Development of a Dynamometer to Study the Performance of Plastic Gears

2007 ◽  
Author(s):  
Mike Cassata ◽  
Martin Morris ◽  
Jorge Abanto-Bueno
Keyword(s):  
High Speed ◽  
Failure Modes ◽  
Gear Tooth ◽  
Digital Camera ◽  
Operating Conditions ◽  
Spur Gears ◽  
Camera System ◽  
Dupont Company ◽  
Plastic Gears ◽  
Flank Surface

A testing facility has been developed to explore the failure modes of plastic gears. The overall goal is the prediction of gear tooth failure for a given set of operating conditions and to classify failure modes of plastic gears. The initial investigation is centered on the testing of plastic spur gears placed on a parallel-shaft drive train between a variable-speed, reversible DC motor and an eddy current dynamometer. The testing apparatus has been designed, fabricated, and refined to deliver consistent results. The dynamometer places two plastic spur gears in mesh, one being the drive gear and the other the driven. Most of the test gear pairs were injection molded, 40-tooth, 0.8 module gears. These gears were molded using Delrin™ 311DP, a polyoxymethylene polymer which is made by the DuPont Company. Optical encoders were attached to the input and output shafts to sense the shaft position providing a measurement of the deflection and wear of the gear teeth. In addition, an infrared temperature sensor was retrofitted to the dynamometer apparatus to measure the tooth-flank surface temperature. All of the tests where the gear flank temperature reached 250°F resulted in a catastrophic failure. The apparatus was also fitted with a high-speed digital camera system capable of sampling 1000 frames per second. The camera recorded the failure of the plastic gears.

Investigation of Contact Characteristics of Long-Fiber Reinforced Plastic Gears Based on Observation With a High-Speed Camera

2010 ◽  
Author(s):  
Tomoki Otawa ◽  
Toshiski Hirogaki ◽  
Eiichi Aoyama
Keyword(s):  
Temperature Distribution ◽  
High Speed ◽  
Gear Tooth ◽  
Dynamic Contact ◽  
Operating Conditions ◽  
Back Surface ◽  
High Speed Camera ◽  
Contact Ratio ◽  
Contact State ◽  
Plastic Gears

We also observed the dynamic contact state of gear meshing in operating conditions with a high-speed camera. The temperature distribution when driving was measured by thermography. Contact ratio is often used to show contact state, but there are currently no reports that describe the dynamic contact ratio of FRP gears although there are some reports on plastic gears. We therefore considered a contact ratio formula based on a new contact model that the dynamic real deflections of the gear tooth. The temperature distribution measurement was done from the side and the upper surface of the gear. The characteristics of heat generation on the surface of each gear tooth were analyzed, and the temperature distribution was analyzed according to the time and each point of the tooth. (1) FRP gears over heated as a result of driving by the metal gear for a long time. The rise in temperature was rapid and was compounded by heat dissipated from the metal gear. (2) The pitch point of the FRP gear tooth had the highest temperature. The reason for this is that the hysteresis heating is large. It is not easy for the gear to dissipate heat. (3) The temperature rose as a result of hysteresis heating. At high torque, the back surface contact and deflection of the teeth also increased because the gear became viscoelastic.

A Virtual Tool for Wear Simulation of Standard and Non-Standard Spur Gears

2012 ◽  
Author(s):  
F. Karpat ◽  
S. Ekwaro-Osire ◽  
E. Karpat
Keyword(s):  
High Speed ◽  
High Performance ◽  
Failure Modes ◽  
Power Transmission ◽  
Wear Behavior ◽  
Gear Tooth ◽  
Load Capacity ◽  
High Load ◽  
Wear Depth ◽  
Spur Gears

There is an industrial demand for the increased performance of mechanical power transmission devices. This need in high performance is driven by high load capacity, high endurance, low cost, long life, and high speed. New designs and modifications in gears have been investigated to obtain high load carrying capacity and increased life with less volume and weight. Tooth wear is one of the major failure modes in gears. Although there are different classifications of wear mechanisms, wear on gears can be simply classified as mild wear, pitting, and severe wear, depending on the wear rate. These types of wear may lead to power transmission losses, decreased efficiency, increased vibration and noise, and gear tooth failure. This paper deals with the simulation of wear for standard and non-standard gears using an analytical approach. A numerical model for wear prediction of gear pair is developed. A wear model based on Archard’s equation is employed to predict wear depth. A MATLAB-based virtual tool is developed to analyze wear behavior of standard and non-standard spur gears with various gear parameters. In this paper, this virtual tool is introduced by using many numerical examples.

scholarly journals Experimental Study on the Skidding Damage of a Cylindrical Roller Bearing

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4075 ◽  
Author(s):  
Qing Zhang ◽  
Jun Luo ◽  
Xiang-yu Xie ◽  
Jin Xu ◽  
Zhen-huan Ye
Keyword(s):  
High Speed ◽  
Large Scale ◽  
Failure Modes ◽  
Roller Bearing ◽  
Weight Ratio ◽  
Operating Conditions ◽  
Roller Bearings ◽  
Light Load ◽  
Cylindrical Roller Bearing ◽  
Cylindrical Roller

As large-scale rotating machines develop toward high rotating speed and high power–weight ratio, skidding damage has become one of the major initial failure modes of cylindrical roller bearings. Therefore, understanding the skidding damage law is an effective way to ensure the safety of machines supported by cylindrical roller bearings. To realize the skidding damage, a high-speed rolling bearing test rig that can simulate the actual operating conditions of aviation bearings was used in this paper, and the skidding damage dynamic behaviors of cylindrical roller bearings were investigated. In addition, to ensure the accuracy of the obtained skidding damage mechanism, the cylindrical roller bearing was carefully inspected by microscopic analysis when the skidding damage occurred. Out results show that instantaneous increases in friction torque, vibration acceleration, and temperature are clearly observed when the skidding damage occurs in the cylindrical roller bearing. Furthermore, under the conditions of inadequate lubrication and light load, the critical speed of skidding damage is rather low. The major wear mechanisms of skidding damage include oxidation wear, abrasive wear, and delamination wear. The white layers are found locally in the inner ring and rollers under the actions of friction heat and shear force.

Tooth Flank Breakage: Influences on Subsurface Initiated Fatigue Failures of Case Hardened Gears

2013 ◽  
Author(s):  
Karsten Stahl ◽  
Bernd-Robert Höhn ◽  
Thomas Tobie
Keyword(s):  
Failure Mode ◽  
Fatigue Failure ◽  
Failure Modes ◽  
Calculation Model ◽  
Operating Conditions ◽  
Material Strength ◽  
Gear Design ◽  
Increased Risk ◽  
Tooth Flank ◽  
Flank Surface

Pitting and tooth root breakage are typical fatigue failure modes of case hardened gears. Both failure types are usually initiated at the surface or close to the surface. General trends in modern gear industry, such as improved gear design with adequate flank modifications, high-quality gear materials and high-performance lubricants, modern manufacturing processes with additional post-processes as shot peening and superfinishing as well as advanced calculation methods, have allowed an optimized utilization of the allowable pitting and bending stress numbers in recent years. As a result of the increased power density, however, the stresses below the surface rise with the consequence of an increased risk of fatigue failure initiation in the material below the surface. This paper describes main characteristics of a failure mode characterized by tooth breakages which start in the area of the active flank from cracks that are typically initiated at a considerable depth beneath the loaded flank surface. Based on theoretical and experimental investigations, relevant influence parameters related to gear design, operating conditions and material strength on the failure mode “Tooth Flank Breakage” will be discussed and basic principles of a developed calculation model to evaluate the risk of such failures presented. Finally, exemplarily experimental results from gear running tests, which failed due to flank breakage, are compared to the results of the new calculation model.

scholarly journals Study of Lubricant Jet Flow Phenomena in Spur Gears

1975 ◽  
Vol 97 (2) ◽  
pp. 283-288 ◽  
Author(s):  
L. S. Akin ◽  
J. J. Mross ◽  
D. P. Townsend
Keyword(s):  
Motion Picture ◽  
High Speed ◽  
Drop Size ◽  
Gear Tooth ◽  
Jet Flow ◽  
Spur Gear ◽  
Spur Gears ◽  
Gear Teeth ◽  
Flow Phenomena ◽  
Oil Jet

Lubricant jet flow impingement and penetration depth into a gear tooth space were measured at 4920 and 2560 using a 8.89-cm- (3.5-in.) pitch dia 8 pitch spur gear at oil pressures from 7 × 104 to 41 × 104 N/m2 (10 psi to 60 psi). A high speed motion picture camera was used with xenon and high speed stroboscopic lights to slow down and stop the motion of the oil jet so that the impingement depth could be determined. An analytical model was developed for the vectorial impingement depth and for the impingement depth with tooth space windage effects included. The windage effects on the oil jet were small for oil drop size greater than 0.0076 cm (0.003 in.). The analytical impingement depth compared favorably with experimental results above an oil jet pressure of 7 × 104 N/m2 (10 psi). Some of this oil jet penetrates further into the tooth space after impingement. Much of this post impingement oil is thrown out of the tooth space without further contacting the gear teeth.

Fundamental Design Issues of Brush Seals for Industrial Applications

2002 ◽  
Vol 124 (2) ◽  
pp. 293-300 ◽  
Author(s):  
Saim Dinc ◽  
Mehmet Demiroglu ◽  
Norman Turnquist ◽  
Jason Mortzheim ◽  
Gayle Goetze ◽  
...  
Keyword(s):  
High Speed ◽  
Failure Modes ◽  
Industrial Applications ◽  
Operating Conditions ◽  
Design Parameters ◽  
Design Criteria ◽  
Seal Design ◽  
Brush Seal ◽  
Brush Seals ◽  
As Stress

Advanced seals have been applied to numerous turbine machines over the last decade to improve the performance and output. Industrial experiences have shown that significant benefits can be attained if the seals are designed and applied properly. On the other hand, penalties can be expected if brush seals are not designed correctly. In recent years, attempts have been made to apply brush seals to more challenging locations with high speed (>400 m/s), high temperature (>650 °C), and discontinuous contact surfaces, such as blade tips in a turbine. Various failure modes of a brush seal can be activated under these conditions. It becomes crucial to understand the physical behavior of a brush seal under the operating conditions, and to be capable of quantifying seal life and performance as functions of both operating parameters and seal design parameters. Design criteria are required for different failure modes such as stress, fatigue, creep, wear, oxidation etc. This paper illustrates some of the most important brush seal design criteria and the trade-off of different design approaches.

Polymer spur gears behaviors under different loading conditions: A review

2017 ◽  
Vol 232 (2) ◽  
pp. 210-228 ◽  
Author(s):  
Akant Kumar Singh ◽  
Siddhartha ◽  
Prashant Kumar Singh
Keyword(s):  
Modeling And Simulation ◽  
Polymer Composites ◽  
Tribological Properties ◽  
Failure Modes ◽  
Operating Conditions ◽  
Spur Gears ◽  
Simulation Studies ◽  
Loading Conditions ◽  
Comprehensive Review ◽  
Tooth Modification

The significance of polymer gears to transmit power and motion is increasing continuously due to their inherent characteristics. Polymer gears have established themselves as attractive alternatives to traditional metal gears in plethora applications. They are light in weight, have lower inertia, and run noiseless than their metal counterparts. This article presents a comprehensive review of the research on polymer spur gears operating under low (0–8 Nm) and moderate (>8 and ≤17 Nm) loading conditions. Different polymers and polymer composites used till date for the fabrication of such gears are included along with different operating conditions. Various design features of polymer gears and tooth modification techniques for the improvement of the performance and durability of these gears have also been included in this review. The aspects of the modeling and simulation studies of the polymer gears are also emphasized in this paper for completeness of the review. The concept of hybrid gears is discussed along with their tribological properties. Various methods of manufacturing of polymer gears and their failure modes are discussed so as to make the article useful for researchers.

Exhaust Pressure Estimation and Its Application to Detection and Isolation of Turbocharger System Faults for Internal Combustion Engines

2011 ◽  
Vol 134 (2) ◽  
Author(s):  
Yue-Yun Wang ◽  
Ibrahim Haskara
Keyword(s):  
High Speed ◽  
Internal Combustion Engines ◽  
Failure Modes ◽  
Combustion Engine ◽  
Pressure Sensors ◽  
Internal Combustion ◽  
Operating Conditions ◽  
Combustion Engines ◽  
Recirculation Flow ◽  
Model Based

Engine exhaust backpressure is a critical parameter in the calculation of the volumetric efficiency and exhaust gas recirculation flow of an internal combustion engine. The backpressure also needs to be controlled to a presetting limit under high speed and load engine operating conditions to avoid damaging a turbocharger. In this paper, a method is developed to estimate exhaust pressure for internal combustion engines equipped with variable geometry turbochargers. The method uses a model-based approach that applies a coordinate transformation to generate a turbine map for the estimation of exhaust pressure. This estimation can substitute for an expensive pressure sensor, thus saving significant cost for production vehicles. On the other hand, for internal combustion engines that have already installed exhaust pressure sensors, this estimation can be used to generate residual signals for model-based diagnostics. Cumulative sum algorithms are applied to residuals based on multiple sensor fusion, and with the help of signal processing, the algorithms are able to detect and isolate critical failure modes of a turbocharger system.

On the Dynamic Gear Tooth Loading as Affected by Bearing Clearances in High Speed Machinery

1982 ◽  
Vol 104 (4) ◽  
pp. 724-730 ◽  
Author(s):  
B. M. Bahgat ◽  
M. O. M. Osman ◽  
T. S. Sankar
Keyword(s):  
High Speed ◽  
Design Method ◽  
Gear Tooth ◽  
Contact Point ◽  
Velocity Ratio ◽  
Spur Gears ◽  
Governing Equations ◽  
Contact Mode ◽  
Gear Teeth ◽  
Geometrical Constraints

The paper studies the effect of bearing clearances in the dynamic analysis of gear mechanisms in high speed machinery. For this purpose, an analytical model is developed based on the interdependence between kinematics and kinetic relationships that must be satisfied when contact is maintained between the journal and its bearing. The contact modes are formulated such that the bearing eccentricity vector must align itself with bearing normal force at the point of contact. The analysis mainly relies on determining the direction of the bearing eccentricity vector defined as the clearance angles βi at the bearing revolutes for each contact mode of the gear teeth. The governing equations of the clearance angles are developed using the geometrical constraints of the contact point location and the velocity ratio. The clearance angles and their derivatives are subsequently used to systematically evaluate kinematic and dynamic quantities of each gear as well as the dynamic tooth load. A pair of rigid tooth spur gears with two revolute clearances is analyzed to illustrate the procedure. The model presented in the paper provides a design method for investigating the effect of bearing tolerances and wear on the evaluation of dynamic tooth load in high speed gearing systems.

scholarly journals Wear of Spur Gears Having a Dithering Motion and Lubricated With a Perfluorinated Polyether Grease

2007 ◽  
Author(s):  
Timothy Krantz ◽  
Fred Oswald ◽  
Robert Handschuh
Keyword(s):  
Wear Rate ◽  
High Speed ◽  
Failure Modes ◽  
Load Level ◽  
Wear Depth ◽  
Spur Gears ◽  
Test Load ◽  
Total Wear ◽  
Gear Contact ◽  
Perfluorinated Polyether

Gear contact surface wear is one of the important failure modes for gear systems. Dedicated experiments are required to enable precise evaluations of gear wear for a particular application. The application of interest for this study required evaluation of wear of gears lubricated with a grade 2 perfluorinated polyether grease and having a dithering (rotation reversal) motion. Experiments were conducted using spur gears made from AISI 9310 steel. Wear was measured using a profilometer at test intervals encompassing 10,000 to 80,000 cycles of dithering motion. The test load level was 1.1 GPa maximum Hertz contact stress at the pitch-line. The trend of total wear as a function of test cycles was linear, and the wear depth rate was approximately 1.2 nm maximum wear depth per gear dithering cycle. The observed wear rate was about 600 times greater than the wear rate for the same gears operated at high speed and lubricated with oil.

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