Torsional Vibrations in Reciprocating Engines

1976 ◽  
Vol 20 (01) ◽  
pp. 32-39
Author(s):  
M. S. Pasricha ◽  
W. D. Carnegie
Keyword(s):  
Torsional Vibration ◽  
Mean Value ◽  
Engineering Practice ◽  
Torsional Vibrations ◽  
Secondary Resonance ◽  
Reciprocating Engines ◽  
Marine Engines ◽  
The Subject ◽  
Theoretical Results ◽  
Crank Mechanism

In the case of reciprocating engines, there are certain critical speeds of running at which the torsional vibrations in the shaft become large in amplitude and introduce an element of danger into the system. Fairly simple methods have been devised for the practical calculations to predict the torsional vibration characteristics from the constants of the machinery. The torsional vibration phenomenon in the running gear of reciprocating machinery is usually dealt with by considering a series of constant inertias connected by sections of massless shafting. In recent years several cases of fractures in the crankshafts of large marine engines have been attributed to the phenomenon of secondary resonance, which is explained from the fact that the effective inertia of each slider-crank mechanism varies about a mean value in relation to the position of the crank. Simplified theories predicted these designs of diesel engines as safe in practice. In view of the importance of the subject of torsional vibrations in engineering practice, the effects of variation in inertia on the torsional vibration of the system are examined in detail in the present paper. A comparison of theoretical results with Goldsbrough's experimental results is included.

Secondary Inertia Effects in the Torsional Vibration of Reciprocating Engines—A Literature Review

1995 ◽  
Vol 209 (1) ◽  
pp. 11-15 ◽  
Author(s):  
D C Hesterman ◽  
B J Stone
Keyword(s):  
Literature Review ◽  
Recent Work ◽  
Current Literature ◽  
Torsional Vibration ◽  
Angular Position ◽  
Inertia Effect ◽  
Secondary Resonance ◽  
Inertia Effects ◽  
Reciprocating Engines ◽  
The Subject

It has been known for some time that the torsional vibration of reciprocating engines and pumps cannot be modelled accurately by representing the reciprocating mechanism by a constant inertia. There have been many publications describing better models than those that use constant inertia and these indicate that the effective inertia of a reciprocating mechanism varies with angular position. The major component of this variation is a twice per revolution cyclic effect—hence the term ‘secondary inertia’. The consequences of this secondary inertia effect can be serious for torsional vibration causing ‘secondary resonance,’ and even instability. This paper contains a review of the current literature on the subject and introduces some recent work by the authors.

scholarly journals The properties of torsional vibrations reciprocating engine shafts.— Part I

1926 ◽  
Vol 113 (764) ◽  
pp. 259-271 ◽  
Keyword(s):  
Quantitative Agreement ◽  
Engineering Practice ◽  
Torsional Vibrations ◽  
Reciprocating Motion ◽  
Numerical Accuracy ◽  
Reciprocating Engine ◽  
Refined Method ◽  
Analytical Results ◽  
The Subject ◽  
Set Up

In a previous paper by the writer an examination was made of the torsional vibrations occurring in a reciprocating engine shaft. The case studied was that of a shaft driven by a six-cylinder engine, all parts except the shaft being considered rigid. Certain interesting results, arising from the action of the reciprocating parts, appeared. On account of the importance of the subject of torsional vibrations in engineering practice, and on account of the unexpected nature of the analytical results, it was considered of some interest to examine in greater detail the effect of the reciprocating parts in producing or modifying the vibrations. For this purpose a model is proposed which, it is considered, is as simple as can be conceived, and which, at the same time, involves the characteristics of reciprocating motion. The model is described and the analytical results obtained in Part I of this paper. To verify the analysis, the model was set up in the laboratory and the vibrations observed. Further, to simplify the experimental work, it was thought sufficient for the purposes of verification to arrange it in the first place so as to give only a qualitative agreement with theory, and therefore a precise quantitative agreement was not aimed at, and should not be looked for. An experiment on a much more refined method is being proceeded with to examine minutely into the numerical accuracy of the theory. The details of the present experiment and the numerical results are given in Part II.

scholarly journals Effect of the reciprocating mass of slider-crank mechanism on torsional vibrations of diesel engine systems

2017 ◽  
Vol 23 (1&2) ◽  
pp. 71
Author(s):  
M.S. Pasricha Pasricha ◽  
F.M. Hashim
Keyword(s):  
Torsional Vibration ◽  
Periodic Variation ◽  
Partial Explanation ◽  
Mean Values ◽  
Resonance Effects ◽  
Reciprocating Engine ◽  
Marine Engines ◽  
Marine Diesel ◽  
Engine Systems ◽  
Crank Mechanism

The torsional vibration phenomenon in the running gear of reciprocating engine systems isusually dealt with by considering a series of constant inertias connected by sections of massless shafting. However in reality, a slider crank mechanism is a vibrating system with varying inertia because the effective inertia of the total oscillating mass of each crank assembly varies twice per revolution of the crankshaft. Large variations in inertia torques can give rise to the phenomenonof secondary resonance in torsional vibration of modern marine diesel engines which can not be explained by conventional theory incorporating only the mean values of the varying inertias. In the past associated secondary resonances and regions of instability tended to be dismissed by most engineers as interesting but of no importance. The situation changed in recent years since there is evidence of the existence of thesecondary resonance effects which could have contributed to a number of otherwise inexplicable crankshaft failures in large slow speed marine engines. The cyclic variation of the polar moment of inertia of the reciprocating parts during each revolution causes a periodic variation of frequency and corres ponding amplitude of vibration of reciprocating engine systems. It also causes an increase in the speed range over which resonance effects are experienced and only a partial explanation of the behaviour of the systems has been worked out. It is impossible to avoid these instabilities by changes in thedesign , unless of course the variations in mass and spring constant can be made zero. In the present paper a critical appraisal of the regions of instability as determined from the equation of motion which takes into account variation of inertia is given. The motion in the form of complex waveforms is studied at different speeds of engine rotation. A comparison of theoretical results with Goldsbrough’s experimental resultsand Gregory’s analysis is included.

A Comparison of Physiological Demand between Self-Propelled and Motorized Treadmill Exercise

2018 ◽  
Vol 7 (4) ◽  
pp. 13-21
Author(s):  
Todd Backes ◽  
Charlene Takacs
Keyword(s):  
Respiratory Exchange Ratio ◽  
Treadmill Exercise ◽  
Cardiopulmonary Exercise Testing ◽  
Mean Value ◽  
The Self ◽  
Mixing Chamber ◽  
Wide Range ◽  
The Subject ◽  
The Mean ◽  
Computer Controlled

There are a wide range of options for individuals to choose from in order to engage in aerobic exercise; from outdoor running to computer controlled and self-propelled treadmills. Recently, self-propelled treadmills have increased in popularity and provide an alternative to a motorized treadmill. Twenty subjects (10 men, 10 women) ranging in age from 19-23 with a mean of 20.4 ± 0.8 SD were participants in this study. The subjects visited the laboratory on three occasions. The purpose of the first visit was to familiarize the subject with the self-propelled treadmill (Woodway Curve 3.0). The second visit, subjects were instructed to run on the self-propelled treadmill for 3km at a self-determined pace. Speed data were collected directly from the self-propelled treadmill. The third visit used speed data collected during the self-propelled treadmill run to create an identically paced 3km run for the subjects to perform on a motorized treadmill (COSMED T150). During both the second and third visit, oxygen consumption (VO2) and respiratory exchange ratio (R) data were collected with COSMED’s Quark cardiopulmonary exercise testing (CPET) metabolic mixing chamber system. The VO2 mean value for the self-propelled treadmill (44.90 ± 1.65 SE ml/kg/min) was significantly greater than the motorized treadmill (34.38 ± 1.39 SE ml/kg/min). The mean R value for the self-propelled treadmill (0.91 ± 0.01 SE) was significantly greater than the motorized treadmill (0.86 ± 0.01 SE). Our study demonstrated that a 3km run on a self-propelled treadmill does elicit a greater physiological response than a 3km run at on a standard motorized treadmill. Self-propelled treadmills provide a mode of exercise that offers increased training loads and should be considered as an alternative to motorized treadmills.

Factors Affecting the Achievement of Students in Economic Subject

2021 ◽  
Vol 12 (3) ◽  
pp. 1330-1336
Author(s):  
Siti Hadijah Che Mat Et.al
Keyword(s):  
Teaching Methods ◽  
Teaching And Learning ◽  
Mean Value ◽  
General Interest ◽  
Factors Affecting ◽  
Teaching And Learning Environment ◽  
Learning Techniques ◽  
Economic Program ◽  
The Subject ◽  
High Level

There are various factors influencing a student’s academic achievement at any level, either primary, secondary or tertiary. These factors include attitudes, learning techniques, general interest in the subject matter, factors related to teacher, family or friends, previous achievements, teaching and learning environment and facilities, infrastructure, and teaching methods. This article explores factors affecting the achievement of student of a course offered in the economic program of universitiutaramalaysia. For this article, a total of 220 students who registered for macroeconomics course at universitiutaramalaysia were randomly selected to be the study sample. of the 220 responses, only 211 were analysed because some questionnaire forms was returned with incomplete information. these students consist of second, third and fourth year students. The study found that among the items in the lecturer preparation factor which came with high mean scores is the item "lecturer shows dedication in teaching". There is no denying that teaching and learning methods incorporating the latest technology and trends are desirable but the study shows that teaching using longstanding approach like using whiteboards is still preferable among students and gives the highest mean value of 7.44, which is a high level score. In terms of learning techniques, the study found that students are not consistent between the goals to achieve excellence with the appropriate effort taken by them. although they want to achieve high excellence in this subject but their efforts and actions are not inclined to that desire

Transient and Unstable Torsional Vibrations on a 4-Stroke Marine Diesel Engine

2003 ◽  
Author(s):  
D. C. Lee ◽  
J. D. Yu
Keyword(s):  
Diesel Engine ◽  
Torsional Vibration ◽  
Marine Diesel Engine ◽  
Torsional Vibrations ◽  
Steady State Condition ◽  
Marine Propulsion ◽  
Friction Clutch ◽  
Marine Diesel ◽  
Noise Measurements ◽  
Unstable Vibration

Under steady state condition, unstable torsional vibration normally does not occur in shafting systems using 4stroke diesel engine due to hysteresis damping of shafting system and relative damping of standard fitted damper. However, the unstable torsional vibration occurs on marine propulsion shafting systems due to slippage of a multi-friction clutch installed between increasing gear box and shaft generator. To identify this unstable vibration and make proper counter measure, the simulation for transient torsional vibration using the Newmark method is introduced in this paper. The mechanism of this unstable vibration is verified by vibration and noise measurements of the shafting system.

Effect of Axial and Torsional Vibrations on Tapping Performance

2016 ◽  
Vol 826 ◽  
pp. 88-92
Author(s):  
Swapnil Pawar ◽  
Sandip Patil ◽  
Pravin Pawar ◽  
Rajkumar Singh
Keyword(s):  
Titanium Alloys ◽  
Torsional Vibration ◽  
Torsional Vibrations ◽  
Taguchi Approach ◽  
Maximum Torque ◽  
Degree Of Reduction

Abrupt breakage of the taps is frequently encountered during tapping threads, especially when tapping on ‘difficult-to-cut’ material like titanium. This work therefore presents an extensive experimentation with the Taguchi approach to investigate maximum torque in tapping on titanium alloys while performing axial and, axial and torsional vibration-assisted tapping (AVAT and ATVAT). The experimentation shows that both AVAT and ATVAT reduce the tapping torqueduring tapping as compared to that of in conventional tapping process. However, ATVAT process had exhibited a higher degree of reduction in torque when compared to AVAT process.

scholarly journals Pengembangan Kartu Domano (Domino Matematika Trigono) Sebagai Media Pembelajaran Pada Matakuliah Trigonometri

2019 ◽  
Vol 9 (1) ◽  
pp. 62-75 ◽  
Author(s):  
Kristian Tantra Sidarta ◽  
Tri Nova Hasti Yunianta
Keyword(s):  
Learning Styles ◽  
Mean Value ◽  
Design Development ◽  
Christian University ◽  
Paired Samples ◽  
Questions And Answers ◽  
The Subject ◽  
Addie Model ◽  
Self Learning ◽  
Research Type

This research aims is to develop a learning media called Domano Card, that is an abbreviation  from Trigono mathematics Dominoes. This media is expected to be valid, effective, and practical to be used as a learning tool for Trigonometry Courses in the college. It is consists of three sets of Domano cards, game boards, and game rules. This Domano Card contains of the pairs of questions and answers. This research type is Research Development (R&D) with ADDIE model (Analyze, Design, Development, Implementation, Evaluate). The subject of this research is 64 active students of Mathematics Education, Satya Wacana Christian University in Trigonometry course. Domano cards are developed based on the students’ learning styles. Validity test was done by 2 validators, there are media experts and material experts It has obtained media feasibility result of 98.71% with very decent category and the result of material feasibility of 92.5% with very decent category. The effectiveness test was done by Paired Samples t-test with SPSS 17. It is indicated that there is a significant differences after the use of Domano Card with the mean value improvement from 57 to 73. The respondents of practicality test are lecturer of Trigonometry course and the lecturer assistant class that obtained 89% with very good category. Based on this development research, it can be concluded that Domano Card media is valid, effective, and practical use as a means of self-learning exercises for students in Trigonometry courses.

THE ALLOCATION OF CUSTOMERS IN A DISCRETE-TIME MULTI-SERVER QUEUEING SYSTEM

2010 ◽  
Vol 27 (06) ◽  
pp. 649-667 ◽  
Author(s):  
WEI SUN ◽  
NAISHUO TIAN ◽  
SHIYONG LI
Keyword(s):  
Performance Measures ◽  
Discrete Time ◽  
Queueing System ◽  
Arrival Rate ◽  
Allocation Problem ◽  
Optimal Outcome ◽  
The Subject ◽  
Multi Server ◽  
Theoretical Results

This paper, analyzes the allocation problem of customers in a discrete-time multi-server queueing system and considers two criteria for routing customers' selections: equilibrium and social optimization. As far as we know, there is no literature concerning the discrete-time multi-server models on the subject of equilibrium behaviors of customers and servers. Comparing the results of customers' distribution at the servers under the two criteria, we show that the servers used in equilibrium are no more than those used in the socially optimal outcome, that is, the individual's decision deviates from the socially preferred one. Furthermore, we also clearly show the mutative trend of several important performance measures for various values of arrival rate numerically to verify the theoretical results.

An Experimental Study of Torsional Vibration Absorbers

2001 ◽  
Author(s):  
Alan G. Haddow ◽  
Steven W. Shaw
Keyword(s):  
Experimental Study ◽  
Dynamic Behavior ◽  
Systematic Study ◽  
Torsional Vibration ◽  
Theoretical Background ◽  
Controlled Environment ◽  
Vibration Absorbers ◽  
Test Apparatus ◽  
First Time ◽  
Theoretical Results

Abstract This paper presents results from tests completed on a rotor system fitted with pendulum-type torsional vibration absorbers. A review of the associated theoretical background is also given and the experimental and theoretical results are compared and contrasted. An overview of the test apparatus is provided and its unique features are discussed. To the best knowledge of the authors, this is the first time that a systematic study of the dynamic behavior of torsional vibration absorbers has been undertaken in a controlled environment.

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