This paper introduces a theoretical analysis of the disturbance compensation methods in positioning systems. There are two major methods used to compensate for disturbances. The first one is based on a loop shaping method and the second one is based on an adaptive learning method. We make a comparison between a resonant filter used as the loop shaping method and an enhanced adaptive feed-forward cancellation (AFC) method used as the adaptive learning method. To compensate disturbances, the resonant filter decreases the gain of the sensitivity function at the disturbance frequency by using the vector locus. The adaptive learning method adjusts the coefficients of the enhanced AFC to compensate for a disturbance. We found that the LTI model of an enhanced AFC is the same as that for a resonant filter when we compared their characteristics. A simulation of the disturbance compensation in a hard disk drive showed that these time responses and frequency responses coincided. Moreover, the results showed advantages of each of the control methods with the exception of the performance. A resonant filter realizes low cost implementation with compare to an enhanced AFC. That is, a resonant filter easier to implement than an enhanced AFC. An enhanced AFC has the utility to realize a high quality function control system simultaneously able to compensate and estimate for disturbances. The results of the evaluation in this study will provide design engineers with guidelines for selecting an optimum control strategy in actual applications.
This paper reveals that lateral softness sensations can emerge in surface tactile tele-presentation systems with force feedback, if the systems have improper displacement measurements and/or stiness mismatches between a fingertip and tactile sensors. In surface tactile tele-presentation systems, friction force should be reproduced on the master device for high fidelity rendering. If, however, the remote tactile sensor is made of soft material to resemble human fingers, users may experience apparent lateral softness, which does not exist in the remote sample. This work investigates such a phenomenon by using a force-reflecting type master-slave system. The phenomenon is analyzed to provide a simple solution to dissolve the lateral stiness problem. The experiments reveal that the selection of displacement sensing point is important to prevent emergence of the apparent softness, in addition to the matching of sensor stiffness. The paper also discusses how the force reflecting gain affects the phenomenon.
Vietnam has the world's largest market share of cashew nuts, and hence a large number of workers are involved in the cashew processing industry. A shelling operation is necessary to acquire a kernel (edible portion) of a cashew. However, it is difficult to automate this operation because of the size variance of a cashew shell, although other cashew processing operations such as steaming and sorting are automated. When the cashew is manually shelled by a sharp blade cutter, not only is the shelling rate very low (when compared to other operations) but also labor conditions are strenuous and unsafe. In particular, the cashew belongs to the sumac family, and hence it should be cautiously handled by workers. This paper presents a machine design for cashew shelling to advance working conditions and production efficiency. The proposed design consists of a conveyor to transport cashews, milling cutters for shelling, and a wedge-shaped splitter for the milled shell. To accommodate for the size variance of cashews, we propose a force controller for milling operation that cuts a cashew shell without damaging the kernel. Experimental results exhibit the effectiveness of the proposed force controller for size variance.
Noncircular bevel gears (NBGs) is a kind of spatial transmission mechanism which can be used to transmit the motion and power between two intersecting axes with a variable transmission ratio and according to a suitable motion program. Given that the pitch curve and tooth profile curve of NBGs are spherical curve rather than plane curve, the research methods on NBGs is complicated than bevel gears as well as plane noncircular gears. In this paper, the pitch curve equations of NBGs are obtained for any order and in any configuration during their pure rolling based on the spherical polar coordinate system. The relationship of least teeth number avoiding undercutting and the pitch curve curvature of NBGs is analyzed. Being directed against high-order involute NBGs drive, a kind of varying-coefficient-profile-shift-modification method has been presented. The equations of the modified addendum and dedendum curves are implemented in MATLAB. The algorithm for generating tooth profile of NBGs by the hypothetical involute modified shaper cutter under UG platform is proposed and some significant examples are included. The 3D models and prototype of a pair of conjugate high-order involute modified NBGs are demonstrated to verify the correctness of this modification method.
Manufacturing cell formation is the first and foremost issue in designing cellular manufacturing system. The main objective in the cell formation problem is to cluster machines into machine cells and parts into part families so that the minimum of both intercell and intracell flows will be achieved. The purpose of this paper is to enhance solving the cell formation problem with the help of e-Learning tools in the educational environment. An efficient method and supporting tool for solving manufacturing cell formation problem are proposed. Therefore, the original similarity coefficient-based heuristic (SCBH) algorithm for solving the cell formation problem is presented. It incorporates the pure combinatorial optimization models for maximization the sum of similarity coefficients between machine/part pairs. Additionally, the LAYOUT tool is offered as a supporting tool for the SCBH. A comparative case study is conducted to validate the performance of the proposed SCBH algorithm and LAYOUT tool, and the results showed that their implementation is significant for reducing both intercell and intracell flows. The results of this work can be helpful for future or existing practitioners to become the real-world cell formation problem solvers.
The operation status of gear device can directly affect the working conditions of the whole machine system. Thus, it is crucial to detect the gear damage as early as possible to prevent the system from malfunction. This paper proposes an intelligent diagnosis method for gear damage using multiple classifiers of support vector machines with extracted failure feature vector. The vibration signal of gear box is employed as the analytical data in this paper. In order to illustrate the representative characters of gear conditions, statistical parameters and characteristic amplitude ratios of frequency bands are extracted from the vibration signals in time-domain and frequency-domain respectively, which are served as failure feature vector for the following diagnosis. Moreover, to reduce the dimensions of the failure feature vector, the technology of principal component analysis is adopted to transform the original failure feature vector into a new smaller set of variables as inputs to classifiers of support vector machines. In order to classify different types of gears, multiple classifiers of support vector machines based on the binary tree are designed. The validity of this approach is investigated by the experiment. Three kinds of gears, namely normal gear, spot damaged gear and pitted gear, are tested on the power circulating type gear testing machine. The vibration accelerations of gear box are measured as original data. Most of the samples are correctly classified by the provided method, which demonstrates the effectiveness of the proposed method on the application of gear damage diagnosis.
This paper discusses a noise reduction structure with a thin Helmholtz resonator array integrated in louver elements. Using theoretical analysis, we derived the propagation constant and characteristic acoustic impedance with consideration for sound wave attenuation in the clearance between two planes for a thin cavity within the louver. The experiments with variation in three conditions were also performed: number of necks, internal thickness of the cavity, and number of partitions. Another experiment was conducted to verify that sound reduction characteristics change depending on the number of holes. The results closely matched with those calculated with consideration for attenuation, demonstrating the validity of the theoretical analysis. With respect to changes in the internal thickness of the cavity, experimental results showed that attenuation increased for clearances of 2 mm, causing significant differences in the sound reduction characteristics. At clearances of 8 mm, there was almost no attenuation in the clearance. Louvers with thin internal dimensions, in which holes diameter equal to the internal thickness of the cavity had been formed, created a larger effect than those with normal open end correction length. This resulted in a reduction in sound reduction frequency. Additionally, when cavities seen from the neck are created on the end face of the louver element as acoustic tubes, the properties of the acoustic tubes are added to the properties of the air spring. This achieved a significant reduction in the sound reduction peak frequency without increasing the volume of the cavity.
A single-stage launch vehicle with hybrid rocket engine, which uses solid fuel and liquid oxidizer, has been studied and developed as a next-generation rocket for scientific observation due to the advantages as low cost, safety, re-ignition, and reduced pollution. Thereupon, the knowledge regarding hybrid rocket system has been gained through the forepart of the conceptual design using design informatics. In the present study, the practical problem defined by using three objective functions and seven design variables for aurora observation is treated so as to contribute the real world using evolutionary computation and data mining for the field of aerospace engineering. The primary objective of the design in the present study is that the down range and the duration time in the lower thermosphere are sufficiently obtained for the aurora scientific observation, whereas the initial gross weight is held down. Investigated solid fuels are five, while liquid oxidizer is considered as liquid oxygen. A hybrid rocket uses one of five kinds of fuels. The condition of single-time ignition is assumed in flight sequence in order to quantitatively investigate the ascendancy of multi-time ignition. A hybrid evolutionary computation between the differential evolution and the genetic algorithm is employed for the multidisciplinary design optimization. A self-organizing map is used for the data mining technique in order to extract global design information. Consequently, the design information regarding the tradeoffs among the objective functions, the behaviors of the design variables in the design space to become the nondominated solutions, and the implication of the design variables for the objective functions have been obtained in order to quantitatively differentiate the advantage of hybrid rocket engine in view of the five fuels. Moreover, the next assignments were also revealed.
Surface roughness is a significant index in evaluating workpiece quality. So research about predicting surface roughness precisely prior to machining is necessary in order to save cost and attain high productivity levels. In this paper, a method called improved particle swarm optimization-least square support vector machine (IPSO-LSSVM) is proposed to predict the surface roughness of end milling. Firstly, an improved particle swarm optimization(IPSO) algorithm is used to optimize the parameters of LSSVM method which have significant influence on the accuracy of LSSVM model. Secondly, a surface roughness prediction model is established through LSSVM method with the optimized parameters. Then prediction accuracy of the established model can be attained through test data. Finally, the prediction accuracy of IPSO-LSSVM method is compared with the accuracy of other methods, and the results show that IPSO-LSSVM method is competent in fields of surface roughness prediction.
This paper quantitatively presents the effect of load directions on the static performance of gas titling pad-journal bearing (TPJB). The gas film thickness is determined in a subsystem composed of the rotor and one pad. Based on pressure distributions obtained from Reynolds equations, integration method is used to predict the bearing static performance. Pad forces and moment balances are considered in calculating the swing angles. Local and global parameters with different load directions are discussed analytically. With the variation of load direction, the global parameters of the bearing keep relatively stable, while the local parameters can make active changes.
This paper aims to describe out-of-plane cutting characteristics of white-coated paperboard subjected to a straight punch/die shearing. Although the existence of the positive and negative clearance condition is empirically known, the features and differences between them have not been sufficiently discussed with respect to the cutting characteristics of paperboard in the past. In the experiment, overlapped punch/die clearance (negative clearance) and cutting direction were varied and investigated. A load cell and a CCD camera were installed to record the cutting load resistance and the side-view deformation of the worksheet. By using the negative clearance, it was revealed that (i) the peak point of cutting load resistance was higher than that of conventional positive and zero clearances. (ii) The worksheet was separated at a shallower indentation depth compared to the other clearance cases. (iii) Material/fiber flow at the sheared zone tended to be suppressed when using the negative clearance. This suppression seems to prevent the generation of long whisker-like dust, as well as its occurrence probability. (iv) Based on the occurrence of the whisker-like dust, a negative clearance range for generating a preferable sheared edge was revealed. Also, such clearances could be used for cutting off the worksheet in various directions.
Jet pipe electro-hydraulic servo valve is the heart of feedback control system, its performance plays an important role in establishing the properties of the system. Dynamic characteristics of the jet pipe servo valve depend on many parameters such as the stiffness of flexure tube and feedback spring or the moment of inertia of torque motor. The research results show that the stiffness of armature assembly and feedback spring are the key parts which can be directly related to the geometric and material parameters of torque motor. A suitable stiffness of the elastic system is necessary because a too low stiffness results in unstable equilibrium while a high stiffness requires a high electric input current. It is required the best stiffness of the flexure tube and the overall system for improving dynamic characteristics. A finite element method analysis is used in mathematical model for finding stiffness of the elastic system, moreover, the effect of amplitude bandwidth on the dynamic characteristics is developed, too. In order to improve the dynamic response bandwidth of two-stage jet pipe electro-hydraulic servo valve, optimal design for the moment of inertia of torque motor is investigated in this paper. The approximate range of the moment of inertia, Ja, is found and the proper cause-effect relationship between the bandwidth and, Ja, is revealed as well.
A new control framework of motion and/or vibration control system design for mechanical systems with a time varying mechanical and control parameters is studied. As examples of such time varying mechanical and control parameters, we can assume a variable damping or stiffness parameter of semi-active control devices and a time varying weighting function in a generalized plant respectively. The mechanical system in the present study is assumed to have also an actuator for active motion and/or vibration control. The active control law to drive the actuator is obtained by a gain-scheduling controller based on linear matrix inequalities (LMIs) so that the closed-loop system is stable for all assumed values of the time varying mechanical and control parameters in the generalized plant. We use the adjustability of the time varying mechanical and control parameters in the closed-loop system to realize given control specifications. As the control law of the time varying parameters in the closed-loop system, a multi-layered feedforward artificial neural network (ANN) is designed as a dynamic map from available signals in the control system to time varying mechanical and control parameters. Design parameters of the ANN are optimized with a genetic algorithm (GA). With a design example of an active positioning and vibration control of a mechanical system with variable damping coefficient, the proposed design approach is shown to be capable of achieving highly sophisticated control specifications that are hard to be satisfied by conventional control methods.
Externally pressurized gas journal bearings with an asymmetric gas supply mechanism have been developed by one of the authors. This bearing has a large load capacity compared with conventional symmetric gas supply bearings because low and high pressurized gases are supplied to loaded and counter-loaded side bearing surfaces, respectively. It has been proposed that this type of bearing has advantageous characteristics applicable for use in a general purpose X-ray computed tomography scanner gantry. The adaptation of this gas bearing to the device can conceivably contribute to an improved performance by increasing the rotational speed and decreasing the operating noise. This is effective for higher precision scanning and for reduction of the level of stress on a patient. Numerical calculations of this bearing were conducted and the resulting characteristics were compared with those of a conventional symmetric supply gas journal bearing. The effectiveness of the bearing for this application was demonstrated by conducting rotation tests using a small size test rig. The bearing diameter and length were 60 and 120 mm, respectively. The test bearing was operated under supply gas pressure controlled conditions. The rotor vibration amplitude decreased under the controlled pressure supply conditions, although the amplitude increased under conventional symmetric gas supply conditions with an increase in rotational frequency. The gas flow rate decreased by 21.4% under controlled supply pressure conditions compared with conventional supply pressure conditions. The rotor of the test rig was safely supported by this bearing, and effective data for the practical operation was obtained.
Two types of novel one-degree-of-freedom seven-bar geared linkage mechanism are presented. The proposed mechanisms consist of an elementary planetary gear train, a slider-crank mechanism or a Scotch yoke mechanism, and a slider-crank mechanism with a variable-length crank. The output link can generate two required output motion cycles while the input link completes a single motion cycle. The structure, graphical displacement analysis, kinematic analysis and dynamic analysis of these mechanisms are discussed. An example is provided to demonstrate the kinematic and dynamic characteristics of the proposed mechanisms.
Conceptual design is the most critical phase of engineering design process since the great majority of product cost is determined and a basic solution that significantly influences other phases is obtained in this phase. In the phase, there are still some vital issues need to be developed, such as applicability to practice, finding high innovative solutions. In this paper, to overcome these challenges, we aim to establish a model of innovative conceptual design process by incorporating systematically TRIZ and QFD into Pahl and Beitz's conceptual design approach. Herein TRIZ is used as a problem finder, a solution trigger, and a solution improver, which is one original contribution of this study. QFD is used for converting customer needs into design parameters that are further taken as criteria in the step of evaluation, which is another original contribution of this study. The applicability of the proposed model is demonstrated through a case study. The case study shows that the proposed model allows designers to find easily innovative and customer-centered solutions. Based on Altshuller's the levels of innovation, the effectiveness of the proposed model is evaluated, and consequently obtained innovative solutions at Level 2-4.
Like all man-made artifacts, Advanced Driver Assistance Systems have certain limitations beyond which they cannot function properly or work at all. The users in the driving domain have diverse backgrounds and it is likely that many of them start interacting with the technology without having gained detailed knowledge, such as by reading user manuals. This study explores whether drivers with only minimal knowledge of the Lane Departure Warning system can recognize the system's speed threshold and update themselves about this in a dynamic driving environment. Since drivers are not always single-mindedly focused on driving so participants were divided into two groups. Group 1 subjects performed only the driving task, while Group 2 was prompted to carry out a secondary task in addition to the primary driving task. Our investigation allowed us to estimate the effects of drivers' minimal mental model of the system working due to lack of sufficient knowledge concerning its capacities upon their 1) learning from experience and 2) situation awareness. It was assumed that the demands of multitasking would impair the driver's ability to observe the system's state and delay the mental model improvement process, compared to a setting in which driving was the only task. Experiment results using a driving simulator have been presented. The results revealed that the number of the drivers, who did not become aware of the operating condition of the LDW system, was quite high for both groups regardless of the nature of their tasks. It had been deduced that the users' preconceptions and expectations due to their limited knowledge about the capacities of the technology, could make them rely on the system to alert them in different situations even when the system was not operating. Hence, these factors can not only adversely affect the social benefits associated with ADAS, but also the acceptance and usability of these systems.
The evolution of a product form during the design process is typically governed by the designer's individual preferences and creative instincts. As a consequence, there is a risk that the product form may fail to satisfy the consumers' expectations or may induce an unanticipated consumer response. This study commences developing a computer aided product-form design (CAPD) tool based on numerical definition scheme (NDS) and back-propagation neural network (BPNN). A NDS approach is employed to depict an explicit product form, and a series of evaluation trials are then performed to establish the correlation between the product form features and the consumers' perceptions of the product image. The results of the evaluation trials are used to construct a BPNN model to predict the likely consumer response to any arbitrary product form. The feasibility of developing a CAPD tool is demonstrated using a 3D knife form in this study.
Recently, infrared imaging technologies have been developing in various industrial fields rapidly. We therefore focus on the infrared ray imagery as a novel method to estimate the gear tooth meshing. In the present report, a high response infrared thermography, which could take a middle infrared ray image of around 4 μm wavelength, was used to investigate the temperature hysteresis on the tooth contact surface of hypoid gear under running conditions. We installed the high reflective mirror of infrared ray at the opposite side of the gear tooth meshing point to obtain the tooth surface images around the entire gear, and estimated the variation o tooth surface temperature at the duration from a tooth meshing to the next tooth meshing. Moreover, using a thermal network model, the modeling of the temperature variation of the gear tooth surface regarding the time is conducted as to predict the temperature after a certain number of rotations. The network model presented in this report is derived from the ones such as Forster network or Cauer network which are based on the concept of thermal capacitance and thermal resistance. This network is investigated to match the actual results on the temperature evolution. Finally, it is clear that the temperature on the tooth surface during a gear rotation can b modeled by first order time delay and the maximum temperature is affected by contact pressure, relative sliding speed between tooth surfaces and average peripheral speed of tooth surface. This proposed method is found to be effective to evaluate the temperature hysteresis on the tooth contact surface of hypoid gear.
Hub unit bearings are key components in automobiles for carrying load and accurate piloting. The hub unit bearing must be of a smaller size and lighter weight to meet the requirements of automobile for higher fuel efficiency, improved ease of movement and freedom in sizing of peripheral components. Reduction of such basic performance as strength, stiffness or the like due to reduced weight must be avoided. In this study, an efficient lightweight of hub unit bearing is investigated by integrating finite element (FE) analysis, uniform design (UD), response surface methodology (RSM), and genetic algorithm (GA). The FE analysis of the hub unit bearing is conducted, its validity is verified by the test of moment rigidity. A multi-objective optimization model with constraint functions is established by RSM according to FE analysis results from the samples of UD. The exterior point penalty function method is used to convert the constrained optimization problem into an unconstrained optimization problem. The normalized weighting method is used to transform the multi-objective optimization problem into a single-objective problem. By ensuring that the maximum equivalent stress is below the yield limit stress and that the rigidity hardly changes, the optimization model is interfaced with an effective GA to match the lightweight target.
We investigated the sound absorption coefficient within a sound-absorbing structure made of layered clearances between two planes. We discussed the experimental results from the existing literature and conducted a theoretical analysis on several different sound-absorbing structures that take into account the viscosity of the boundary layer at the clearances. First, we examined the case of thin sheets placed in parallel. Then, we examined the case where the size of the clearance continuously changed perpendicular to the direction of incidence of the sound waves. Subsequently, we examined the case where the clearance continuously decreased in the direction of incidence of the sound waves. In latter two cases, the transfer matrix used in the calculations was divided into elements perpendicular or coincident to the direction of incidence of the sound waves and the size of the clearance for each element was changed in a stepwise fashion. We then calculated the sound absorption coefficients for various structures and dimensions and observed that the calculated and experimental data agreed well. On the basis of the calculation simulation, the differences between the calculated and experimental absorption coefficient data were attributed mainly to the changes in the flexure of the sheet materials. The proposed calculation methods will be useful in determining the absorption coefficient of such shapes, and in the design of sound-absorbing materials that use such shapes.
To improve cutting performance and suppress chatter vibration during machining of large mechanical parts with a long slender cutting tool, a design method was investigated for a tuned mass damper imbedded tool arbor. To clarify the effects of the dynamic stiffness and damping ratio of the weight which is supported at both ends inside the hollow space of the arbor on the dynamic compliance at the end of the arbor, finite element analysis was conducted. First, since the weight has twisting vibration in its 2nd order natural mode, it is necessary to consider 2 degrees of freedom of the motion to optimize the damper. Then, the relationship between the motion of the damper and damping performance is clarified in accordance with the change in spring constant of the weight. From the results, an area exists where there is little change in the maximum negative real part of the compliance due to the change in spring constant. Designing the spring constant in this area stabilizes the damping performance. Furthermore, comparison of the results of finite element analysis and the conventional particle model analysis revealed that the results of finite element analysis show a smaller real part of the compliance than those of particle model analysis. This is because the inertial forces of the weight are applied not to the end of the arbor but to the tool holder side of the arbor and the damping effect is smaller than that in the particle model.
Acoustic transducers with large radiation surfaces are used to handle planar object without any physical contact. To more accurately describe the dynamic performance of such transducer with strong coupling effect due to the large lateral scales, a mathematical model with flexural boundary conditions and gas inertia is presented in this paper. A coupled 3D finite element method model has been built and simulated with an identical experimental condition. The influences of dynamic coupling on the transducer performances and the levitation behaviors have been studied. We have found that under the strong dynamic coupling between the PZT and the large vibrator, the lowest impedance of the transducer shifts to the 2nd resonant frequency, instead of locating at the 1st resonant in a general case. Experiments have been set up to validate the coupling effects. Good agreement between the calculations and the experimental results indicates that the coupling plays an important role in the dynamic behaviors of the transducers with large lateral scales. Our work has improved the model's precision and provides an optimization tool to construct acoustic transducers used in the Near Field Acoustic Levitation.
Gear is one of the most important and commonly used components in machine system. Some gear failure may lead to fatal damage of the entire system, or even huge losses in industrial production. Early detection of gear damage is crucial to prevent the machine system from malfunction. This paper provides an intelligent diagnosis method for gear damage based on techniques of empirical mode decomposition and support vector machines. By the data processing of empirical mode decomposition, the original signal are decomposed into a finite set of intrinsic mode functions with frequency bands ranging from high to low. The characteristic energy ratios of intrinsic mode functions are acquired as representative parameters of the signal. Furthermore, statistical parameters of standard deviation, root mean square value, kurtosis and skewness are extracted from the original signal. Characteristic energy ratios and statistical parameters are combined as failure feature vectors to be input to the support vector machines classifiers for gear damage diagnosis. The validity of the presented method is confirmed by the application of monitoring gear conditions during the cyclic fatigue test. The vibration accelerations of gear box are acquired to illustrate the progression of pitting damage. Most of the gear conditions are identified, indicating the effectiveness of the proposed method.
In order to verify the validity of the design for the orthogonal variable transmission ratio face gear pair, a five-axis CNC machine tool was used to machine this gear. The cutter tooth profile coordinate system, orthogonal variable ratio face gear machining coordinates, the model for the round-corner at tooth tip, the contact line model and CNC machining models were established by using space gear meshing theory and the machining principle of five-axis CNC machine tools. The method of machining this gear along the contact line has been obtained through the combination of the envelope method and milling principle. Cutter tooth profile equations, coordinate transformation matrices between the non-circular gear tooth surface and orthogonal variable transmission ratio gear tooth surface, transition surface equations and five-axis motion equations were derived. The rolling experiment and tooth surface measurement experiment were conducted on the gear, which was processed by a five-axis CNC machine. The results show that the tooth surface accuracy of the orthogonal variable transmission ratio face gear is high. The design of the orthogonal variable transmission ratio face gear, and its processing method using a five-axis NC machine have been verified.
While the concepts of RSSR-SS motion generation, order defect elimination and branch defect elimination have all been well-researched over the years (individually and in combination), a major challenge exists when considering a general RSSR-SS optimization model for motion generation in the mathematical analysis software Matlab. To overcome this challenge, this work presents a small-scale nonlinear equation system for RSSR-SS motion generation. The equation system also includes inequality constraints to eliminate order defects and branch defects.
This paper presents the results of a transient analysis of thermal elastohydrodynamic lubrication (TEHL) of a rough cylinder on a rough flat surface in line contact with non-Newtonian lubricant blended with Al2O3 nanoparticles. The simultaneous systems of time-dependent modified Reynolds equation, elasticity equation and energy equation with initial conditions were solved numerically using multigrid multilevel with full approximation technique. In this study, the effect of Al2O3 nanoparticle additives, surface roughness and sudden overload on TEHL of two surfaces in line contact were examined. The minimum film thickness and the pressure spike increase slightly with an increase in nanoparticle concentration. For TEHL with Al2O3 nanoparticle additives, the film temperature increases very little due to thermal enhancement of nanofluids.