Applied Mechanics and Materials Vols. 138-139

Abstract: Non-obstructive particle damping (NOPD) is developing in combination with particle damping technique, impact damping technique and material science. NOPD technology has good damping characteristic and nicer effect on vibration absorption. In the paper experiments of vibration absorption characteristic for beam applying NOPD are done and some conclusions are obtained, which affords important reference for engineering application of NOPD technique.

Abstract: For one cantilever steel beam, according to the stress concentration principle resulted from the small hole, four small holes were drilled at different positions to form the local damage of the steel beam. The modal tests including the displacement modal and the strain modal were conducted before and after the steel beam was damaged. The test results indicated: from the decreased frequency, one could only judge on the whole that the steel beam had been damaged, but could not determine the detailed damaged positions; the detailed damaged positions of the steel beam were also difficult to be determined by the displacement modal test whether by ripple technique or by hammering technique, but could be determined by the strain modal test by hammering technique, especially under the first order of modal. The research achievements can offer some references for the diagnosis of local damage of engineering structures by the strain modal analysis method.

Abstract: Tool condition monitoring, mainly tool breakagedetection for high-speed machining (HSM), is an importantproblem to solve; however, the techniques or types ofsensors applied in other research projects present certaininconveniences. In order to improve tool breakage monitoringsystems, a simple, effective, and fast method ispresented herein. This method is based on the discretewavelet transform (DWT) and statistical methodologies.The effectiveness of the method is based on the measurementsof the feed-motor current signals using inexpensivesensors. It is well-known that during the cutting process,the motor current is related to the tool condition.

Abstract: This paper explores the effect of grain size on machining strength in an Fe-Cr-Ni alloy (AISI 316L). Ideal grain growth law [1], was used to obtain the activation energy level for this steel, which was 185 kJ.mol^-1 [2]. The initial grain size was measured (12 μm) and considering these values, both temperature and time values needed to achieve a final grain size ten times larger than the initial one, could be calculated, which were 1200°C and 2 hours. Ternary phase diagram analysis showed that austenite was stable at this temperature. Following, samples of 200 mm length were annealed and quenched in water to prevent any formation of sigma (μ) phase. Annealed and as-received bars were then used to compare their machining strength. Results showed that the machining strength is higher in the as received condition than the one after annealing (127 μm). It may be concluded that the bigger the grain size, the lower its machining strength. It is believed that this is caused by the pile-up of dislocations on grain boundaries, since this material exhibits large plastic deformation before fracture.

Abstract: The boron-doped diamond film electrode grown on tantalum substrate (BDD/Ta) was prepared by hot filament chemical vapor deposition (HFCVD) technique. The morphology and quality of BDD/Ta film electrode were investigated by SEM and Raman spectroscopy respectively. The electrochemical behavior of the BDD/Ta film electrodes in Na₂SO₄ solution was also investigated by cyclic voltammetry and the window potential of BDD/Ta film electrode in Na₂SO₄ solution is of 4.1V, the hydrogen and oxygen evolution potentials are of-1.8V and +2.3V respectively. The characteristic measurements of BDD/Ta film electrode and its application to degradation of high concentration organic wastewater indicated that BDD/Ta film electrode have a series of advantages, including high overpotential for oxygen revolution, high current efficiency, good removal of chemical oxygen demand (COD).

Abstract: This paper proposed a design of the office chair with multi fitness function (multi-functional office chair for short) which can mainly achieved comfortably office; adjust the reline angle, doing fitness activities, such as stretched movement, kicking motion, sit-ups and so on. It not only satisfies the needs of people's daily work, rest and fitness exercise, but also meets the design requirements of ergonomics.

Abstract: TiCu-based bulk metallic glasses with large plasticity (up to 10%) were fabricated by copper mold suction casting. The detailed studies showed that the large plasticity resulted from the nanoscale heterogeneities formed upon solidification, which resulted in extensively shear band formation, branching and interaction.

Abstract: A new series of functionalized ionic liquids containing ester-group were synthesized through a typical two-step way. The physicochemical properties of the functionalized ionic liquids were studied and the tribological properties of them as lubricants for steel-steel contact were evaluated on an SRV friction and wear tester and compared with the perfluoroalkylpolyether (PFPE), a low-volatility and fluorine containing lubricant, and a conventional ionic liquid, 1-butyl-3-methy imidazolium tetrafluoroborate (LB104), which is nonfunctionalized. Results showed that all the ionic liquids studied in this paper have better lubricities than PFPE as lubricants for steel-steel friction pairs. Functionalized ionic liquids show worse friction reducing abilities at relatively lower loads, which could be ascribed to their higher viscosities, but they always exhibit better anti-wear abilities than LB104. The possible friction mechanisms were discussed.

Abstract: Acoustic emission is a very important test among non-destructive tests, and it has been applied for the detection of failures in various types of equipment in the petroleum industry, such as pressure vessels, tanks and pipelines. In this study, the effect of pre-existing uniform corrosion on the corrosion fatigue specimen and smooth specimen on fatigue behaviour of API 5L X70 steel pipeline in long life range was investigated by using acoustic emission in fatigue test. The presence of pre-existing uniform corrosion specimen, produces by 4 month immersion in sulphuric acid, H₂SO₄ (concentration 0.2 ml H₂SO₄ in 5000 ml deionized water ). Fully reverse (R = -1) constant amplitude fatigue test were done in corrosion fatigue and smooth specimen in different stress amplitudes. It was found that, effect of pre-existing uniform corrosion significantly reduced the fatigue life of the steel pipeline. The correlations of accumulative AE counts for corrosion fatigue higher than fatigue test because of the mechanisms of possible AE sources due to corrosion.

Abstract: Withdrawn at authors request.