Using Robust Design Methods for the Fir-Tree Optimization Problem

2018 ◽  
Author(s):  
Boris Vasilyev ◽  
Anton Salnikov ◽  
Artem Semenov
Keyword(s):  
Optimization Problem ◽  
Complex Stress ◽  
Complex Stress State ◽  
Strength Characteristics ◽  
Strength Parameter ◽  
Strength Parameters ◽  
High Pressure Turbine ◽  
Tree Optimization ◽  
Low Mass ◽  
The Stability

The difficulty of providing the required strength characteristics of wheel locking joints is due to a complex stress state, the presence of stress concentrators, differences in contacting-part materials’ characteristics, and possible deviations in sizes from nominal values [1]. Providing stable strength characteristics and a low mass are important requirements. This paper suggests an approach to the strength-mass optimization of a disc and fir-tree joint of a high-pressure turbine and considers the scattering of dimensions within tolerances. The main stages of optimization are shown, criteria for evaluating the robustness of the structure are proposed, and recommendations for the practical robust optimization of a real design are given. The results of various optimization approaches and strength-parameter dispersions of various configurations’ locking joints are compared. It is shown that decreasing the number of teeth increases the stability of the strength parameters.

scholarly journals Strength Characteristics of Preformed Foam Concrete

2019 ◽  
Vol 8 (4) ◽  
pp. 8213-8216 ◽  
Keyword(s):  
Experimental Investigation ◽  
Coarse Aggregate ◽  
Strength Test ◽  
Strength Characteristics ◽  
Strength Parameter ◽  
Light Weight ◽  
Foam Concrete ◽  
Strength Parameters ◽  
Light Weight Concrete ◽  
Parameter Test

The study deals with the usage of perforated foam of various percentages to that of coarse aggregate to produce light weight concrete. With the day to day increase in industries and civilization’s expansion it has become very much necessary to produce structures with proficiently lesser weight. Its usage has become more proficient in construction of building in earthquake prone areas. This experimental investigation deals with the study of strength parameters of light weight concrete by performing various strength test and its various behavior s such as compression, tensile and flexure are studied by adding preformed foam at various proportions of 0%, 2%, 5%, 10%, 20% and 40%. All these strength parameter test are performed on 7th day, 14th day and 28th day respectively from day of casting

scholarly journals Inversion analysis of strength parameters of loess cutting high slope in Jijiayuan, Shanxi

2021 ◽  
Vol 276 ◽  
pp. 01019
Author(s):  
Yu Xi ◽  
Jifei Zhao ◽  
Gang Li
Keyword(s):  
Moisture Content ◽  
Complex Problem ◽  
Strength Parameter ◽  
Plastic Limit ◽  
Strength Parameters ◽  
High Slope ◽  
Loess Slope ◽  
Stability Of Slopes ◽  
The Stability ◽  
Inversion Analysis

In the process of analyzing the stability of loess slope, determining the value of strength parameter c and φ is a much more complex problem, and there is not mature and systematic method. In this paper, the inverse analysis of the value c and φ in Shanxi Jijiayuan cutting loess slope, about 51.6m, by bishop method and Spencer method based on the statistical strength indexes. To analyze the stress of the slope used finite element and compare the inverse result and test data. The result indicates the value of c will control the stability of slopes in Q3 layer, and the value of φ will control the stability of slopes in Q2; the inverse result is close to the result with direct shear test when the moisture content is sample’s plastic limit moisture content. we can select strength parameters obtained though the direct and quick shear under the conditions that the soil sample’s moisture content is plastic limit moisture content for evaluation the slope stability. For the high slope, it should be cautious to select the φ in the lower part.

scholarly journals Latency-Optimal Computational Offloading Strategy for Sensitive Tasks in Smart Homes

Sensors ◽  
2021 ◽  
Vol 21 (7) ◽  
pp. 2347
Author(s):  
Yanyan Wang ◽  
Lin Wang ◽  
Ruijuan Zheng ◽  
Xuhui Zhao ◽  
Muhua Liu
Keyword(s):  
Queue Length ◽  
Optimization Problem ◽  
Time Slot ◽  
Smart Homes ◽  
Back Pressure ◽  
Smart Devices ◽  
Smart Device ◽  
Simulation Results ◽  
Computational Offloading ◽  
The Stability

In smart homes, the computational offloading technology of edge cloud computing (ECC) can effectively deal with the large amount of computation generated by smart devices. In this paper, we propose a computational offloading strategy for minimizing delay based on the back-pressure algorithm (BMDCO) to get the offloading decision and the number of tasks that can be offloaded. Specifically, we first construct a system with multiple local smart device task queues and multiple edge processor task queues. Then, we formulate an offloading strategy to minimize the queue length of tasks in each time slot by minimizing the Lyapunov drift optimization problem, so as to realize the stability of queues and improve the offloading performance. In addition, we give a theoretical analysis on the stability of the BMDCO algorithm by deducing the upper bound of all queues in this system. The simulation results show the stability of the proposed algorithm, and demonstrate that the BMDCO algorithm is superior to other alternatives. Compared with other algorithms, this algorithm can effectively reduce the computation delay.

scholarly journals Determination of Mechanical Properties of Altered Dacite by Laboratory Methods

Minerals ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 813
Author(s):  
Veljko Rupar ◽  
Vladimir Čebašek ◽  
Vladimir Milisavljević ◽  
Dejan Stevanović ◽  
Nikola Živanović
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Rock Mass ◽  
Uniaxial Compressive Strength ◽  
Rock Material ◽  
Strength Parameter ◽  
Gradual Transition ◽  
Strength Parameters ◽  
Triaxial Compressive Strength ◽  
Heterogeneous Rock

This paper presents a methodology for determining the uniaxial and triaxial compressive strength of heterogeneous material composed of dacite (D) and altered dacite (AD). A zone of gradual transition from altered dacite to dacite was observed in the rock mass. The mechanical properties of the rock material in that zone were determined by laboratory tests of composite samples that consisted of rock material discs. However, the functional dependence on the strength parameter alteration of the rock material (UCS, intact UCS of the rock material, and mi) with an increase in the participation of “weaker” rock material was determined based on the test results of uniaxial and triaxial compressive strength. The participation of altered dacite directly affects the mode and mechanism of failure during testing. Uniaxial compressive strength (σciUCS) and intact uniaxial compressive strength (σciTX) decrease exponentially with increased AD volumetric participation. The critical ratio at which the uniaxial compressive strength of the composite sample equals the strength of the uniform AD sample was at a percentage of 30% AD. Comparison of the obtained exponential equation with practical suggestions shows a good correspondence. The suggested methodology for determining heterogeneous rock mass strength parameters allows us to determine the influence of rock material heterogeneity on the values σciUCS, σciTX, and constant mi. Obtained σciTX and constant mi dependences define more reliable rock material strength parameter values, which can be used, along with rock mass classification systems, as a basis for assessing rock mass parameters. Therefore, it is possible to predict the strength parameters of the heterogeneous rock mass at the transition of hard (D) and weak rock (AD) based on all calculated strength parameters for different participation of AD.

FEM Analysis and Experimental Study for Bond Strength of High-Strength Coating by Wedged Load Test Method

2010 ◽  
Vol 152-153 ◽  
pp. 1058-1061
Author(s):  
Zhou Wei ◽  
Xiao Xia Zhang
Keyword(s):  
Bond Strength ◽  
Adhesion Strength ◽  
Fem Analysis ◽  
High Strength ◽  
Pressure Head ◽  
Optical Microscope ◽  
Complex Stress ◽  
Complex Stress State ◽  
Load Test ◽  
Test Method

A wedged load test method is used to evaluate the adhesion strength of high-strength coatings, which have been processed with various sintering parameters. In this test, for stress concentration at cut tip, cracks are always induced and expanded rapidly cross the interface between coating and substrate. Macro-fracture and SEM image of coating interface of high-strength coating are characterized using optical microscope and scanning electron microscopy (SEM), respectively. In order to evaluate the bonding properties between coating and substrate effectively, corresponding finite element (FE) analysis has been conducted to evaluate the adhesion strength of high-strength coating. And stress distributions cross the interface of high-strength coating are obtained. The stress analysis can help to evaluate the bond strength of high-strength coating. Because of small specimen and contact relationship between wedged pressure head and wedged cuts, complex stress state is affected by many factors resulting from interface, and also by the thickness of coating.

Stability Prediction of Surrounding Rocks and Optimum Design of Roof-Bolt Parameters in Deep Roadway

2013 ◽  
Vol 353-356 ◽  
pp. 436-439
Author(s):  
De Sen Kong ◽  
Yong Po Chen
Keyword(s):  
Prediction Method ◽  
Simulation Method ◽  
Complex Stress ◽  
Roof Bolt ◽  
Deformation And Failure ◽  
Long Run ◽  
Research Findings ◽  
Stress Environment ◽  
Classification Prediction ◽  
The Stability

In order to forecast the stability of deep roadway and optimize the parameters of bolts, the complex stress environment and the multivariate surrounding rocks characteristics of deep roadway were analyzed. Then the classification prediction method and the numerical simulation method were simultaneously used to analysis the stability of surrounding rocks. Furthermore, the supporting parameters of bolts were also designed optimally. It was shown that the characteristics of stress distribution, deformation and failure zone of surrounding rocks are not ideal. So it is necessary to optimize the supporting parameters of deep roadway. All these research findings will provide the theory basis for bolts of deep roadway and will ensure the optimization of bolts and the stability of deep roadway in the long run.

Application of the concept of the criterion of equivalence of complex stress state to simple tension for assessing the fatigue resistance of structural materials. Part 1. Review of some experimental data with the preparation of the necessary information for subsequent use

2021 ◽  
pp. 24-27
Author(s):  
P.N. Kozlov
Keyword(s):  
Stressed State ◽  
Fatigue Resistance ◽  
Numerical Data ◽  
Structural Materials ◽  
Complex Stress ◽  
Complex Stress State ◽  
Static Loads ◽  
Simple Tension ◽  
Long Time ◽  
Equivalence Criterion

A brief overview of the features of the fatigue resistance of some steels is given with the selection of terms, concepts and numerical data necessary for the subsequent compilation and verification of the equivalence criterion in relation to assessing the ability of structural materials to resist fatigue for a long time under the action of certain combinations of alternating and static loads. Keywords: regular loading cycle, extremely stressed state, static stressed state, bending, torsion, biaxial static tension. [email protected]

scholarly journals Numerical Modeling of a Punch Penetration Test Using the Discrete Element Method

2020 ◽  
Vol 28 (2) ◽  
pp. 1-7
Author(s):  
Rouhollah Basirat ◽  
Jafar Khademi Hamidi
Keyword(s):  
Numerical Modeling ◽  
Discrete Element Method ◽  
Numerical Models ◽  
Confining Pressure ◽  
Discrete Element ◽  
Numerical Results ◽  
Strength Parameter ◽  
Penetration Test ◽  
Strength Parameters ◽  
Element Method

AbstractUnderstanding the brittleness of rock has a crucial importance in rock engineering applications such as the mechanical excavation of rock. In this study, numerical modeling of a punch penetration test is performed using the Discrete Element Method (DEM). The Peak Strength Index (PSI) as a function of the brittleness index was calculated using the axial load and a penetration graph obtained from numerical models. In the first step, the numerical model was verified by experimental results. The results obtained from the numerical modeling showed a good agreement with those obtained from the experimental tests. The propagation path was also simulated using Voronoi meshing. The fracture was created under the indenter in the first step, and then radial fractures were propagated. The effects of confining pressure and strength parameters on the PSI were subsequently investigated. The numerical results showed that the PSI increases with enhancing the confining pressure and the strength parameter of the rock, including cohesion and the friction angle. A new relationship between the strength parameters and PSI was also introduced based on two variable regressions of the numerical results.

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