scholarly journals Plastic limit bearing calculation of blasting-roof in deep hole mining and its applications

2019 ◽  
Vol 6 (7) ◽  
pp. 190074
Author(s):  
Wei Wang ◽  
Zhouquan Luo ◽  
Yaguang Qin ◽  
Jun Xiang
Keyword(s):  
Boundary Conditions ◽  
Calculation Method ◽  
Virtual Work ◽  
Theoretical Calculations ◽  
Limit State ◽  
Mechanical Analysis ◽  
Deep Hole ◽  
Plastic Limit ◽  
Analysis Model ◽  
Various Boundary Conditions

A plastic bearing calculation method for a blasting-roof is proposed to solve the problem of determining the blasting-roof thickness in deep hole mining. A mechanical analysis model for the plastic bearing was built for the typical boundary conditions of blasting-roofs. The external and internal work of the blasting-roof are equal under the plastic limit state through calculation. The limit bearing formulae of blasting-roofs under various boundary conditions were derived based on the principle of virtual work. A Vertical Crater Retreat stope was taken as the object, and the safe blasting-roof thickness was determined to be 6 m using the derived formula (considering the safety coefficient). A numerical model of stope was constructed using the Surpac-Flac3D technique, while the blasting-roof stability was simulated under different thicknesses. Variations in the simulated indexes (stress and plastic zone volume) prove that the theoretical calculations are reliable. The plastic bearing calculation method can provide a new method to determine the blasting-roof thickness in deep hole mining.

A High Precision and Convenient Method to Analyze the Mechanics of Scissor Lift Platform under the Action of Combined Loads

2014 ◽  
Vol 618 ◽  
pp. 503-508
Author(s):  
Fei Peng Qu ◽  
Yuan Xue
Keyword(s):  
Calculation Method ◽  
Virtual Work ◽  
Optimization Method ◽  
Mechanical Analysis ◽  
Drive Unit ◽  
Typical Structure ◽  
Virtual Work Principle ◽  
Nodal Force ◽  
Combined Loads ◽  
Calculation Results

Scissor lift platform had lots of kinematic pairs and the mechanics relations between them were complex. So mechanics analysis became the focus by researchers. The mechanical model of scissor lift platform under the action of combined loads was built in the paper. The calculation formula of nodal force of scissor transmission unit was given used the transfer matrix method. The calculation formulas of drive units were given on the virtual work principle. Also the calculation method of nodal forces of drive units was given. How the different distributions of drive unit influence on the nodal force was analyzed. The drive units’s position optimization method was given in this paper. In order to verify the reliability of this calculation method, an calculation example of typical structure was given. The calculation results given by the method in this paper was identical with the result given by finite element method. The conclusions obtained could serve as theoretical guidance and reference for mechanical analysis and optimal design of scissor transmission mechanism.

scholarly journals Calculation Method for Plates with Discrete Variable Thickness Under Uniform Loading or Hydrostatic Pressure

2018 ◽  
Vol 23 (4) ◽  
pp. 835-853
Author(s):  
G. Aryassov ◽  
D. Gornostajev ◽  
I. Penkov
Keyword(s):  
Hydrostatic Pressure ◽  
Boundary Conditions ◽  
Variable Thickness ◽  
Analytical Method ◽  
Calculation Method ◽  
Theoretical Calculations ◽  
Complex Loading ◽  
Experimental Results ◽  
Test Machine ◽  
Special Equipment

Abstract The article proposes a new analytical method for the calculation of plates with constant and variable rigidity parameters. This method renders it possible to decrease the weight of the plates working under hydrostatic pressure by using variable thicknesses. Firs, a short overview of existing calculation methods and their results are compared. It is shown that all existing methods depend on boundary conditions. Then is given the theory of the proposed calculation method is described and calculations for plates with constant and variable thickness worked under uniformly loaded forces and hydrostatic pressure are made. The results are compared to the FEM calculations and experimental results obtained by a tensile test machine and special equipment. Calculation results obtained by the proposed analytical method and FEM results are very close. Deviations are not more than 11%. Deviations between theoretical calculations and experimental results depend on loading type and design of the test specimens but maximum values are not more than 17%. The proposed calculation method does not depend on the boundary conditions and can be used for plate calculations. Especially for plates with difficult design and complex loading.

Buckling Analysis of Double-Layer Piezoelectric Nanoplates Surrounded by Elastic Foundations and Thermal Environments Considering Nonlocal and Surface Energy Models

2017 ◽  
Vol 34 (4) ◽  
pp. 483-494 ◽  
Author(s):  
S. Rafieian ◽  
M. Hashemian ◽  
M. Pirmoradian
Keyword(s):  
Finite Difference ◽  
Boundary Conditions ◽  
Surface Stress ◽  
Surface Effect ◽  
Virtual Work ◽  
Buckling Analysis ◽  
Electric Voltage ◽  
Elastic Foundations ◽  
Various Boundary Conditions ◽  
Thermal Environments

AbstractThis study investigated the effects of considering surface and nonlocal energy parameters on the buckling analysis of double piezoelectric nanoplate (DPNP) embedded in elastic foundations and thermal environments. Both in-phase and out-of-phase modes of buckling and various boundary conditions are studied and compared with each other. The governing equations were derived by drawing on the principle of virtual work and then solved by employing the finite difference method. Finite difference solution was validated using Navier's method and journal references. A parametric study was also launched in order to investigate the effects of the external electric voltage, nonlocal parameters, different boundary conditions, elastic foundations and thermal environments on the surface effect of DPNP buckling. The obtained numerical results showed that the influence of surface stress on in-phase and out-of-phase modes of buckling of the DPNP was enhanced by augmenting the nonlocal parameters and external electric voltage; on the other hand, it was found to be decreased by increasing elastic foundations and temperature changes. In addition, the value of surface stress effects for the in-phase mode was higher than that of the out-of-phase one.

Upon Impact Numerical Modeling of Foam Materials

2017 ◽  
Vol 54 (2) ◽  
pp. 195-202
Author(s):  
Vasile Nastasescu ◽  
Silvia Marzavan
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Numerical Modeling ◽  
Numerical Analysis ◽  
Numerical Methods ◽  
Boundary Conditions ◽  
General Character ◽  
Foam Material ◽  
Various Boundary Conditions ◽  
Specific Behaviour

The paper presents some theoretical and practical issues, particularly useful to users of numerical methods, especially finite element method for the behaviour modelling of the foam materials. Given the characteristics of specific behaviour of the foam materials, the requirement which has to be taken into consideration is the compression, inclusive impact with bodies more rigid then a foam material, when this is used alone or in combination with other materials in the form of composite laminated with various boundary conditions. The results and conclusions presented in this paper are the results of our investigations in the field and relates to the use of LS-Dyna program, but many observations, findings and conclusions, have a general character, valid for use of any numerical analysis by FEM programs.

scholarly journals A Unified Spectro-Geometric-Ritz Method for Vibration Analysis of Open and Closed Shells with Arbitrary Boundary Conditions

2016 ◽  
Vol 2016 ◽  
pp. 1-30 ◽  
Author(s):  
Dongyan Shi ◽  
Yunke Zhao ◽  
Qingshan Wang ◽  
Xiaoyan Teng ◽  
Fuzhen Pang
Keyword(s):  
Boundary Conditions ◽  
Vibration Analysis ◽  
Ritz Method ◽  
Free Vibration Analysis ◽  
Analysis Model ◽  
Arbitrary Boundary ◽  
Fourier Cosine ◽  
Auxiliary Functions ◽  
Arbitrary Boundary Conditions ◽  
Closed Shells

This paper presents free vibration analysis of open and closed shells with arbitrary boundary conditions using a spectro-geometric-Ritz method. In this method, regardless of the boundary conditions, each of the displacement components of open and closed shells is represented simultaneously as a standard Fourier cosine series and several auxiliary functions. The auxiliary functions are introduced to accelerate the convergence of the series expansion and eliminate all the relevant discontinuities with the displacement and its derivatives at the boundaries. The boundary conditions are modeled using the spring stiffness technique. All the expansion coefficients are treated equally and independently as the generalized coordinates and determined using Rayleigh-Ritz method. By using this method, a unified vibration analysis model for the open and closed shells with arbitrary boundary conditions can be established without the need of changing either the equations of motion or the expression of the displacement components. The reliability and accuracy of the proposed method are validated with the FEM results and those from the literature.

The Quasi-Static Analysis for Two-Dimensional Thin Plates

2011 ◽  
Vol 255-260 ◽  
pp. 166-169
Author(s):  
Li Chen ◽  
Yang Bai
Keyword(s):  
Boundary Conditions ◽  
Eigenfunction Expansion ◽  
Solution Space ◽  
Expansion Method ◽  
Fundamental Solutions ◽  
Thin Plates ◽  
Elastic Plates ◽  
Various Boundary Conditions ◽  
Eigenfunction Expansion Method ◽  
Concentration Phenomena

The eigenfunction expansion method is introduced into the numerical calculations of elastic plates. Based on the variational method, all the fundamental solutions of the governing equations are obtained directly. Using eigenfunction expansion method, various boundary conditions can be conveniently described by the combination of the eigenfunctions due to the completeness of the solution space. The coefficients of the combination are determined by the boundary conditions. In the numerical example, the stress concentration phenomena produced by the restriction of displacement conditions is discussed in detail.

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