scholarly journals Different Deformation Patterns in High Core Wall Rockfill Dams: A Case Study of the Maoergai and Qiaoqi Dams

2019 ◽  
Vol 2019 ◽  
pp. 1-17
Author(s):  
Rui Feng ◽  
Yun-Long He ◽  
Xue-Xing Cao
Keyword(s):  
Deformation Behaviour ◽  
Horizontal Displacement ◽  
Wide Range ◽  
Deformation Law ◽  
Mechanical Behaviours ◽  
Measured Deformation ◽  
Dam Deformation ◽  
Deformation Patterns ◽  
Reservoir Filling ◽  
Displacement Patterns

The time-dependent behaviour of high rockfill dams is complex and not easy to accurately predict. Many discrepancies were revealed by the comparison of the observed deformation histories of different dams, and the deformation of some high rockfill dams did not correspond to the general deformation law. Field monitoring is therefore an effective method for understanding complex dam deformation behaviour. In this paper, actual measured deformation data resulting from continuous monitoring of the Maoergai and Qiaoqi dams are analysed. These two dams have similar heights, crest lengths, and alluvium overburden thicknesses. Our aim is to explain the actual deformation histories on the basis of the mechanical behaviours of these dams in order to warn engineers about potential problems that cannot be predicted. The results indicate that the deformation patterns of the two dams are completely different. The dam construction and water impoundment schedule is the major reason for the different horizontal displacement patterns. The reservoir filling rates and rainfall are the main reasons for the different settlement patterns. The case histories are useful for understanding the wide range of possible postconstruction deformation in a dam.

Nonlinear dynamic behaviour of guy cables in turbulent winds

2001 ◽  
Vol 28 (1) ◽  
pp. 98-110 ◽  
Author(s):  
Bruce F Sparling ◽  
Alan G Davenport
Keyword(s):  
Finite Element ◽  
Dynamic Behaviour ◽  
Aerodynamic Drag ◽  
Numerical Study ◽  
Horizontal Displacement ◽  
Wind Loading ◽  
Second Phase ◽  
Nonlinear Coupling ◽  
Wide Range ◽  
Cable Vibrations

Large amplitude cable vibrations are difficult to predict using linear theory due to the presence of sag in the suspended profile. A numerical study was therefore undertaken to investigate the dynamic behaviour of inclined cables excited by imposed displacements. To model the nonlinear nature of cable response, a time domain finite element approach was adopted using nonlinear catenary cable elements. Two types of horizontal displacement patterns were enforced at the upper end of the guy. In the first phase of the study, harmonic displacement histories with a wide range of forcing frequencies were considered. In the second phase, random enforced displacements were used to simulate the motion of a guyed mast in gusty winds. The influence of aerodynamic drag and damping forces was investigated by performing analyses under still air, steady wind, and turbulent wind conditions. It was found that nonlinear coupling of related harmonic response components was significant at certain critical frequencies, particular when the excitation was harmonic and acted in the plane of the guy. Positive aerodynamic damping was shown to effectively suppress resonant and nonlinear coupling response.Key words: cables, structural dynamics, wind loading, finite element method, nonlinear analysis, guyed towers.

scholarly journals High-Temperature Flow Behaviour and Constitutive Equations for a TC17 Titanium Alloy

2019 ◽  
Vol 38 (2019) ◽  
pp. 168-177 ◽  
Author(s):  
Liu Shi-feng ◽  
Shi Jia-min ◽  
Yang Xiao-kang ◽  
Cai Jun ◽  
Wang Qing-juan
Keyword(s):  
Titanium Alloy ◽  
High Temperature ◽  
Constitutive Equation ◽  
Constitutive Equations ◽  
Deformation Behaviour ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Compression Tests ◽  
Average Absolute Relative Error ◽  
Wide Range

AbstractIn this study, the high-temperature deformation behaviour of a TC17 titanium alloy was investigated by isothermal hot compression tests in a wide range of temperatures (973–1223 K) and strain rates (0.001–10 s−1). Then, the constitutive equations of different phase regimes (α + β and single β phases) were developed on the basis of experimental stress-strain data. The influence of the strain has been incorporated in the constitutive equation by considering its effect on different material constants for the TC17 titanium alloy. Furthermore, the predictability of the developed constitutive equation was verified by the correlation coefficient and average absolute relative error. The results indicated that the obtained constitutive equations could predict the high-temperature flow stress of a TC17 titanium alloy with good correlation and generalization.

A Method to Determine Unstable Point and its Impact Estimation in Debris-Blocking Dam Monitoringsurvey Network

2011 ◽  
Vol 55-57 ◽  
pp. 698-703
Author(s):  
Da Bing Huang ◽  
Zhi Qiang Yang ◽  
Zhen Shi
Keyword(s):  
Earth Pressure ◽  
Monitoring Network ◽  
Horizontal Displacement ◽  
Approximate Model ◽  
Deformation Monitoring ◽  
Deformation Model ◽  
Observation Data ◽  
Network Stability ◽  
Other Information ◽  
Dam Deformation

The purpose of this paper is to determine the unstable points of debris-blocking dam deformation network and to lay the foundation for later accurate monitoring and data processing, for the reason that the affection of earth pressure and water-level-fluctuation lead to increased instability to debris-blocking dam. The author signed one horizontal displacement deformation monitoring network, measured two groups data by changing some point’s horizontal displacement with man, judged the point’s stability of the network by the method of mean gap and obtained the deformation model, and analysis the model sensitivity. The results is that the deformation network stability meet the design requirements through application the method in Fengjie Debris-blocking dam which blocked the stones debris for Shirushan tunnel, the actual displacement amount had been proven similar as the result with the method; It is concluded that this method have some practical value in deformation monitoring because it can construct the approximate model by direct observation data, which is smaller rely on other information.

Research on Deformation Law of Deep Excavation Supporting Structures in Beijing Metro Station

2011 ◽  
Vol 243-249 ◽  
pp. 2338-2344
Author(s):  
Qing Yuan Li ◽  
Yang Wang
Keyword(s):  
Horizontal Displacement ◽  
Internal Force ◽  
In Situ Monitoring ◽  
Deep Excavation ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Metro Station ◽  
Deep Foundation Pit ◽  
Deformation Law

Taking deep excavation engineering in North Region of Senlin Park Station of Beijing Olympic Subway branch as engineering background, deformation law of enclosure structure of deep excavation are studied by the in-situ monitoring means .It shows that the maximum horizontal displacement of retaining pile is closely related with excavation depth and time. When the deep foundation pit is excavated to a certain depth, and steel brace hasn’t been erected, horizontal displacement of the pile tops is maximum. The location of the maximum horizontal displacement shifts down with foundation pit excavation and steel brace erection. With steel brace application, steel axis force decrease, so steel brace can effectively control horizontal displacements of retaining pile and internal force of steel in the pile. In addition, temperature has a certain effect to axis force of steel brace.

Clamp Load Retention of Bolted Joints Under Alternating and Superposed Thermal Stress

2011 ◽  
Author(s):  
Markus Duchardt ◽  
Christina Berger ◽  
Ulrich Wuttke
Keyword(s):  
Thermal Stress ◽  
Automotive Industry ◽  
Static Load ◽  
Deformation Behaviour ◽  
Bolted Joints ◽  
Bolted Joint ◽  
Power Train ◽  
Driving Experience ◽  
Percent Improvement ◽  
Wide Range

Current efforts for using lighter materials are essentially determined by economic and ecological parameters. The automotive industry can expect a 8 to 10 percent improvement in fuel usage with a mere 10 percent reduction in vehicle weight. Lighter vehicles facilitate easier braking, and reduced collision impact, thereby creating a superior driving experience for consumers. Magnesium and aluminium alloys are common materials for a wide range of applications including engine and power train components, as well as under-hood applications with operating temperatures of up to 150°C. Today’s state-of-the-art joining method for lightweight materials is the use of aluminium fasteners. Several studies have been conducted to describe and analyze the static load behaviour of bolted joints; to date, however, the pre-load retention behaviour under alternating as well as superposed thermal stress has yet to be characterized. The current research project investigates effect of alternating stress on the bolted joint while also considering such variables as different material combinations, varying levels of load, and changes in temperature. Our main focus is on the embedding amounts and the surface pressure limits of the substrate(s), with special consideration made for time-dependent deformation mechanisms. Furthermore, based on the generated material parameters, the deformation behaviour will be reproduced and simulated.

Static and Dynamic Strain Ageing in Two-Phase Gamma Titanium Aluminides

2000 ◽  
Vol 646 ◽  
Author(s):  
U. Christoph ◽  
F. Appel
Keyword(s):  
Titanium Aluminide ◽  
Titanium Aluminides ◽  
Deformation Behaviour ◽  
Dynamic Strain ◽  
Dynamic Strain Ageing ◽  
Two Phase ◽  
Fast Kinetics ◽  
Strain Ageing ◽  
Wide Range ◽  
Dislocation Pinning

ABSTRACTThe deformation behaviour of two-phase titanium aluminides was investigated in the intermediate temperature interval 450–750 K where the Portevin-LeChatelier effect occurs. The effect has been studied by static strain ageing experiments. A wide range of alloy compositions was investigated to identify the relevant defect species. Accordingly, dislocation pinning occurs with fast kinetics and is characterized by a relatively small activation energy of 0.7 eV, which is not consistent with a conventional diffusion process. Furthermore, the strain ageing phenomena are most pronounced in Ti-rich alloys. This gives rise to the speculation that antisite defects are involved in the pinning process. The implications of the ageing processes on the deformation behaviour of two-phase titanium aluminide alloys will be discussed.

Modelling levitated 2-lobed droplets in rotation using Cassinian oval curves

2018 ◽  
Vol 846 ◽  
pp. 1088-1113 ◽  
Author(s):  
Haruki Ishikawa ◽  
Katsuhiro Nishinari
Keyword(s):  
Deformation Behaviour ◽  
Stationary Solutions ◽  
Suitable Model ◽  
Maximum Deformation ◽  
Proposed Model ◽  
Wide Range ◽  
Deformation Length ◽  
Central Cross Section ◽  
The Stability ◽  
The Relationship

A simple model of rotating 2-lobed droplets is proposed by setting the outline shape of the droplet to the Cassinian oval, a mathematical curve that closely resembles in shape. By deriving the governing equation of the proposed model and obtaining its stationary solutions, the relationship between the angular velocity of rotation and the maximum deformation length is explicitly and precisely calculated. The linear stability analysis is performed for the stationary solutions, and it is demonstrated that the stability of the solutions depends only on the ratio of the deformation length to the radius of the central cross-section of the droplet, which is independent of the physical properties of the droplet. Via comparison with an experimental study, it is observed that the calculated result is consistent with the deformation behaviour of actual 2-lobed droplets in the range where the stationary solution of the proposed model is linearly stable. Therefore, the proposed model is a suitable model for reproducing the steady deformation behaviour of 2-lobed droplets in a wide range of viscosities, surface tensions, densities and initial radii of the droplet, and especially if the viscosity of the droplet is low, the entire process of deformation of the 2-lobed droplet, including the unsteady breakup process, can be very well reproduced by the proposed model.

The Study of Deformation Law of a Super Deep Foundation Pit in the Process of Dismantling the Inner Support

2014 ◽  
Vol 638-640 ◽  
pp. 614-619
Author(s):  
Bo Liu ◽  
Qing Nan Liu ◽  
Yi Yan Zhao ◽  
Bing Hui Chen
Keyword(s):  
Horizontal Displacement ◽  
Deformation Monitoring ◽  
Maximum Point ◽  
Deep Foundation ◽  
Foundation Pit ◽  
Deep Foundation Pit ◽  
Supporting Structure ◽  
The Earth ◽  
Earth Pressures ◽  
Deformation Law

Dismantling the inner support of deep foundation pit is a risk point.It is of great importance to guarantee the safety of foundation pit when removing the inner support, and the deformation monitoring and analysis in the process of dismantling inner support is crucial. In this paper, a super deep foundation pit engineering as the research background.Through monitoring and analyzing the law of a deep horizontal displacement of the supporting structure,ground settlement, vertical settlement and axial force of support in the process of support demolition,which can be obtained that: the settlement of surface ground around the foundation shows spatial and temporal clearly and the distribution of deep horizontal displacement of supporting structure is similar to the parabolic which the maximum point constant upward shift with supporting continuous removed.Soil pressure of supporting shared with support removing process is changing, and the earth pressures support sharing is increasing. From the monitoring results, the demolition scheme is reasonable and effective and meets the requirements of design and environment.

High Temperature Deformation of AlN/CrN Multilayers using Nanoindentation

2004 ◽  
Vol 841 ◽  
Author(s):  
F. Giuliani ◽  
A. Goruppa ◽  
S. J. Lloyd ◽  
D. Teer ◽  
W. J. Clegg
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
High Temperature ◽  
Tool Steel ◽  
Deformation Behaviour ◽  
High Temperature Deformation ◽  
Temperature Deformation ◽  
Cross Sectional ◽  
Transmission Electron ◽  
Deformation Patterns

ABSTRACTThe aim of this paper is to investigate the deformation behaviour of an AlN/CrN multilayer with wavelengths varying from 6–400 nm, deposited on M42 tool steel and how this varies as the temperature is increased to 500 °C. These measurements have been correlated with changes in deformation patterns using cross-sectional transmission electron microscopy, where sections have been prepared directly through the indents.

scholarly journals Investigation into the micro deep drawing capabilities of a specially engineered refined aluminium alloy

2018 ◽  
Vol 190 ◽  
pp. 10001
Author(s):  
A. Dhal ◽  
S.K. Panigrahi ◽  
M.S. Shunmugam
Keyword(s):  
Deep Drawing ◽  
Deformation Behaviour ◽  
Annealing Treatment ◽  
Coarse Grained ◽  
Strain Response ◽  
Post Mortem ◽  
Strain Localisation ◽  
Micro Deep Drawing ◽  
Refined Microstructure ◽  
Wide Range

During miniaturisation, size of the part comes close to grain size of the material. There is an overall decrease in the total number grains undergoing deformation and most of these are surface grains. Therefore, microscale deformation is marked by abnormal stress-strain response which limits the manufacturing capabilities of microforming. Two distinct phenomena responsible for this are: (i) dominance of single crystal deformation behaviour, and (ii) increased strain localisation due to incompatibly between surface and core grains during deformation. The present work attempts to neutralise these effects by increasing the number of grains in the deformation zone. This has been achieved by engineering refined microstructure in the materials. To develop the refined microstructure, cryorolling followed by controlled annealing treatment has been employed. Microscale deformation behaviour and microforming capabilities of the refined material have been compared with its coarse-grained counterpart by analysing their tensile curves and by post-mortem study of micro deep drawn components over a wide range of sample thicknesses. Material with fully recrystallised, equiaxed, strain-free refined microstructure is found to have the best strain hardening response both in micro and macro deformation domains. This property is also reflected in the micro deep drawing capabilities of the same material.

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