Applied Mechanics and Materials Vols. 446-447

Abstract: The environmental concerns brought during pickling process of stainless steel in HNO₃-containing acids need urgent attention. Choosing the hydrochloric acid pickling process as study object, this paper conducted a systematic study of the effect of temperature on the electrochemical behavior of stainless steel in hydrochloric acid solution. Research indicated that as temperature rose, the corrosion potential of 430SS in hydrochloric acid solution moved to positive direction with band to a narrow 0.1V. Meanwhile, the current intensity increased which indicated the acceleration of corrosion rate. In addition, the anode Tafel slope increased firstly and decreased later while the cathode Tafel slope increased slightly.

Abstract: The existence of variations in the injection molding process conditions leads to the inconsistency of molded parts quality during the molding cycles. In this research, the variations of cavity pressure-time profiles integrals over the molding cycles were accounted as the molded parts quality variations. Thereafter, the correlations between injection molding process settings and the degree of consistency of molding process were investigated by applying cavity pressure measurement, Taguchi design of experiments approach and signal to noise ratio. The results derived from experiments indicated that an increase approximately as high as five times in the capability of injection molding may be achieved. Under the best setting condition, the cavity pressure profiles were relatively smooth and similar. Low screw rotational speed, high injection speed and short packing time led to the inconsistency elevation of injection molding.

Abstract: The growing demand for light weight materials for the application in the aircraft industries, aerospace industries, marine, sports and recreation industries has attracted the usage of fiber reinforced materials especially GFRP composites. Usage of these kind of materials are exponentially increasing because of its specific engineering characteristics like high strength to weight ratio. Drilling of these materials has been always a challenge because of its heterogeneous nature. Better hole quality is required for these materials for the assembly into components. In this work delamination analysis was attempted using digital image processing, experiments are carried out for 27 holes using full factorial design and it was observed that scanned images obtained using a flat bed scanner (HP, 1300 DPI) used for digital image processing, gives better visualization for delamination. The feed rate is the most influencing parameter out of the three process input parameters considered.

Abstract: Hydroxyapatite (HA) has been widely utilized in the biomedical applications due to its chemical and structural features that are similar to the natural bones. The addition of organic components enhances the flexibility of the HA-based composites which result in increasing its molding ability into any desirable shapes. In this article, preparation of hydroxyapaptite/silk fibroin (HA/SF) composite using sol-gel method is reported. The optimal condition for preparing the HA/SF composites was determined by judging from their crystallite size, crystallinity and particle size distribution, morphology and calcium/phosphorus (Ca/P) ratio investigated with X-ray diffraction analysis, particle size analyzer, scanning electron microscopy and energy dispersive X-ray spectroscopy, respectively. The HA/SF composite was successfully prepared in the binary solvent of ethanol and water at the optimal volume ratio of 4:1. At this solvent condition, the composites had a uniform rod-liked shape, ranging from 30-70 nanometers. The Ca/P ratios of all composites are close to the theoretical value of about 1.67.

Abstract: The wire saw for slicing wafers process is free abrasive machining process. In this paper, we summarize the sawing mechanism for free abrasive wire saw, and think that the sawing mechanism is mainly rolling-indenting removal. But there are two forms of the force which causing the abrasives to roll and indent in the workpiece surface, one form the force acts on the abrasives by shear stress and hydrodynamic pressure, another form the force acts on the abrasives by wire saw. We design an experiment to verify the form of the force, and think that the second form of the force mainly causes the abrasive to roll and indent in the workpiece surface.

Abstract: The irradiation-induced hardness change in a commercial P92 ferritic/martensitic steel has been investigated through 3.5MeV Fe-ions irradiations to a dose of 0.29dpa at room temperature, 673K and 973K combined with nanoindentation techniques. The results show that irradiation-induced hardening was observed at the room temperature, and softening occurred at 673K and 973K. The hardening at room temperature is ascribed to the crystal defects in the steel generated by Fe-ions irradiations. The softening at 673K and 973K may be caused by the recovery of the defects.

Abstract: Shock-induced phase transition under intensive impact loading can strongly change the dynamic behavior of materials and wave propagation features. Dynamic constitutive modeling is one of the key problems in this area. We established a 3D dynamic incremental constitutive equation of phase transition with N transforming phases considering pressure, shear stress and temperature based on the Gibbs free energy. We also proposed an evolution equation for the product phase taking account both the over driving force and the growing space. The dynamic stress-strain response predicted by the model for TiNi specimen undergoing martensitic transition fitted the experimental result well, which demonstrates the present model can describe the dynamic deformation behavior of materials during phase transition process under impact loading.

Abstract: In order to get the single cortical neurons fitting the study of patch-clamp technique.use the kunming mouse with the birth of 10 days or so, and separate neurons in the cerebral cortex through acute separation technology and enzymatic hydrolysis. A cone-shaped adherent neurons are selected and observed in rapid dissociation and cell activity status under the inverted microscope. Different ion channel blockers is added to the extracellular fluid and used whole-cell recording which can obtain Na ⁺, K ⁺ and other ion channel currents. This method can obtain good morphological and physiological characteristics of both single cortical neurons, confirming that the method applied to cortical neurons by patch clamp technique, which has significant value for in-depth research on drugs, toxins and other physical factors on the electrical activity of neuronal ion channels and signal transduction mechanism of the effect.

Abstract: Atomization quality affects directly burning process in the cylinder so as to further impact on dynamic characteristics, economical efficiency and emission standard. In theory, based on influences of jet dispersion properties for cavitations and jet development model of the mixture of emulsified oil and gas, it is found that high pressure emulsified oil contains lots of tiny water drops, which can increase a atomizing angle for spraying. Compared with the atomizing shapes of absolute diesel oil and emulsified diesel oil at various time, the results show: jet form of mixture changes dynamical characteristics of emulsified diesel oil when it is spraying from the nozzle orifice and its diversification of characteristics also correlates with the atomizing angle. When the percentage of water contents of emulsified diesel oil is 10%, the atomizing angle can get the maximum, which increases by 35%. At the same time, the jet atomizing angle will be increased and the jet valid length will be reduced when the container pressure is improved.

Abstract: Diesel engines are widely used in logistics and haulage as vehicular prime movers. In the mechanized and fast-moving forward world of today, the consumption of petroleum products has become an important yardstick of a country’s prosperity. This ever-increasing consumption has led the world to face the twin challenge of energy shortage and environmental deterioration. Natural gas has been one of the highly considered alternative fuels for both spark ignition (S.I) and compressed ignition (C.I.) engines. The advantages and benefits of CNG have made it the preferred choice as alternative fuel in the transportation sector. This present study focused on the effects of retrofitted direct injection C.I. engine with mono-CNG system to its performance and exhaust emissions. The engine speed was varied from 850 rpm to 2500 rpm, with load test conditions of 0Nm, 27.12Nm and 53.23Nm, using an engine dynamometer. Results indicated that CNG has the potential to provide better fuel consumption compared to diesel fuel. Meanwhile, the characteristics of exhaust gas emissions such as smoke opacity and CO2 gave promising results compared to CO, HC and NOX, for diesel combustion.