Presentation of Empirical Equations for Estimating Internal Friction Angle of GW and GC Soils in Mashhad, Iran Using Standard Penetration and Direct Shear Tests and Comparison with Previous Equations

Presentation of empirical equations for estimating engineering properties of soils is a simple, low cost and widely-used method. One of the major concerns in using these equations is evaluating their accuracy in different conditions and regions which often lead to doubts about obtained results. Most of these equations were derived in special laboratories, different climate conditions and in soils with different geotechnical and geological engineering properties and were generalized to other conditions. The main question is that whether these methods are also applicable to other conditions. Using local equations and narrowing the usage range of various methods based on each region’s properties are appropriate methods to solve these problems. This leads to simplified and faster analysis and high reliability in the obtained results. In this paper, empirical equations were derived to estimate internal friction angle, based on SPT numbers of Mashhad City’s soils in Iran, using SPT and direct shear tests results from 50 samples (25 GW and 25 GC soil samples). The results showed similar values for predicted?φ?values by SPT test and?φ?values determined by direct shear tests.

Influence of Wind Deviation Angle on n-Hexane Evaporation Loss of Internal Floating-Roof Tanks

With the increasing attention to environmental protection,it is still necessary to strictly control the oil evaporation loss from the IFRT(internal floating-roof tank)to the atmosphere.Upon using n-hexane as a representative of light oil,the effects of the WDAs(wind deviation angles)on airflow distribution,the wind speed,the n-hexane vapor concentration,and the evaporation loss rate in the IFRT were investigated,and the mass transfer of the vapor-air was analyzed.The results are shown as follows:when the WDA is 0°,the vapor concentration in the gas space above the floating deck is the lowest;when the WDA is 22.5°,the oil evaporation loss rate is the largest;when the WDA is 45°,the vapor concentration is the highest,but the evaporation loss rate is the smallest.It is recommended to arrange the vent to the wind direction with an angle of 45°to reduce the evaporation loss and protect the atmospheric environment.

Orientation Angle of Molecules at Hexadecane-Water Interface Studied with Total Internal Reflection Second Harmonic Generation

取向角度是在接口反映分子的结构的一个重要参数。以便获得这个参数，第二包括第二泛音代(SHG ) 订非线性的分光镜的技术并且加频率产生震动的光谱学(SFG -- 对) 成功地从各种各样的极化通过非线性的信号的分析被使用了。在一些 SHG 和 SFG -- 对实验，全部的内部思考(TIR ) 配置被采用了得到提高的信号。然而，极化分析和在 TIR 配置下面的界面的分子的取向角度的计算的详细过程上的报告仍然是很少的。在这份报纸，我们在 TIR 和 Non-TIR 下面在 hexadecane 水接口测量了二个分子的取向角度试验性的配置。在 TIR 配置从极化分析测量的结果在于，那些从 Non-TIR 配置获得了。这个工作在 TIR-SHG 配置下面在接口在分子的取向角度的决心表明极化分析的可行性和精确性。

Strain amplitude-dependent internal friction of as-cast high damping magnesium alloy during cyclic vibration

An investigation on strain amplitude-dependent internal friction （IF） of an as-cast high damping Mg-7 wt% Ni alloy was carried out. In the range of our tested strain amplitudes, whether the strain amplitude is increasing or decreasing, the strain amplitude-dependent IF curve can be divided into two stages： one is the strain amplitude weakly dependent part and the other is the strain amplitude strongly dependent part. However, after several cyclic vibrations, the IF values measured during the strain amplitude increasing are smaller than those obtained during the strain amplitude decreasing. The phenomenon is also observed at 100 C. Partial dislocations generate a short-range slip under the cyclic stress to be responsible for it.

Combined effects of topography and bottom friction on shoaling internal solitary waves in the South China Sea

A numerical study to a generalized Korteweg-de Vries (KdV) equation is adopted to model the propagation and disintegration of large-amplitude internal solitary waves (ISWs) in the South China Sea (SCS). Based on theoretical analysis and in situ measurements, the drag coefficient of the Chezy friction is regarded as inversely proportional to the initial amplitude of an ISW, rather than a constant as assumed in the previous studies. Numerical simulations of ISWs propagating from a deep basin to a continental shelf are performed with the generalized KdV model. It is found that the depression waves are disintegrated into several solitons on the continental shelf due to the variable topography. It turns out that the amplitude of the leading ISW reaches a maximum at the shelf break, which is consistent with the field observation in the SCS.Moreover, a dimensionless parameter defining the relative importance of the variable topography and friction is presented.

Effect of soil cohesion and friction angles on reverse faults

Severe faults have caused many earthquakes around the world throughout history.More recently,earthquakes have occurred in Taiwan,China(Chi-Chi fault),and elsewhere,causing loss of lives and destroying many buildings and structures.These tectonic movements have gained attention from engineers,and in the past 15 years,the focus has been on faulting mechanisms.In this study,a physical model(1 g)was fabricated and used to evaluate the impact of a reverse fault in a field with a tunnel.In the 1 g model,researchers installed additional gauges on the tunnel,so that all the displacements could be adjusted,and all the responses could be monitored during faulting.An experimental study of various soil properties(cohesion and friction angles)in reverse faults on the tunnel lining were carried out and are described herein.A comparison of results for different levels of soil cohesion revealed that it can dramatically reduce the displacement by as much as 40%,and that friction angles of 27ºcan record approximately 60%more displacements than at 37º.Furthermore,a comparison of fault angles of 30ºand 60ºindicates that the displacements can be different by more than 43%in cohesionless soil and about 64%for a friction angle of 27º.

The measure of friction angles for different types of granular material

The aim of this research is to deepen the knowledge of the role of friction on the dynamics of granular media; in particular the friction angle is taken into consideration as the physical parameter that drives stability, motion and deposition of a set of grains of any nature and size. The idea behind this work is a question: is the friction angle really that fundamental and obvious physical parameter which rules stability and motion of granular media as it seems from most works which deal with particle dynamics? The experimental study tries to answer this question with a series of laboratory tests, in which different natural and artificial granular materials have been investigated in dry condition by means of a tilting flume. The characteristic friction angles, both in deposition(repose) and stability limit(critical) conditions, were measured and checked against size, shape, density and roughness of the considered granular material. The flume tests have been preferred to "classical" geotechnical apparatuses(e.g. shear box) since the flume experimental conditions appear closer to the natural ones of many situations of slope stability interest(e.g. a scree slope). The results reveal that characteristic friction angles depend on size and shape of grains while mixtures of granules of different size show some sorting mechanism with less clear behaviour.

EFFECT OF AGING ON INTERNAL FRICTION,ELASTIC MODULUS AND MECHANICAL PROPERTIES OF TERNARY Mn-Cu-Al ALLOYS

Internal friction and elastic modulus of ternary Mn-Cu-Al alloys containing 56—60 wt-% Mn,0-3.59 wt-% Al were measured with acoustic frequency,1 kHz,in the tempera- ture range of-150 to 150℃.It was found that when the specimen was aged in the temperature range under the spinodal curve within the miscibility gap(400—500℃),the internal fric- tion increases with an increase of the aging time and reaches a maximum value at a certain ag- ing time which is shorter with a higher aging temperature.Two internal friction peaks which did not appear before the aging were observed above room temperature after a definite aging time.These are respectively the martensitic tranformation peak and the relaxation peak orig- inating from the stress-induced movement of the twin boundaries.The former peak shifts to- ward higher temperatures with an increase of the aging time,whereas the relaxation peak ap- pearing at 15℃,is independent of the aging time and temperature.The activation energy as- sociated with the relaxation peak was found to be 0.56 eV which is about the same as that of the relaxation peak in binary alloy containing 90 wt-% Mn.It was also found that the hardness,strength and the brittleness of the specimen increase when aged below the spinodal curve within the miscibility gap.The addition or Al enhances the strength but reduces the in- ternal friction of the specimen.A choice of suitable aging time and temperature can give an optimum compromise of high strength and high internal friction.Analysis of experimental re- sults suggests that spinodal decomposition leads to Mn-rich zones in the specimen and thus causes the phase transformation and the change of mechanical properties of the specimen.

Internal Friction in Rail Waist of BNb and BNbRE Steels

The internal frictions of the specimens in the waist centre of the commercial BNb and BNbRE rails, which were left in air for two years, were measured. It is found that there is an obvious Snoek-Kê-Koester （SKK） peak in both steels, and still exists a measurable deformation-enhanced Shock peak（DESP） in the specimens of the BNbRE steel. The internal frictions in the deformed specimens of the both steel rails were also measured. Unlike the case of the tread specimens showing a decrease of SKK damping due to deformation, the SKK damping of the rail waist specimens increases after deformation; and the specimens containing rare earth（RE） show more noticeable damping increase than those without RE. The results of the internal friction measured during ascending and descending temperature under 700℃ show that there is a high temperature damping which can be completely disappeared during descending temperature for both steels.

Experimental Study and Fatigue Analysis of Vortex-Induced Vibration of Umbilical Cable Considering Internal Friction

In order to investigate the effect of internal friction of umbilical cable on its vortex-induced vibration(VIV)responses,the experimental study on VIV of bond umbilical cable(BUC)and un-bond umbilical cable(UBUC)was carried out in an experimental tank.A current generator in the laboratory simulated the uniform current,and the current velocities were observed in real time by using a Doppler Velocimeter.In addition,different sizes of top tension were applied to the umbilical cable model.The VIV responses of the umbilical cable model were measured by using Fiber Bragg grating(FBG)strain sensors.The displacement responses of umbilical cable model were reconstructed based on the experimental strain data processed by modal superposition method.In this paper,the traveling wave characteristics,the spatial-temporal distribution characteristics of frequency and fatigue damage of the BUC and UBUC under VIV are studied.The experimental results show that there are obvious differences between BUC and UBUC in the response characteristics of VIV.The UBUC appears the traveling wave sooner than BUC,but its standing wave characteristics are more obvious than those of BUC at high velocities.Compared with BUC,the spatial-temporal distribution of UBUC frequencies appears wide-band distribution sooner,but has narrower bandwidth in the"lock-in"state.The level of fatigue damage of BUC was approximately the same as that of UBUC.

Influence of temperature rate on transitory internal friction during reverse martensitic transformation for Ti_(50)Ni_(27)Cu_(23) alloy

Internal friction （IF） spectra during reverse martensitic transformation from 35 to 135°C at different temperature rates of 0.5,0.75,and 1°C/min for Ti50Ni27Cu23 shape memory alloy （SMA） samples were measured with a dynamic mechanical analyzer,respectively.The IF spectra were characterized by IF peak increasing progressively and peak shifting toward high temperature with an increase in temperature rate.An iterative approach was used to calculate the precise intrinsic and approximate transitory IF contributions to the normal IF spectrum.The quantitatively analyzed results indicate that the transitory IF of this alloy is nonlinearly dependent on the temperature rate and obeys a power law with a power coefficient of 0.55.The predicted and experimental IF spectra at different temperature rates of 0.75 and 1°C/min agree well with each other,respectively.

Fe–Al Phase Formation Studied by Internal Friction during Heating Process

We systematically investigate the internal friction properties of a Fe-(43 at.%)Al powder mixture compact during the heating process with the expectation to understand the phase formation and transition process.Three internal friction peaks are successively observed during the heating process from room temperature to 750℃,but almost completely disappear in the subsequent cooling process.Three internal friction peaks exhibit obvious measuring frequency dependence,which increases with decreasing the frequency.The first internal friction peak originates from the micro-sliding of weak bonding interface between Al particles corresponding to a recr.ystallization process of deformed Al particles.The second internal friction peak is attributed to a phase formation process associated with the formation of the intermediate phase Fe2Al5.The third internal friction peak is considered to result from the formation of the FeAl intermetallic compound owing to the reaction of Fe2Al5 and residual Fe initiated by a dramatic thermal explosion reaction.

Suggestion of advanced regression model on friction angle of fault gouge in South Korea

Although friction characteristics of fault gouge are important to understand reactivation of fault,behavior of earthquake,and mechanism of slope failure,analysis results of fault gouge have low accuracy mostly than those of soils or rocks due to its high heterogeneity and low strength.Therefore,to improve the accuracy of analysis results,we conducted simple regression analysis and structural equation model analysis and selected major influential factors of friction characteristics among many factors,and then we deduced advanced regression model with the highest coefficient of determination(R^(2)) via multiple regression analysis.Whereas most coefficients of determination in simple regression analysis are below0.3-0.4,coefficient of determination in multiple regression analysis is remarkably large as 0.657.

SNOEK-Kê-K■STER PEAK OF INTERNAL FRICTION IN Fe-P-N ALLOYS

The internal friction and precipitate phases of the deformed Fe-P-N alloys have been investigated. It has been found that the ratio of depends on the content of P and the relation holds if the content of N is lower than 30wt.ppm and the content of P is lower than 640wt.ppm. It shows that the intercept K2 is related to the presence of the atomic pairs and clusters of P in the alloy matrix.

Effect of precipitation on internal friction of AZ91 magnesium alloy

The effect of precipitation on the internal friction(IF)of AZ91 magnesium alloy was investigated by using X-ray diffraction(XRD)analysis,scanning electron microscope(SEM)observation,and dynamic mechanical analysis(DMA).Six different states of alloy were prepared by applying different heat treatment processes:as-cast,in-complete solid solution,complete solid solution,micro-precipitation,continuous precipitation and continuous-discontinuous precipitation.It was found that the internal friction of in-completely solid-solutionized,completely solid-solutionized and micro-precipitated specimens showed a similar characteristic,and the grain boundary relaxation is completed depressed due to the Al atoms supersaturated in theα-Mg solution.However,a thermal relaxation internal friction peak was observed for continuously precipitated and continuously-discontinuously precipitated specimens at around 438 K and frequency of about 1 Hz,which was attributed to the grain boundaries relaxation.Furthermore,it was found that the relaxation of theβ-Mg17Al12/α-Mg phase interfaces should give its contribution to the background internal friction in the as-cast,continuously precipitated and continuously-discontinuously precipitated specimens.

INTERNAL FRICTION OF GRAIN BOUNDARIES IN Fe-P AND Fe-P-La ALLOYS CONTAINING TRACE Cu

The grain boundary internal friction(GBIF)in Fe-P and Fe-P-La alloys containing trace Cu has been studied.It is found that an addition of 0.584—0.722 wt-% La obviously reduces the IF,shifts grain boundary peaks towards higher temperatures,and produces a small addi- tional peak at even higher temperature.The mechanism of GBIF is explained as the movement of defects of atomic size,namely point defects,at gram boundaries and/or their clusters un- der stress.

Internal friction peak and damping mechanism in high damping aluminium alloy laminate

A new aluminium alloy laminate characterized by high damping, corrosion resistance and weldablity was developed. The laminate designed for required aforesaid functions was actually a composite material, which was made of two anti corrosive layers (Al), two damping layers (ZnAl alloy) and one reinforcing layer (AlMg alloy) by hot rolling. The damping characteristics were studied and it was found that there was an internal friction peak at about 50 ℃ on internal fraction vs temperature curve for the laminate. For this reason, the activation energy of the peak was calculated. The origin and damping mechanism for this peak was researched by means of SEM, TEM, X ray and DSC. It is considered that the peak is caused by the interaction between dislocations and point defects in damping layers (AlZn alloy). i.e. by the movement of dislocations dragging point defects under the action of thermal activation. The laminate is remained at room temperature for a long time, it will weaken or even disappear with the restoration of the crystal microstructure and the reduction of the dislocation density in the ZnAl alloy layers. The mechanism of the peak is in conformity with that of the dislocation induced damping. [

EFFECT OF BIAS STRESS ON NON-LINEAR INTERNAL FRICTION OF Al-Mg ALLOY

The influence of longitudinal and torsional bias stresses on anomalous amplitude-dependent internal friction was studied.The longitudinal bias stress may always weaken the anomalous amplitude-dependent effect,while the torsional one may induce different effects from differ- ent directions applied.Bias stress effect exhibits only in properly heat treated and cold worked ahoy specimens.The anomalous amplitude-dependent internal friction peaks,P_3,P_2 and P_1, are found to be related closely to slant dislocation kink chains.Thus,the application of bias stress to internal friction would be contributed to the study on dislocation structure.

EFFECT OF SLIP ORIENTATION ON STRESS RESPONSE,INTERNAL FRICTION AND ULTRASONIC ATTENUATION DURING CYCLIC DEFORMATION IN Al SINGLE CRYSTALS

The variation of cyclic stress,internal friction and ultrasonic attenuation during cyclic deformation and relations among them have been investigated with different slip orientation Al single crystals.The results indicate that the value of cyclic stress σ,internal friction Q^(-1)and ultrasonic attenuation △α depend obviously on the slip orientation.There are large differences in above three parameters for different slip orientation Al crystals.In early stage of fatigue life,σ and △α increase and Q^(-1)decreases with cycles N,and △α reached maxi- mum before σ,while Q^(-1)and σ get the valley and the peak,respectively,at same cycles.