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Showing papers in "Transactions of the Japan Society of Mechanical Engineers. C in 1992"


Journal ArticleDOI
TL;DR: In this paper, a flexible and incremental sheet metal bulging machine using a path-controlled spherical roller was developed for the small-batch manufacture of nonsymmetrical shallow shells, which performed a wide range of sheet metal shaping on complex shapes, for example, pyramidal shells, shells of the frustum of a pyramid, shallow pans and embossed panels.
Abstract: A flexible and incremental sheet metal bulging machine using a path-controlled spherical roller has been developed for the small-batch manufacture of nonsymmetrical shallow shells. The computer operations-controlled bulging machine performed a wide range of sheet metal shaping on complex shapes, for example, pyramidal shells, shells of the frustum of a pyramid, shallow pans and embossed panels. In order to predict the forming limit of incremental shaping, a new incremental bulging test by a ball punch was performed on an annealed aluminum sheet, and the experimental results showed that fracture occurred when the thickness strain reached n constant value. An approximate calculation method for the maximum bulging height of the shell was proposed, using this fracture limit and a geometrical deformation model. The predictions for the shell of the frustum of a quadrangular pyramid and the quadrangular pyramidal shell were in reasonably good agreement with experimental values for the annealed aluminum sheet.

44 citations


Journal ArticleDOI
TL;DR: In this article, the sliding mode control (SMC) is applied to a magnetic bearing system and compared with the PID control method for the flexible rotor supported by magnetic bearings by simulation and experiments on both the lift off and rotation.
Abstract: In this paper, the sliding mode control, a typical method of nonlinear adaptive control and robust control, is applied to a magnetic bearing system. It has its roots in the relay and bang-bang control theory. Sliding mode control is a high-speed switching feedback control; for example, the gains in each feedback path switch between two values according td certain rules. This control law drive system's state trajectory to a user-chosen surface in the state space is called the sliding surface for all subsequent time. The sliding surface is called the switching surface by another name because if the state trajectory is above the surface, a control path has one gain and a different gain if the trajectory drops below the surface. From this control, the system is restricted to this surface and is stabilized. This method is very robust for parameter change, modelling error, disturbance, and so on. The sliding mode control method is compared with the PID control method for the flexible rotor supported by magnetic bearings by simulation and experiments on both the lift off and the rotation.

31 citations


Journal ArticleDOI
TL;DR: In this paper, the stability of a cantilever beam subjected to one-dimensional leakage flow is investigated, and the critical flow velocities and the natural frequencies on the neutral stability are determined as a function of gap width.
Abstract: The stability of a cantilever beam subjected to one-dimensional leakage flow is investigated. The motion of such a beam is expressed as the sum of the first few eigenfunctions of a cantilever beam. The critical flow velocities and the natural frequencies on the neutral stability are determined as a function of gap width. Experimental results are in agreement with analytical ones. The complex frequency of the four lowest modes of the system is calculated in several representative cased as a function of flow velocity. In the case that the beam is clamped at the upstream end, the system is found to lose stability by coupled-mode flutter. On the other hand, in the case that the beam is clamped at the downstream end, the system is found to lose stability by divergence first, and successively lose stability by flutter with increasing flow velocity.

29 citations


Journal ArticleDOI
TL;DR: In this article, the authors investigated nonlinear liquid motion in a partially filled annular cylindrical tank, in response to a pitching excitation, considering the nonlinearity of the liquid surface oscillation is considered in the response analysis of the sloshing motion.
Abstract: Nonlinear liquid motion in a partially filled annular cylindrical tank, in response to a pitching excitation, is investigated. The nonlinearity of the liquid surface oscillation is considered in the response analysis of the sloshing motion. Basic equations are derived by employing the variational principle. The nonlinear ordinary differential equations governing the liquid surface oscillation are then derived by applying Galerkin's method to the basic equations. The effects of the ratio of inner radius to outer one on liquid surface oscillation are discussed. The time histories of the liquid surface displacement are calculated to the harmonic pitching excitations. An experiment was conducted using a model tank. A good agreement was found between the theoretical and experimental results. It is shown that the nonlinear analysis is important for estimating the sloshing responses.

26 citations


Journal ArticleDOI
TL;DR: In this paper, the lateral oscillation of the rope is coupled with the mass-spring system through nonlinear terms to obtain the obvious approximate solution by the method of multiple scales with nonlinear scales.
Abstract: The system composed of a rope with a time-varying length and two mass-spring systems hanging at its end is considered to be the analytical model of an elevator. The lateral oscillation of the rope is excited sinusoidally by the horizontal displacement at the upper end of the rope. There exists a problem of passage through resonance with a slowly varying natural frequency of the rope. Furthermore the lateral oscillation of the rope is coupled with the oscillation of the mass-spring system through nonlinear terms. First, we obtain the obvious approximate solution by the method of multiple scales with nonlinear scales. This solution is numerically derived for confirmation by the method of characteristics. It is examined that the moving velocity of the rope influences the maximum amplitude of the. rope oscillation. Our experimental results agree qualitatively with the theoretical ones. Furthermore, we show that the lateral oscillation of the rope and the vertical oscillation of the cab influence each other in a specific case.

15 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of mistuning for free-standing blades and integral shroud blades are studied by means of Monte Carlo simulation and sensitivity analysis, and it is found that weakly coupled systems with low damping are very sensitive to mistuning.
Abstract: When calculating the resonant response of bladed turbine disks, it has been expedient to assume that all blades on a given disk are identical. This leads to the prediction that all blades experience the same amplitude of displacement and stress when excited by forces harmonically related to the rotor speed. However, it has been shown experimentally that significant variations in these amplitudes occur for different blades on the same disk. These variations arise due to the effects of mistuning, which refers to small differences in blade characteristics. In this paper, effects of mistuning for free-standing blades and integral shroud blades are studied by means of Monte Carlo simulation and sensitivity analysis. It is found that weakly coupled systems with low damping are very sensitive to mistuning. Also, the validity of the lumped model used in this paper is examined by comparing the calculated results with experimental data.

14 citations


Journal ArticleDOI
TL;DR: In this paper, the shape of resonance curves changes markedly depending on the relative angular position of the unbalance to the crack, and an unstable region appears for a certain range of angular position.
Abstract: In a horizontal rotating shaft containing a transverse crack, the vibration characteristics at the major critical speed are investigated. In a theoretical analysis, a model whose spring characteristic is approximately represented by a power series is treated. The analytic results are compared with the results of numerical simulation with a model of a piecewise linear spring characteristic. Experiments with a flexible rotating shaft system are also performed. The following points are clarified : ( a ) In the case of a comparatively large unbalance, the shape of resonance curves changes markedly depending on the relative angular position of the unbalance to the crack, and an unstable region appears for a certain range of angular position. This phenomenon is similar to the case of vertical shafts. ( b ) In the case of a comparatively small unbalance, the shape of resonance curves is not affected by the direction of the unbalance and an unstable region always appears. This is a phenomenon particular to the horizontal shaft.

14 citations


Journal ArticleDOI
TL;DR: In this article, the design of an electrical model for the photovoltaic effect in a PLZT element to estimate, in advance, the performance of an optical actuator consisting of a PLC.
Abstract: This paper deals with the design of an electrical model for the photovoltaic effect in a PLZT element to estimate, in advance, the performance of an optical actuator consisting of a PLZT element. The results of the basic experiment on the photovoltaic effect are shown, and they indicate that a parallel circuit including a current source, a resistance and a capacitance may be applicable to an electrical model for the photovoltaic effect, under the consideration of the lumped system. Then, the step response of the photovoltage is obtained theoretically according to the electrical model proposed. Since the theoretical results agree well with the results of the basic experiment, the electrical model proposed can be considered to be valid for practical use. Important aspects of the design of an exact model are also pointed out.

12 citations


Journal ArticleDOI
TL;DR: In this article, a vibrationless access control which is robust for parameter variations is proposed. But, the authors consider the case where the control force has no frequency component within the range of varying natural frequencies.
Abstract: This paper describes a vibrationless access control which is robust for parameter variations. It is important for the vibrationless access control of a positioning mechanism with mechanical flexibility to eliminate residual vibration at a target position even if natural frequencies of the mechanism vary. From the relation between the residual vibration amplitude and the frequency spectrum of feedforward control force, it is found that the control force can be robust for the natural frequency variations if the control force has no frequency component within the range of varying natural frequencies. In the proposed method, an enlarged system is first constructed in the modal coordinates for a virtual mechanism which has a few natural frequencies within the varying range of the concerned natural frequency. The optimal control theory is next applied to the enlarged system and the vibrationless feedforward control force is calculated. The improved robustness of the proposed vibrationless access control is demonstrated with experimental results.

12 citations


Journal ArticleDOI
TL;DR: In this paper, an improved floating liner method by means of hydrostatic bearings has been developed to measure accurately the frictional force as a function of crank angle under the firing operation.
Abstract: The present paper refers to the studies on the frictional characteristics between piston rings and cylinder liners in reciprocating internal combustion engines. An improved floating liner method by means of hydrostatic bearings has been developed to measure accurately the frictional force as a function of crank angle under the firing operation. The major results are that : ( i ) the measured frictional force shows the boundary or mixed lubrication near the dead centers, but shows mainly the fluid lubrication during mid-strokes ; ( ii ) the total frictional loss is reduced, but the peak friction just after the dead centers increases with the decrease in engine speed or oil viscosity ; and (iii) the peak friction at the beginning of the expansion stroke increases remarkably due to the gas pressure in cylinder, and this increasing tendency is promoted according to the reduction in the number of piston rings.

10 citations


Book ChapterDOI
N. Ino, A. Machida, K. Tsugawa, Y. Arai, Hiromu Hashimoto1, A. Yasuda 
TL;DR: In this article, the authors developed an expander for a helium liquefier of 100 L/h capacity used for a superconducting generator, which uses a thrust bearing exerting a significant influence on the reliability of the turbine.
Abstract: The authors developed an expander for a helium liquefier of 100 L/h liquefaction capacity used for a superconducting generator. This paper focuses on the development of the shaft-bearing system, which uses a thrust bearing exerting a significant influence on the reliability of the turbine. An externally pressurized thrust bearing was used to support the high thrust load resulting from the high expansion ratio of the turbine. The characteristics of the bearing were estimated based on analytical solution of the theory of complex velocity potential. Good agreements were found between theoretical results and exprimental ones and the practicality of the design method was verified.

Journal ArticleDOI
TL;DR: In this article, an active mass damper with a new structure was developed to implement active vibration control for tall buildings, in which a moving mass is supported by multistage rubber bearings.
Abstract: An active mass damper with a new structure was developed to implement active vibration control for tall buildings, in which a moving mass is supported by multistage rubber bearings. Because of this structure, the damper can be installed on the roof of the building. This means that no indoor space is needed for the damper. Furthermore, the structure can reduce the operational friction and distortion in the mass acceleration as well. For control of the damper, a variable gain control law was proposed, by which the damper can perform against not only winds and weak earthquakes but also strong earthquakes, while it keeps its displacement within a stroke limit of the hydraulic actuators. Excitation tests were carried out for an experimental model of the damper in which a 5300 kg mass was supported by 4 multistage rubber bearings and controlled by 2 hydraulic actuators in a horizontal direction. Through the tests and simulation studies, it was confirmed that the structure and the control law were effective for active vibration control of tall buildings.

Journal ArticleDOI
TL;DR: In this paper, the authors developed a new type of mobile robot which had a spherical wheel, an arch-shaped body and motion controlling mechanisms installed inside the wheel, called this spherical robot's controlling system IWBS (Inner Wheel Balancing System).
Abstract: The authors developed a new type of mobile robot which had a spherical wheel, an arch-shaped body and motion controlling mechanisms installed inside the wheel. The robot can travel every direction and perform unique actions by virtue of its spherical wheel and motion controlling mechanisms. We call this spherical robot's controlling system IWBS (Inner Wheel Balancing System). The robot is inherently of a stable structure because of its large radius of the wheel and low positioned center of gravity. However, if a load is applied on the top of the body, the robot become unstable. Therefore, the robot is of a quasi-stabled structure. The compound gravity center control of the IWBS enabled this quasi-stabled robot to be controlled not only its postural stability but also every directional locomotion. This paper describes a development concept and mechanisms of the robot, computer simulation performed on the personal computer and experimental results of the robot fabricated concerning to the roll inclination control, running straight and along the S-shaped path control. By applying the learning control method proposed here, we have achieved the intelligent roll inclination control of the robot. It is expected that the robot can become one of the next generation robots for industrial as well as for personal use by developing its capabilities.

Journal ArticleDOI
TL;DR: In this article, the authors presented methods for design of frequency cost and robust control by applying the theory of H∞ control in stochastic optimal control with a feed forward link.
Abstract: In stochastic optimal control with a feedforward link, there are two problems, one is the difficulty of design by frequency-shaped cost functionals, the other is the problem that the level of the frequency response increases beyond the frequency range of an assumed disturbance dynamics. In this study, to overcome these defects of the stochastic vibration control, methods for design of frequency cost and robust control are presented by applying the theory of H∞ control. In the numerical calculation using a single-degree-of-freedom system, the usefulness of the presented method using the H∞ control was verified.

Journal ArticleDOI
TL;DR: In this paper, the experimental study of seismic response behavior of piping systems in the industrial facilities such as petrochemical plants and nuclear power plants is presented. But the authors focus on the nonlinear dynamic response of piping system due to frictional vibration appeared among piping and supporting devices.
Abstract: This report deals with the experimental study of seismic response behavior of piping systems in the industrial facilities such as petro-chemical plants and nuclear power plants. Special attention is focussed on the nonlinear dynamic response of piping systems due to frictional vibration appeared among piping and supporting devices. 3 dimensional mock-up piping model having 30 m Iength and 8 inches diameter is excited by large scale (15 m x 15 m) shaking table. Power spectra of the response vibration and loading-response relations in the form of hysteresis loop under several excitation levels are calculated. Response reduction effect caused by frictional vibration is evaluated and demonstrated in terms of "response reduction factor". Numerical simulation by use of nonlinear simplified friction model is also performed and calculated piping response is compared with those from vibration tests.

Journal ArticleDOI
TL;DR: In this article, two types of model reference adaptive steering systems are proposed: one type puts emphasis on yaw rate of the vehicle which a driver perceives dominantly under ordinary driving conditions; and another one put emphasis on lateral acceleration under critical driving conditions, such as obstacle avoidance.
Abstract: This paper presents a new control method by an adaptive front steering system. Two types of model reference adaptive steering systems are proposed in this paper : one type puts emphasis on yaw rate of the vehicle which a driver perceives dominantly under ordinary driving conditions : and another one puts emphasis on lateral acceleration of the vehicle which a driver perceives dominantly under critical driving conditions, such as obstacle avoidance. The parameters of the vehicle are treated as unknown and are identified by the least square method with a time variant forgeting factor. The control method used in this paper is a pole assignment type adaptive self-tuning control method. Simulation results show that the running safety is improved significantly and that the driver burden is decreased under critical driving conditions.

Journal ArticleDOI
TL;DR: In this article, a study on acoustic emission in the bending fatigue process of spur gear teeth is presented, where the relationship between the AE parameters and the fatigue crack propagation, as well as the effects of the gear material and the case depth on the AE characteristics in the fatigue damaging process of a gear tooth were determined.
Abstract: This paper presents a study on acoustic emission (AE) in the bending fatigue process of spur gear teeth. Research was conducted on AE signals, AE cumulative event count, AE event count rate, frequency spectra of AE signals and crack length in the bending fatigue process of case-hardened and normalized spur gear teeth. The relationship between the AE parameters and the fatigue crack propagation, as well as the effects of the gear material and the case depth on the AE characteristics in the fatigue damaging process of the gear tooth, was determined. Basic data were obtained for the prediction of bending fatigue crack initiation of the gear tooth by means of the AE method.

Journal ArticleDOI
TL;DR: This paper describes on the evaluation of grouping with plural master cells for a cellular robotic system (CEBOT) as one of the group robotic systems and proposes the cross-dependence matrix in the cells, which represents the relations between the cells and executing task steps.
Abstract: Control architecture is an important problem for the distributed intelligent system. We describe on the evaluation of grouping with plural master cells for a cellular robotic system (CEBOT) as one of the group robotic systems. For the evaluation of the grouping, we use network energy as the estimation function, which we have proposed in a previous paper. By describing the grouping of the network with plural master cells as cores in a subnetwork, we represent the effect for the group structure of the organization or the society. Then for the estimation of the grouping of the network, which is organized by autonomous robotic units called "cells, " we propose the cross-dependence matrix in the cells. The matrix is led from the "task matrix, " which represents the relations between the cells and executing task steps. Finally, we show the simulation results for the example of the organized network by the cellular robotic system. This paper also describes mathematically the efficiency of grouping of the orgnization or the society.


Journal ArticleDOI
TL;DR: In this article, the authors investigated the impact force and impact duration of a tennis racket, considering the strong nonlinearity of the restoring force of the ball and strings, and estimated the coefficient of restitution of the tennis racket using a personal computer.
Abstract: There are a number of unclarified points regarding the impact phenomena and the optimum design of tennis rackets. The present study is based on the idea that the dynamics of a racket consists of the dynamics of a rigid body with an arm swing given at a grip as a boundary condition, an impact between a ball and strings with racket frame as an input force, and the structural vibration of the racket. In this paper, impact force and impact duration are investigated, considering the strong nonlinearity of the restoring force of ball and strings. Furthermore, the coefficient of restitution of the tennis racket is estimated using a personal computer on the basis of the impact phenomena and the experimental modal analysis. In order to predict the contact duration, which has an influence on the racket vibration, a simple impact model has been proposed, i.e., that the contact duration is determined by the natural period of a whole system composed of the mass of the ball, the stiffness of the ball and strings, and the reduced mass of the racket at the impact point on the racket face. The calculated results agree fairly well with the experimental results.

Journal ArticleDOI
TL;DR: In this paper, a new type of microactuator applicable to the artificial muscle for driving robots has been devised and analytical procedures for designing the actuator have been derived, which has the characteristics of simple structure, flexibility and is given the moving and deforming abilities of bending, waving, holding, and coiling according to the arrangement of a longitudinal reinforcing fiber.
Abstract: In this paper, a new type of microactuator applicable to the artificial muscle for driving robots has been devised and analytical procedures for designing the actuator have been derived. The actuator has the characteristics of simple structure, flexibility, and is given the moving and deforming abilities of bending, waving, holding, and coiling according to the arrangement of a longitudinal reinforcing fiber. Several types of rubber actuators were prepared, and their static characteristics were measured and compared with the theoretical ones. Some applications were also considered. It was found that the holding force should be estimated in consideration of three-dimensional stresses and an increase in an inner diameter, and that the actuator using the material of lower Young modulus gives stronger force if the other states are under the same conditions.

Journal ArticleDOI
TL;DR: In this paper, the critical conditions of ice formation and stability of supercooled water in cooled circular tubes were examined for four kinds of tube inner diameters under various Reynolds numbers.
Abstract: Basic experiments were carried out concerning the possibility of continuous ice making in supercooled water in a forced flow. In the experiments, the critical conditions of ice formation and stability of supercooled water in cooled circular tubes were examined for four kinds of tube inner diameters under various Reynolds numbers. It was understood that two ice growth modes of annular ice and dendritic ice appeared in the cooling tube according to the degree of supercooling. Nondimensional correlation equations of supercooling for ice nucleation in laminar and turbulent flow regions were derived as a function of the nondimensional ratio of thermal boundary thickness to the pipe length, which length is defined as the distance from the position where the mixing average temperature of the flowing water becomes below freezing point to the pipe downstream end.


Journal ArticleDOI
TL;DR: This paper deals with a path planning method for a structure configuration of Cellular Robotic System (CEBOT) which consists of a large number of autonomous robotic units called "cells," and proposes a method for distributed decision making for the path planning, which employs a genetic algorithm.
Abstract: This paper deals with a path planning method for a structure configuration of Cellular Robotic System (CEBOT) which consists of a large number of autonomous robotic units called "cells." Since the CEBOT is one of the dynamically reconfigurable robotic systems, we propose a method for distributed decision making for the path planning, which employs a genetic algorithm. A genetic algorithm is a search algorithm based on the principle of natural selection and natural genetics. The decision making is improved according to the survival rule for the planning candidates. According to the concept of a distributed intelligent system, we propose a "distributed genetic algorithm, " in which the survival is selected in each local area. We present the simulation results for the planning in two cases as follows : ( 1 ) the case using a general genetic algorithm and ( 2 ) the case using a distributed genetic algorithm.

Journal ArticleDOI
TL;DR: In this paper, an object-oriented modeling of an autonomous distributed manufacturing system and its application to the production scheduling is discussed from the viewpoint of information processing in the manufacturing system, and a distributed production scheduling method is proposed on the basis of the autonomous decision making of the individual components and their coordinations.
Abstract: This paper deals with an object-oriented modeling of an autonomous distributed manufacturing system and its application to the production scheduling. The architecture of the autonomous distributed manufacturing systems is discussed from the viewpoint of information processing in the manufacturing system. An object-oriented modeling method is applied to describe the decision-making activities and the communication activities of the components, such as the manufacturing devices and the workpieces. The activities of the objects are discussed in detail from the viewpoint of the production scheduling. The contents of the objects are clarified, and the part-of relations and the is-a relations between the objects are also established. A distributed production scheduling method is proposed on the basis of the autonomous decision making of the individual components and their coordinations.

Journal ArticleDOI
TL;DR: In this paper, the damping characteristics of a composite structure beam, which is composed of a steel pipe and fiber-reinforced plastic (FRP), were investigated both theoretically and experimentally.
Abstract: The advantages of fiber-reinforced plastic (FRP) are that it has low density and high damping capacity. However, FRP had not yet been commonly used in machine tool structures because of its low Young's modulus, cheeping characteristics, and so on. The most probable use of FRP in machine tools seems to be in combination with a conventional material like steel in order to compensate for the low Young's modulus. In this paper, the damping characteristics of a composite structure beam, which is composed of a steel pipe and FRP, were investigated both theoretically and experimentally. The effects of the fiber direction, each wall thickness of the steel pipe and the FRP on the damping capacity were clarified. It has also been made clear that if the diameter of the composite structure is permitted to increase compared with that of the original steel structure, the damping capacity can be markedly increased under the condition of constant flexural rigidity.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the motions of each part based on dynamics, taking account of the friction force between the parts, which results in simultaneous differential equations, which can be solved numerically using an electronic computer.
Abstract: Universal joints, which transmit torque through the balls guided in such a manner that they always lie in the plane bisecting the angle between the driving-shaft and driven-shaft, are called ball-type constant-velocity joints. The authors presented papers on the analysis of this type of universal joint based on statics neglecting the friction force between their components. To obtain more precise estimations of the internal forces and the moments, it appears to be important to evaluate the effect of the friction between the parts. Furthermore, grasping the relative motions of the parts, such as rolling of the balls on the tracks, is beyond the scope of static analysis. In this study, the authors analyze the motions of each part based on dynamics, taking account of the friction between the parts. The analysis results in simultaneous differential equations, which can be solved numerically using an electronic computer.


Journal ArticleDOI
TL;DR: This paper presents anobject-oriented model of design process and an object-oriented design support system which assists the basic design of machine tools which is analyzed in the case of machining centers.
Abstract: This paper presents an object-oriented model of design process and an object-oriented design support system which assists the basic design of machine tools. The process of the basic design of machine tools is analyzed in the case of machining centers. The design process is represented by a series of phases, each of which consists of two steps. The first step is to select the design parameters and the second step is to determine the values of the design parameters. The "design object" is defined here as encapsulated information which is dealt with through phases of the design process. The model of the design process is represented by trees and their relations. A tree represents the generalization-specification relation of design objects which are nodes of the tree. The relations among the trees constitute the whole-part relation. A design support system is developed based on the object-oriented model of the design process.

Journal ArticleDOI
TL;DR: In this paper, the role of wear particles in severe-mild wear transition was studied using a pin-on-disk type wear test rig, and it was observed that a mild wear surface is produced by back transfer of mild wear particles generated in the severe wear mode.
Abstract: The mechanism of severe-mild wear transition and the role of wear particles in that process are studied using a pin-on-disk type wear test rig. Wear particles are continuously removed by air pressure. With the removal of wear particles, severe-mild wear transition does not occur. During the wear process, the worn surface of a pin specimen is sometimes observed with the optical microscope. It is observed that a mild wear surface is produced by back transfer of mild wear particles generated in the severe wear mode. onto the friction surface. When the entire area of apparent contact becomes a mild wear surface, the wear mode changes to mild. These results indicate that the mild wear mode is exhibited after the production of a mild wear surface; and that in severe-mild wear transition, Wear particles play the role of oxygen conveyer as an oxide needed for the generation of a mild wear surface.