A simplified calculation model for the sliding contact boundaries in a hydrostatic piston mechanism

2018 ◽  
Vol 113 (1) ◽  
pp. 143-163
Author(s):  
Jung-Hun Shin ◽  
Kum-Won Cho
Keyword(s):  
Calculation Model ◽  
Sliding Contact ◽  
Piston Mechanism ◽  
Simplified Calculation ◽  
Contact Boundaries

Roof Cover Impact on Cooling Energy Use of Office Buildings

2014 ◽  
Author(s):  
Moncef Krarti
Keyword(s):  
Energy Use ◽  
Energy Savings ◽  
Simulation Analysis ◽  
Calculation Model ◽  
Office Building ◽  
Climate Zones ◽  
Building Energy Use ◽  
Detailed Simulation ◽  
Simplified Calculation ◽  
The Impact

This paper analyzes the impact of roof covers on office building energy use for representative US climate zones. In particular, the study presented in the paper investigates the potential annual cooling energy use savings that roof covers could provide using whole-building simulation analysis to evaluate the performance of a 2-story office building in five US locations. Three parameters of the roof covers including their size, height, and transmittance, are considered in the analysis. The simulation results indicate that while roof covers had similar affects on buildings in all climate zones, their impact in reducing cooling energy usage is different and is more pronounced in cooler climates. Specifically, roof covers could potentially achieve cooling energy savings of up to: 25% in Houston, 33% in Atlanta, 31% in Nashville, 38% in Chicago, and 41% in Madison. Based on the detailed simulation analysis results, a simplified calculation model is developed to help the estimation of cooling energy savings as a function of the roof cover size, height, and transmittance.

scholarly journals Study on Simplified Model and Numerical Solution of High-Speed Angular Contact Ball Bearing

2020 ◽  
Vol 2020 ◽  
pp. 1-17
Author(s):  
Guang Zeng ◽  
Chunjiang Zhao ◽  
Xiaokai Yu ◽  
Biao Sun ◽  
Zhigang Xiao ◽  
...  
Keyword(s):  
High Speed ◽  
Artificial Bee Colony Algorithm ◽  
Artificial Bee Colony ◽  
Ball Bearing ◽  
Calculation Model ◽  
Ball Bearings ◽  
Initial Value ◽  
Angular Contact Ball Bearing ◽  
Bee Colony ◽  
Simplified Calculation

For the calculation model of high-speed angular contact bearing has many variables, the large root difference exists, and the Newton iterative method solving the convergence depends on the initial value problems; thus, the simplified calculation model is proposed and the algorithm is improved. Firstly, based on the nonlinear equations of variables recurrence method of the high-speed angular contact ball bearing calculation model, it is proved that the ultimate fundamental variables of calculation model are the actual inner and outer contact angles, the axial and radial deformations. According to this reason, the nonlinear equations are deformed and deduced, and the number of equations is reduced from 4Z + 2 to 2Z + 2 (Z represents the number of rolling bodies); a simplified calculation model is formed. Secondly, according to the small dependence of the artificial bee colony algorithm on the initial value, an improved artificial bee colony algorithm is proposed for the large root difference characteristics of high-speed ball bearings. The validity of the improved algorithm is verified by standard test function. The algorithm is used to solve the high-speed angular contact ball bearing calculation model. Finally, the deformations of high-speed angular contact ball bearings are compared and verified by experiments, and the results of improved algorithm show good agreement with the experiments results.

scholarly journals Multiaxial Fatigue Life Calculation Model for Engineering Components in Rolling-Sliding Contact

2018 ◽  
Vol 188 ◽  
pp. 02016
Author(s):  
Robert Basan ◽  
Tea Marohnić
Keyword(s):  
Fatigue Life ◽  
Complex Geometry ◽  
Calculation Model ◽  
Multiaxial Fatigue ◽  
Sliding Contact ◽  
Engineering Practice ◽  
Critical Plane ◽  
Principal Axes ◽  
Critical Plane Approach ◽  
Crack Initiation Criterion

Number of important engineering components and elements such as gears, rollers, bearings operate in conditions of rolling-sliding contact loading. Determination of fatigue lives of such components and elements is very important for engineering practice but remains quite chalenging task due to complex states of stress and strain in the material in the vicinity of contact (multiaxiality, non-proportionality, rotation of principal axes, mean compressive stress) as well as complex contact conditions such as loading amplitude, complex geometry of bodies in contact, type of lubrication, value of coefficient of friction, etc. Proposed fatigue life calculation model for cases of rolling-sliding contact is based on critical plane approach in the form of Fatemi-Socie crack initiation criterion. Developed model was implemented in the case of gears teeth flanks in mesh and compared with results and fatigue lives of gears reported in literature. Good agreement was determined confirming validity of developed model. Further advantage of presented approach and developed model is obtained information on critical location(s) and critical plane(s) orientation which can subsequently be used for estimation of crack shapes in initial phases of their growth and later damage type into which they can be expected to develop.

scholarly journals Fire Resistance of Axially Loaded Slender Concrete Filled Steel Tubular Columns – Development of a Three-Dimensional Numerical Model and Comparison with Eurocode 4

10.14311/1089 ◽  
2009 ◽  
Vol 49 (1) ◽  
Author(s):  
A. Espinós ◽  
A. Hospitaler ◽  
M. L. Romero
Keyword(s):  
Numerical Model ◽  
Fire Resistance ◽  
Numerical Models ◽  
Three Dimensional ◽  
Calculation Model ◽  
Construction Technology ◽  
Tubular Columns ◽  
Highly Nonlinear ◽  
Structural Engineers ◽  
Simplified Calculation

In recent years, concrete filled tubular (CFT) columns have become popular among designers and structural engineers, due to a series of highly appreciated advantages: high load-bearing capacity, high seismic resistance, attractive appearance, reduced column footing, fast construction technology and high fire resistance without external protection. In a fire, the degradation of the material properties will cause CFT columns to become highly nonlinear and inelastic, which makes it quite difficult to predict their failure. In fact, it is still not possible for analytical methods to predict with enough accuracy the behaviour of columns of this kind when exposed to fire. Numerical models are therefore widely sought. Many numerical simulations have been carried out worldwide, without obtaining satisfactory results. This work proposes a three-dimensional numerical model for studying the actual fire behaviour of columns of this kind. This model was validated by comparing the simulation results with fire resistance tests carried out by other researchers, as well as with the predictions of the Eurocode 4 simplified calculation model. 

scholarly journals Modelling and Structural Design for Parallel Umbrella-Shaped Cable-Strut Structures Based on Stationary Potential Energy Principles

2019 ◽  
Vol 2019 ◽  
pp. 1-24 ◽  
Author(s):  
Mingmin Ding ◽  
Bin Luo ◽  
Lifeng Han ◽  
Qianhao Shi
Keyword(s):  
Potential Energy ◽  
Structural Design ◽  
Local Deformation ◽  
Calculation Model ◽  
Total Weight ◽  
Stationary Potential ◽  
Design Variables ◽  
Static Responses ◽  
Height Increase ◽  
Simplified Calculation

A method for the modelling and structural design of a parallel umbrella-shaped cable-strut structure (PUSC) is presented. First, simplified calculation models of a PUSC are built. Next, based on the principle of stationary potential energy, the relationships among the cable sectional areas, prestress forces, vector height, sag height, overall displacement, and local deformation are proposed. Then, the static responses of the PUSC under vertical loads and wind loads are put forward. Finally, a calculation model of a 100 m-span PUSC is developed and optimized to verify the feasibility of the proposed method. The results show that when the combinations of the loading, variation ranges of the vector height and sag height, and material properties of the components are given, the sectional areas of the cables, dimensions of the inner strut, and prestress forces of these components can be obtained. A greater external load requires a corresponding increase in vector height and sag height to increase the overall stiffness, leading to larger sectional dimensions of the components and a greater prestress of the entire structure. Therefore, the total weight of the cables and inner struts are determined. Moreover, because the weight of the cables decreases and the weight of the inner struts increases as the vector height and sag height increase, the total weight of the cables and struts decreases sharply during the initial stage, decreases gradually during the second stage, and increases slowly during the last stage after reaching the minimum value. For the optimal design of the calculation model, using the vector height and sag height as design variables provides an adequate geometric stiffness and a suitable prestress for the PUSC to fulfill the requirements of all the loading combinations.

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