Nickel based single crystal alloys have excellent properties such as heat resistance, corrosion resistance and creep resistance, which are widely used in aerospace and other national defense fields. Severe work hardening occurs in the process of cutting nickel based single crystal alloy. How to improve the machining quality and grasp the cutting deformation mechanism has become the research focus.

The three-probe method for separating the spindle rotation error and the specimen form error is extensively described in the literature. An attractive feature is its application in in-process measurement. However, the resulting uncertainty is studied far less extensively. In this paper, an evaluation and propagation method for the uncertainty, as well as for an uncertainty reduction, is given based

A mathematical model of a bike-rider’s longitudinal and lateral dynamics was used to study the influence of road conditions (tyre-road friction coefficient) on cycling individual time trial (ITT) performance and pacing strategy. A dynamic optimisation approach was used on different simulated 40-km-ITT courses, where environmental variables (i.e. slope and wind), the presence of corners and the tyre-road

In American football, high quality training focused on catching is currently not done with passing machines due to their poor pass accuracy and precision. From a coach’s point of view, accurate and precise passing machines are needed to relieve the quarterback from too much training effort. The two aims of this study were to increase the precision of a passing machine and develop an accurate pass prediction

The study of biomechanical and physiological variables allows human movement scientists to investigate the characteristics of movement patterns in cyclists. While straightforward and well-investigated, linear measures may not adequately capture the underlying complexity of movements during cycling. Therefore, a non-linear phase-space measure (ML1) was applied to forces and heart rates of nine cyclists

The surface roughness of friction pairs plays a significant role in the formation of hydrodynamic fluid film between rod-seal interface. To investigate the influence of rod surface roughness on lubrication characteristics of hydraulic reciprocating seal, the friction force and the net leakage of seal under quasi-constant speed conditions and variable speed conditions are compared and analyzed, by using

This work builds a comprehensive adhesion model by finite elements (FEA) for a deformable hemisphere subject to fretting. The hemisphere is constrained between two rigid and frictionless plates as it loaded in the normal direction and followed by prescribe oscillatory tangential motions. The material for the deformable hemisphere is gold (Au). The normal direction adhesion contact is based on the classic

Using an analytical solution of the Euler’s Elastica, we stumbled upon peculiar shapes of a cantilever beam subject to a large value of shear follower force at the free end. Intrigued by whether such shapes existed or not, we set out to realise an experimental apparatus to validate our predictions. Attaining such system, in reality, is not at all a trivial task. Indeed, it has represented a tremendous

The present study proposed some novel designs that can surpass the most widely used louver fin geometry for air-cooling applications. Innovative fin types such as ring fins, circular disk fins, and hexagonal disk fins are numerically modeled and compared with a louver fin-and-flat tube heat exchanger in terms of thermal resistance in the same pumping power. Flow visualization is also carried out by

The Representative Volume Element (RVE) plays a central role in the homogenization of random heterogeneous microstructures, especially for composite and porous materials, with a view to predicting their effective properties. A quantitative evaluation of its size is proposed in this work in linear elasticity and linear thermal conductivity of random heterogeneous materials. A RVE can be associated with

Losses in control valves drag down the average overall efficiency of electrohydraulic systems to only about 22% from nearly 75% for standard pump-motor sets. For achieving higher energy efficiency in slower systems, direct pump control replacing fast-response valve control is being put in place through variable-speed motors. Despite the promise of a quicker response, displacement control of pumps has

Virtual process planning offers advantages in terms of predicting servo and contouring errors ahead of time, and taking corrective action by modifying the program or CNC parameters. Successful application of virtual process planning requires accurate models that capture the dynamics of feed drives. Identification of such models is typically time consuming. This paper presents a pole search method used

In this study, through an analysis of vibration response characteristics of joint surface stiffness on dangerous rock mass, the relationship formula between amplitude ratio of the dangerous rock mass to the bedrock and the length of the bonding section of the joint surface is determined. The stability of the rock mass can be evaluated by combining the formula with the existing rock-mass limit equilibrium

In this study, H∞ optimization is conducted for a tuned inerter damper (TID) with negative stiffness device (denoted as TID_NSD) subjected to harmonic support excitation. The study shows that there are still two nonzero-frequency fixed points independent of the damping of the TID_NSD; therefore, the optimum tuning frequency and damping ratio for the TID_NSD are, respectively, derived based on the well-known

The abrupt rock-related hazards, such as landslide, rock burst, and collapse, seriously threaten the safety and service life of engineering works. Precursory information on critical transitions preceding sudden fracture is of great significance in rock mechanics and engineering. This study investigates the critical slowing down feature of acoustic emission (AE) signals and precursory indicators during

Treating weak saturated soil foundation by drainage powder jetting pile foundation can not only increase the bearing capacity of the foundation but also accelerate the drainage and consolidation process of the foundation. Having been commonly used in engineering, the plum blossom pile layout scheme is based on the foundation axisymmetric consolidation model (the powder jetting pile is the model center

Abstract In this work, the fractional order theory of thermoelasticity is introduced to study a two-dimensional fiber-reinforced problem in a half-space. The governing equations are formulated by considering the effect of the magnetic field, gravity, and moving heat source on a fiber-reinforced linearly thermoelastic isotropic medium. These equations are then transformed into non-dimensional forms

Damage detection is one important target in structural health monitoring (SHM). Vibration‐based damage detection has attracted more attention in the past decades by tracking the modal parameter changes of objective structures. This paper presents the work on developing a novel Bayesian fast Fourier transform (FFT) method for damage detection using the Bayes factor based on ambient vibration data. Based

Abstract Square-circle hybrid section (SCHS) tubes under axial loading which combine the advantage of square tubes and circular tubes are investigated. Firstly, effective finite element models of SCHS tubes are established to study the crashworthiness characteristics. Through a series of finite element models, the influence of the geometry on the behaviour of crashworthiness is studied, including relative

Purpose This study aims to present an automated guided logistics robot mainly designed for pallet transportation. Logistics robot is compactly designed. It could pick up the pallet precisely and transport the pallet up to 1,000 kg automatically in the warehouse. It could move freely in all directions without turning the chassis. It could work without any additional infrastructure based on laser navigation

Membraneless Microfluidic Paper Fuel Cells (MMPFCs) are promising devices to harvest energy for various portable applications. This is primarily because such devices eliminate the need for membrane, and external pumps due to the built-in co-laminar flow, and embedded capillaries, respectively. However, these devices have enormous scope to optimize their performance. Herein, investigations on MMPFC

The effects of pre-strain and subsequent electrically assisted annealing on the mechanical behaviors of two different (Al–Mg and Al–Si–Mg) aluminum alloys during electrically assisted dual stage forming are experimentally investigated. First, a specimen is deformed to a specific pre-strain by uniaxial tension and then automatically unloaded. After that, the pre-strained specimen is subjected to electrically

In order to solve the problem that there is no effective evaluation method for the precision degradation state of inertial test turntable, a prediction model for the position precision degradation trend of test turntable was proposed based on the Hidden Markov Model (HMM) algorithm and Particle Filter (PF) algorithm. The initial parameter of the PF algorithm was optimized by the Particle Swarm Optimization

In this study, we developed prototypes of boring tools with anisotropic dynamic stiffness, and their chatter stability was investigated analytically and experimentally. In Part 1, a novel design of boring tools with an anisotropic structure was proposed to improve the nominal stiffness in boring operation, thus resulting in higher chatter stability in simulation. In this part (Part 2), anisotropic

Harmonic positioning errors can negatively affect the positioning accuracy of the ball screw drive system. This paper addresses the problem of harmonic positioning error suppression in ball-screw drives using Adaptive Feedforward Cancellation (AFC). AFC method is integrated with the dual (i.e., rotational and translational) feedback structure used in ball-screw drives. The ability of AFC to quench

Concentrated Polymer Brushes (CPBs) have great potential to improve tribological properties under severe sliding conditions, even at the macroscopic scale, and thus are expected to apply to mechanical sliding components. However, the durability of CPBs has remained as a challenge for industrial applications. Here, we focused on a combination of CPBs and surface texturing technology to increase their

The old asperity model of Fuller and Tabor had demonstrated almost 50 years ago surprisingly good correlation with respect to quite a few experiments on the pull-off decay due to roughness of rubber spheres against roughened Perspex plates. We revisit here some features of the Fuller and Tabor model in view of the more recent theories and experiments, finding good correlation can be obtained only at

Bio-inspired Al2O3/rGO fibrous monolithic ceramics with bamboo-like architectures exhibit excellent fracture-resistant behaviors and high structural reliability. The tribological performances and wear mechanisms of these composites were investigated in this study. Results showed that the composites exhibited relatively moderate tribological behaviors with lower and more stable friction coefficients

This paper proposes a new methodology for fretting fatigue life assessment. It uses a combination of multiaxial fatigue criteria, the theory of critical distances and a node-displacement wear algorithm to account for the initiation life under fretting. Further, the extended finite element method is considered to compute the propagation life. A new method is also introduced to predict the crack propagation

The evolution of fretting wear with the number of cycles for Inconel 690 steam generator tubes against AISI 420 pads in air at room temperature was studied in a 90° cross-cylinder configuration. Tests were performed under a contact load of 10 N and a displacement amplitude of 50 μm to a total number of cycles between 102 and 106. Fretting wear associated with gross slip was identified as the main damage

An efficient method of calculation of the fundamental frequency of a corner-supported composite sandwich plate having a lumped mass at its centre is proposed in this work. The corresponding dynamic problem is solved using the Hamilton principle and the Rayleigh-Ritz method. The panel is modelled using the first order shear deformation theory. The panel deflection and angles of rotation are approximated

Using a controlled surface wrinkling strategy, we designed a flexible energy harvesting system made from a compliant substrate, stiff skin layer, a thin PZT film, and an interdigitated electrode sandwich structure. This energy harvesting system, which operates under compressing and releasing operating modes that are common in nature and engineering, accommodates orders-of-magnitude increases in maximum

The thermomechanical behavior of porous RDX single crystals is studied under dynamic loading using an anisotropic dislocation-based crystal plasticity model that accounts for deformation-induced heating. A micromechanics-based framework is proposed to account for micro-inertially confined dynamic collapse of pores. A suite of finite element calculations are carried out to systematically elucidate the

Nonuniqueness of solutions is always a challenge when pressure transient analysis is used for characterization of spatial heterogeneity. This problem arises when there is insufficient data to uniquely constrain solutions. Although the nonuniqueness cannot be eliminated, it can be reduced to some extent. Aside from increasing the frequency of measurements and improving quality of the data, integration

Despite recent advances in synthesis and manufacturing of porous materials and devices, producing porous structures with targeted properties is still an expensive, trial-and-error procedure. A powerful way to accelerate this process and to guide manufacturing is to use numerical design of porous media. Current numerical porous media design methodologies typically include a random microstructure generator

Comprehension of the heat transfer process and associated thermo-mechanical interaction with skin tissue is the key issue on successful application of thermal treatment techniques. The purpose of this paper is to explore thermo-mechanical behavior taking place the instantaneously heated skin tissue via an analytical approach. The generalized thermo-elastic model involving dual-phase-lag model of bioheat

A reconstruction of admissible reference signals for the inner dynamics upon a prescribed output reference of a dynamical system is a one of the key problems stated in the control theory. We address this problem with respect to a class of driftless dynamical systems representing nonholonomic kinematics of the N-trailers equipped with the on-axle and off-axle hitching, including difficult cases of the

This paper addresses the asymptotic stabilization of a class of continuous-time nonlinear systems under a sampled-data control. The proposed approach is based on a quasi linear parameter varying (quasi-LPV) model for the nonlinear system and the use of a parameter dependent looped-functional to deal with the aperiodic sampling effects. Explicitly taking into account that the model parameters are functions

In modern days, the vapour compression refrigeration system is followed in almost all air-conditioning applications. Due to the high ambient temperature during extreme summer conditions, the commercial vapour compression refrigeration system made with cost competitiveness are not in a position to meet the required indoor conditions (27°C Dry Bulb Temperature and 19°C Wet Bulb Temperature) within a

Cobalt-chromium alloy (F-90) and duplex stainless steel (DSS-2205) belong to the family of metallic biomaterials, which are frequently used for the manufacture of dental prosthetics, artificial implants including knee and hip joints. This article addresses the investigation highlights of electrical discharge machining (EDM) of Co-Cr alloy and duplex stainless steel using different electrode materials

The present study invokes the application of Cattaneo-Christov theory for the thermal analysis in the buoyancy driven three dimensional flow of Maxwell nanofluid. The flow is induced above the vertical bidirectional stretching sheet. The phenomena of thermophoresis and Brownian diffusion of nanoparticles in the flow Maxwell liquid are deliberated with the help of Buongiorno model for nanofluid. The

In the present study, the electro-mechanical responses of smart laminated composite plates with piezoelectric materials are derived using a two-dimensional (2 D) displacement-based non-polynomial higher-order shear deformation theory. The kinematics of the mathematical model incorporates the deformation of laminates which account for the effects of transverse shear deformation and a non-linear variation

In this article, an adaptive neural network control system is proposed for a quarter car electrohydraulic active suspension system coping with dynamic nonlinearities and uncertainties. The proposed control system is primarily designed to stabilize a sprung mass position of the quarter car electrohydraulic active suspension. Linear controllers such as the proportional–integral–differential controller

Dynamic oscillating behavior of the flexible structure immerged in viscous fluids has attracted growing attention and been widely used in various practical applications. A general electricity-structure-fluid coupled model for the forced dynamic responses of a cantilever immersed in fluids, with partially distributed macro fiber composite, is proposed in this paper. Based on the classical Euler–Bernoulli

This paper presents the design, fabrication and characterization of a novel micro electromagnetic linear actuator, which exhibits two highlights: slider self-alignment and self-attachment capability. Such characters are realized by deliberately utilizing the attractive force between the permanent magnets (Nd 2 Fe 14 B) of the slider and nickel ferromagnetic cores embedded in the stator. Actuation is

The elastic-plastic properties of mesoscale electrodeposited LIGA Ni alloy specimens are investigated as a function of specimen size, strain rate, and material composition. Two material compositions are studied: a high-strength fine-grained Ni-Fe alloy and a high-ductility coarse-grained Ni-Co alloy. The specimens have thicknesses of approximately 200 μ m and gauge widths ranging from 75 μ m to 700

Powered ankle-foot orthosis (PAFO) is a field of wearable robotics that improves the lives of people of old age or with physical impairments by aiding in the wearer's ankle joint movements. Most of the PAFOs developed thus far offer only one degree-of-freedom (dof), which uses the talocrural joint alone as the axis of rotation, where the emphasis is on moving forward. However, because this type of

In this study, the effects of contact forces on the rollers of a mecanum wheeled robot are investigated. Modeling structures are constructed for the cases of single and multiple contact forces. A simulation environment is developed to examine these two cases. A theoretical model is proposed in order to reflect reality in the simulation environment. It is shown that single contact force assumption generates

This article presents a method for modeling the dynamics and minimum vibration controller design of a 3-DOF parallel mechanism, the so-called Tripteron. The proposed comprehensive dynamic model consists of the dynamic model of the prismatic actuators, variable friction in them, and dynamics of flexibility in the limbs which caused vibration of the robot’s end-effector by considering a spring-damper

A novel unilateral Harpoon shift is developed as an alternative for conventional cone-type synchronizers used in electric vehicles equipped with multi-speed clutchless automated manual transmission (CLAMT), aiming to improve the gearbox’s efficiency and performance. Harpoon shift can overcome the drawbacks of traditional synchronizers, including friction loss and wear, and simplify gearshift control

The microscopic pore structure of coal affects the content of adsorbed gas. The microstructure of coal sample before and after loading is different, which will affect the adsorption and permeability of coal seam gas. In order to study this difference, the authors carried out mercury intrusion experiments on coal containing different coal samples and used nondestructive nuclear magnetic resonance (NMR)

In this paper, the Ritz method is adopted to investigate the vibration characteristics of isotropic moderately thick annular spherical shell with general boundary conditions. The energy expressions of the annular spherical shell were established based on the first-order shear deformation theory (FSDT). The spring stiffness method is introduced to guarantee continuity and simulate various boundary conditions

In order to obtain the relationship between fractal dimension and energy dissipation of rock-like materials under initial stress state, a variable cross-section split Hopkinson pressure bar (SHPB) test system with active confining pressure loading device was used to carry out impact compression and splitting tests on cemented sand specimens. The impact test results show that (1) the prediction value