Wind loads on structures are commonly described as stationary phenomena that occur in neutral atmospheric conditions at the synoptic scale with velocity profiles in equilibrium with the atmospheric boundary layer. Nevertheless, structural systems can be also affected by thunderstorm outflows, which are non-stationary local phenomena at the mesoscale that occur in convective conditions with totally

Tribological behavior of nickel aluminum alloy containing silver constructed by powder metallurgy was investigated in a broad temperature range. It is noticed that Ni3Al alloy-20 wt% Ag exhibits favorable lubricating properties especially at and above 800 °C. The self-lubricating alloy possesses coefficient of friction (CoF) and wear rate (WR) low to 0.2 and 1–2 × 10−5 mm3/Nm, respectively. Moreover

Electron beam powder bed fusion (EBPBF) is a beneficial processing route to fabricate Ti6Al4V alloy for aerospace applications due to its relatively low lead time and the possibility of topology optimization. The dry sliding wear behavior of EBPBF-Ti6Al4V against steel and alumina counterballs from room temperature (RT) to 500 °C was investigated to evaluate the influence of EBPBF processing and microstructure

In the present work, the slurry erosion tests were carried out to investigate the influence of heat treatment on slurry erosion process of ferritic X10CrAlSi18 stainless steel using a slurry pot test rig. X10CrAlSi18 stainless steel was tested in as-received condition and after annealing at three different temperatures: 600 °C, 800 °C and 1000 °C. Degradation of materials due to slurry erosion depends

The performance of iron boride coatings on carbon steel (cs) produced through thermal diffusion was investigated under tribo-corrosion conditions and compared with bare CS and 316L stainless steel. The tribological experiments involved reciprocating tests under both dry sliding and tribocorrosion conditions with a ball-on-flat geometry. The coatings demonstrated enhanced wear resistance primarily due

The effects of the macroscopic surface morphology caused by the uneven wear on friction induced vibration were investigated. The experimental results showed the uneven wear in the sliding direction produced the contact plateaus with large theoretical contact lengths at the leading edge and increased the unstable vibrations. A numerical analysis of the contact pressure distribution in different macroscopic

The exact contact theory is an efficient alternative to the more general yet computationally expensive Finite Element Method for the detailed study of elastostatic contact problems. For its application in conformal contact problems, the exact contact theory needs to be fed with influence coefficients (ICs) appropriate for non-planar solids. An analytical approximation of the ICs for non-planar solids

Abrasive waterjet cutting is a competitive manufacturing technology in the aerospace, defense and automotive industries which, as power users, require state of the art process performances in terms of stability and product assurance, due to their demanding quality standards. Meeting such requirements is a relevant technical challenge for abrasive waterjet cutting, due to insufficient monitored data

Considering the wide application of dry belt fining and the importance of residual stress for bearing parts, this paper has characterized the residual stresses distribution along the depth generated by dry belt finishing after hard turning on hard materials AISI52100. The influences of applied force and finishing duration on residual stresses were experimentally investigated. The results were then

In this paper, we study the adhesion behavior of a circular and extensible plate adhered to a rigid substrate based on the finite deformation theory. The energy method is used to derive the governing equations associated with boundary conditions. Due to the highly nonlinear nature of the problem and undetermined parameters on the boundary conditions, we solve the system of equations by an optimization-based

Buckling of a biaxially compressed anisogrid stiffened composite cylindrical panel with clamped edges is considered in this paper. The panel is subjected to compressive load applied to its curved sides. This loading results in the biaxial compression of the panel due to Poisson's effect. The anisogrid lattice reinforcement of the panel is modelled as a layer with average effective stiffness characteristics

Rolling element bearing (REB) is a critical component in any rotating machinery. It is subjected to surface damage during operation due to localised fatigue. Any prediction about damage severity helps in effective maintenance planning. Defect size estimation is one of the methods of assessing damage severity in REB and is the subject of this study. Several researchers have formulated analytical as

Recently, a unified fractional heat conduction model is newly proposed, which is a further improvement of the fractional thermoelasticity theory. It would be interesting to know how the newly developed fractional derivative definitions affects the thermal fracture behavior when some defects such as cracks exist in the medium. This work is aimed at analyzing the thermal fracture problem of an elastic

The onset of stationary convection in electrohydrodynamic thermal instability of Jeffrey nanofluid layer saturating a porous medium for free-free, rigid-free and rigid-rigid boundaries is studied. Darcy-Jeffrey fluid model is used to describe rheological behaviour of nanofluid. The conservation of mementum equations are modified due to the presence Jeffrey parameter and under the influence of applied

Isomorphism identification is an essential step in mechanism configuration synthesis. Although various detection methods have been proposed, some of them can only effectively identify kinematic chains (KCs) within 10 links or complex programs that are needed to identify multilink KCs. In this study, a new isomorphism identification method is proposed based on the distance concept of graphs and the

In this article, the investigation of the use of a rolling particle damper under sinusoidal excitation is described. A rolling particle damper is a type of ball vibration absorber and consists of a rotating cylinder placed on a curved track mounted on a primary system. The rotating cylinder is partially filled with granular materials. When the rotating cylinder rolls inside the curved track, the granular

In this article, an adaptive nonsingular terminal sliding mode control scheme based on fractional order is proposed for a cable-driven manipulator with external disturbances, where the concentration is uncertain and the upper limit is known or unknown. Furthermore, a new adaptive fractional-order nonsingular fast terminal sliding mode algorithm with time-delay estimation is developed. The delay estimation

In this study, the transfer matrix method for multibody systems is used to study the vibration characteristics of a tracked vehicle system. The transfer matrix method has the advantages of not needing the global dynamics equations of the system, low order of system matrices, and fast dynamics computation speed. According to the solution process of vibration characteristics, a detailed dynamics model

In this article, a rotary valve is developed to obtain accurate high-frequency sinusoidal vibration waveforms. Then, a uniaxial electro-hydraulic shaking table controlled by a set of parallel rotary valves is constructed, which can superpose the sinusoidal vibration waveforms. The non-sinusoidal vibration waveforms including triangular vibration waveform, rectangular vibration waveform, sawtooth vibration

Over the past few years, deep learning–based techniques have been extensively and successfully adopted in the field of fault diagnosis. As the diagnosis tasks become more complicated, the structure of the traditional convolutional neural network (CNN) has to become deeper to deal with them, while the gradient of fault features may vanish within the deep network. In addition, all the features are treated

Since the last few decades, research in the area of robotics technology has been emphasizing in the modeling and development of cognitive machines. A cognitive machine can have multiple cognitive capabilities to be programmed to make it artificially intelligent. Numerous cognitive modules interact to mimic human behavior in machines and result in such a heavily coupled system that a minor change in

Innovative thin-walled structures, bio-inspired by the microstructure of Morpho wings, were proposed as energy absorbing devices in this study. A finite element model, experimentally validated, was used to investigate the crush responses and deformation modes of 18 multi-layered tubes with different geometrical configurations. The crashworthiness parameters were determined for the bio-inspired structures

This study is in investigation of free vibration behavior of functionally graded hyperboloidal and barrel helices with variable cross section. Material and geometric variations of noncylindrical helices are assumed to be along the rod axis. Governing differential equations of motion, including rotatory inertia, axial and shear deformations are derived by the Timoshenko beam theory. Then, transfer matrix

A three-dimensional (3D) fiber stress formula was developed to reduce the deviation of the two-dimensional (2D) fiber stress formula in calculating the 3D stress. The on-axis and off-axis stress–strain relationship was first presented. The 3D fiber stress formula was then derived analytically. Finite element method (FEM) of filament-wound (FW) thick-walled cylinders with symmetrical/balanced-layers

This article presents an analytical approach to investigate the geometrically nonlinear response of doubly curved imperfect shallow shells made of functionally graded carbon nanotube reinforced composite (FG_CNTRC) under in-plane and lateral loads. For all of the case studies, the edges of shells are assumed to be diaphragm supports, which are subjected to in-plane edge-loads. The governing equations

By analyzing nonlinear and nonstationary vibration signals from the spindle device of the mine hoist, it is a challenge to overcome the difficulty of fault feature extraction and accurately identify the fault of rotor-bearing system. In response to this problem, this paper proposes a new approach based on variational mode decomposition (VMD), SVM, and statistical characteristics such as variance contribution

An integrated approach was followed for determining the optimized process parameters for hybrid laser-tungsten inert gas (TIG) welding of 316L(N) stainless steel which involve FEM followed by optimization. FEM-based model was developed to predict the thermal distribution for a various combination of welding process parameters. The hybrid heat source combining conical and double-ellipsoidal heat sources

The single-point incremental forming process is an emerging process, which presents an alternative to the conventional sheet metal forming processes like hydroforming and drawing. It is known to be perfectly suited for prototyping and small series. For example, the incremental forming process offers the possibility of manufacturing medical prosthesis or implants specific to each patient, which are

The most common type of diversion structure used in boulder streams is a trench weir. It is a simple structure built below the bed level of streams, and the top of it is covered with bottom rack. Bottom rack consists of bars of various shapes like circular, rectangle, T-shaped, etc. It is placed over the trench weir with a desired porosity to control sediment ingestion into trench. In this present

The effect of gas tungsten arc welding (GTAW) process parameters and its impact on the titanium TWB was studied experimentally as well as using numerical simulation. Bead characteristics of BoP trials (bead on plate) were analyzed based on Taguchi L27 orthogonal array by taking welding current (115 A, 125 A, 135 A), welding speed (4.1 mm/s, 5.8 mm/s, 7.5 mm/s) and arc length (3 mm, 4 mm, 5 mm) as process

Purpose As in real applications several alternating current (AC) currents may be injected to the electronic devices, this study aims to analyze their effects on the lifetime of the solder joints and, consequently, shed the light on these effects at the design phase for other researchers to consider. Design/methodology/approach In this paper, the authors investigated on current waveform shapes on the

Time‐frequency analysis of structural vibration responses provides essential information for structural system identification, modal updating, and condition assessment. However, spurious peaks introduced by the strong noise will significantly increase the false positive rate as well as compromise the sparse time‐frequency signal representation. This paper proposes a high‐resolution time‐frequency representation

In this paper, a novel method to fabricate quartz glass electromagnetically actuated ring resonator for gyroscope application is presented. Sacrificial supporting structures were employed for the fabrication. The fabricated device was electromagnetically driven at resonance, with the resonant frequency of 42 KHz. The Q-factor at the atmospheric pressure was about 142. The frequency difference between

The triboelectric nanogenerator (TENG) has been demonstrated to be a promising technology for harvesting mechanical energy and powering electronic devices. However, it is difficult to make TENG output stable because of the irregular movement of actual mechanical sources in the environment, and the inefficient energy utilization limits its application. In this study, we propose a contact-separation

Purpose This paper aims to present a concise review on the variant state-of-the-art dynamic task allocation strategies. It presents a thorough discussion about the existing dynamic task allocation strategies mainly with respect to the problem application, constraints, objective functions and uncertainty handling methods. Design/methodology/approach This paper briefs the introduction of multi-robot

For nano-porous anodized aluminum oxide (AAO) template based low temperature solid oxide fuel cells (LT-SOFCs), anode structure has crucial effects on electrochemical characteristics because of triple phase boundary densities and electrical connectivity of metal catalysts on porous AAO substrates. In this study, we investigated effects of fabrication processes of Ni anode for AAO template based LT-SOFCs

In this study, the description of energy absorption capacity in different deformation modes in the perforation of thin metallic aluminum 1100-H12 targets is presented. The targets were impacted with 19 mm diameter hard steel cylindrical projectiles of varying nose profiles, viz. ogive, blunt, conical and hemispherical shape. Effect of oblique impact on the perforation behavior of 255 mm diameter circular

The Hugoniot Elastic Limit (HEL) and spall strength of an ultrahigh strength Al-Zn-Mg-Cu alloy in natural aging (NA), peak aging (PA) and over aging (OA) states have been measured under different shock stresses. It is found that the HEL and the spall strength of this alloy following these three heat treatments are independent of peak stress (or strain rate). The PA alloy shows the highest HEL ranging

A solid contact model with high accuracy is required for mixed lubrication calculation to predict friction loss and wear in sliding parts by computer aided engineering; however, existing models have numerous limitations. A new asperity contact model was constructed to determine contact states using the roughness parameters of pairs of surfaces. Although the contact states differed greatly depending

The objectives of this investigation were to experimentally and analytically investigate the dynamics of a medium sized, relatively high speed ball bearing supported turbocharger (TC). In order to achieve the objectives a TC test rig was designed, developed and instrumented with a combination of strain gauge based load sensors and proximity probes. The sensors were used to measure the axial and frictional

A mixture model suitable for thermal effect on EHL of emulsions is proposed. The maximum temperature rise occurs at the emulsion layer because sliding occurs mainly in the emulsion layer to generate shear heating, and it increases with increasing oil concentration, slide-to-roll ratio, mean speed and load. The rise in surface temperature of the rollers decreases with the increase in the adsorbed layer’s

Roll-to-roll (R2R) printing technologies have been widely adopted in a variety of engineering fields, e.g., organic photovoltaics and flexible electronics, owing to the advantages of cost and throughput. Although a minimum feature size of 100 nm has been demonstrated on R2R systems, the layer to layer registration accuracy (i.e., overlay accuracy) still remains as low as tens of microns, which prevents

Air flotation rails are widely used in semiconductor production lines to produce an airflow film for handling components such as liquid crystal glass substrates. During transportation, the glass substrate deforms with a large curvature, which inclines the airflow film between each hole in the rail and substrate. This study theoretically and experimentally investigated the pressure field of an inclined

A new method for measurement of the pitch deviation of a scale grating by an optical angle sensor based on the laser autocollimation is proposed. In the proposed method, the scale pitch deviation is evaluated through detecting the change in the angles of diffraction of the first-order diffracted beams, which is associated with the change in the scale pitch deviation. The optical angle sensor unit is

The research work undertaken in this article addresses the use of electro-rheological (ER) lubricant for controlling the performance of spherical thrust bearing system. In the present work numerical investigation of a circular recessed spherical thrust bearing system with a capillary restrictor lubricated with ER lubricant has been described. The governing Reynolds equation for spherical thrust bearing

Protic ionic liquids (PILs) hybrid was applied as a lubricant additive with various functions in water-ethylene glycol solution (WG). The anticorrosion performance of the hybrid was evaluated by means of cast iron chips test and electrochemical measurement. It improves the anticorrosion effect of WG on cast iron. Meanwhile, the tribology experiment shows that the hybrid reinforces antifriction and

Establishing the static equilibrium position of the tilting-pad journal bearing is key to determining the bearing performance. Methods for establishing the equilibrium were divided into three groups and compared. The fastest convergence was achieved using the quasi-Newton methods, namely the Anderson mixing scheme and Broyden's methods. Root-finding boundaries and the Armijo rule were implemented into

As an ideal reinforcing nanofiller, graphene platelets (GPLs) can significantly improve physical properties of nanocomposites, which have attracted considerable attention for design and development of advanced lightweight nanocomposite structures in engineering. In this paper, a sandwich cylindrical structure is considered for dispersion properties of wave propagation by axisymmetric isogeometric analysis

The present work is an experimental study of two oscillating rigid plates placed in side-by-side configuration, hinged at their leading edges, subjected to low subsonic flow. This problem is investigated using smoke-wire flow visualization, hot-wire anemometry, and time resolved particle image velocimetry. It is found that beyond a critical Reynolds number, the plates set into oscillatory motion. This

An accurate constitutive model is one of the basic aspects to ensure a precise simulation. This study presents an improved unified viscoplastic model to simulate the various behavior of P92 steel under low cycle fatigue (LCF) and creep fatigue interaction (CFI) loadings. In the proposed model, an accumulated inelastic strain dependent parameter is introduced into the nonlinear kinematic hardening rule

A finite volume based approach is employed in the solution of unit cell problems at different orders of the asymptotic field expansion to construct a homogenization theory for anti-plane shear loading of unidirectional fiber-reinforced periodic structures. This new construction complements and further extends our recent contribution to asymptotic homogenization based on locally-exact elasticity unit

This article details a new Model Predictive Control algorithm ensuring robust stability and control feasibility for uncertain nonlinear multi-input multi-output dynamical systems considering uncertain time-delay effects. The proposed control algorithm is based on construction of a Lyapunov–Krasovskii functional as terminal cost. Incorporation of this terminal cost into the Model Predictive Control

The control of twin rotor multi-input multi-output system is difficult as it is subjected to model uncertainties and external disturbances. Furthermore, there also exists a coupling between pitch and yaw positions, which makes the system more difficult to control them separately. Considering the above difficulties in twin rotor multi-input multi-output system control, H∞-based robust controller is

A new adaptive time delay estimation technique with sliding mode control method is proposed and investigated in this passage for cable-driven manipulators. Time delay estimation technique is an effective tool to compensate for unmodeled dynamics and unknown disturbance, and adaptive time delay estimation performs better due to its adaptive control gain. The proposed adaptive method is based on the

Viscoelastic material is widely used in automotive structures due to its outstanding vibration-damping characteristics with appropriate stiffness. Viscoelastic material, which has viscosity and elasticity, shows energy absorption and dissipation. The material properties of viscoelastic material are dependent upon time, temperature, and loading path. Hence, these characteristics have to be considered

In view of the relatively serious situation of chest injuries in current vehicle accidents, this study aims to determine the chest injuries characteristics in frontal vehicle collisions under different overlaps. The frontal impact simulation was first established and conducted based on the latest THOR dummy model with different overlaps. By comparing chest dynamic output indicators under three different

The tie rod is one of the key components affecting the steering stability and reliability in the steering system of heavy vehicles. In order to meet the heavy load steering requirements of heavy vehicles, the steering system is universally the electro-hydraulic power steering system (EHPSS). The hydraulic actuators used in the EHPSS are double hydraulic cylinders, which are connected in series and