Abstract
The dimensioning of a conveyor pulley shell is a computationally demanding task. A conveyor system may have dozens of pulleys, whose fast, reliable, and economical dimensioning is important for competitiveness. The present dissertation is aimed to develop faster and more accurate methods to determine the stress state of pulley shell. The contributions aimed are to gain information on the real belt-cylinder contact pressure distribution and to develop differential methods that take into account the stiffness of the shaft and the end plates in the stress state of the cylinder shell.
The thesis is divided into the experimental and the computational sections. In the experimental section, measurement devices are designed to determine the contact pressure between the belt and the cylinder shell. The measurements are implemented at both the drive and tail end, using various belt wrap angles with one common belt type. According to the test results, mathematical equations are determined based on Tschebyscheff and cosine series development.
The computational section first compared the stress and displacement states of the contact pressure, calculated with mathematical equations and the uniformly distributed loads, which are calculated by FEM. Because the mathematical description of the measured contact pressure proved to be complicated, and the stress and displacement states between the measured contact pressure and uniformly distributed loads are nearly equal, it is functional to use uniformly distributed loads also in later calculations.
In the mathematical model of the cylinder shell, sine and cosine double Fourier series are used to describe the load and displacement states.
Loads and deformations are divided into symmetrical and antisymmetrical components which uncouples the corresponding unknown coefficients, thus resulting into two systems of equations, both having three unknowns for each (m,n) terms. Further, international loads and stresses are solved.
One of the goals of the thesis is to develop a rapid and accurate method for dimensioning the pulley shell. The goal is reached as the method provides more accurate stress results than traditional joint supported shell equations. Maximum stresses appear particularly at the ends of the shell, where the cracks usually initiate. In addition, the solution time required by the novel method is only a fraction of that
of total FEM solution and modelling.
The thesis is divided into the experimental and the computational sections. In the experimental section, measurement devices are designed to determine the contact pressure between the belt and the cylinder shell. The measurements are implemented at both the drive and tail end, using various belt wrap angles with one common belt type. According to the test results, mathematical equations are determined based on Tschebyscheff and cosine series development.
The computational section first compared the stress and displacement states of the contact pressure, calculated with mathematical equations and the uniformly distributed loads, which are calculated by FEM. Because the mathematical description of the measured contact pressure proved to be complicated, and the stress and displacement states between the measured contact pressure and uniformly distributed loads are nearly equal, it is functional to use uniformly distributed loads also in later calculations.
In the mathematical model of the cylinder shell, sine and cosine double Fourier series are used to describe the load and displacement states.
Loads and deformations are divided into symmetrical and antisymmetrical components which uncouples the corresponding unknown coefficients, thus resulting into two systems of equations, both having three unknowns for each (m,n) terms. Further, international loads and stresses are solved.
One of the goals of the thesis is to develop a rapid and accurate method for dimensioning the pulley shell. The goal is reached as the method provides more accurate stress results than traditional joint supported shell equations. Maximum stresses appear particularly at the ends of the shell, where the cracks usually initiate. In addition, the solution time required by the novel method is only a fraction of that
of total FEM solution and modelling.
| Original language | Finnish |
|---|---|
| Place of Publication | Tampere |
| Publisher | Tampere University |
| ISBN (Electronic) | 978-952-03-1621-1 |
| ISBN (Print) | 978-952-03-1620-4 |
| Publication status | Published - 2020 |
| Publication type | G4 Doctoral dissertation (monograph) |
Publication series
| Name | Tampere University Dissertations - Tampereen yliopiston väitöskirjat |
|---|---|
| Volume | 276 |
| ISSN (Print) | 2489-9860 |
| ISSN (Electronic) | 2490-0028 |