An Experimental and Analytical Study of Connection Forces in High-Speed Mechanisms

1975 ◽  
Vol 97 (4) ◽  
pp. 1166-1174 ◽  
Author(s):  
S. Dubowsky ◽  
S. C. Young
Keyword(s):  
High Speed ◽  
Analytical Study ◽  
Dominant Role ◽  
Mechanical Systems ◽  
Design Engineers ◽  
Experimental Behavior ◽  
Dynamic Forces

The increases in the dynamic forces within the connections of high-speed mechanical systems due to connection clearances and mechanism elasticity are of great interest to design engineers. These forces, which can play a dominant role in the performance and life of these systems, are experimentally studied in this investigation, and the observed experimental behavior is correlated with the results of analytical predictions. The experiments performed confirm the importance of clearances in machine joints on the amplification of connection forces. The effects of connection friction and mechanism elasticity on the connection forces are also investigated.

Controlled Arming of Mechanical Systems Embedded into Embarked Electrical Systems

2014 ◽  
Vol 555 ◽  
pp. 209-216
Author(s):  
Gheorghe Negru
Keyword(s):  
Kalman Filter ◽  
Mechanical System ◽  
High Speed ◽  
Mechanical Systems ◽  
Electrical Systems ◽  
General Motion

The paper presents an application of the Kalman filter to achieve the controlled arming of mechanical system embedded into embarked electrical systems (FMES). The solution of FMES which contain mechanical subsystems electronically controlled could significantly reduce the influence, on their functioning, of the general motion of high speed object (HSO) .

Needle Fatigue Analysis for High-Speed Knitting Machines

1995 ◽  
Author(s):  
Richard H. Lyon ◽  
Leonid M. Malinin
Keyword(s):  
High Speed ◽  
Transfer Functions ◽  
High Capacity ◽  
Time History ◽  
Stationary Problem ◽  
Element Analysis ◽  
Speed Increase ◽  
Design Engineers ◽  
Machine Element ◽  
Needle Longevity

Abstract In modern, high capacity circular knitting machines, the small and fragile latch needles are often a performance-limiting machine element (Schuler, 1980). For these machines, the operating circumferential speed may exceed 1.5 m/sec. Due to the kinematics of the process, the cam driven needles are exposed to periodic excitation with frequency proportional to the speed. Increase in rotational speed gives rise to needle head fatigue breakages unless special design measures are undertaken. Frequencies up to 15 kHz have been observed and up to 60 kHz may be expected in the vibration spectrum. To understand what particular features of needle design may be responsible for their longevity, several techniques were developed to apply Finite Element Analysis software to estimating the fatigue life under a non-harmonic periodic loading. The known FEA packages handle dynamics of a system with such loading as a general non-stationary problem, whereas much more efficient solution can be constructed by combining the analytical solution for a one DOF system under recurring impulses (5-functions of amplitude A) at the moments 0, T, 2T, …, and the natural modes of the system (with the driving point fixed) provided by FEA. As applied to the system in question, from the broad frequency range of the excitation forces and displacements, only frequencies close to those providing maxima to the transfer functions from the driving point to the head of the needle were selected. These frequencies are referred to further on as the response frequencies. Then the time history simulating polyharmonic stresses in the dangerous area was generated and processed according to the chosen fatigue criteria (a corrected linear hypothesis of damage summation, see below). Thus for any given node of the needle a point on the S-N diagram was obtained. A wide spread desktop package, ALGOR, was selected as a Linear Stress Analysis solver. The described procedure is built on top of this package and allows design engineers to make judgements as to what design is more advantageous for needle longevity.

Estimation of Dynamic Forces in Very High-Speed Impact Forging

1966 ◽  
Vol 88 (4) ◽  
pp. 369-372 ◽  
Author(s):  
M. J. Hillier
Keyword(s):  
Approximate Solution ◽  
Velocity Field ◽  
Plane Strain ◽  
Energy Method ◽  
Coulomb Friction ◽  
High Speed ◽  
Admissible Velocity ◽  
High Speed Impact ◽  
Dynamic Forces ◽  
Very High

A study is made of three methods of estimating die loads in impact forging: By approximate solution of the equations of equilibrium; by an energy method, assuming plane sections remain plane; and using the energy method in association with a kinematically admissible velocity field. Results are given for die pressures and die loads for axisymmetric and plane-strain forging of disks and slabs with smooth dies, perfectly rough dies, and for the case of Coulomb friction.

Westinghouse AP1000 Advanced Plant Simplification Results, Measures, and Benefits

2002 ◽  
Author(s):  
C. K. Paulson
Keyword(s):  
Mechanical Systems ◽  
Clear Distinction ◽  
Regulatory Requirements ◽  
Information Display ◽  
Design Engineers ◽  
Control Functions ◽  
Digital Components ◽  
And Control ◽  
Current Systems ◽  
Plant Control

A clear distinction between advanced plants, such as the Westinghouse AP1000 and AP600, and evolutionary plants is the policy in the latter to use current systems’ and buildings’ configurations. This approach does not promote simplification or streamlining, especially in the mechanical systems of the plant. The most significant simplification in evolutionary designs has arguably been in the plant electronics where compact digital components and multiplexing have led to improvements, especially in the areas of information display, installation, and testing. The Westinghouse advanced, passive plants take a different approach. Their design engineers presume that if regulatory requirements can be satisfied by using passive systems, then active plant systems that are only designed to meet plant control functions and not burdened with meeting a safety pedigree can be implemented. This separation of safety and control allows the plant designer to focus on systems’ optimization and reliability by reducing complexity and its associated cost. This design policy has led Westinghouse to the AP600 and AP1000 plant configurations, both of which incorporate significant improvements in areas of plant simplification and enhanced safety.

Identification of Vibration Parameters of Mechanical System Utilizing Low-Cost MEMS Accelerometers

2019 ◽  
Vol 894 ◽  
pp. 1-8
Author(s):  
Khanh Duong Quang ◽  
Huong Vuong Thi ◽  
Anh Luu Van
Keyword(s):  
High Speed ◽  
Low Cost ◽  
Damping Ratio ◽  
Vibration Reduction ◽  
Mechanical Systems ◽  
Micro Electro Mechanical Systems ◽  
Mems Accelerometer ◽  
System Parameters ◽  
Mems Accelerometers ◽  
Vibration Parameters

Multi-axial mechanical systems commonly encounter the problem of vibration while attempting to drive machining systems at high speed. Many effective methods based on feed-forward and feedback control have been proposed and applied for vibration reduction. In order to design controllers all methods require the exact knowledge of system parameters: vibration frequency and damping ratio. In recent years, low-cost Micro Electro Mechanical Systems (MEMS) accelerometers have been used for many applications in industry. This paper presents the advantage of low cost MEMS accelerometer to identify vibration parameters of mechanical systems in comparison to conventional expensive devices.

Experimental study on frictional loss of high-speed bearings based on free-deceleration and energy-balance methods

2019 ◽  
Vol 71 (4) ◽  
pp. 509-514 ◽  
Author(s):  
Shengli Tian ◽  
Xiaoan Chen ◽  
Tianchi Chen ◽  
Ye He
Keyword(s):  
Energy Balance ◽  
Rotational Speed ◽  
High Speed ◽  
Mechanical Systems ◽  
Coupling Factor ◽  
Thermomechanical Coupling ◽  
Frictional Torque ◽  
Frictional Loss ◽  
Content Type ◽  
Relationship Of

Purpose The purpose of this study is to investigate accurate and effective experimental methods for measuring the frictional loss of bearings (FLB) in mechanical systems and to measure the effect of various operating parameters on the frictional loss of high-speed mechanical systems. Design/methodology/approach Two novel methods were studied in this paper to measure the FLB: the free-deceleration method and the energy-balance method. A special high-speed motorised spindle and a friction loss test rig were designed and built to measure the effects of rotational speed, lubrication, preload and operating temperature on the FLB. Findings The experimental results showed that the frictional torque of bearings increases initially but then decreases with an increase in rotational speed. Similarly, the FLB decreases initially and then increases with an increase in temperature because of the influence of the viscosity–temperature relationship of the lubricant and the thermomechanical coupling factor. The optimal lubricant flow was determined, and the effectiveness of a novel preload online adjusting device was verified through experiments. Originality/value The research results of this paper provide the basis and methods for the measurement, reduction and prediction of the FLB in mechanical systems.

Analysis of Tapered Roller Bearings Considering High Speed and Combined Loading

1976 ◽  
Vol 98 (4) ◽  
pp. 564-572 ◽  
Author(s):  
J. Y. Liu
Keyword(s):  
High Speed ◽  
Analytical Study ◽  
Roller Bearing ◽  
Combined Loading ◽  
Sliding Velocity ◽  
Friction Forces ◽  
Tapered Roller Bearing ◽  
Rolling Contacts ◽  
Tapered Roller ◽  
Tapered Roller Bearings

This paper presents an analytical study of the load distribution in a tapered roller bearing operating at a high speed and under combined loading. The friction forces at the rolling contacts and the cage forces are not considered. A numerical example showing, among other things, the effects of misalignment and speed on the bearing fatigue life and the sliding velocity at the flange contact is given.

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