THSII (Toyota Hybrid system II) drive-line. Idling vibration of a vehicle usually occurs by engine force of 1st order of combustion. But there are other engine forces lower than 1st order of combustion frequency. We call these vibrations ‘Idling vibration at low frequency range’ on this paper. Engine speed during idle of V6 engine rear wheel drive hybrid vehicle is 1000rpm, and 1st order of combustion frequency is 50Hz. On the other hand, engine force of idling vibration at low frequency range is 0.5th order of engine revolution (8.3Hz) which is caused by combustion pressure difference every 1 engine cylinder. THSII drive-line has different torsional vibration characteristics comparing with conventional gasoline engine vehicle with automatic transmission.
2015-06-15
Technical Paper
2015-01-2253
Kimitoshi Tsuji, Katsuhiko Yamamoto
It is important for vehicle concept planning to estimate fuel economy and the influence of vehicle vibration in advance, on virtual engine specifications and a virtual vehicle frame. In this paper, I will show the power plant model with electrical starter, battery and alternator that can predict transient torque and combustion heat results. Also vibration result with the power plant model connected to vehicle inertia model will be shown. The power plant was 1.3L 4cyl NA. The discussed vehicle was small size and 1300kg. The power plant model was realized by energy based model using VHDL-AMS. Here, VHDL-AMS is modelling language stored in IEC international standard (IEC61691-6) and can realize multi physics on 1D simulation. The modeling language supports electrical, magnetic, thermal, mechanical, fluidic and compressive fluidic domain. The model was created in house by fully VHDL-AMS and validated on ANSYS SIMPLORER.
2015-06-15
Technical Paper
2015-01-2254
WenbIn Shangguan
The driving pulley in the Engine Front End Accessory Drive System (EFEAD) is usually used as a torsional vibration damper for the crankshaft. Although the crankshaft torsional vibrations are dampened, the torsional vibration is absorbed by the inertia ring of the driving pulley and then is transmitted to the EFEAD. The isolation pulley is a new device and is to reduce the belt tension fluctuation by isolating the belt transmission from the crankshaft torsional vibrations. In the isolation pulley, there are two inertia rings, one is used to damp the crankshaft vibration and another one is to drive the EFEAD. The purpose of this paper is to study design method for isolation pulley to reduce the EFEAD vibrations. An EFEAD with five-pulley system and isolation pulley is taken as studying example and a non-linear model is established to predict the dynamic response of the pulleys, tensioner motion and pulley slips.
2015-06-15
Technical Paper
2015-01-2294
Kodali Ajay Krishna, Pankaj Bhardwaj, Sanjeev Patil, Mansinh Kumbhar
One of the primary excitation sources in a passenger car comes from the powertrain [1]. Refinement of powertrain induced noise is one of the major tasks during a full vehicle NVH refinement. For better fuel efficiency and emission norms, vehicle manufacturers need to focus drastically on reducing the weight and also at the same time achieving defined NVH targets. Due to ever increasing demand for reducing the development cycle of the design, most critical decisions have to be made at the concept stage of the powertrain design itself. Combustion excitation forces and powertrain radiated noise are the most important design factors along with the thermal, durability, and strength requirements that must be evaluated during concept stage and also during other stages of the development process. Solution time for calculating the radiated noise using the existing acoustic solvers is very high and requires very expensive resources (software and hardware).
2015-06-15
Technical Paper
2015-01-2293
Manchi Venkateswara Rao, S Nataraja Moorthy, Prasath Raghavendran
Tactile vibration during vehicle key on/off is one of the critical factors contributing to the customer perceived quality of the vehicle. Minimization of the powertrain transient vibration in operating conditions such as key on/off, tip in/out and engagement/disengagement of engine in hybrid vehicles must be addressed carefully in the vehicle refinement stage. Source of start/stop vibration depends on many factors like engine cranking, engine rpm at which the combustion process starts and rate of engine rpm rise etc. The transfer path consists of elastomeric mounts of powertrain and vehicle structure from mounts to tactile response location. In this paper, the contribution of rigid body motion of powertrain of a front wheel drive vehicle during key on/off is analyzed in both frequency and time domain. The signal is analyzed in frequency domain by using Fast Fourier Transform, Short Time Fourier Transform and Wavelet Analysis. The merits and demerits of each method are illustrated.
2015-06-15
Technical Paper
2015-01-2295
Aniket Parbat, Todd Tousignant, Kiran Govindswamy
The definition of vehicle and powertrain level targets is one of the first tasks toward establishing where a vehicle will reside with respect to the current or future state of industry. Target setting at the vehicle level is relatively straightforward. Realization of these targets relies on a combination of competitive powertrain (source) and vehicle (path) NVH performance. Assessment of vehicle NVH performance (sensitivity) is well understood, and can be accomplished through determination of customer interface response to measured excitations at the source input locations. However, definition of powertrain source targets can be more difficult, particularly if powertrain level data (as acquired in a hemi-anechoic powertrain test cell) is not available. In addition to powertrain source noise and vibration levels, methods have been developed for quantification of powertrain radiated sound quality issues which can propagate to the vehicle.
2015-06-15
Technical Paper
2015-01-2298
Stephen Chittick, Mark Swindell, Samir Raorane
As part of the long-term business strategy Jaguar Land Rover (JLR) has designed and developed a new family of advanced, highly efficient engines for future models. The all-new Ingenium family of inline 4 cylinder engines will increase JLR's capability to offer high performance engines with class-leading levels of refinement, whilst ensuring continued significant reductions in vehicle emissions. This paper details the NVH development of the lead engine, a 2.0 litre common rail turbo diesel. The task from the outset of this new programme was to reduce the mass of the engine by 21.5kg, whilst also improving the structural attenuation by 5 dB in comparison to the outgoing engine. Improving the structural attenuation by 5 dB was not only a key enabler in reducing combustion noise, but also helped to achieve a certified CO2 performance of 99 g/km in the all-new Jaguar XE model, by allowing more scope for increasing cylinder pressure forcing without compromising NVH.
2015-06-15
Technical Paper
2015-01-2299
Dhanesh Purekar
In comparison to medium duty and heavy duty diesel engines, NVH development of light duty diesel engines requires significant collaboration with the OEM. Typically, competitive benchmark studies and customer expectations define the NVH targets at the vehicle and subsequently cascaded down at the powertrain level. For engine manufacturing companies like Cummins, it is imperative to work closely with OEM to deliver on the NVH expectations. In certain situations, engine level NVH targets needs to be demonstrated in the OEM or 3rd party acoustic test facility for contract approvals. However, this is a difficult task to accomplish, considering the differences between acoustic test facilities and hardware, instrumentation, etc. In addition, engine itself is a big contributor to the noise variation. This technical paper documents one such case study conducted on a standalone light duty diesel engine in three different acoustic test facilities.
2015-06-15
Technical Paper
2015-01-2288
Abdelkrim Zouani, Joseph Stout, Salah Hanim, Changshen Gan, Gabriela Dziubinschi, William Baldwin, Zhi fu
A new turbocharged 60◦ 2.7L V6 gasoline engine has been developed by Ford Motor Company for both the pickup truck and car applications. This engine was code named “Nano” due to its compact size and features a CGI cylinder block, an Aluminum ladder, an integrated exhaust manifold and twin turbochargers. The goal of this engine is to deliver 120HP/L, ULEV70 emission, fuel efficiency improvements and leadership level NVH. This paper describes the upfront design and optimization process used for the NVH development of this engine; it will discuss the critical NVH design features and the final results relative to the benchmarks.
2015-06-15
Technical Paper
2015-01-2287
Yaqiong Deng, Xiandi Zeng
Among the lower frequency vehicle NVH problems, booming noise is one of the most concerned issues. There are all kinds of booming noises from different driving conditions such as idling, driving away, and driving at lower speed on coarse road. In order for a vehicle to avoid those booming noises, the vehicle has to be designed to have the right structures and right counter -measures for all conditions possible for booming noise. One of the most common booming noise sources is the torsional vibration of the powertrain and driveline for rear-wheel drive and four-wheel drive vehicle. The solutions for this problem are either to use a torsional dynamic absorber or to use a lower stiffness clutch. Both solutions require the modal frequency of the torsioanal vibration of the powertrain and driveline. At early design stages, vehicle prototype is not available for measuring this frequency. Analytical method is usually used to calculate this frequency.
Viewing 1 to 30 of 40838