Brake experiments were conducted on a typical kind of friction blocks of a high-speed train. The friction and wear, interfacial temperature, vibration, and noise generated at or by the brake interface were investigated, and the interrelationship between the vibration response and the contact behaviour of interface was analysed. The results showed the friction coefficient, vibration energy, and noise

Generation of surface topography is important. Thanks to it, functional properties of machined elements can be predicted. It leads to reductions in cost and time of experimental investigations. In this paper, methods of random surface topography modeling are reviewed. Methods of generation of surface topographies of Gaussian and non-Gaussian height probability distribution are shown. The particular

A three-dimensional model of an external gear pump and a new application of an algorithm for the measurement of the unsteady flow rate in hydraulic pipes are presented. The experimental delivery flow ripple was compared with the outcomes of a simulation under different operating conditions. A comprehensive computational fluid dynamics model of the pump and of the high-pressure delivery circuit was

This paper presents a numerical study of regular and hierarchical honeycomb structures subjected to out-of-plane impact loading. The specific energy absorption capacity of honeycomb structures via nonlinear explicit finite element analysis is investigated. The constructed finite element models are validated using experimental data available in the literature. The honeycomb structures are optimized

Accurate fault prediction of rolling bearing can predict the operation condition in advance, which is an important means to ensure the safety and reliability of rotating machinery. Aimed at the data processing of rolling bearing vibration signal with multi-fault and long time series, an intelligent fault prediction model based on gate recurrent unit and hybrid autoencoder is proposed in this paper

This study presents an investigation of the wave propagation of a rectangular sandwich composite plate with tunable magneto-rheological fluid core. The constituent parts of this rectangular sandwich composite plate are the base layer, magneto-rheological fluid core, and limiter layer. Magneto-rheological fluid core is embedded within the base and limiter layers. Also, the upper and lower layers are

In this study, we considered the coordination and vibration control for two sets of flexible satellite systems with input constraints and actuator failures. The parameters of both systems were kept uniform, and one was called the master flexible satellite, and the other one was called slave flexible satellite. The two sets of the flexible satellite systems were modelled as partial differential equations

A nonlinear stiffness and nonlinear inertial vibration isolator is proposed in this article. It consists of an inerter, a damper, and spring elements. The nonlinear stiffness characteristic is achieved through a negative stiffness structure based on the diamond-shaped structure that generates nonlinear displacement terms. The nonlinear inertial characteristic is implemented via a geometrical nonlinear

The macroscopic and microscopic characteristics of flash-boiling spray were experimentally investigated with various optical measurement techniques. The effects of ambient pressure and fuel temperature on flash-boiling characteristics in multi-hole gasoline direct injection injector were analyzed. The analysis was focused on the spray structure and atomization droplet size distributions. In order to

A negative-stiffness damper (NSD) that incorporates eccentric columns and high-stiffness springs is proposed for vibration mitigation from drilling equipment to a semi-submersible platform. Eccentric columns are considered as negative-stiffness elements, which can provide high static stiffness and achieve negative stiffness with hysteresis energy dissipation caused by buckling mode transition under

In order to study the effect of high temperature cycling on the physical and mechanical properties of rock materials, a box-type resistance furnace was used to conduct high temperature cycling at 400°C 10 times on sandstone specimens in coal mine, and the impact compression tests under 8 loading rates were carried out using a split Hopkinson bar (SHPB) device. Results showed that, with the increase

The finite element model of a dual-rotor system was established by Timoshenko beam element. The dual-rotor system is a coaxial rotor whose supporting structure is similar to that of an aero-engine rotor system. The inner rotor is supported by three bearings, which makes it a redundantly supported rotor. The outer rotor connects the inner rotor by an intershaft bearing. The spectrum characteristics

Magnetoelectric (ME) effect is a product property arising out of the interactions between the piezoelectric and the magnetostrictive phase. Multi-phase ME composites being multifunctional materials find use in myriad of applications. In this work, epoxy free two phase and three phase embedded ring ME composites have been fabricated by the press-fit technique. For a comparative study, three phase conventional

Fracture and fragmentation in three dimensions are of great importance to understand the mechanical behaviour of quasi-brittle materials in failure stress states. In this paper, a generic computational model has been developed in an in-house C/C++ code using the combined finite-discrete element method, which is capable of modelling the entire three-dimensional fracturing process, including pre-peak

Data-driven tuning is an alternative to model-based controller design where controllers are directly identified from data, avoiding a plant identification step. In this paper, an approach to tune limited-complexity controllers from data for linear systems is proposed. The controller is parametrized as a linear combination of a large set of basis functions and the proposed algorithm allows to select

This paper aims to develop an approach for the reconfiguration of a parallel kinematic manipulator (PKM) with four degrees of freedom (DoF) designed to tackle tasks of diagnosis and rehabilitation in an injured knee. The original layout of the 4-DoF manipulator presents Type-II singular configurations within its workspace. Thus, we proposed to reconfigure the manipulator for avoiding such singularities

This paper presents a procedure for the evaluation of the conservation state and restoration efficiency of nineteenth century camorcanna vaults based on the analysis of objective features extrapolated from non-destructive vibration testing data. The camorcanna vault in “Salone Grande” of the ninteenth century Villa Greppi in Monticello Brianza, near Milan, Italy, was chosen as an application example

This paper presents a screw theory approach for the computation of the instantaneous rotation axes of indeterminate spherical linkages. Since the last part of the XIX century, the determination of the instantaneous rotation, or velocity, centers of planar mechanisms has been studied using the Aronhold-Kennedy theorem, extended to the spatial case until the second part of last century. In the beginning

Nowadays, robots equipped with a single camera, such as micro aerial vehicles (MAVs), are easily found at affordable costs. They can be used in different tasks, including the building of 3D environment maps. For building such maps, monocular simultaneous localization and mapping (SLAM) methods are employed, which usually generate sparse or semi-dense representations that are ill-suited for navigation

In this study, the deformation and damage behaviors of sandwich plates with composite foam core subjected to high velocity impact of metallic foam projectile are investigated. A series of experiments was conducted to address the dynamic response, failure modes and energy absorption characteristics of the sandwich plates with different configurations. The dynamic behavior of the sandwich plates was

In this paper we have investigated, using finite element calculations performed in ABAQUS/Explicit [1], the effect of ab initio geometric imperfections in the development of multiple necking patterns in ductile rings subjected to dynamic expansion. Specifically, we have extended the work of Rodríguez-Martínez et al. [2], who studied the formation of necks in rings with sinusoidal spatial perturbations

Loosening of threaded connection under impact loading is important in engineering structures such as the fuze on a projectile. It is difficult to predict the loosening behavior of threaded connection under impact loading due to their high nonlinearities introduced by friction and discontinuity. This paper investigated the loosening response of a threaded connection under a series of impact loadings

The ballistic tests of Q&P980 resistance-spot-welded (RSW) overlapping plates impacted at RSW joint by round-nosed bullet were performed using a single-stage gas gun system with a laser velocity interferometer system for any reflector (VISAR). The deformation and fracture mechanism of the RSW specimens were investigated by using the VISAR measured results, the metallographic cross-section observation

Achieving high workpiece accuracy is the long-term goal of machine tool designers. There are many causes for workpiece inaccuracy, with thermal errors being the most common. Indirect compensation (using prediction models for thermal errors) is a promising strategy to reduce thermal errors without increasing machine tool costs. The modelling approach uses transfer functions to deal with this issue;

In this paper the idea of Self-Optimizing Machining Systems (SOMS) is introduced and discussed. Against the background of Industry 4.0, here the focus is the technological level of discrete workpiece production by mechanical machining processes utilizing related machine tools and equipment. Enabling technologies, principles, and methods are described that allow for the implementation of machining systems

An experimental study on gas–liquid two-phase flow characteristics in a low-specific-speed centrifugal pump is presented via employing multiple investigation techniques, such as visualization observation, measurements of acoustic emission and vibration, etc. Specially, three different flow conditions were inspected, namely gas locking initiation, critical cavitation with/without free-gas presence,

This paper investigates the nonlinear bending behavior of sandwich plates with functionally graded auxetic 3D lattice core. First and foremost, an auxetic 3D lattice metamaterial with negative effective Poisson’s ratio (EPR) is designed and examined via theoretical and finite element methods with experimental verifications using specimens fabricated by 3D printing. Furthermore, three functionally graded

This article deals with the power flow control in a hybrid power system, which is composed of a fuel cell, photovoltaic system and a super capacitor. The super capacitor has been employed with an aim to ameliorate the performance of the hybrid power system. In addition, it takes into account the energy fluctuations of photovoltaic energy sources and the slow dynamic of the fuel cell. Each source is

Quadrotor or unmanned helicopter is a mobile robot which often flies in unknown environment to perform special missions. In navigational tasks, the robot is intended to fly autonomously toward a target position by following an optimum trajectory. For a successful navigation, controlled attitude, minimum position and velocity error and obstacles collision avoidance are often considered during trajectory

As the ocean data acquired by the Argo project is increasingly huge, how to use artificial intelligence to analyze it so as to discover the distribution and variation of ocean temperature with space and time becomes an important research topic in the world. In this article, a spatio-temporal dependence-based tensor fusion method is proposed, which can be used to determine and analyze the thermocline

In this paper, the performances of a novel jet impingement solar air collector (JISAC) using flat and pin-fin absorbers were experimentally investigated. The experimental observations in a JISAC have been made under the climatic conditions of Coimbatore city in India during the year 2019. The thermo-hydraulic analyses were conduced to study the influence of pressure drop across the perforated jet plate

Pneumatic dual reciprocating bellows pump has been widely used in chemical transportation due to its good sealing and anticorrosion performances. Nevertheless, the large outlet pulsation limits its performances on precise transportation and control of the fluid. Although the design of employing flexible linkage between the bellows has been proposed as an effective solution for this shortcoming, the

In the heat exchangers, twisted tape insert is a technique to enhance heat transfer. In this paper, the experimental and numerical investigations are arranged to analyze thermal performance with entropy generation analysis on single and double strip helical screw tape inserts. The finite volume method is used with shear stress transport K-ω model to analyze fluid flow in tube with inserts. The Nusselt

Relaxation behavior provides specific information that indicates stress development with elapsed time for the determination of material characterization and constituting of material modeling. In addition, anomalous relaxation behavior of polymeric materials enables experimental analysis of some theoretical variables in constitutive equation. Equilibrium stress is one of the most prevailing variables

In this article, the horizontal hinged heavy duty servo cylinder is taken as the research object. In the actual working process, while the servo hydraulic cylinder outputs the curve force, the cylinder body will also rotate with the hinge point to a certain extent. Because the position of the center of gravity is constantly changing, and the weight of the cylinder body is too large, the friction causes

Melamine-formaldehyde is the most common resin used in the production of high-pressure laminates and low-pressure laminates (melamine impregnated paper), due to its properties of durability, good fire, and heat resistance and good moisture resistance. High-pressure laminate is a common choice for horizontal and vertical applications in the construction and furniture industries, thanks to its durability

This article demonstrates a combined H∞ feedback control design for linear time-invariant and linear parameter-varying systems and optimal sensors and actuator selection. The combined design problem is systematically constructed as a mixed Boolean semidefinite programming optimization problem. We impose Big-M reformulations to the non-deterministic polynomial-time-hard coupled problem to be solved

Electrohydraulic shaking tables provide a direct means to evaluate structural performance under actual vibration conditions. The control–structure interaction is one of the most important reasons for the degradation of the control performance of the shaking table. This article establishes a series of novel analytical models to investigate the control–structure interaction effects between double shaking

High-entropy alloys (HEAs) that have revolutionized the alloy design of strength-ductility trade-off, provide a pathway for the development of high strength solid-lubricating composites. Herein, a high performance AlCoCrFeNi HEA based composite reinforced with different contents of solid lubricant Ag was prepared by Spark Plasma Sintering technique. The composites retain the structure of nano-coupling

Atomic Force Microscope (AFM) is used to characterise the frictional response of surfaces with varying roughness parameters in dry and in the presence of fully formulated lubricants. The surface roughness has shown to affect nanoscale friction. The characteristics involved the investigation of roughness, small-scale adhesive forces and nanoscale friction using AFM in lateral force mode. The fluid-cell

The interactions of different additives in engine oils can create synergistic or antagonistic effects. This paper studies how mixing different organic friction modifier additives affects friction reducing properties of lubricants in the boundary lubrication regime. Amines of different degree of saturation were mixed with either glycerol monooleate (GMO) or oleic acid in hexadecane. The model lubricants

The tribological performance of metro rigid overhead lines against pantograph sliders was experimentally studied. The test parameters from actual metro lines were adopted. During testing, the friction force, wear volume, temperature, vibration of the pantograph slider, voltage drop, and current correlating with arc ablation were collected. The worn topography of the slider and wire was observed. Experimental

Investigations were performed to study the effect of graphite surface texturing on the friction coefficient reduction of graphite-steel sliding pair in dry flat contact. Friction tests were carried out using an Optimol SRV 5 tester, equipped with a rotation pin-on-disc module. Graphite discs of 100 mm diameter and 10 mm thickness were tested. Surface texturing was made with abrasive jet machining.

In this paper, the contact problem between a cylinder and a half-space with a crystalline anisotropic behavior is solved. The model is based on semi-analytical methods to solve a three dimensional contact problem. A numerical technique based on a Voronoi tessellation is implemented using the Eshelby's equivalent inclusion method to account for the effect of the material microstructure on the contact

To overcome two critical deficiencies i.e. poor self-lubricating and short life of engine bearing, a CuSn10 layer along with newly designed h-BN/graphite coating is deposited on the surface of an engine bearing. The tribological and mechanical properties of the engine bearing are studied. Firstly, the porosities of the CuSn10 layer and h-BN/graphite coating are low due to the powder-filled action and

Inconel 718 is widely used in different industries including aerospace where part quality concerns drive manufacturing process developments. However, despite extensive research, machining of Inconel 718 is still very challenging, often triggering severe surface quality problems. High temperatures and pressures generated at the contact zone during machining of this class of materials as well as high

Machined surface integrity of bearing rings is often the main concern for the bearing manufacturers as it affects their fatigue life. The present study investigates the surface integrity of AISI 52100 bearing rings finished by precision hard turning and grinding and its influence on fatigue life. A twin-disk machine is used to evaluate the RCF life. As main results, precision hard turning can achieve

A periodically supported beam on a visco-elastic half-space is considered to model the vibration of railway tracks. The viscosity of the half-space is assumed to be of the Kelvin-Voigt type. Making use of the concept of equivalent dynamic stiffness, the reaction of the half-space to the sleepers is replaced by a system of identical spring located under each sleeper. The frequency-dependent equivalent

In the first Part (Part I) of this series, the plane quasi-static incremental problem was formulated as a mixed complementarity-inclusion problem and as a linear complementarity problem. The current paper (Part II of the series) presents a numerical examination for the existence or the occurrence of multiple solutions to the quasi-static incremental problem of a two degree of freedom elastic system

We critically assess diffuse interface models for fluid transport in fractured porous media. Such models, often called fracture phase field models, are commonly used to simulate hydraulic stimulation or hydraulic fracturing of fluid-saturated porous rock. In this paper, we focus on the less complex case of fluid transport in stationary fracture networks that is triggered by a hydro-mechanical interaction

Tendon-driven actuation allows for light and compact manipulator designs with enhanced safety features. One of the key challenges in model-based control of tendon-driven robots is the increased complexity of the dynamic model, due in large part to difficult-to-model behavior like nonlinear dynamic deformation and friction at the tendons. While purely data-driven modeling approaches, e.g., neural networks

In Minimally Invasive Surgery (MIS) surgeons operate through small incisions in the body of the patient and due to the lack of the degrees of freedom their capability to manipulate the organs is limited. Thus, surgeons are forced to adopt awkward postures and this may lead to musculoskeletal injuries. This paper presents a new articulated mechanism designed for application in MIS providing an additional