INCREASING FATIGUE DURABILITY OF A BOLT JOINT/SRIEGINĖS JUNGTIES CIKLINIO ILGAAMŽIŠKUMO DIDINIMAS TAIKANT DETALIŲ TARPUSAVIO PASUKIMIŲ BŪDĄ

2000 ◽  
Vol 6 (4) ◽  
pp. 262-267
Author(s):  
Algimantas Krenevičius ◽  
Kęstutis Vislavičius
Keyword(s):  
Mathematical Model ◽  
Computer Program ◽  
Fatigue Failure ◽  
Personal Computer ◽  
Fatigue Curve ◽  
Fatigue Durability ◽  
Miner’S Rule ◽  
The Mathematical Model ◽  
Personal Computer Program ◽  
Survival Condition

A method of increasing the fatigue durability of a bolt joint is considered. It is based on the position of the nut with respect to the bolt. Turning the nut causes its threads to be in contact with different threads of the bolt during sequential periods of use. The thread of the bolt which experiences the highest loading is in contact with the first (most dangerous) thread of the nut. With further nut turns, the bolt thread experiences less loading because of the contact with another (less dangerous) threads of the nut. Reducing the loading in this way can increase the fatigue durability. The nut position with respect to the bolt can be controlled using different heights of washer-bushing. The durability calculation is based on the fatigue curve for the bolt joint when it is tested without turning the nut. The sum of damage is calculated for all points of the bolt thread which are in contact with the first turn of the nut for any loading period. According to the Miner's rule, fatigue failure occurs when the sum of damage is equal to one. The mathematical model for calculating the maximum fatigue durability of bolt joint is given. It is assumed that the height of washer-bushing, the number of turns of the nut and the fatigue curve for the threaded bolt joint are known. The survival condition is that for any point on the bolt, the sum of damage after the last loading period must be less than one. A personal computer program for the fatigue durability calculation is prepared, and some example problems are solved. An analysis of the results is presented.

Dynamic Analysis for the Design of CALM System in Shallow and Deep Waters

1997 ◽  
Vol 119 (3) ◽  
pp. 151-157 ◽  
Author(s):  
Y.-L. Hwang
Keyword(s):  
Mathematical Model ◽  
Dynamic Analysis ◽  
Model Test ◽  
Time Domain ◽  
Time Domain Analysis ◽  
Mooring Lines ◽  
Deep Waters ◽  
Wave Drift ◽  
The Mathematical Model ◽  
Survival Condition

This paper presents a time domain analysis approach to evaluate the dynamic behavior of the catenary anchor leg mooring (CALM) system under the maximum operational condition when a tanker is moored to the terminal, and in the survival condition when the terminal is not occupied by a tanker. An analytical model, integrating tanker, hawser, buoy, and mooring lines, is developed to dynamically predict the extreme mooring loads and buoy orbital motions, when responding to the effect of wind, current, wave frequency, and wave drift response. Numerical results describing the dynamic behaviors of the CALM system in both shallow and deepwater situations are presented and discussed. The importance of the line dynamics and hawser coupled buoy-tanker dynamics is demonstrated by comparing the present dynamic analysis with catenary calculation approach. Results of the analysis are compared with model test data to validate the mathematical model presented.

scholarly journals SYNTHESIS OF PROGRAM AND FINITE LAWS OF MOTION IN ANALYTICAL MODELS OF CONTROL OF THE FINAL STATE OF BIOMECHANICAL SYSTEMS

2019 ◽  
Vol 19 (1) ◽  
pp. 93-99
Author(s):  
V Zagrevskiy ◽  
O Zagrevskiy
Keyword(s):  
Mathematical Model ◽  
Computer Program ◽  
Center Of Mass ◽  
Material Point ◽  
Object Motion ◽  
Reference Points ◽  
Analytical Models ◽  
Final State ◽  
Finite Control ◽  
The Mathematical Model

Aim. The article deals with developing a computer program to simulate the movement of the object with a given initial and final speed and fixed travel time. Materials and methods. The analysis, as a method of biomechanics, allows us to assess the biomechanical state of the athlete in real sports exercises. The function of motion synthesis is the ability to predict the trajectory and behavior of the biomechanical system at specified reference points of the phase structure of the simulated motion. The article deals with one of the methods of biomechanical synthesis of movements: synthesis of control of the final state of biomechanical systems, based on the reduction of finite control to a given program control after attenuation of the transient component of acceleration. The mathematical description of the object motion is based on the known law of finite control with feedback. Integration of the mathematical model constructed in the form of the differential equation of the second order was carried out by one of the numerical methods of integration: Runge–Kutta method of the fourth order of accuracy. Consideration of the method is based on a mathematical apparatus describing the motion of a material point, which can be represented by a common center of mass of a biomechanical system, a joint, a center of mass of a segment, etc. Results. The mathematical model of the motion of a material point with the given kinematic parameters of motion at the initial and final moments is implemented in a computer program in the Visual Basic 2010 language environment based on the integrated development environment Visual Studio Express 2013. The output provides numerical and visual support for simulation results. Conclusion. It is shown that the developed computer model of the method always implements the goal of motion: to transfer an object from a given initial state by speed to a given final state for a fixed time of movement.

scholarly journals Finite element analysis of a single conductor with a Stockbridge damper under Aeolian vibration

2021 ◽  
Author(s):  
Oumar Barry
Keyword(s):  
Mathematical Model ◽  
Finite Element ◽  
Fatigue Failure ◽  
Excitation Frequency ◽  
Element Model ◽  
Element Analysis ◽  
Vibrational Response ◽  
Aeolian Vibration ◽  
The Mathematical Model ◽  
Stockbridge Damper

A finite element model is developed to predict the vibrational response of a single conductor with a Stockbride damper. The mathematical model accounts for the two-way coupling between the conductor and the damper. A two-part numerical analysis using MATLAB is presented to simulate the response of the system. The first part deals with the vibration of the conductor without a damper. The results indicate that longer span conductors without dampers are susceptible to fatigue failure. In the second part, a damper is attached to the conductor and the effects of the excitation frequency, the damper mass, and the damper location are investigated. This investigation shows that the presence of a properly positioned damper on the conductor significantly reduces fatigue failure.

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