Effects Of Interface Conditions Research Articles

Effects of interface conditions on tribological and hysteretic behaviors of symmetric friction connections

The symmetric friction connection (SFC), a type of slotted-bolt connection, is widely employed to dissipate seismic energy in earthquake-resistant structures. Quasi-static tests were conducted on seven SFCs to investigate effects of various interface conditions on tribological and hysteretic behaviors of the SFCs. The friction pair in focus is composed of high-hardness abrasion-resistant steel (Bisalloy 450) and mild steel (Q355B). The test results reveal that hysteretic behavior of the SFC is highly influenced by interface pressure and shot blasting for their significant effects on wear mechanisms. In this study, abrasive wear, adhesive wear and oxidation wear coexist in the process of dry sliding friction. A critical interface pressure of 42.1 MPa is recommended to achieve desirable tribological and hysteretic behaviors of the SFC. The SFC can efficiently recover its strength by removing wear products from the contact surfaces and then reapplying the bolt clamping force, indicating good repairability. Furthermore, in the presence of impurities on contact surfaces, using a rotary wire brush machine is advisable for surface preparation instead of employing shot blasting treatment. These insights and recommendations provide valuable guidance for engineers and practitioners, aiding them in improving the design process to achieve favorable seismic behavior of the SFC in seismic-resistant structures.

A Universal Size Design Principle for Stretchable Inorganic Electronics to Work Consistently under Different Interface Conditions

AbstractStretchable inorganic electronics are usually designed and calibrated under free interface condition, while the interface conditions between the devices and skins/organs in practical applications are rather complex (free, slidable, or bonded) and may switch among them. In the ideal situation, the mechanical and electrical performances have to be consistent under different interface conditions, to ensure the accuracy and robustness of the devices. Here, the effect of interface conditions on the mechanical and electrical performances is studied for stretchable inorganic electronics with different configurations by theoretical analysis, finite element analysis and experiment. A universal size design principle is proposed for stretchable inorganic electronics to work consistently under different interface conditions, i.e., the period length of the devices/interconnects has to be the same order of magnitude as the encapsulation thickness or less. To ensure the comfort of human skin/organs, micron‐scale geometrical design is necessary for epidermal electronics according to the above designed principle. This finding is of great significance for ensuring the accuracy and robustness of stretchable inorganic electronics in practical applications.

Effect of interface condition on the hydraulic characteristics of a pump-turbine at various guide vane opening conditions in pump mode

The importance of renewable energy will increase rapidly due to the global regulation of carbon dioxide emissions to cope with global warming. However, renewable energy has a high output variation because of the fluctuating characteristics of the energy source. Therefore, pumped-storage power stations require high flexibility and reliability in operation under off-design conditions, especially in the pump mode. When a pump-turbine operates under various part load conditions in pump mode, highly dynamic phenomenon such as stationary vortex and rotating stall occur. The performance characteristics in pump mode are vital for the safe and effective operation. A number of studies have been conducted to investigate the flow characteristics in a turbine or pump mode under different GVOs through numerical simulations. However, the studies about the influence of the position of the interface and the steady and unsteady interface condition on the pump characteristics of pump-turbines have been not completely clear. In this paper, the three-dimensional steady and unsteady Reynolds-averaged Navier–Stokes equations were solved for a detailed analysis of the influence of interface conditions with various guide vane opening conditions in pump mode. To ensure the reliability of the numerical analysis, the numerical results were validated in comparison with the experimental data.

Effect of interface condition on the undrained capacity of subsea mudmats under six-degree-of-freedom loading

The effect of soil–foundation interface condition on the undrained capacity of rectangular mudmat foundations under loading in six degrees of freedom is investigated. Undrained failure envelopes for mudmats with zero-tension interface have been derived from finite-element analyses, and compared with the solutions from traditional methods and established for an unlimited-tension interface condition. The zero-tension interface has minimal effect on failure envelopes in the absence of moment, but significantly reduces the load-carrying capacity of mudmats under all other load paths that include moment. The traditional method for predicting the capacity of shallow foundations under multi-directional loading generally predicts lower capacity under any combined loading condition in comparison with the finite-element results for mudmats with zero-tension interface. Algebraic expressions are proposed to describe failure envelopes for mudmats with zero-tension interface. The proposed expressions can be implemented in an automated calculation tool to enable essentially instantaneous generation of failure envelopes and optimisation of a foundation design as a function of foundation dimension or material factor.

Contact Stress Analysis and Fatigue Life Prediction of a Turbine Fan Disc

AbstractFan discs are critical components of an aero engine. In this paper, contact stress and life prediction of a turbine fan disc were investigated. A simplified pin/disc model was conducted to simulate the practical working condition under applied loads using finite element (FE) analysis. This study is devoted to examining the effects of interface condition of pin/disc such as gap and coefficient upon the maximum stress. The FE model indicated that the maximum stress occurs at the top right corner in the second pin hole, and larger gap or friction coefficient has a significant effect on the maximum stress. In addition, FE analysis without considering friction is also conducted. The results show that the dangerous point is similar to the result which considers friction and the stress state is relatively larger than that of considering friction. Finally, based on FE analysis result, life prediction for the fan disc is conducted to combine the material

Effects of Interface Condition on Performance of Road Pavements with Non-Linear Granular Materials

The main results of a numerical investigation into the effects of interface condition on the critical response and predicted performance of flexible pavements with granular bases are presented. In addition, the influence of using linear elastic and non-linear elastic models for granular base characterization, on the design life of typical road structures with granular bases under various combinations of layer interface conditions is examined. Repeated load triaxial tests are carried out and non-linear regression analyses on tests results are performed to determine the constitutive model parameters. The Asphalt Institute distress models for fatigue cracking and rutting using both linear and non-linear analyses are utilized to estimate the pavement design life. It is shown, among others, that interface condition affects significantly the critical response of pavement structures and hence their predicted performance. Furthermore, the results indicate that the use of linear assumption to characterize granular base and sub-base behaviour, grossly over-estimates the design life of pavement structures. This effect strongly depends on interface conditions used between the pavements layers.

Effects of interface conditions and long-term stability of passive intermodulation response in printed lines

An experimental investigation of the effect of conductor-to-substrate interface on distributed passive intermodulation (PIM) generation in printed microstrip lines has been undertaken using the custom-designed microwave laminates with removed surface bonding layers and with the commercial adhesion promotion applied to the conductor underside. The study of long-term stability of PIM performance of the printed circuits is reported for the first time. The comprehensive measurement results, observations of the self-improvement of the PIM performance and the effect of panel bending on PIM generation in printed boards with different finishing are presented. A consistent physical interpretation of the observed phenomena is proposed. The results of this study provide new important considerations for the design and characterisation of low-PIM printed circuits.

Effects of Interface Conditions on Thermo-Mechanical Fields of Multi-Phase Nano-Fibers/Particles

The stress field of a multi-phase spherical / cylindrical inhomogeneity with arbitrary interface bonding conditions, subjected to both a uniform temperature change and a uniform hydrostatic tension, is presented. Imperfect bonding conditions are modeled using linear spring model and coherent interface model. In nanosize inhomogeneities, since the surface energy is not negligible with respect to the bulk energy, the effect of surface stresses is incorporated into the formulation. Accurate estimates for the thermal stresses of a functionally graded coated inhomogeneity with perfect and /~or imperfect interfaces are given. The influence of coating stiffness, coating thickness and interface conditions on the distribution of stress field is examined. It is observed that even a very thin coating has a prominent effect on stress distribution; hence, its exclusion from the model will lead to erroneous results.

INTERFACE CONDITION INFLUENCE ON PREDICTION OF FLEXIBLE PAVEMENT LIFE

The effects of interface condition on the life of flexible pavements have been determined. The methodology consists of implementing a previously derived interface constitutive model into the Kenlayer programme to compute the stresses and strains in typical flexible road structures. The shell transfer functions for fatigue cracking and terminal serviceability were used to estimate the pavement life. The behaviour of in‐service pavements indicates that the condition of the bonding between pavement layers plays an important role in the road structures performance. Premature failure of road sections due to layer separation, leading to redistribution of stresses and strains in the pavement structure, is often encountered, especially in areas where the vehicles are more likely to apply horizontal forces. In computing the critical stresses and strains, most of the mechanistic design procedures of flexible pavement structures consider that pavement layers are completely bonded or completely unbounded.

INTERFACE CONDITION INFLUENCE ON PREDICTION OF FLEXIBLE PAVEMENT LIFE

Abstract The effects of interface condition on the life of flexible pavements have been determined. The methodology consists of implementing a previously derived interface constitutive model into the Kenlayer programme to compute the stresses and strains in typical flexible road structures. The shell transfer functions for fatigue cracking and terminal serviceability were used to estimate the pavement life. The behaviour of in‐service pavements indicates that the condition of the bonding between pavement layers plays an important role in the road structures performance. Premature failure of road sections due to layer separation, leading to redistribution of stresses and strains in the pavement structure, is often encountered, especially in areas where the vehicles are more likely to apply horizontal forces. In computing the critical stresses and strains, most of the mechanistic design procedures of flexible pavement structures consider that pavement layers are completely bonded or completely unbounded.

Modelling a spin-selective interface between ferromagnetic electrodes and a carbonnanotube—towards the enhanced giant magnetoresistance effect

The effect of interface conditions on the giant magnetoresistance (GMR) is studied. It isshown that the GMR changes drastically in the presence of extra magnetic monolayers atthe ferromagnetic electrodes. The monolayers may make the spin-dependent conductancechannels nearly or completely closed if they are antiferromagnetically exchangecoupled to the electrodes. It is shown that the conductance spectrum of the devicereflects, to a large degree, the internal band structure of the nanotube. Thereforethe GMR effect is quite sensitive to the relative bands’ line-up of electrodes andthe nanotube and it may be tuned by a gate voltage applied to the nanotube.

Effect of Interface Conditions on Yield Behavior of Passivated Copper Thin Films

Wafer curvature was used to study the thermal–mechanical behavior of 1-μm Cu thin films capped with a 100-nm-thick Si3N4 layer. These films were grown with either a Ta or a Si3N4 underlayer. Films on Si3N4 that were exposed to oxygen at the film/capping layer interface or at the center of the copper layer exhibited Bauschinger-like yielding at low stress. Stacks deposited under continuous vacuum, with a Ta underlayer, with carbon exposure at the upper surface of the copper film, or with oxygen exposure of only the underlayer did not demonstrate the anomalous yielding. Preferential diffusion of oxygen into copper grain boundaries or interfaces is the likely cause of the early yield behavior. Possible mechanisms include an increase in interface adhesion due to the presence of oxygen in solution and diffusion-induced dislocation glide as an additional driving force for dislocation motion at low applied stress.

Effects of Interface Condition and Horizontal Wheel Loads on the Life of Flexible Pavement Structures

The effects of interface condition and horizontal wheel loads on the life of flexible and semirigid pavements were determined. The methodology consisted of implementing a previously derived interface constitutive model into the ABAQUS finite element program to compute the stresses and strains in typical flexible and semirigid road structures. The Shell transfer functions for fatigue cracking and terminal serviceability were used to estimate the life of the two pavements. The study revealed that the horizontal loads acting at the pavement surface lead to dramatically increased tensile strains at the top and bottom of the wearing course and at the top of the binder course. This may justify the initiation of cracking at the surface of the pavement and not at the bottom of the asphalt layer, as generally assumed. For semirigid pavements, the condition of the wearing-binder course interface affects the strains in the wearing course, whereas the condition of the binder-base interface affects the horizontal strain field in the binder layer more as well as the vertical strains at the top of the subgrade. For flexible pavements, the condition of the interface between the wearing and binder courses dramatically changes the strain field in the wearing and binder layers and increases the vertical strains at the top of the granular base and subgrade layers. The cumulative effect of the interface condition and horizontal forces acting at pavement surface is expressed by a dramatic reduction in pavement life, especially for the semirigid pavement.

架橋ポリエチレン/エポキシ樹脂複合材料中のトリーイング破壊に及ぼす界面条件及びその傾斜角の影響

架橋ポリエチレン/エポキシ樹脂複合材料中のトリーイング破壊に及ぼす界面条件及びその傾斜角の影響

Effect of interface conditions on the behaviour of a Freeman hip endoprosthesis

The femoral element of a total hip replacement is a composite structure of two, or perhaps three, components — the endoprosthesis, the bone and, where present, the cement. The interfacial conditions are such that complete structural continuity does not necessarily obtain. That this is so has often been suspected due to the observed loosening which can occur in vivo. In modelling the system, typically for finite element analysis, it has usually been considered to be monolithic, such that tensile and shear stresses could be transmitted across the interfaces as well as the normal compressive stress. Here the femoral component of a Freeman hip replacement is considered, implanted without bone cement, and analyses are carried out under monolithic, i.e. fully bonded, and non-bonded assumptions. Simultaneously the effect of retaining the neck of the femur, one of the features of using this particular prosthesis, is also examined.

Effect of interface conditions on the optoelectronic measurement of carcass meat quality

Fiber optic light guides were used to illuminate the interiors of isolated meat samples or parts of commercial carcasses and to sample the light within. To maximize the dynamic range, an array was used to set the gain and high voltage of the photomultiplier at each wavelength. Optical fibres in contact with lean meat returned far less light than fibers just above the meat surface since the high specular reflectance from the rough surface of wet meat was by-passed. The formation of oxymyoglobin on aerobocally exposed meat surfaces was detected. Metabolic changes in the meat after slaughter caused progressive changes around 400 nm in ratiometric spectra. Reflectance from lean meat was increased when optical fibers were perpendicular to muscle fibers and was decreased when optical fibers were parallel and coaxial with muscle fibers. Layers of adipose tissue within the meat increased reflectance but this was temperature-dependent. Adipose tissue reflected more light at colder temperatures. Connective tissues (collagen and elastin) within meat fluoresced with a peak excitation around 370 nm and peak emissions around 440 nm and (or) 510 nm (depending on the biochemical type). The effect of fluorescence was minimal in ratiometric measurements made on meat with only a single monochromator.

Simplified theory for the behaviour of buried flexible cylinders under the influence of uniform hoop compression

The elastic behaviour of a long flexible cylinder buried in an infinite elastic medium and acted on by uniform hoop compressions is examined. A simplified solution is obtained, which can be used to accurately and efficiently determine the cylinder response. The simplified theory is used to obtain a parametric solution to the cylinder buckling problem. The effects of interface condition, elastic ground parameters, load behaviour, and finite thickness on the critical hoop compression are considered. A straightforward method is developed for predicting the prebuckling displacements and bending moments which result from the influence of initial geometrical imperfections and nonhydrostatic field stresses.

Effects of Interface Conditions on the Bending of Laminated Beams

Effects of Interface Conditions on the Bending of Laminated Beams