Applied Mechanics and Materials Vols. 34-35

Abstract: In recent years, manufacturing processes have become more and more complex, manufacturing activities generate large quantities of data, so it is no longer practical to rely on traditional manual methods to analyze this data. Data mining offers tools for extracting knowledge from data, leading to significant improvement in the decision-making process. Association rules mining is one of the most important data mining techniques and has received considerable attention from researchers and practitioners. The paper presents the basic concept of association rule mining and reviews applications of association rules in manufacturing, including product design, manufacturing, process, customer relationship management, supply chain management, and product quality improvement. This paper is focused on demonstrating the relevancy of association rules mining to manufacturing industry, rather than discussing the association rules mining domain in general.

Abstract: Periodic impulses in vibration signals and its repeating frequency are the key indicators for diagnosing the localized damage of rolling element bearings. A new method, so called time-wavelet energy spectrum, is proposed to extract the characteristic frequency of faulty elements. It is applied to analyzing the vibration signals of bearings under normal and faulty (with damage on outer race, inner race and ball respectively) statuses. The analysis results show that the time-wavelet energy spectrum is effective in extracting the repeating frequency of periodic impulses. It can not only extract the relatively significant fault feature of outer race damage, but also can extract the weaker fault features of inner race and ball damage.

Abstract: Wireless sensor network overcomes the limitations of conventional tethered measurement techniques. It can be used in many situations where conventional tethered sensors cannot be employed due to the safety requirements, space limitation, and wiring cost. Thus it can further expand testing area, and improve measurement performance. A vibration monitoring system is developed based on wireless sensor network. Its architecture and principle are introduced, and its performance is validated by signal generator simulation and a gearbox vibration test.

Abstract: Due to environmental concerns and the coming legislations, pollution-free and eco-friendly minimum quantity lubrication (MQL) technology has become focus of attention in manufacture field. The MQL and cooling system in this work has been designed, fabricated and used. The cutting performance of MQL with cooling air compare with the conventional cooling method in milling of GH4169 aerospace superalloy is evaluated based on analysis of cutting force and surface finish. The effect of cutting parameters (depth of cut, feed rate) on machining performances is analyzed. The experimental results show that, the application of MQL and cooling air brings about a lower cutting force, better surface finish compared to conventional coolant environment.

Abstract: A condition monitoring and fault diagnosis system for heavy duty diesel engines used in off-highway vehicles is developed. Via this system, the vibration, rotating speed or angle, temperature and pressure signals can be collected simultaneously at a high speed. The software is developed using virtual instrument technique. The system provides various types of signal analysis methods, and manual and intelligent diagnosis functions. Its performance is validated in engineering practice. The system can be generalized for monitoring and diagnosis of various reciprocating engines.

Abstract: The S beam of a production SUV appeared instable deformation in frontal crash test, which was not beneficial to occupant protection. So the deformation of S beam should be controlled to improve the crashworthiness. Inner improvement structures were proposed according to the prototype S beam. A frontal crash FE model and a multi-rigid body model were developed and validated to investigate the crash safety of frontal impact. The influences of the improvements to the deformation of S beam and the energy absorption of longitudinal beams were analyzed by the FE model, and the injury risks of head and thoraces were analyzed by the multi-rigid body model. The better improvement structure was adopted in the frame for the crash test to validate the effectiveness of improved scheme, and the result shows better crash performance of frontal impact for prototype vehicle. Meanwhile, simulation study on crash safety of 40% offset crash were also conducted, which indicated that improved scheme was also beneficial for crash safety of 40% offset crash.

Abstract: For the theory and feature of EDM notching, the actual situation thermal model was established; by finite element method, EDM notch process base on killing and activating elements was successfully simulated, thermal and stress after notching was analyzed, while the conditions and mechanism of cracks generation was discussed.

Abstract: Low temperature ammonia plasma surface treatment on asphalt base carbon fiber is reported with 150°C for 60min, 200°C for 60min and without treatment. The surface topography, chemical composition and structural changes were followed by Atomic force microscope(AFM), X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy, of which indicate the treatment could improve the density of carbonyl and amino functional group on the surface of carbon fiber, which can also changed carbon crystalline structure. The density of carbonyl and amino functional group was shown higher for the fibers treated at 150°C than for the fibers treated at 200°C which could be attributed to the temperature and introduced Si element factors.

Abstract: Based on an interactive genetic algorithm implemented the bags innovation design and optimization, a structure that contains 10 operators system integrity algorithm is built, including individual programs, constraints structure, species maintenance, individual evaluation, selection, restructuring, variation, optimization control, decoding and interactive selection. The bags visualization species have been constructed, and the optimization methods can be realized through crossover and mutation genetic manipulations. The experimental results confirmed the effectiveness.

Abstract: The butt welding of 45 carbon structural steel has been analyzed using a nonlinear transient finite element (FE) model. With numerical analysis technology, welding heat transfer and thermal elasto-plastictity have been progressed. Also the effects of welding seam growth with heating source movement have been studied using the birth and death technique. For this purpose, a 3-D structural and thermal direct-coupled solution has been used to obtain the temperature changing curves and residual stresses distributions. In addition, the variations of physical properties of material with temperature have been taken into account. Results indicate that the heating speed of welding is rapid, and the distributions of residual stresses are not symmetrical along the welding seam’s centerline, and the residual stresses are change along the welding direction and also in the plate-thickness. It has been shown that use of 3-D direct coupled-field and nonlinear transient model will lead to more accurate and realistic results.