A dynamic contact wear model of ball bearings without or with distributed defects

2020 ◽  
Vol 234 (24) ◽  
pp. 4827-4843
Author(s):  
Xi Zhang ◽  
Hua Xu ◽  
Wei Chang ◽  
Hui Xi ◽  
Shiyuan Pei ◽  
...  
Keyword(s):  
Dynamic Contact ◽  
Ball Bearings ◽  
Wear Model ◽  
Wear Rates ◽  
Contact Wear ◽  
Body Dynamics ◽  
Ball Diameter ◽  
Dynamic Wear ◽  
Multi Body ◽  
The Ideal

A dynamic contact wear model of ball bearings consisting of wear degree and position distribution is proposed by integrating the developed contact wear model, multi-body dynamics and raceway waviness or ball diameter differences. Subsequently, the dynamic wear characteristics, not only for the ideal bearing under different axial and radial loads, but also for the bearing with above defects are analysed. The influences of load, typical waviness orders and amplitude on the wear of each ball against both raceways are evaluated and qualitatively validated. Finally, the dynamic characteristics of ball bearings with one ball larger are discussed, and then vibration frequency and wear rates distinction are verified by the experiment with working-surface roughness measurement as a way for wear rate assessment.

Analysis of the dynamic contact between rotating spur gears by finite element and multi-body dynamics techniques

2001 ◽  
Vol 215 (4) ◽  
pp. 423-435 ◽  
Author(s):  
K Lee
Keyword(s):  
Finite Element ◽  
Contact Point ◽  
Equations Of Motion ◽  
Mass Effect ◽  
Dynamic Contact ◽  
Spur Gears ◽  
Gear Teeth ◽  
Body Dynamics ◽  
Tooth Surfaces ◽  
Multi Body

A numerical method is presented for the dynamic contact analysis of spur gears rotating with very high angular speeds. For each gear an elastic tooth of distributed mass is connected to a rigid disc with kinematic constraints, and finite element formulations are used for the equations of motion of the teeth. The velocity and acceleration as well as the position of the contact point sliding on the mating gear teeth are precisely computed by simultaneously using the motions of a pair of rotating tooth surfaces. The equations of motion subjected to the kinematic constraint and contact condition are solved by enforcing the velocity and acceleration constraints as well as the displacement constraint. In the numerical simulation the importance of the mass effect of gear teeth is demonstrated, and it is shown that the solution is obtained even if gears repeat contact and separation.

Charnley wear model for validation of hip simulators' ball diameter versus polytetrafluoroethylene and polyethylene wear

1997 ◽  
Vol 211 (1) ◽  
pp. 25-36 ◽  
Author(s):  
I C Clarke ◽  
V Good ◽  
L Anissian ◽  
A Gustafson
Keyword(s):  
Femoral Head ◽  
Clinical Data ◽  
Polyethylene Wear ◽  
Test Duration ◽  
Cobalt Chromium ◽  
Wear Model ◽  
Wear Rates ◽  
Ball Diameter ◽  
Relationship Of

Wear rates of polytetrafluoroethylene (PTFE) and polyethylene cups were compared in 9-channel and 12-channel simulators, using serum lubrication and gravimetric techniques for wear assessment. Cobalt-chromium (CoCr) and alumina ceramic femoral heads in 22-42 mm diameter range were used to validate simulator wear rates against clinical data. This was also the first study of three femoral head sizes evaluated concurrently in a simulator (with three replicate specimens) and also the first report in which any wear experiments were repeated. Fluid absorption artefacts were within ± 1 per cent of wear magnitude for PTFE and ± 8 per cent for polyethylene and were corrected for. Wear rates were linear as a function of test duration. Precision within each set of three cups was within ±6 per cent. The wear rates from experiments repeated over 15 months were reproducible to within ± 24 per cent. However, the magnitudes of the simulator wear rates were not clinically accurate, the PTFE wear rates (2843 mm3/106 cycles; 22 mm diameter) were over three times higher than in vivo, the polyethylene 30 to 50 per cent on the low side (23 mm3/106 cycles; 22 mm diameter). Volumetric wear rate increased with respect to size of femoral head and a linearly increasing relationship of 7-8 per cent/mm was evident with respect to femoral head diameter for both PTFE and polyethylene. These data compared well with the clinical data.

Study on the mechanical effect and wear behaviour of middle trough of a scraper conveyor based on DEM–MBD

2021 ◽  
pp. 135065012110592
Author(s):  
Haozhou Ma ◽  
Xuewen Wang ◽  
Bo Li ◽  
Zhaoyang Liu ◽  
Wenjie Bi ◽  
...  
Keyword(s):  
Mechanical Effect ◽  
Wear Behaviour ◽  
Wear Model ◽  
Random Occurrence ◽  
Coal Particles ◽  
Body Dynamics ◽  
Scraper Conveyor ◽  
Uneven Wear ◽  
Three Body ◽  
Multi Body

Middle trough is the main-force portion of a scraper conveyor during transport, and its performance directly affects the reliability and service life of the scraper conveyor. To investigate the wear of a middle trough, a coupling-wear model of a middle trough was built to analyse the motion state and stress of a scraper, and the wear of the middle trough was analysed according to the wear morphology of the middle plate. The research results demonstrated that the simulation model based on coupling of the discrete element method and multi-body dynamics could effectively simulate the transport conditions of a scraper conveyor. The wear of the middle trough was mainly caused by three-body wear. Formation of three-body wear required that the coal particles between the scraper (chain) and middle plate must be in a certain position and posture, and the coal particles were subjected to the normal force of the scraper (chain) and middle plate. Constant fluctuation in the movement and force of the scraper (chain) resulted in uneven wear of the middle trough and random occurrence of three-body wear. This study provides a theoretical basis for wear prediction of the middle trough of a scraper conveyor and a simulation basis for further research on the wear resistance of a middle trough.

scholarly journals Estimating maximum bite performance in Tyrannosaurus rex using multi-body dynamics

2012 ◽  
Vol 8 (4) ◽  
pp. 660-664 ◽  
Author(s):  
K. T. Bates ◽  
P. L. Falkingham
Keyword(s):  
Body Size ◽  
Feeding Behaviour ◽  
Ontogenetic Change ◽  
Positive Allometry ◽  
Musculoskeletal Models ◽  
Terrestrial Animal ◽  
Body Dynamics ◽  
Mode Of Life ◽  
Scaling Analyses ◽  
Multi Body

Bite mechanics and feeding behaviour in Tyrannosaurus rex are controversial. Some contend that a modest bite mechanically limited T. rex to scavenging, while others argue that high bite forces facilitated a predatory mode of life. We use dynamic musculoskeletal models to simulate maximal biting in T. rex . Models predict that adult T. rex generated sustained bite forces of 35 000–57 000 N at a single posterior tooth, by far the highest bite forces estimated for any terrestrial animal. Scaling analyses suggest that adult T. rex had a strong bite for its body size, and that bite performance increased allometrically during ontogeny. Positive allometry in bite performance during growth may have facilitated an ontogenetic change in feeding behaviour in T. rex , associated with an expansion of prey range in adults to include the largest contemporaneous animals.

Sir Robert Stawell Ball and methodologies of modern screw theory

2002 ◽  
Vol 216 (1) ◽  
pp. 1-11 ◽  
Author(s):  
H Lipkin ◽  
J Duffy
Keyword(s):  
Computational Geometry ◽  
Rigid Body ◽  
Lie Algebra ◽  
Screw Theory ◽  
Mechanical Design ◽  
Ball Screw ◽  
Dual Numbers ◽  
Body Dynamics ◽  
Rigid Body Mechanics ◽  
Multi Body

The theory of screws was largely developed by Sir Robert Stawell Ball over 100 years ago to investigate general problems in rigid body mechanics. Nowadays, screw theory is applied in many different but related forms including dual numbers, Plilcker coordinates and Lie algebra. An overview of these methodologies is presented along with a perspective on Ball. Screw theory has re-emerged after a hiatus to become an important tool in robot mechanics, mechanical design, computational geometry and multi-body dynamics.

Tanker Truck Sloshing Simulation Using Bi-Directionally Coupled CFD and Multi-Body Dynamics Solvers

2014 ◽  
Author(s):  
Michael S. Barton ◽  
David Corson ◽  
John Quigley ◽  
Babak Emami ◽  
Tanuj Kush
Keyword(s):  
Body Dynamics ◽  
Tanker Truck ◽  
Multi Body

Development of a Simulation Model to Investigate Tool Wear in Ti-6Al-4V Alloy Machining

2011 ◽  
Vol 223 ◽  
pp. 535-544 ◽  
Author(s):  
Volker Schulze ◽  
Frederik Zanger
Keyword(s):  
Tool Wear ◽  
High Strength ◽  
State Variables ◽  
Wear Model ◽  
Fem Model ◽  
Load Variations ◽  
Wear Rates ◽  
Simulation Results ◽  
Mechanical Machining ◽  
Very High

Titanium alloys like Ti‑6Al‑4V have a low density, a very high strength and are highly resistant to corrosion. However, the positive qualities in combination with the low heat conductivity have disadvantageous effects on mechanical machining and on cutting in particular. Ti‑6Al‑4V forms segmented chips for the whole range of cutting velocities which influences tool wear. Thus, optimization of the manufacturing process is difficult. To obtain this goal the chip segmentation process and the tool wear are studied numerically in this article. Therefore, a FEM model was developed which calculates the wear rates depending on state variables from the cutting simulation, using an empirical tool wear model. The segmentation leads to mechanical and thermal load variations, which are taken into consideration during the tool wear simulations. In order to evaluate the simulation results, they are compared with experimentally obtained results for different process parameters.

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