Applied Mechanics and Materials Vols. 152-154

Abstract: For the shortcomings of existing SDG modeling methods in fault diagnosis, a data-driven semi-quantitative SDG automatic graphical modeling approach and a direct manual SDG graphical modeling approach are investigated. Function failure analysis procedures and data modeling process based on system principle are introduced in detail, and relevant graphical modeling tool are developed. A fault diagnosis modeling for the air supply system of certain type of aircraft is taken as an illustration to verify the validity of proposed modeling method.

Abstract: In producing thin wall ductile iron (TWDI) cooling rate must be strictly maintained to prevent carbide formation. There are many ways to control cooling rate BUT the most independent one is by casting design. By choosing this parameter major changes in equipment and raw material used in the foundry can be avoided. This paper discusses the effect of gating system design on microstructure and mechanical properties of 5 mm TWDI plate. A casting design based on vertical gating system is made to produce 1, 2, 3, 4, and 5 mm TWDI plates. Plate with 5 mm thickness becomes an interesting subject due to its position as the thickest and furthest from ingate in casting design with a new concept. There are three designs coded as T1, T2, and T3. These three designs were also used in making 1 and 3 mm TWDI plates of which the result has been published. The plate with 5 mm thickness will be used for automotive components. Casting design simulation for filling flow and solidification were conducted with Z-Cast. Result of flow simulation shows that the filling flow happens in two kinds. Result of solidification shows that T3 has the highest solidification rate. In the experiment, the moulds used were furan sand. Experiment result shows that all the designs have microstructure consisting of nodule graphite in ferrite matrix, no trace of carbide and skin effect are formed. Skin effect length is various for all designs. The highest nodularity is only 72% and nodule count shows only 700 nodules/mm2. Brinell hardness number for all design is beyond standard given by JIG G5502. As for UTS and elongation none of the designs exceed the minimal standard. Experiment results confirms simulation result. Compared to the previous result nodularity and nodule count decrease and curve trends for every result are not similar.

Abstract: This paper studies the working principle of TBM cutterhead and analyzes the models of cutterhead breaking rocks. A revised model is presented to think about some rock factors based on the CSM model, in which the attribute of wall rock such as foliation, joint spacing, the angle between boring axis and the surface of foliation and abrasiveness had be taken into account. This probably describes more exactly the real conditions of TBM to break wall rock. To raise the level of design and manufacturing of TBM cutterhead, some advices are provided to design main parameters of TBM and excavating parameters.

Abstract: With in-phase steering, there might be some change at the driving performance of multi-axle vehicle. A five-axle vehicle model has been built with ADAMS software, and the control strategy has been built with Simulink software. The driver steering and speed control model with variable ratio was built. The comparative overtaking simuliation of whole wheel steering and only first two-axle wheels steering was processed. With the simulation, it can be found that, in the same movement track cases, comparing to the only first two-axle steering now used in vehicles, with in-phase whole wheel steering, the angle of steering wheel became smaller, the centroid yaw-rate was reduced, and vehicle movement track was closer to target track. The manipulation performance of vehicle was improved, and the labor intensity of the driver.was reduced. This provides a certain amount of theoretical research for the multi-axle steering vehicle control.

Abstract: In recent years, several sheet hydroforming methods have been introduced by researchers. Despite the advantages of these methods, they have some limitations. The author [1] already proposed a novel sheet hydroforming method that is a combination of the standard and hydromechanical sheet hydroforming processes. The proposed method has the advantages of both processes and eliminates their limitations. In this method, a polyurethane diaphragm was used as a part of die-set to control the blank holder force. In this paper, the effect of polyurethane hardness on the effective parameters of the combined sheet hydroforming die-set such as forming pressure, thickness distribution of formed cup and maximum thinning zone of formed cup was investigated experimentally. It was shown that a softer polyurethane needs to a higher oil pressure to prevent wrinkling in the flange of the part. And tearing occurs at higher level of forming pressure. Also it was shown that by softer polyurethane, better thickness distribution was obtained.

Abstract: In recent years, machine learning techniques have been widely used in intelligent fault diagnosis field. As a major unsupervised learning technology, cluster analysis plays an important role in fault intelligent diagnosis based on machine learning. In rolling bearing fault diagnosis, the traditional spectrum analysis method usually adopts the resonant demodulation technology, but when the inner circle, rolling body or multi-point faults produce composite modulation, it is difficulty to identify the fault type from demodulation spectral lines. According to this, a novel rolling bearing fault diagnosis method based on KFCM (Kernel-based Fuzzy C-Means) cluster analysis is proposed. Through clustering on test data and the known samples, the memberships of test data are obtained. From these, the rolling bearing fault type can be determined. Experimental results show that this method is effective.

Abstract: This paper proposed a method for using the integration of surface electromyography (iSEMG) signals to compute the assistive force produced by wearable assistive robot (WAR). A study was conducted to analyze a subject during lifting his leg tied with different weights. The iSEMG of vastus lateralis (VL) muscle was computed. Then the linear correlation between muscle force and iSEMG was obtained. Finally, the assistive force produced by WAR could be computed by the linear correlation with iSEMG. We find that the effect of assistive force produced by WAR can be clearly analyzed by iSEMG.

Abstract: Recently small satellites have become increasingly popular because of their ability to provide educational institutes with the chance to design, construct, and test their spacecraft from beginning to the possible launch due to the low launching cost and development of microelectronics (Figure 1). Clearly, using only electromagnetic coils instead of different types of actuators will serve the purpose of weight reduction where every grams counts. But some restrictions described in the paper limit utilising only “Electromagnetic” actuation for 3D stabilisation and adversely affects the efficiency of the controller. However, there are some theories developed recently that have made the aforementioned purpose feasible. In this paper a new control method based on Fuzzy Logic Control (FLC) is presented that keeps the satellite in desired conditions only by electromagnetic coils. More precisely, an approach of Fuzzy control which is incorporated with electromagnetic actuation is presented for the in-orbit attitude control of a small satellite. The design is developed to stabilize the spacecraft against disturbances with a three-axis stabilizing capability. The paper also describes the required hardware and the design and development of the magnetic torquers.

Abstract: As a main handling device the portal crane is widely used in port, railroad, etc.The crane handling procedure is mainly carried out through its combined-boom system luffing or swing .In general, in order to reduce drive power and improve the operational performance, the luffing trajectory should meet the design requirement. At the same time, structure stress should be secured in the whole process of handling the cargo. Recently, to deal with more heaver and further cargo, the portal crane is becoming more large-scale. So that the large-scale components such as jib elastic deformation effect on large displacement motion cannot be ignored longer. In addition to the structure high speed motion in the process of handling also make the structure dynamic behaviors spending more obvious specially in the condition of luffing combined with swing. However, the problem for this dynamic behavior brings about to physical design sometimes has no method to solve according to the conventional analysis algorithm and dynamics method. To reduce the deviation caused by the common analysis, design and analysis method based on the multibody is put forward in this thesis. According to the method, the result on the luffing trajectory and stress-time history are analyzed easily. So that it ensure the efficiency and increase the accuracy of the initial design according to the conventional design and analysis method.

Abstract: In order to precisely control signals generators，we designed hardware of waveform signal generator by using AT89C51 Microcontroller, on this basis, design program of the sine wave, triangle wave, square wave and saw tooth wave detailed , final testing of the system as a whole and performance testing , these have high practical and useful in the production.