The Experts below are selected from a list of 57 Experts worldwide ranked by ideXlab platform
K W Dalgarno - One of the best experts on this subject based on the ideXlab platform.
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The meshing of timing belt teeth in Pulley Grooves
2016Co-Authors: T H C Childs, K W Dalgarno, M H Hojjati, M J Tutt, A J DayAbstract:Abstract: The work described here has been carried out to obtain a better understanding of the tooth root cracking failure mode of timing belts. Previous work has demonstrated the close dependence of this on the tooth deflections of fully meshed teeth, generated by torque transmission, but has not considered the additional distortions generated in the partially meshed conditions at entry to and exit from a Pulley Groove. Approximate compatibility and constitutive equations are combined with a rigorous consideration of tooth equilibrium in partial meshing to show how bending moments are generated at both exit from a driven Pulley and entry to a driving Pulley. Experimentally determined belt lives correlate very well with a combined measure of fully meshed tooth strain and strain due to bending at entry or exit. The analysis also shows that this strain measure reduces with increasing belt tooth stiffness, confirming the importance of a high tooth stiffness for a long belt life. Tooth force variations through the partial meshing cycle have also been predicted and compared with measurements obtained from a special strain gauge instrumented Pulley. A greater Pulley rotation than is predicted is required for a belt tooth to seat in a Pulley Groove. There is room for improvement in the modelling
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Experimental and finite element studies of the running of V-ribbed belts in Pulley Grooves:
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 1998Co-Authors: D Yu, T H C Childs, K W DalgarnoAbstract:AbstractA finite element model of a complete loop of V-ribbed belt running between two torque transmitting Pulleys has been created to study the mechanics of contact between a belt rib and Pulley Groove. It has been validated against experimental measurements of radial movement of a K-section belt running on 80 mm diameter Pulleys. Patterns of sticking and slip between the belt and Pulley are predicted. Of particular interest are the patterns of traction in entry and exit regions and, in fully seated regions, the variations with distance from the cord line. Both steady state and transient behaviours are modelled. Successful computations have only been achieved after developing a simplified description of the belt rubber's incompressible hyperelasticity, based on subsidiary experimental and finite element testing. Of major interest is the severe contact conditions predicted on driving Pulleys compared to driven Pulleys at the same loading.
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Finite element analysis of synchronous belt tooth failure
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 1993Co-Authors: K W Dalgarno, Andrew J. Day, T H C ChildsAbstract:This paper describes a finite element analysis of a synchronous belt tooth under operational loads and conditions with the objective of obtaining a greater understanding of belt failure by tooth root cracking through an examination of the strains within the facing fabric in the belt. The analysis used the ABAQUS finite element program, and was based on a two-dimensional finite element model incorporating a hyperelastic material model for the elastomer compound. Contact between the belt tooth face and the Pulley Groove was modelled using surface interface elements which allowed only compression and shear forces at the contact surfaces. It is concluded that the critical strains in the facing fabric of the belt, and therefore the belt life, are largely determined by the tangential loading condition on the belt teeth.
T H C Childs - One of the best experts on this subject based on the ideXlab platform.
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The meshing of timing belt teeth in Pulley Grooves
2016Co-Authors: T H C Childs, K W Dalgarno, M H Hojjati, M J Tutt, A J DayAbstract:Abstract: The work described here has been carried out to obtain a better understanding of the tooth root cracking failure mode of timing belts. Previous work has demonstrated the close dependence of this on the tooth deflections of fully meshed teeth, generated by torque transmission, but has not considered the additional distortions generated in the partially meshed conditions at entry to and exit from a Pulley Groove. Approximate compatibility and constitutive equations are combined with a rigorous consideration of tooth equilibrium in partial meshing to show how bending moments are generated at both exit from a driven Pulley and entry to a driving Pulley. Experimentally determined belt lives correlate very well with a combined measure of fully meshed tooth strain and strain due to bending at entry or exit. The analysis also shows that this strain measure reduces with increasing belt tooth stiffness, confirming the importance of a high tooth stiffness for a long belt life. Tooth force variations through the partial meshing cycle have also been predicted and compared with measurements obtained from a special strain gauge instrumented Pulley. A greater Pulley rotation than is predicted is required for a belt tooth to seat in a Pulley Groove. There is room for improvement in the modelling
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Experimental and finite element studies of the running of V-ribbed belts in Pulley Grooves:
Proceedings of the Institution of Mechanical Engineers Part C: Journal of Mechanical Engineering Science, 1998Co-Authors: D Yu, T H C Childs, K W DalgarnoAbstract:AbstractA finite element model of a complete loop of V-ribbed belt running between two torque transmitting Pulleys has been created to study the mechanics of contact between a belt rib and Pulley Groove. It has been validated against experimental measurements of radial movement of a K-section belt running on 80 mm diameter Pulleys. Patterns of sticking and slip between the belt and Pulley are predicted. Of particular interest are the patterns of traction in entry and exit regions and, in fully seated regions, the variations with distance from the cord line. Both steady state and transient behaviours are modelled. Successful computations have only been achieved after developing a simplified description of the belt rubber's incompressible hyperelasticity, based on subsidiary experimental and finite element testing. Of major interest is the severe contact conditions predicted on driving Pulleys compared to driven Pulleys at the same loading.
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Finite element analysis of synchronous belt tooth failure
Proceedings of the Institution of Mechanical Engineers Part D: Journal of Automobile Engineering, 1993Co-Authors: K W Dalgarno, Andrew J. Day, T H C ChildsAbstract:This paper describes a finite element analysis of a synchronous belt tooth under operational loads and conditions with the objective of obtaining a greater understanding of belt failure by tooth root cracking through an examination of the strains within the facing fabric in the belt. The analysis used the ABAQUS finite element program, and was based on a two-dimensional finite element model incorporating a hyperelastic material model for the elastomer compound. Contact between the belt tooth face and the Pulley Groove was modelled using surface interface elements which allowed only compression and shear forces at the contact surfaces. It is concluded that the critical strains in the facing fabric of the belt, and therefore the belt life, are largely determined by the tangential loading condition on the belt teeth.
Giuseppe Carbone - One of the best experts on this subject based on the ideXlab platform.
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EHL-Squeeze in High Loaded Contacts: The Case of Chain CVT Transmissions
Strojniski Vestnik-journal of Mechanical Engineering, 2010Co-Authors: Michele Scaraggi, Leonardo De Novellis, Giuseppe CarboneAbstract:We analyze the lubrication conditions at the pin-Pulley interface in a Gear Chain Industrial chain CVT. In particular, we focus on the squeeze of oil which occurs as soon as the pin enters the Pulley Groove. The duration time to complete the squeeze process compared with the running time the pin takes to cover the entire arc of contact is fundamental to determine what actually is the lubrication regime at the interface. Taking into account that for normal CVT operations the time the pin spends in contact with the Pulley Groove is of about 0.01 s (traveling time), we show that rms surface roughness less than 0.1 μm and squeezing load of about 1kN acting on the pin, corresponding to values adopted in such systems, guarantee a fully lubricated EHL regime at the interface. We also show that during low-velocity CVT operations, the lubrication regime at the interface is determined by a succession of hydrodynamic and mixed lubrication stages in an order strictly related to the squeezing load history.
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The Lubrication Regime at Pin-Pulley Interface in Chain CVTs
Journal of Mechanical Design, 2008Co-Authors: Giuseppe Carbone, Michele Scaraggi, Leonardo SoriaAbstract:This paper deals with the strongly nonstationary squeeze of an oil film at the interface between the chain pin and Pulley in chain belt continuously variable transmission. We concentrate on the squeeze motion as it occurs as soon as the pin enters the Pulley Groove. The duration time to complete the squeeze process compared with the running time the pin takes to cover the entire arc of contact is fundamental to understand whether direct asperity-asperity contact occurs between the two approaching surfaces to clarify what actually is the lubrication regime (elastohydrodynamic lubrication (EHL), mixed, or boundary) and to verify if the Hertzian pressure distribution at the interface can properly describe the actual normal stress distribution. The Hertzian pressure solution is usually taken as a starting point to design the geometry of the pin surface; therefore, it is of utmost importance for the designers to know whether their hypothesis is correct or not. Taking into account that the traveling time, the pin spends in contact with the Pulley Groove, is of about 0.01 s, we show that rms surface roughness less than 0.1 μm, corresponding to values adopted in such systems, guarantees a fully lubricated EHL regime at the interface. Therefore, direct asperity-asperity contact between the two approaching surfaces is avoided. We also show that the Hertzian solution does not properly represent the actual pressure distribution at the pin-Pulley interface. Indeed, after few microseconds a noncentral annular pressure peak is formed, which moves toward the center of the pin with rapidly decreasing speed. The pressure peak can grow up to values of several gigapascals. Such very high pressures may cause local overloads and high fatigue stresses that must be taken into account to correctly estimate the durability of the system.
Toru Fujii - One of the best experts on this subject based on the ideXlab platform.
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Study on New Developed CVT Having Third Pulley, Tensioner Using Dry Hybrid V-Belts - How Does It Transmit Power at Both Steady and Transitional States?
SAE transactions, 2004Co-Authors: Masafumi Inowaki, Toru Fujii, Kazuya Okubo, Ryuichi Kido, Mitsuhiko Takahashi, Makoto TanikakeAbstract:A new three-Pulley CVT (Continuously Variable Transmission) with a tensioner has been developed using dry hybrid V-belts. It can transmit higher torque than conventional two-Pulley CVT without a tensioner, because the tensioner increases not only a lap angle where power is transmitting but also it can always keep the belt tension optimum. This study shows whether the Euler's power transmitting theory is applicable to the tensioner type CVT to characterize the CVT operation for preliminary design. The tensioner type CVT has also high shifting speed and it does not need large thrusts on both driving and driven Pulleys during shifting since the minimum tension for torque transfer is assured in the slack-side string. The FEM analysis revealed the shifting mechanism and showed that the transmitting force distribution in the Pulley Groove for the newly developed CVT is almost the same as that for the conventional CVT.
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Study on Noise Generation Mechanism for Dry Hybrid Type CVT - Influence of Block Motions and Surface Roughness of Pulley on Sound Pressure
SAE Technical Paper Series, 2004Co-Authors: Junya Kanagawa, Toru Fujii, Kazuya Okubo, Ryuichi Kido, Mitsuhiko TakahashiAbstract:In order to reveal the mechanism of noise generation from CVT (Continuously Variable Transmissions) using a dry hybrid V-belt, the power spectrum of sound from a two-Pulley CVT system and its variation with respect to rotational speed were measured. The experimental results showed that the frequency of the first peak in the power spectrum of the observed sound linearly increased with increasing the rotational speed of the Pulley. The sound frequency of the first peak coincides with the frequency derived from the belt block pitch and the belt speed. Then, sound intensity analyses were conducted to identify noise sources of CVT. The experimental results reveal that unpleasant sound whose frequency is high occurs due to the collision or slip between CVT blocks and the Pulley Groove at the entrance and the exit of V-Groove Pulleys. Pulley surface roughness strongly affects the noise level. Additionally, the location of noise source varies due to surface roughness of the Pulley Groove. Movement of blocks in the radial direction at the entrance of the Pulley Groove is strongly related to the noise.
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Study on transmitting mechanisms for CVT using a dry hybrid V-belt:: numerical simulation of transmitting forces and Pulley thrusts at steady and transitional states
JSAE Review, 1999Co-Authors: Takeshi Miyazawa, Toru Fujii, Shinya Kuwabara, Keizo NonakaAbstract:Abstract An advanced numerical model is proposed to analyze the power transmitting mechanisms for CVT (Continuously Variable Transmissions) using a dry hybrid V-belt. The model consists of linear springs representing the rigidities of blocks, rubber and cord, and interface elements which identify slippage between a Pulley and blocks. By using the present model, forces acting on the belt were calculated not only at steady states but also during transitional states where the speed ratio is shifted. Calculated results well coincide with experimental ones. The behavior of blocks in a Pulley Groove and the relation between Pulley thrusts and the properties of shifting the speed ratio are revealed.
Mitsuhiko Takahashi - One of the best experts on this subject based on the ideXlab platform.
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Study on New Developed CVT Having Third Pulley, Tensioner Using Dry Hybrid V-Belts - How Does It Transmit Power at Both Steady and Transitional States?
SAE transactions, 2004Co-Authors: Masafumi Inowaki, Toru Fujii, Kazuya Okubo, Ryuichi Kido, Mitsuhiko Takahashi, Makoto TanikakeAbstract:A new three-Pulley CVT (Continuously Variable Transmission) with a tensioner has been developed using dry hybrid V-belts. It can transmit higher torque than conventional two-Pulley CVT without a tensioner, because the tensioner increases not only a lap angle where power is transmitting but also it can always keep the belt tension optimum. This study shows whether the Euler's power transmitting theory is applicable to the tensioner type CVT to characterize the CVT operation for preliminary design. The tensioner type CVT has also high shifting speed and it does not need large thrusts on both driving and driven Pulleys during shifting since the minimum tension for torque transfer is assured in the slack-side string. The FEM analysis revealed the shifting mechanism and showed that the transmitting force distribution in the Pulley Groove for the newly developed CVT is almost the same as that for the conventional CVT.
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Study on Noise Generation Mechanism for Dry Hybrid Type CVT - Influence of Block Motions and Surface Roughness of Pulley on Sound Pressure
SAE Technical Paper Series, 2004Co-Authors: Junya Kanagawa, Toru Fujii, Kazuya Okubo, Ryuichi Kido, Mitsuhiko TakahashiAbstract:In order to reveal the mechanism of noise generation from CVT (Continuously Variable Transmissions) using a dry hybrid V-belt, the power spectrum of sound from a two-Pulley CVT system and its variation with respect to rotational speed were measured. The experimental results showed that the frequency of the first peak in the power spectrum of the observed sound linearly increased with increasing the rotational speed of the Pulley. The sound frequency of the first peak coincides with the frequency derived from the belt block pitch and the belt speed. Then, sound intensity analyses were conducted to identify noise sources of CVT. The experimental results reveal that unpleasant sound whose frequency is high occurs due to the collision or slip between CVT blocks and the Pulley Groove at the entrance and the exit of V-Groove Pulleys. Pulley surface roughness strongly affects the noise level. Additionally, the location of noise source varies due to surface roughness of the Pulley Groove. Movement of blocks in the radial direction at the entrance of the Pulley Groove is strongly related to the noise.
