Influence of Clearance on the Dynamics of Chain CVT Drives

2006 ◽  
Author(s):  
Nilabh Srivastava ◽  
Yi Miao ◽  
Imtiaz U. Haque
Keyword(s):  
Dynamic Performance ◽  
Suitable Model ◽  
Multibody Model ◽  
System A ◽  
Automotive Transmission ◽  
Chain Link ◽  
Variable Transmission ◽  
Coulomb Approximation ◽  
A Chain ◽  
Chain Links

A continuously variable transmission (CVT) is an emerging automotive transmission technology that offers a continuum of gear ratios between desired limits. The present research focuses on developing models to understand the influence of clearance on the dynamic performance of a chain CVT drive. Clearances may arise in such a CVT during the assembly process or during extensive continual operation of the system, which further leads to wear and failure of the system. A detailed planar multibody model of a chain CVT is developed in order to accurately capture the dynamics characterized by the discrete structure of the chain, which causes polygonal excitations in the system. A suitable model for clearance between the chain links is embedded into this multibody model of the chain CVT. Friction between the chain link and the pulley sheaves is modeled using continuous Coulomb approximation theory. The mathematical models, the computational scheme, and the results corresponding to different loading scenarios are discussed. The results discuss the influence of clearance parameters on the dynamic performance, the axial force requirements, and the torque transmitting capacity of a chain CVT drive.

Dynamics of Chain CVT Drives: Effects of Friction Characteristic

2007 ◽  
Author(s):  
Nilabh Srivastava ◽  
Imtiaz U. Haque
Keyword(s):  
Mathematical Models ◽  
Axial Force ◽  
Dynamic Performance ◽  
Continuously Variable Transmission ◽  
Friction Characteristic ◽  
Contact Patch ◽  
Multibody Model ◽  
Variable Transmission ◽  
Torque Capacity ◽  
A Chain

A chain CVT is a type of friction-limited continuously variable transmission that provides a continuum of gear ratios with fewer moving parts. The dynamic performance and torque capacity of a chain CVT drive rely significantly on the friction characteristic of the contact patch between the chain and the pulley. Since the friction characteristic of the contact patch may vary in accordance with the loading and design configurations, it is crucial to study the influence of friction characteristic on the performance of a CVT. Two different mathematical models of friction, which characterize different operating/loading conditions, are embedded into a detailed planar multibody model of chain CVT in order to understand the various friction-induced effects in the system. The mathematical models, the computational scheme, and the results corresponding to different loading scenarios are discussed. The results discuss the influence of friction characteristics on the dynamic performance, the axial force requirements, and the torque transmitting capacity of a chain CVT drive.

Out-of-Plane Bending Testing of Chain Links

2005 ◽  
Author(s):  
Cecil Melis ◽  
Phillipe Jean ◽  
Pedro Vargas
Keyword(s):  
Empirical Relationship ◽  
Chain Link ◽  
Out Of Plane ◽  
Bending Stresses ◽  
Test Frame ◽  
Scale Test ◽  
Plane Bending ◽  
A Chain ◽  
Chain Links ◽  
Mooring Chain

Several mooring chains of an off-loading buoy failed after only 8 months of service. These chains were designed according to conventional fatigue assessment using API RP 2SK T-N curves to a fatigue life or 20 years with a factor of safety equal to 3 on life. Of particular interest is that the mooring chain failure underwent significant mooring chain motions that caused interlink rotations. Although traditionally neglected, these interlink rotations, when combined with significant chain tensions can cause bending stresses in the chain links. In this paper we identify a mechanism, here identified as Out-of-Plane Bending (OPB) that explains the extensive fatigue damage causing the mooring chains of the off-loading buoy to fail. A full scale test frame was constructed that has the capacity of applying inter-link rotation to a pre-tensioned chain. Although the test frame limits the number of links that can be tested together as a chain, a significant amount of testing was performed for the following chain sizes: 1. 81 mm Studded Grade R3S. 2. 107 mm Studdless Grade RQ3. 3. 124 mm Studless Grade R4. 4. 146 mm Studless Grade RQ4. Various pretension levels were used, with instrumentation to extract link angles and chain link stresses. In this paper the OPB mechanism is explained, and the test frame and results are presented. An empirical relationship is found to predict the OPB stresses in the chain links as a function of pretension and inter-link rotation. The OPB stress relationship obtained was applied to the failed mooring chain of the off-loading buoy with reasonable agreement. To comply with Single Buoy Moorings (SBM) requirements addressing publication of internal research, many of the graphs included in this paper have had the stress values removed from the y-axis. However, with SBM’s management approval, some numerical references to stress amplitudes remain in the text. Overall, this limitation does not detract from the study, trends are evident and relevant comparisons can be made.

scholarly journals STRESS ANALYSIS AND TOPOLOGY OPTIMIZATION OF A CHAIN BUCKET ELEVATOR USING ANSYS

2021 ◽  
Vol 61 (1) ◽  
pp. 292-306
Author(s):  
Edward Yin ◽  
Emmanuel M. Seckley ◽  
Evans Kesse Asiedu ◽  
Stephen Cobbinah
Keyword(s):  
Topology Optimization ◽  
Maximum Load ◽  
Maintenance And Repair ◽  
Ratchet Mechanism ◽  
Repair Costs ◽  
Chain Link ◽  
Bucket Elevator ◽  
A Chain ◽  
Time Required ◽  
Chain Links

A failure of conveyor chain links in a production process can cause unscheduled shutdowns, which increase the throughput time coupled with damaged buckets and chain links, which increase maintenance and repair costs. Since failures of conveyor chains are inevitable, this research aims to modify the design of the chain bucket elevator by incorporating a ratchet mechanism, which will prevent the chain bucket assembly from dropping to the bottom of the chain bucket elevator whenever there is a chain-link failure and also avoid the jamming of the bucket chain assembly against one another when dropping to the bottom of the elevator during failure. The number of damaged buckets and chains will be minimal, thereby reducing the maintenance and repair costs. Also, the time required for replacing the failed chain link will be reduced, which in turn, will reduce the down-time, thereby increasing the production rate. The ratchet mechanism, which can withstand a maximum load of 38.10 kN, comprises a toothed wheel, a pawl, and a spring. An analytical method was employed for the initial analysis and the results were verified using the FEM. Topology Optimization was carried out on the beam and lever with results showing a 20% and 26% weight reduction from the original, respectively. The stresses induced in the beam and lever increased significantly by 36% and 47 %, respectively, because of the optimization, however, they remained within the acceptable limits.

Risk-Based Inspection Planning for Mooring Chain

2002 ◽  
Author(s):  
Jan Mathisen ◽  
Kjell Larsen
Keyword(s):  
Probabilistic Modelling ◽  
Structural Components ◽  
Inspection Planning ◽  
Single Chain ◽  
Chain Link ◽  
Northern North Sea ◽  
A Chain ◽  
Series Systems ◽  
Chain Links ◽  
Mooring Chain

The use of risk-based inspection planning for offshore structural components is becoming quite familiar. This paper describes an application of this technique to mooring chain. In many cases, the technique is based on probabilistic modelling of fatigue crack growth in the structural components, and updating of the failure probability on the basis of inspections. The extension of this basis from a single component to very many components is necessary to tackle series systems, such as mooring chain, where a fatigue fracture can arise in any chain link. The theoretical basis for the analysis is described, including details of the model for stochastic dependency between the chain links. Results are shown that compare failure probabilities for a single chain link and a chain segment. The effects of various levels of inspection coverage are illustrated. An example of a cost optimal inspection plan is developed for mooring chain on an FPSO in the northern North Sea.

Dynamics of CVT Chain Drives: Mechanichal Model and Verification

1997 ◽  
Author(s):  
Jürgen Srnik ◽  
Friedrich Pfeiffer
Keyword(s):  
Power Transmission ◽  
Contact Forces ◽  
Coulomb’S Friction ◽  
Joint Forces ◽  
Chain Link ◽  
Frictional Forces ◽  
Contact Situation ◽  
A Chain ◽  
Chain Drives ◽  
Chain Links

Abstract This paper deals with the dynamics of continuously variable (CVT) chain drives. According to the discrete structure of the chain, which causes the polygonal actions, the mechanical model contains each chain link and pulley as a separate body. While a chain link is part of a strand, only joint forces including friction act on the chain links, whereas in the contact situation additional impulsive and frictional forces in the contact zones between the chain link’s rocker pins and the tapered surfaces of the cone pulleys have to be taken into account. For the calculation of the contact forces Coulomb’s friction law as well as a time sparing continuous approximation are applied. Simulation results show the influence of the cone pulley’s deformation on the power transmission. They also show the repercussion of the polygonal action. Furthermore the chain’s pitch influence on the vibrational behavior of the transmission is discussed. A comparison of calculated and measured tensional forces verifies the model presented.

Risk-Based Inspection Planning for Mooring Chain

2004 ◽  
Vol 126 (3) ◽  
pp. 250-257 ◽  
Author(s):  
Jan Mathisen ◽  
Kjell Larsen
Keyword(s):  
Probabilistic Modelling ◽  
Structural Components ◽  
Inspection Planning ◽  
Single Chain ◽  
Chain Link ◽  
Northern North Sea ◽  
A Chain ◽  
Series Systems ◽  
Chain Links ◽  
Mooring Chain

The use of risk-based inspection planning for offshore structural components is becoming quite familiar. This paper describes an application of this technique to mooring chain. In many cases, the technique is based on probabilistic modelling of fatigue crack growth in the structural components, and updating of the failure probability on the basis of inspections. The extension of this basis from a single component to very many components is necessary to tackle series systems, such as mooring chain, where a fatigue fracture can arise in any chain link. The theoretical basis for the analysis is described, including details of the model for stochastic dependency between the chain links. Results are shown that compare failure probabilities for a single chain link and a chain segment. The effects of various levels of inspection coverage are illustrated. An example of a cost optimal inspection plan is developed for mooring chain on an FPSO in the northern North Sea.

Dynamic Performance of Neck Protection Devices: Performance Analysis Based on a Simplified Multibody Model of the Human Neck

2012 ◽  
Author(s):  
Massimiliano Gobbi ◽  
Gianpiero Mastinu ◽  
Giorgio Previati ◽  
Ermes Tarallo
Keyword(s):  
Soft Tissues ◽  
Mechanical Response ◽  
Dynamic Performance ◽  
Safety Devices ◽  
Anatomy And Physiology ◽  
Multibody Model ◽  
Impulsive Loads ◽  
Protection Devices ◽  
Safety Systems ◽  
Deformation System

This work is focused on the evaluation of the dynamic performance of different neck protection devices. In order to evaluate the mechanical response of the safety devices, a multibody model of the human neck has been developed in Matlab™ SimMechanics™. The mechanical behavior of the neck is described in the paper and different injury indices are presented and compared. The information about anatomy and physiology of the cervical spine of the neck has been collected from the literature, with particular focus on the mechanism of damage of vertebrae, disks and soft tissues. The multibody model has been validated against experimental data available in the literature concerning impulsive loads representative of crash phenomena. By means of the presented model, some relevant injury indices are computed for an accident involving a motorcyclist. Since the focus has been set on mild injuries of the neck, the simulated crash should cause a high probability of injuries of the neck together with a low probability of damages of the head while wearing a standard helmet. The performance of neck safety devices that link the helmet with the thoracic-shield are evaluated and compared. For sake of clearness, three types of neck safety devices are considered referencing to US patents: an airbag jacket, a 3D cushion wrapping the motorcyclist’s neck, and a “spring and dampers” system. The airbag jacket has been modeled as a high stiffness and low deformation system by considering the airbag in its fully deployed configuration and by neglecting its dynamic performance during inflation phase. The other safety devices have been modeled as lumped parameters spring-damper systems. A sensitivity analysis on the injury indexes has been performed by changing the stiffness and the damping parameters of these safety systems. The injury indexes collected by simulating the different neck safety systems have been compared.

scholarly journals Oceanithermus desulfurans sp. nov., a novel thermophilic, sulfur-reducing bacterium isolated from a sulfide chimney in Suiyo Seamount

2004 ◽  
Vol 54 (5) ◽  
pp. 1561-1566 ◽  
Author(s):  
Koji Mori ◽  
Takeshi Kakegawa ◽  
Yowsuke Higashi ◽  
Ko-ichi Nakamura ◽  
Akihiko Maruyama ◽  
...  
Keyword(s):  
Sequence Similarity ◽  
Growth Conditions ◽  
Cellular Fatty Acid ◽  
Rrna Gene ◽  
Good Growth ◽  
Chain Link ◽  
Circular Structure ◽  
Hybridization Test ◽  
A Chain ◽  
Cellular Fatty Acid Profile

A novel thermophilic, microaerophilic, sulfur-reducing bacterium designated strain St55BT was isolated from a sulfide chimney in the hydrothermal field of Suiyo Seamount (Izu-Bonin Arc, Western Pacific). Cells of the isolate were rod-shaped and tended to form a chain-link circular structure (a rotund body) at exponential phase under good growth conditions. The isolate was a chemoheterotroph requiring yeast extract for growth. Although strain St55BT used oxygen as an electron acceptor, it could not form colonies in an oxygen concentration of more than 5 % (v/v). The isolate also used nitrate, nitrite or elemental sulfur in the absence of oxygen. A phylogenetic analysis based on the 16S rRNA gene sequence revealed that the isolate was closely related to Oceanithermus profundus, belonging to the phylum ‘Deinococcus–Thermus’ (sequence similarity 99·5 %). However, strain St55BT differed from O. profundus in terms of usage of electron donors, cellular fatty acid profile and DNA G+C content. In addition, a DNA–DNA hybridization test indicated low relatedness between the isolate and O. profundus. For the reasons given above, the name Oceanithermus desulfurans sp. nov. is proposed for strain St55BT (=NBRC 100063T=DSM 15757T).

scholarly journals Boundary Detection and Enhancement of Islanding Operation Investigation Under Fault Condition

2017 ◽  
Author(s):  
Aref Pouryekta ◽  
Vigna K. Ramachandaramurthy ◽  
Sanjeevikumar Padmanaban ◽  
Lucian MIHET-POPA
Keyword(s):  
Distribution Systems ◽  
Dynamic Performance ◽  
Boundary Detection ◽  
Sensitivity Factor ◽  
Voltage Sensitivity ◽  
Autonomous Operation ◽  
System A ◽  
Autonomous Mode ◽  
Dynamic Voltage ◽  
Islanding Operation

Distribution systems can form islands when faults occur. Each island represents a subsection with variable boundaries subject to the location of a fault(s) in the system. A subsection with variable boundaries is referred to as island in this paper. For operation in autonomous mode, it is imperative to detect the island configurations and stabilize these subsections. This paper presents a novel scheme for the detection of islanding boundaries and stabilizing the system during autonomous operation. In the first stage, a boundary detection method is proposed to detect the configuration of the island. In the second stage a dynamic voltage sensitivity factor (DVSF) is proposed to assess the dynamic performance of the system. In the third stage, a wide area load shedding program is adopted based on DVSF to shed the load in weak busbars and stabilize the system. The proposed scheme is validated and tested on a generic 18-bus system using a combination of EMTDC/PSCAD and MATLAB softwares.

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