scholarly journals Nonlinear Characteristics Analysis of Eccentric Rotor System Based on FEM

2020 ◽  
pp. 235-244
Author(s):  
Choluk Ri ◽  
Chunghyok Chae ◽  
Kwanggyun Sin ◽  
Yongil Sin ◽  
Kwangil Ri ◽  
...  
Keyword(s):  
Mathematical Modeling ◽  
Nonlinear Dynamics ◽  
Rotor Dynamics ◽  
Rotor System ◽  
Ansys Software ◽  
Nonlinear Characteristics ◽  
Double Support ◽  
Eccentric Rotor ◽  
Characteristics Analysis ◽  
The Relationship

In this paper, based on the theory of rotor dynamics, the nonlinear dynamics of a rotor system with an eccentric rotor is analyzed. Taking the double-support rotor system with a single turntable as the object, the mathematical modeling method of the rotor system with an eccentric rotor and the rotation analysis of the turntable are analyzed in detail. According to ANSYS software, the influence of eccentricity on the rotor system and the relationship between eccentricity and nonlinearity are analyzed.

Research of Strength of Rotor System about Containing Blade Crackle Based on Nonlinear Dynamics

2010 ◽  
Vol 44-47 ◽  
pp. 1158-1162
Author(s):  
Xiao Bo Liu ◽  
Kai Qin Li
Keyword(s):  
Nonlinear Dynamics ◽  
Stress Distribution ◽  
Rotor System ◽  
Ansys Software ◽  
Rotating Shaft ◽  
Alloy Material ◽  
Interior Stress ◽  
Nonlinear Dynamics Model ◽  
Nonlinear Dynamic Stability ◽  
Intensity Stress

As the condition of a certain blade cracked of rotor system of fans, limited short-axletree nonlinear dynamics model is used ,the vibration frequency and nonlinear dynamic stability single-disc rotor is discussed, interior stress distribution and size of rotating shaft after loaded is analyzed concretely by ANSYS software. Through contrast X, Y, X-Y three directions stress distribution of rotating shaft interior, for entity model of near support disc and shaft, it is observed that its field of stress distribution compare dense is near--support field，also stress concentration is relatively bigger after load is added. Meanwhile ANSYS software is used to calculate by simulation this relation of the blade cracking spread width-temporal of four different alloy material and to count the intensity、stress distributing and the axial displacement of the axletree. The best numerical value about elastic modulus and hardness of the material is found by analysis the curve of crackle width- time function.

scholarly journals A Field Measurement Based Wind Characteristics Analysis of a Typhoon in Near-Ground Boundary Layer

Atmosphere ◽  
2021 ◽  
Vol 12 (7) ◽  
pp. 873
Author(s):  
Dandan Xia ◽  
Liming Dai ◽  
Li Lin ◽  
Huaifeng Wang ◽  
Haitao Hu
Keyword(s):  
Turbulence Intensity ◽  
Field Measurement ◽  
Three Dimensional ◽  
Wind Data ◽  
Statistical Characteristics ◽  
Gust Factor ◽  
Characteristics Analysis ◽  
Wind Characteristics ◽  
The Mean ◽  
The Relationship

The field measurement was conducted to observe the wind field data of West Pacific typhoon “Maria” in this research. With the application of ultrasonic anemometers installed in different heights (10 m, 80 m, 100 m) of the tower, the three dimensional wind speed data of typhoon “Maria” was acquired. In addition, vane-type anemometers were installed to validate the accuracy of the wind data from ultrasonic anemometers. Wind characteristics such as the mean wind profile, turbulence intensity, integral length scale, and wind spectrum are studied in detail using the collected wind data. The relationship between the gust factor and turbulence intensity was also studied and compared with the existing literature to demonstrate the characteristics of Maria. The statistical characteristics of the turbulence intensity and gust factor are presented. The corresponding conclusion remarks are expected to provide a useful reference for designing wind-resistant buildings and structures.

Mathematical Alternatives to Standard Probability that Provide Selectable Degrees of Precision

2017 ◽  
Author(s):  
Terrence Fine
Keyword(s):  
Mathematical Modeling ◽  
Mathematical Models ◽  
Theory Of Measurement ◽  
Belief Functions ◽  
Standard Practice ◽  
Mathematical Probability ◽  
Comparative Probability ◽  
The Relationship ◽  
Standard Probability

This chapter challenges the nearly universal reliance upon standard mathematical probability for mathematical modeling of chance and uncertain phenomena, and offers four alternatives. In standard practice, precise assignments are made inappropriately, even to the occurrences of events that may be unobservable in principle. Four familiar examples of chance or uncertain phenomena are discussed, about which this is true. The theory of measurement provides an understanding of the relationship between the accuracy of information and the precision with which the phenomenon under examination should be modeled mathematically. The model of modal or classificatory probability offers the least precision. Comparative probability, plausibility/belief functions and upper/lower probabilities are carefully considered. The selectable precision of these alternative mathematical models of chance and uncertainty makes for an improved range of levels of accuracy in modeling the empirical domain phenomena of chance, uncertainty, and indeterminacy. Knowledge of such models encourages further thought in this direction.

scholarly journals Daily Players’ Satisfaction with Pitching Performance Could Predict Shoulder and Elbow Injuries in High-school Baseball Pitchers: A Prospective Time-to-event Study

2021 ◽  
Author(s):  
Hitoshi Shitara ◽  
Tsuyoshi Tajika ◽  
Takuro Kuboi ◽  
Tsuyoshi Ichinose ◽  
Tsuyoshi Sasaki ◽  
...  
Keyword(s):  
High School ◽  
Event Study ◽  
Operating Characteristics ◽  
Time To Event ◽  
Elbow Injury ◽  
Shoulder Range Of Motion ◽  
Elbow Injuries ◽  
Characteristics Analysis ◽  
Baseball Pitchers ◽  
The Relationship

Abstract The relationship between baseball pitchers’ satisfaction with their own performance and the incidence of shoulder and elbow injuries is unclear. We analyzed the relationship between daily satisfaction scores before injury and incidence of shoulder/elbow injury in high-school baseball pitchers in this prospective, time-to-event study. We collected baseline data on baseball experience, height, weight, elbow and shoulder range of motion, and shoulder muscle strength. The 108 enrolled participants aged 15-17 years were divided into satisfied (88) and unsatisfied (22) groups based on the Receiver operating characteristics analysis results that revealed the cutoff value to be 4 points. The incidence of injury was 10.2% and 50.0% in the satisfied and unsatisfied groups, respectively. We observed that high-school baseball pitchers with a low satisfaction significantly increased the risk of shoulder and elbow injuries: these players had a 7.3-times greater risk of injuries and a 1.9-times earlier occurrence of injuries than pitchers who are satisfied with their performance. High-school baseball pitchers who had low satisfaction with their pitching performance had higher risk of shoulder and elbow injuries and lower time to injury than satisfied pitchers. Daily evaluation of players’ self-satisfaction could predict shoulder and elbow injuries in high-school baseball pitchers.

scholarly journals Applying Methods of Mathematical Modeling in Cattle Breeding

2019 ◽  
Vol 8 (12) ◽  
pp. 185-187 ◽  
Keyword(s):  
Mathematical Modeling ◽  
Animal Husbandry ◽  
The Body ◽  
Body Parts ◽  
Method Of Least Squares ◽  
Linear Measurements ◽  
Cattle Breeding ◽  
Modern Methods ◽  
Meat Productivity ◽  
The Relationship

In this manuscript has presented the results of applying modern methods of mathematical modeling in animal husbandry. To conduct the research has used the method of least squares, which has reflected in the work by approximation probabilistic non-linear relations, making it possible to establish the relationship between different measurements the body parts of animal and meat productivity, and linear measurements of the udder.

Aerodynamic Characteristics Analysis of High-Speed Train on Cutting under Crosswinds

2013 ◽  
Vol 300-301 ◽  
pp. 62-67
Author(s):  
Kun Ye ◽  
Ren Xian Li
Keyword(s):  
High Speed ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
High Speed Train ◽  
Aerodynamic Forces ◽  
Cutting Depth ◽  
Cutting Slope ◽  
Characteristics Analysis ◽  
Relationship Of ◽  
The Relationship

Cutting is an effective device to reduce crosswind loads acting on trains. The cutting depth, width and gradient of slope are important factors for design and construction of cutting. Based on numerical analysis methods of three-dimensional viscous incompressible aerodynamics equations, aerodynamic side forces and yawing moments acting on the high-speed train, with different depths and widths of cutting，are calculated and analyzed under crosswinds，meanwhile the relationship of the gradient of cutting slope and transverse aerodynamic forces acting on trains are also studied. Simulation results show that aerodynamic side forces and yawing moments acting on the train（the first, middle and rear train）decrease with the increase of cutting depth. The relationship between transverse forces (moments) coefficients acting on the three sections and the cutting depth basically is the three cubed relation. The bigger is cutting width，the worse is running stability of train. The relationship between yawing moments coefficients acting each body of the train and the cutting width approximately is the three cubed relation. The transverse Aerodynamic forces decreased gradually with the increase of the gradient of cutting slope, the relationship between yawing moments coefficients acting each body of the train and the gradient of cutting slope basically is the four cubed relation.

Dynamic Behavior Analysis of Three-Span Rotor-Bearing System with Rub-Impact Fault

2012 ◽  
Vol 460 ◽  
pp. 160-164 ◽  
Author(s):  
Song He Zhang ◽  
Yue Gang Luo ◽  
Bin Wu ◽  
Bang Chun Wen
Keyword(s):  
Nonlinear Dynamics ◽  
Behavior Analysis ◽  
Dynamic Model ◽  
Dynamic Behavior ◽  
Rotor System ◽  
System Response ◽  
Rotor Bearing ◽  
Set Up ◽  
Bearing System ◽  
Main Influence

The dynamic model of the three-span rotor-bearing system with rub-impact fault was set up. The influence to nonlinear dynamics behaviors of the rotor-bearing system that induced by rub-impact of one disc, two discs and three discs were numerically studied. The main influence of the rotor system response by the rub-impact faults are in the supercritical rotate speed. There are mutations of amplitudes in the responses of second and third spans in supercritical rotate speed when rub-impact with one disc, and there are chaotic windows in the response of first span, and jumping changes in second and third spans when rub-impact with two or three discs.

A Novel Polyaxial Strength Criterion for Rock Materials Under General Stress Condition

2018 ◽  
Vol 10 (08) ◽  
pp. 1850082 ◽  
Author(s):  
Yugui Yang ◽  
Feng Gao ◽  
Chengzheng Cai ◽  
Peijian Chen
Keyword(s):  
Stress State ◽  
Stress Condition ◽  
Strength Criterion ◽  
Friction Angle ◽  
External Loading ◽  
Nonlinear Characteristics ◽  
Rock Materials ◽  
Wide Range ◽  
Confining Pressures ◽  
The Relationship

Yielding or failure of rocks under the action of external loading is complicated due to the dependence on pressure sensitivity and Lode angle. In this study, a generalized hyperbolic strength criterion is proposed to describe the strong nonlinear characteristics of rocks over a wide range of confining pressures. The relationship between failure stress and instantaneous friction angle of rocks is analyzed based on nonlinear Mohr strength envelope. In order to reflect the influence of intermediate principal stress on the strength of rock materials, the generalized hyperbolic criterion has further been extended to complicated stress state. The failure criterion allows the possibility of transitions from an equilateral triangle to circle, which greatly improves the durability and applicability to describe the strength characteristics of various rocks under complicated stress state. The validity of the proposed criterion is verified by comparing predictions with experimental results of rocks.

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