Showing papers in "Applied Mechanics and Materials in 2006"

Mode I and Mode II Fracture Toughness Testing for a Coarse Grain Marble

Abstract: A series of fracture toughness tests have been conducted on a type of coarse grain marble. The tests were carried out either in pure mode I or in pure mode II conditions by using the cracked chevron notched Brazilian disc (CCNBD) specimen. A total number of 44 CCNBD specimens were tested, half in pure mode I and the rest in pure mode II, to obtain reliable values for mode I and mode II fracture toughness (KIc and KIIc) of the tested marble. The average value of KIc for this marble was approximately about 1.12 MPa m showing a good agreement with those reported for similar coarse grain marbles. The mode II fracture toughness was found to be 2.25 MPa m in average which is approximately twice the mode I fracture toughness. However, the conventional fracture criteria suggest that the mode I fracture toughness should be higher than the mode II fracture toughness, (KIc>KIIc). According to these criteria, the ratio of KIIc / KIc is a figure typically between 0.63 and 0.96. It is shown in this paper that enhanced mode II fracture toughness of CCNBD specimen could be due to the effects of highly negative T-stress when the specimen is subjected to mode II. It is also shown that an improved prediction for the ratio KIIc / KIc can be achieved when the effect of T-stress is taken into account.

Effects of Laser Welding Conditions on Toughness of Dissimilar Welded Components

Abstract: Welding dissimilar materials become inevitable in engineering industries. There are many issues/problems associated with the welding of dissimilar materials, related to the welding process and its parameters. The current work investigates the effect of laser welding conditions on the toughness of dissimilar welded components. In this study, CO2 laser welding has been successfully applied for joining 316 stainless steel with low carbon steel (F/A). Design of experiment techniques has been used for different effective welding parameters (laser power, welding speed, and focus position) to optimize the dissimilar F/A joints in terms of its mechanical properties. Taguchi approach was applied to optimize the welding parameters. Three factors with five levels each (L-25) were employed in these models. Impact strength was measured at room temperature by using the universal pendulum impact tester. The results were compared with the impact strength of the base material. The results were analysed using ANOVA and S/N ratio for optimal parameters combination. It is evident that Taguchi approach has decreased the number of experiments without negative effects on the result.

Development of the Humanoid Robot LOLA

Abstract: This paper presents the performance enhanced humanoid robot LOLA which is currently being manufactured. Hardware design, controllers and simulation are based on ex- perience gained during the development of the robot JOHNNIE. The objective of the current research project is to realize a fast, human-like and autonomous walking motion. To enable an optimal design of the robot with respect to lightweight construction, motor and drive sizing, an appropriate simulation model is required. Dynamics simulation is a key tool to develop the hardware and control design properly. For hardware design and detailed dynamic analysis a comprehensive model including motor and gear dynamics is required, while for controller de- sign and stability analysis a simplified model for global system dynamics is sufficient. Both robots are characterized by a lightweight construction. In comparison to JOHNNIE, the new robot LOLA has a modular, multi-sensory joint design with brushless motors. Moreover, the previously purely central electronics architecture is replaced by a network of decentral joint controllers, sensor data acquisition and filtering units and a central PC. The fusion of motor, gear and sensors into a highly integrated mechatronic joint module has several advantages for the whole system, including high power density, good dynamic performance and reliability. Ad- ditional degrees of freedom are introduced in elbow, waist and toes. Linear actuators are used for the knee joints to achieve a better mass distribution in the legs.

Nonlinear Response of an Oscillator with a Magneto-rheological Damper Subjected to External Forcing

Abstract: This paper examines the dynamics of a single degree of freedom nonlinear model, representing a quarter of an automobile with a semi-active, nonlinear suspension. Assuming that the kinematic excitation caused by the road surface profile is harmonic, the principal resonance and frequency entrainment are obtained for regions of the model parameters. Changing the excitation frequency and road profile amplitude we analyze possible chaotic vibrations and bifurcations of the system.

Economic growth and its effects on carbon emission in China

Abstract: This paper intends to present the authors' analysis of the relationship between the GDP growth and carbon emission in China today with the correlative analytical method(R2=0.958 1).The authors' conclusion is that the present economic development pattern mainly dependent on the investment and structural expansion of secondary industry has strong impact on the emission increase of greenhouse gas.The investment rate of China exceeds 35%-40% of GDP during the period of 1980 to 2003,which is higher than other countries.As a result,China has brought about tremendous development of its heavy industry with ever increasing consumption of energy resources.Such a consequence,on the one hand,has led to higher proportion of secondary industry to the whole macro-economy(over 50%).On the other hand,its energy consumption has to be dependent heavily on coal(over 60%),which emits large amounts of gases than oil or natural gas.Thus,it will be inevitable to consume more energy and increase the emission of greenhouse gases in future.However,under the background of globalization,our economic growth should depend more on technological improvement,scientific and institutional innovation.With the high efficient use of renewable energy and environment-friendly technology,China can and is sure to make contributions to global efforts to prevent global warming.Therefore,it can be predicted that the carbon emission intensity will gradually slow down with the economic development and the adjustment of its industrial structural system.

A nonlinear and non-ideal wind generator supporting structure

Abstract: We present a simple mathematical model of a wind turbine supporting tower. Here, the wind excitation is considered to be a non-ideal power source. In such a consideration, there is interaction between the energy supply and the motion of the supporting structure. If power is not enough, the rotation of the generator may get stuck at a resonance frequency of the structure. This is a manifestation of the so-called Sommerfeld Effect. In this model, at first, only two degrees of freedom are considered, the horizontal motion of the upper tip of the tower, in the transverse direction to the wind, and the generator rotation. Next, we add another degree of freedom, the motion of a free rolling mass inside a chamber. Its impact with the walls of the chamber provides control of both the amplitude of the tower vibration and the width of the band of frequencies in which the Sommerfeld effect occur. Some numerical simulations are performed using the equations of motion of the models obtained via a Lagrangian approach.

Quality assurance/quality control for monitoring and analysis of trace triazines in water

Abstract: The present paper is aimed at reporting the authors' improved effective method for monitoring six triazines(including Atrazine,Deethylatrazine,Deisopropylatrazine,Atrazine-2-hydroxy,Simazine and Prometryn)by using ENVI-18 column as a solid phase extractor and high performance liquid chromatography as an analyzer.At the same time,quality assurance and quality control(QA/QC)has also been discussed in the paper.As is known,triazine pesticides are used worldwide as herbicides to control weed-sprawling in the crop fields.Since pesticide residues are generally present in trace amounts in the environment,it is of great significance to establish an effective system for enrichment and analysis.The research results reveal that the recoveries of six triazines prove to range from 94% to 116%,while the method detection limits range from 0.08 μg/L to 0.18 μg/L.The method reproducibility and detection limits can prove to be able to meet the demand of trace analysis and QA/QC control.The given method can also be used for three environmental aquatic samples,in which no triazines exist in table-water and tap-water form.However,the water sample gained from a river proves to be contaminated by triazines.And the concentrations of atrazine and prometryn in the river have also been detected as(7.12±0.54)μg/L and(9.33±0.27)μg/L.

On route-choice analysis of hazardous materials transportation

Abstract: This paper intends to introduce the author's analysis on the general framework of hazardous materials (hazmat) risk during the road transportation that may be caused by the route choice, the vehicle or traveling risk source and the impact area. It has mainly discussed the route-independent and route-dependent factors, including the factors correlated to intrinsic road characteristics, meteorological conditions, traffic characteristics and the population density. As is known, the risk analysis is of the premise to the hazmat optimal routing, which is of utmost importance both to the decision-making of government and the carrier itself. The present paper has also discussed the importance of the bi-level routing management model while giving a detailed analysis on the possibilities to minimize the accident probabilities and population exposure models. And, in final analysis, the hazmat routing problem can be resolved with impedance-adjusting node-labeling shortest path-selection algorithm and link-labeling shortest path-selection algorithm. Moreover, a detailed study on the population exposure zone has also been done, taking full account into the error terms of the overlaps between adjacent links, which is also worthy of careful calculation.

Flexural Testing of Composite Sandwich Structures with Digital Speckle Photogrammetry

Abstract: Composite sandwich structures are finding increasingly widespread use in fields ranging from aerospace and wind turbines to sports applications such as skis and surfboards. The high specific stiffness that composite sandwich structures can provide lends them well to these applications. However, the operational environment of these structures is frequently aggressive and often results in damage during service. The extent and effect of damage incurred is an important factor in the design and maintenance of composite sandwich structures. Failure of an individual component can be catastrophic for the rest of the structure. The purpose of this investigation was, firstly, to ascertain whether DSP was a viable technique for determining strain fields within composite sandwich structures. Secondly, to determine whether four point flexure would give rise to pure flexure between the central rollers, and if not, to understand what load conditions were present. This investigation was also carried out with a view to extend the investigation into the effect of defects on composite sandwich structures manufactured by RIFT. The grounds for selection of composite sandwich structures normally lie in their flexural performance. Reliable and accurate quantitative testing methods for evaluating the flexural performance of sandwich panels are needed if composite sandwich structures are to be used safely and effectively. In addition, methods to determine the effect of damage and defects on flexural behaviour of sandwich structures is particularly important for designing the repair and maintenance regimes of composite sandwich components.

On Approximate Analytical Solutions for Vibrations in Cracked Plates

Abstract: Recent NATO funded research on methods for detection and interpretation methodologies for damage detection in aircraft panel structures has motivated work on low-order nonlinear analytical modelling of vibrations in cracked isotropic plates, typically in the form of aluminium aircraft panels. The work applies fundamental aspects of fracture mechanics to define an elliptical crack, and the local stress field and loading conditions, arbitrarily located at some point in the plate, and then derives an analytical expression for this that can be incorporated into the PDE for an edge loaded plate with various possible boundary conditions. The plate PDE is converted into a nonlinear Duffing-type ODE in the time domain by means of a Galerkin procedure and then an arbitrarily small perturbation parameter is introduced into the equation in order to apply an appropriate solution method, in this case the method of multiple scales. This is used to solve the equation for the vibration in the cracked plate for the chosen boundary conditions, which, in turn, leads to an approximate analytical solution. The solution is discussed in terms of the perturbation approximations that have been applied and highlights the phenomenology inherent within the problem via the specific structures of the analytical solution.

Application of Generalized Differential Quadrature Method to the Bending of Thick Laminated Plates with Various Boundary Conditions

Abstract: Bending analysis of thick laminated rectangular plates with various boundary conditions is presented using Generalized Differential Quadrature (GDQ) method Based on the Reissner first order shear deformation theory, the governing equations include a system of eight first order partial differential equations in terms of unknown displacements, forces and moments Presence of all plate variables in the governing equations provide a simple procedure to satisfy different boundary condition during application of GDQ method to obtain accurate results with relatively small number of grid points even for plates with free edges Illustrative examples including various combinations of clamped, simply supported and free boundary condition are given to demonstrate the accuracy and convergence of the presented GDQ technique Results are compared with other analytical and finite element predictions and show reasonably good agreement

Pollution and risk evaluation of heavy metals in soil and agro-products from an area in the Taihu Lake region

Abstract: The present paper has done a detailed analysis to the samples collected from the soil and farm produce from a polluted farmland near a smelter in the Taihu Lake area with the respective contents of Pb,Cd,Hg,As,Cu,Zn,Ni,Cr and Se analysed in 2005.The pollution situation of the soil and farm produce has been assessed with the national background and guideline values of State Environmental Quality Category II,and by the values of the State Food Security Standard.And,finally,a general assessment of the exposure level by the food and drinking intake of the produce from the polluted and is given,while taking into account the R_fD values recommended by USEPA(2000).The results of the analysis indicate that the contents of the 8 metals both of the paddy and vegetable lands proved much higher than those stipulated in the National Background Standards in the area and the Nemeiro Indices detected indicated a heavy compound pollution of the multiple heavy metals,with Pb,Cd being most heavily polluted.Among the 9 metals of the samples,Pb and Cd were far above the State Food Guideline limits.Of all the farm produce,the metal contents of stem and leaf vegetables of crowndaisy,water spinach and cole reached the dangerous metal-content allowable levels.Thus,serious health risks are highly likely to get exposed to for the local people through their drinking and eating of the above-said farm produce,especially in case of potentially intense exposure to Cd,Pb and As.Therefore,serious concerns may arise as to the soil environmental pollution and health hazards due to the serious metal-pollutes soil in the Taihu Lake area.

Stresses in Ultrasonically Assisted Turning

Abstract: Ultrasonically assisted turning (UAT) is a novel material-processing technology, where high frequency vibration (frequency f ≈ 20kHz, amplitude a ≈15μm) is superimposed on the movement of the cutting tool. Advantages of UAT have been demonstrated for a broad spectrum of applications. Compared to conventional turning (CT), this technique allows significant improvements in processing intractable materials, such as high-strength aerospace alloys, composites and ceramics. Superimposed ultrasonic vibration yields a noticeable decrease in cutting forces, as well as a superior surface finish. A vibro-impact interaction between the tool and workpiece in UAT in the process of continuous chip formation leads to a dynamically changing stress distribution in the process zone as compared to the quasistatic one in CT. The paper presents a three-dimensional, fully thermomechanically coupled computational model of UAT incorporating a non-linear elasto-plastic material model with strain-rate sensitivity and contact interaction with friction at the chip–tool interface. 3D stress distributions in the cutting region are analysed for a representative cycle of ultrasonic vibration. The dependence of various process parameters, such as shear stresses and cutting forces on vibration frequency and amplitude is also studied.

Proposals for controlling flexible rotor vibrations by means of an antagonistic SMA/composite smart bearing

Abstract: Recent EPSRC funded research at Glasgow University, Swansea University, and Virginia Polytechnic and State University, and collaborative work with the Karlsruhe University of Applied Sciences, on the application of shape memory alloy (SMA) elements integrated within glass epoxy composite plates and shells is currently leading to the design of a novel smart bearing based on the principle of antagonistic action. In this system a ball bearing is fitted halfway down a glass epoxy composite tube, entering through one end of the tube. The tube has both ends rigidly built in to the support frame. The tube is divided into two regions, one on each side of the centrally located bearing. SMA strips are bonded in two independent sets of four, each set running axially along half the length of the tube and separated by 90 o around the tube. The four strips in each set are electrically connected in series to a high current power supply that can be switched in or out, and the current set, as required. This provides a convenient and fast way of heating each set of SMA strips through the martensite-to-austenite transformation temperature, and provides a significant axial contraction load on the tube in either direction. Previous FE analysis has provided predictions for converting an axial contraction load into useful stiffening of the structure in the radial and hoop directions. This introduces the potential for modification of the dynamic performance of the flexible rotor. In addition to separate heating each half of the active bearing has its own independent forced-air cooling system. Previous work by one of the authors, and others, has shown that a single SMA/composite active bearing can be very effective in both altering the natural frequency of the fundamental whirl mode as well as the modal amplitude. The drawback with that design has been the disparity in the time constant between the relatively fast heating phase and the much slower cooling phase which is reliant on forced air, or some other form of cooling. This form of design means that the cooling phase of one half, still using forced air, is significantly assisted by switching the other half into its heating phase, and vice versa, thereby equalising the time constants, and giving a faster push-pull load on the centrally located bearing; a loading which is termed ‘antagonistic’ in this paper. The experimental system is discussed in terms of potential performance and control issues.

On criterion of social and environmental risk of reservoir dams

Abstract: The present research is about the evaluation criteria of the casualty, economic loss, impact of society and environment that the reservoir dams may bring about. As is known, the evaluation risk criterion on the impact of the society and environment is less discussed both at home and abroad. This paper has selected 8 important influencing factors, 4 of which are concerning the threat to the population, city importance, significant facilities, and cultural relics, historical sites, art collectors, rare and precious animals and plants and the other 4 of which are river configuration, animal and its habitat, natural and historical heritages, industrial pollution to the environment. The factors could be quantified by following the expert experience and then integrated into the social and environmental impact indices. An accordance with the Chinese situation, the paper presents a risk criterion of social and environmental preliminary reality by using FN curve as in the evaluation of human casualty in Australia. The primary application results in 6 Chinese reservoir dams show that the risk criterion and its integrated method are practical and reasonable on the whole and it can be applied in reservoir dam risk evaluation in the near future.

Effects of water control on rice growth and its intake of cadmium on Cd contaminated soil

Abstract: The present article is aimed at reporting the authors' pot rice-growing experiments in hoping to investigate the effects of different ways of water control on rice yields and its intake of Cd,that is,continuous flooding,dry cultivation and mid-way drainage in different growing stages.The results of our experiments indicate that dry cultivation brings about remarkable effects on the rice growth and brings about the lowest yields.Compared with the continuous flooding,dry cultivation tends to decrease the rice yields by 28.74%.On the other hand,continuous flooding tends to bring about relatively higher yields,but not the highest.Drainage at tillering and filling periods could increase the rice yields more remarkably than continuous flooding,that is,by 14.58% vs.10.27%.The content of Cd in brown rice proves the least with the continuous flooding,while the dry cultivation and midseason drainage in different growing stages tend to increase its content in brown rice,which appears most obviously with dry cultivation.In our experiments,dry cultivation has brought about an increase of Cd content as high as by 166.31%.On the other hand,the influence on Cd content in brown rice with the mid-way drainage proves weakest.Thus,it can be concluded that continuous flooding is the most favorable to be chosen as a cultivation method on Cd contaminated soil,with the drainage cultivation following.In addition,dry cultivation is also likely to affect rice growth with an obvious increase of the Cd content,for which it is unfavorable to be chosen on Cd contaminated soil.

Three-Dimensional Elasticity Solutions for Isotropic and Generally Anisotropic Bodies

Abstract: Classical methods of two-dimensional elasticity can be extended to give an exact solution of the three-dimensional problem for the beam — i.e. a general solution for the pris- matic bar loaded on its lateral surfaces, subject only to the restriction that the tractions can be expanded as power series in the axial coordinate z. A series of sub-problems Pj is defined by successive partial differentiations with respect to z. For isotropic materials, a recursive al- gorithm can be used for generating the solution to Pj+1 from that for Pj in the context of the Papkovich-Neuber solution. For the generally anisotropic material, a similar strategy is proposed, based on partial integrations of Stroh’s formulation of the two-dimensional problem.

Stability Switches in a Neutral Delay Differential Equation with Application to Real-Time Dynamic Substructuring

Abstract: In this paper delay differential equations approach is used to model a real-time dynamic substructuring experiment. Real-time dynamic substructuring involves dividing the structure under testing into two or more parts. One part is physically constructed in the lab- oratory and the remaining parts are being replaced by their numerical models. The numerical and physical parts are connected via an actuator. One of the main difficulties of this testing technique is the presence of delay in a closed loop system. We apply real-time dynamic sub- structuring to a nonlinear system consisting of a pendulum attached to a mass-spring-damper. We will show how a delay can have (de)stabilising effect on the behaviour of the whole system. Theoretical results agree very well with experimental data.

An Investigation of Residual Stress Effects due to the Anodic Bonding of Glass and Silicon in MEMS Fabrication

Abstract: Anodic bonding is widely-used in the fabrication of Micro-Electro-Mechanical Systems (MEMS) devices to join silicon and glass components. The process involves the application of temperature, moderate pressure and an electric field. This paper investigates residual stresses arising during anodic bonding, focusing on the resulting induced distortions. Components of a MEMS silicon rate sensor, in which a silicon wafer is anodically bonded to Pyrex™ glass, were used as the vehicle for the investigation. Distortions generated by the anodic bonding process when using two different electrode configurations (point and planar) were measured using a surface optical profiler. These showed a particular pattern across the wafers for both configurations. An efficient FEM study was carried out to model the qualitative effect of the following residual stress sources; thermal stress, glass shrinkage due to structural relaxation and compositional gradients due to ion migration. Importantly, the FE model takes account the actual multi-device wafer-level configuration, as opposed to a single device. The results demonstrate that compositional gradients can make a significant contribution to the observed pattern of distortions.

A Wavelet Approach for the Analysis of Bending Waves in a Beam on Viscoelastic Random Foundation

Abstract: This paper deals with the mathematical model of dynamic behaviour of a beam resting on viscoelastic random foundation for which the modulus of subgrade reaction is assumed to be a homogeneous random function of the space variable. An approximate analytical solution for the fourth-order differential equation with random parameters is obtained in the case of a ∞ C -class correlation function. This higher order regularity of correlation function implies the regularity of associated stochastic function [1] in the sense of the mean-square analysis [2]. The numerical results for the average displacement have been obtained by using Bourret’s approximation method. A special method of finding inverse Laplace transform based on the wavelet theory is adopted and used in the numerical examples.

Numerical simulation on water-inrush from the seam floor based on the coupled analysis of seepage and damage

Abstract: The present paper aims to introduce the authors' simulation of the instable failure process of seam floor above confined aquifer under mining. Our simulation was done numerically based on the theory of the flow and damage coupling by using F-RFPA 2D (Coupling System of Flow Solid in Rock Failure Process Analysis). The paper also made a discussion with F-RFPA 2D the water outburst mechanism from the seam floor and predicted the position of the water outburst. In accordance with the geological conditions of Yangcun coalmine, a mechanical model for the mining process simulation of seam No.17 with average height of 1.2 m was established. The simulation results show that, when the coal of 26.8 m long was mined, the failure zone caused by the shear and tension was developed due to the water retarding formation as well as other factors concerned in the nearby zones. Then the failure zone would gradually perforate into the underlying confined aquifer, which in turn may lead to the water outburst. In such a situation, the displacement and flow volume would increase suddenly after the water outburst. Statistically the vertical flow proved to be 650 m3/(d·m) with the displacement being 700 mm. The maximum depth of the failure zone reached 13 m below the seam. And in turn the failure would also cause water-inrush from the karst aquifer No.12 and No.13 but might not be linked to karst aquifer No.14 and Ordovician system. In such a case, the aquifer No.14 and Ordovician system would usually turn to be the major threat to seam No.17. As a matter of fact, the water-pressure test with Yangcun Coalmine before and after the coal excavation was designed with its two working faces, whose results indicate that the maximum fractured depth has reached 12.35 m under the seam floor. The given result is actually consistent with that of the numerical simulation. Therefore, F-RFPA 2D can be used in predication of water-inrush in coalmining.

Automatic Balancing of a Rigid Rotor with Misaligned Shaft

Abstract: Abstract. We present a nonlinear analysis of the dynamics of an automatic ball balancer (ABB) for rotors which are both eccentric and misaligned. The ABB consists of two or more ball bearings which are free to travel around a circular race at a fixed distance from the shaft. The balls, after a transient response, find a steady state which balances the rotor. Following the previous work of Green et al. at Bristol, we have included the effect of shaft misalignment which causes the rotor to precess. This can be countered by having two ABB races at different axial locations along the shaft. Mathematically, we use a Lagrangian approach to derive the equations of motion for the system. It is found that, contrary to the case of flexible rotors that are subject to eccentricity and shaft bending, there is no choice of co-ordinate system which leads to autonomous governing equations. Simulations are then computed which illustrate the role of the ball damping coefficient.

Studies of the Sensitivity of Brake Squeal

Abstract: The problem of ‘brake squeal’ in the automotive industry remains despite over 70 years of research: the phenomenon is still surprisingly unpredictable and poorly understood. The literature has moved from very simple lumped parameter models to ever more sophisticated finite element models, but testing theory against measurements has been hindered by the difficulty in obtaining repeatable results. It would seem the phenomenon is extremely sensitive to changes in parameters beyond an experimenter’s control. This paper describes recent results from a project to identify and quantify the sources of uncertainty within sliding contact systems and to determine the sensitivity of the friction-coupled system to uncertain parameters. The theoretical approach taken is to use a linear analysis based on the uncoupled transfer functions of two general subsystems to predict stability when they are coupled by a sliding point contact. The model is tested using a pin-on-disc rig whose uncoupled transfer functions can be measured. Using a stability criterion based on the roots of the characteristic equation of the system, the sensitivity of model predictions to parameter variations is investigated numerically. It is shown that using a realistic range of parameters the root locations change considerably and enough to change stability predictions. As the complexity of the model is increased reliable results become harder to achieve as the characteristic equation becomes more ill-conditioned. This is not simply a result of the high order of the system, but is thought to be a result of particular mode combinations. Experimental work shows uncoupled transfer functions vary over time and by enough to significantly affect squeal predictions. These results suggest reasons for the difficulty in obtaining repeatable measurements and for the unreliability of squeal prediction theories developed so far. If the reasons for the sensitivity of squeal can be understood it may be possible to design sliding contact systems that are more robust.

Study on evaluation models of severity degree of dam failure impact

Abstract: Dam risk assessment technique has already been used in the field of dam safety management abroad especially in Canada, Australia and USA in recent twenty years. There are more than 85 000 dams in China and about one-third of them are with severe deficiency and in high risks. Therefore it is real necessary to use this kind of technique to assist prioritizing dam maintenance or rehabilitation, reducing risks caused by dam failure. The technique consists of two important research objectives, dam-break probability analysis and dam failure impact evaluation. Dam failure impact includes three main factors: loss of life, financial loss, society and environment. How to evaluate the severity degree by means of these three factors comprehensively is a challenge of dam rehabilitation decision-making. The paper is to present a comprehensive evaluation coefficient for dam-break severity degree. The study introduces integrative assessment function L which considered weights S_i respectively of life loss, financial loss, society and environment, and their severity coefficients F_i, formed as linear weighted sum method. In order to integrate loss of life, financial loss, society and environment in accordance with existing laws and regulations in China, logarithm non-linear or linear models of data normalization are established to deal with their different units. A series of quantitative values of L which divide disaster event into deferent degree are suggested according to Chinese situation. The method and evaluation model is practically applied at 5 reservoir dams to appraise their severity degree of failure impact respectively and the comparison of these results are made to decide which one is more severe. The analyzed result shows that hazard of all these 5 dams would be extreme severe and should report to State Council as soon as the event of dam break occur.

Numerical simulation analysis of overburden crack belt developing disciplinary

Abstract: The numerical simulation software FLAC-3D can be used to analyze the developing disciplinary of the roof breakage.It needs to measure,get basic data,found suitable mathematics model,numerical simulation analysis,and the results are credibility and accurate.And the conclusion can be used to forecast the crack developing height of the roof breakage.

Towards the Modelling of Fretting Wear and Fatigue Interaction in Spline Couplings

Abstract: The prediction of fretting wear and fretting fatigue is a significant issue for the design of high-performance aeroengine spline couplings, due to the potential for slip between the highlyloaded spline teeth under cyclic loads. The work reported here builds on previous work on simpler (Hertzian) laboratory test configurations to take a step towards a unified fretting wear and fatigue modelling approach, which considers the evolution of contact geometry with material removal and consequently the changes in fatigue-pertinent subsurface stresses. The approach calculates the local wear, that it is the wear at each contact node, as a function of local contact pressure and local slip. The influence of wear damage on fretting fatigue behaviour is quantitatively assessed by computing the change of a shear strain based fatigue damage parameter, i.e. the critical-plane Fatemi-Socie parameter. The application of the simulation tool to the complex geometry of a helical spline coupling is discussed.

The Effects of Cold Forming and Welding Residual Stress States on the Buckling Resistance of Orthogonally Stiffened Cylinders

Abstract: The buckling resistance of orthogonally stiffened cylinders is investigated for elastic critical buckling and non-linear elasto-plastic buckling tests. The effects of residual stresses arising from cold forming the cylinder and welding frame components are considered in the analysis of two stiffened cylinder models with similar material weights and different geometric spacings. A static axial load is applied to the models to represent loading from the supported structure followed by a non-linear elasto-plastic buckling step representing a wave loading combined with hydrostatic pressure, producing large displacement compartment buckling. Residual stress is shown to cause a reduction in buckling resistance of approximately 25% in the stiffened cylinder segments.

Application of fuzzy comprehensive evaluation in water quality assessment for the west inflow of Taihu Lake

Abstract: The present paper aims to introduce the authors' investigation and research of the water quality of 13 rivers into the lake lying in west area of the Taihu Lake catchments It has given a detailed description of the water quality of the rivers by means of the Fuzzy membership function As is known, fuzzy membership function is propitious to describe the fuzzy features of water quality Therefore,considering the main factors that may affect the Taihu Lake water quality, the paper has chosen five parameters that can be used to appraise the quality, such as dissolved oxygen (DO), permanganate demand index (COD_ Mn), ammonium nitrogen (NH_3-N), total nitrogen (TN) and the total phosphorus (TP) as the appraisal factors In doing so, it is of great significance to assign the weight parameters in the primary water quality assessment for the rationality of the results Improved Analytic Hierarchy Process (IAHP) that has combined qualitative with quantitative, objective with subjective was put forward in the paper for weight value calculation on the basis of the original testing data, better solution to the problem of weight value affected by man-made factors, and better reflecting of fuzzibility between the levels of water quality And finally, fuzzy membership function has been established with the corresponding membership well calculated Fuzzy comprehensive evaluation method can thus be used to appraise the water quality of 13 rivers into the lake lying in western area of the Taihu Lake catchments Results of the investigation indicate that 8 rivers of the 13 rivers were belong to Ⅴ grade, and the 5 rivers in the same Ⅴ grade are polluted seriously according to the membership of comprehensive appraise The evaluation results have offered scientific basis for evaluating the renovating projects and investment of inflow river in this region

Time fluctuations of major coal accidents in China

Abstract: The aims of this paper are to explore the time fluctuations about major coal accidents and the relationship between different kinds of accidents.Using SPSS 13.0 and through analyzing 1 433 coal major accidents reports from 1970,the author found major coal accidents correlate with different month and time periods.Most accidents occurred in Nov,Apr,Mar,May and July and what happened in Feb(Asymp.Sig=0.018),9:00-13:00 every day(Asymp Sig=0.000) is the least. Relations between kinds of accidents and death numbers(Asymp Sig=0.000),marsh gas accidents,grime blast,mining fire,mining floods,coal and gas outburst influence significantly.Deaths of each major coal accident dose not decrease from 1970.Changes of accidents along with dates didn't fluctuate distinctly.To prevent coal major incidents,corresponding time periods and accident types must be paid more attention.

Emergency shelter amount confirm and location optimized

Abstract: It is an important measure for the international society establishing the emergency shelter to deal with the emergent events and victimsAnd also,the emergency shelter is the temporary living place for people in modern big cities to avoid the danger of natural disasters,such as the earthquake,fire,explosion,flood,and so onIn this paper,based on the layout rule of the emergency shelter and the emergency location,the ascertain method of the amount and the volume emergency shelter is developedBeside that,the optimize network model is also studied to solve emergency shelter location problems