Bearing Wear and Its Effect on Shaft Alignment

2004 ◽  
Vol 41 (03) ◽  
pp. 102-107
Author(s):  
Ronald Bradshaw
Keyword(s):  
Stiffness Matrix ◽  
Numerical Results ◽  
Reduction Gear ◽  
Total Load ◽  
Wear Rates ◽  
Flexible Shaft ◽  
Modal Characteristic ◽  
Shaft Alignment ◽  
Approach Zero

The combined wear of water-lubricated bearings supporting a flexible shaft has a modal characteristic, that is, the cumulative wear can be represented by distinct patterns (modes) that increase geometrically at unique rates. The instantaneous wear rates decrease exponentially with time and approach zero asymptotically. The total load on the outboard bearings decreases and the total load on the inboard bearings increases: the redistribution of outboard and inboard loads is controlled by the shaft stiffness matrix (the reaction influence numbers). The characteristics of modal wear are examined and the changes in alignment loads are calculated, particular attention being paid to reduction-gear loads. Numerical results are displayed.

Tool Wear Analysis of MTConnect Production Data

2021 ◽  
Author(s):  
David Stock ◽  
Aditi Mukhopadhyay ◽  
Rob Potter ◽  
Andy Henderson
Keyword(s):  
Tool Wear ◽  
Cutting Tool ◽  
Numerical Control ◽  
Machining Process ◽  
Total Load ◽  
Wear Rates ◽  
Wear Analysis ◽  
Nc Program ◽  
Small Set ◽  
Key Steps

Abstract This paper presents the analysis of data collected using the MTConnect protocol from a lathe with a Computer Numerical Control (CNC). The purpose of the analysis is to determine an estimated cutting tool life and generate a model for calculating a real-time proxy of cutting tool wear. Various streams were used like spindle load, NC program blocks, the mode, execution etc. The novelty of this approach is that no information about the machining process, beyond the data provided by the machine, was necessary to determine the tool’s expected life. This method relies on the facts that a) it is generally accepted cutting loads increase with tool wear and b) that many CNC machines rely on a small set of regularly run CNC programs. These facts are leveraged to extract the total load for each run of each program on the machine, creating a dataset which is a good indicator of tool wear and replacement. The presented methodology has four key steps: extracting cycle metadata from the machine execution data; computing the integrated spindle loads for every cycle; normalizing the integrated spindle loads between different programs; extracting tool wear rates and changes from the resulting dataset. It is shown that the method can successfully extract the signature of tool wear under a common set of circumstances which are discussed in detail.

Rotordynamics analysis of a quill-shaft coupling-rotor-bearing system

2014 ◽  
Vol 229 (8) ◽  
pp. 1385-1398 ◽  
Author(s):  
S Feng ◽  
HP Geng ◽  
L Yu
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Natural Frequency ◽  
Stiffness Matrix ◽  
Equation Of Motion ◽  
Numerical Results ◽  
The Finite Element Method ◽  
Rotor Bearing ◽  
Bearing System ◽  
Element Method

A quill-shaft coupling-rotor-bearing system is modeled and reported in this paper. The system consists of two rotors connected by a quill-shaft coupling in which each rotor is supported by two bearings. The stiffness matrix of the quill-shaft coupling is deduced and the equation of motion of the system is obtained by using the finite element method. Finally, the rotordynamics analysis of the system is conducted. The numerical results show that more frequency veering points occur for the quill-shaft coupling-rotor-bearing system compared with those of single rotor. In addition, the stiffness of the flexural element has significant effects on the first bending natural frequency of the quill shaft when the length of the quill shaft becomes shorter.

Stiffness of Parallel Manipulators With Serially Connected Legs

2014 ◽  
Vol 6 (3) ◽  
Author(s):  
Han Sung Kim ◽  
Harvey Lipkin
Keyword(s):  
Structural Analysis ◽  
Stiffness Matrix ◽  
Parallel Manipulators ◽  
Numerical Results ◽  
Analysis Software ◽  
Singular Configurations ◽  
Leg Stiffness ◽  
General Method

A simple yet general method determines the stiffness matrix for parallel manipulators with serially connected legs. Link and actuator flexibilities for each leg are modeled by flexibility matrices that are additive. The effect of passive joints is implicitly included using reciprocal screws to yield a leg stiffness matrix that is generally singular. Since the legs act in parallel the leg stiffnesses are additive and yield the manipulator stiffness. The method is applicable to overconstrained, exactly constrained, and underconstrained robots in generic or singular configurations. It is illustrated using the Tricept robot containing a passive constraint leg and an overconstrained translating manipulator. Numerical results are confirmed using commercial structural analysis software.

Shaft Alignment Methods with Strain Gages and Load Cells

1980 ◽  
Vol 17 (01) ◽  
pp. 8-15
Author(s):  
Robert B. Grant
Keyword(s):  
Reduction Gear ◽  
Bending Moments ◽  
Strain Gages ◽  
Direct Bearing ◽  
Load Cells ◽  
Shaft Alignment

The paper presents methods of aligning propulsion shafting using load cells for direct bearing reaction measurement and procedures for shafting alignment by measurement of shaft bending moments with strain gages. Additionally, a unique means of measuring reduction gear and stern tube bearing reactions is described.

Stiffness Matrix Evaluation for a Dual-Reeved Tensile Truss

2013 ◽  
Author(s):  
Jerry Xiong ◽  
Michael P. Hennessey
Keyword(s):  
Stiffness Matrix ◽  
Stewart Platform ◽  
Open Loop ◽  
Numerical Results ◽  
Point Of View ◽  
Experimental Results ◽  
Matrix Elements ◽  
Compliance Matrix ◽  
Line Segments ◽  
Directional Stiffness

Researchers have evaluated the stiffness matrix for different robots and structures, including the Stewart platform style tensile truss. However, none of the configurations analyzed to date involve “dual-reeving,” a common industrial rigging technique whereby cables are spatial loops, vs. open-loop elements, such as those represented by simple line segments. The 4-node/4-loop kinematic configuration analyzed contains 4 symmetric nodes and loops and provides competition for a comparable-sized Stewart platform from the perspective of directional stiffness. Additionally, like the Stewart platform, only a modest amount of off-diagonal compliance matrix elements are present, which from a practical and intuitive point of view, can be advantageous. The methodology used and illustrated in detail is easily generalized to adapt to more involved configurations. Numerical results are obtained for a specific example and compared with those from a Stewart platform. Lastly, some experimental results compare favorably with those derived analytically and evaluated numerically.

Workload Perception of Air Traffic Control Officers and Pilots During Continuous Descent Operations Approach Procedures

2019 ◽  
Vol 9 (1) ◽  
pp. 2-11
Author(s):  
Marina Efthymiou ◽  
Frank Fichert ◽  
Olaf Lantzsch
Keyword(s):  
Fuel Consumption ◽  
Traffic Control ◽  
Air Traffic Control ◽  
Negative Impact ◽  
Air Traffic ◽  
Reduce Fuel Consumption ◽  
Total Load ◽  
Open Path

Abstract. The paper examines the workload perceived by air traffic control officers (ATCOs) and pilots during continuous descent operations (CDOs), applying closed- and open-path procedures. CDOs reduce fuel consumption and noise emissions. Therefore, they are supported by airports as well as airlines. However, their use often depends on pilots asking for CDOs and controllers giving approval and directions. An adapted NASA Total Load Index (TLX) was used to measure the workload perception of ATCOs and pilots when applying CDOs at selected European airports. The main finding is that ATCOs’ workload increased when giving both closed- and open-path CDOs, which may have a negative impact on their willingness to apply CDOs. The main problem reported by pilots was insufficient distance-to-go information provided by ATCOs. The workload change is important when considering the use of CDOs.

Effects of stator splitter blades on aerodynamic performance of a single-stage transonic axial compressor

2020 ◽  
Vol 14 (4) ◽  
pp. 7369-7378
Author(s):  
Ky-Quang Pham ◽  
Xuan-Truong Le ◽  
Cong-Truong Dinh
Keyword(s):  
Stokes Equations ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Aerodynamic Performance ◽  
Numerical Results ◽  
Single Stage ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Operating Stability ◽  
Length Coverage

Splitter blades located between stator blades in a single-stage axial compressor were proposed and investigated in this work to find their effects on aerodynamic performance and operating stability. Aerodynamic performance of the compressor was evaluated using three-dimensional Reynolds-averaged Navier-Stokes equations using the k-e turbulence model with a scalable wall function. The numerical results for the typical performance parameters without stator splitter blades were validated in comparison with experimental data. The numerical results of a parametric study using four geometric parameters (chord length, coverage angle, height and position) of the stator splitter blades showed that the operational stability of the single-stage axial compressor enhances remarkably using the stator splitter blades. The splitters were effective in suppressing flow separation in the stator domain of the compressor at near-stall condition which affects considerably the aerodynamic performance of the compressor.

Influence of Multiwall Carbon Nanotube on mechanical and wear properties of Copper – Iron composite

2020 ◽  
Vol 17 (1) ◽  
pp. 7570-7576 ◽  
Author(s):  
H. Sh. Hammood ◽  
S. S. Irhayyim ◽  
A. Y. Awad ◽  
H. A. Abdulhadi
Keyword(s):  
Carbon Nanotubes ◽  
Volume Fraction ◽  
Hybrid Composites ◽  
Hydraulic Press ◽  
Dry Sliding Wear ◽  
Multiwall Carbon Nanotube ◽  
Wear Properties ◽  
Sem Images ◽  
Wear Rates ◽  
Multiwall Carbon

Multiwall Carbon nanotubes (MWCNTs) are frequently attractive due to their novel physical and chemical characteristics, as well as their larger aspect ratio and higher conductivity. Therefore, MWCNTs can allow tremendous possibilities for the improvement of the necessarily unique composite materials system. The present work deals with the fabrication of Cu-Fe/CNTs hybrid composites manufactured by powder metallurgy techniques. Copper powder with 10 vol. % of iron powder and different volume fractions of Multi-Wall Carbon Nanotubes (MWCNTs) were mixed to get hybrid composites. The hybrid composites were fabricated by adding 0.3, 0.6, 0.9, and 1.2 vol.% of MWCNTs to Cu- 10% Fe mixture using a mechanical mixer. The samples were compressed under a load of 700 MPa using a hydraulic press to compact the samples. Sintering was done at 900°C for 2 h at 5ºC/min heating rate. The microscopic structure was studied using a Scanning Electron Microscope (SEM). The effect of CNTs on the mechanical and wear properties, such as micro-hardness, dry sliding wear, density, and porosity were studied in detail. The wear tests were carried out at a fixed time of 20 minutes while the applied loads were varied (5, 10, 15, and 20 N). SEM images revealed that CNTs were uniformly distributed with relative agglomeration within the Cu/Fe matrix. The results showed that the hardness, density, and wear rates decreased while the percentage of porosity increased with increasing the CNT volume fraction. Furthermore, the wear rate for all the CNTs contents increased with the applied load.

Elasto-plastic state of curve beam system subjected to complex loading

1996 ◽  
Vol 18 (4) ◽  
pp. 14-22
Author(s):  
Vu Khac Bay
Keyword(s):  
Cylindrical Shell ◽  
Solution Method ◽  
Complex Loading ◽  
Numerical Results ◽  
Elastic Solution ◽  
Plastic State ◽  
Curve Beam ◽  
Elastic State ◽  
Elastic Plastic ◽  
Beam System

Investigation of the elastic state of curve beam system had been considered in [3]. In this paper the elastic-plastic state of curve beam system in the form of cylindrical shell is analyzed by the elastic solution method. Numerical results of the problem and conclusion are given.

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