Applied Mechanics and Materials Vol. 87

Abstract: Edible films based on whey protein isolate and sodium caseinate were prepared by uniform design method. Glycerol has been incorporated into the edible films as a plasticizer. For all types of films, the influences of components and forming temperature on film properties, such as mechanical properties, water solubility, optical properties, gas and water vapor permeability were investigated. The results suggested that glycerol was the most important factor influencing all the properties of edible composite protein films. However, both increases of sodium caseinate concentration and glycerol content contributed to decrease the barrier properties of gas and water vapor. Among the films studied, group D (prepared with 5% whey protein isolate, 2% sodium caseinate, 50% glycerol at the temperature of 50 °C) showed moderate mechanical properties, optical properties, water solubility and maximum barrier properties of gas and water vapor, with tensile strength=5.85MPa, elongation=101.20%, transparency=91.4%, gas permeability rate=49.92cm³ m^-2 d^-1 0.1MPa^-1 and water vapor permeability of 0.128×10^-11 g m^-1 s^-1 Pa^-1, 0.260×10^-11 g m^-1 s^-1 Pa^-1, 0.513×10^-11 g m^-1 s^-1 Pa^-1, 1.252×10^-11 g m^-1 s^-1 Pa^-1 at the RH gradient of 10-40%, 10-50%, 10-60%, 10-70%, respectively.

Abstract: Advanced ceramics are difficult to do machining due to brittle nature. High cutting forces will generate in the machining, which will affect the surface integrity of final product. Selection of proper machining parameters is important to obtain less cutting force. The present work deals with the study and development of a cutting force prediction model in end milling operation of Aluminum Nitride ceramic. The cutting force equation developed using Response Surface Methodology (RSM) to analyze the effect of Spindle speed, feed rate and axial depth of cut. The cutting tests were carried under dry condition using two flute square end micro grain carbide end mills.

Abstract: Investigating Fatigue is one the most important factors in designing most mechanical structure. The reason is that, in many cases, the specimens of the structure break down without any warning or signal. Nano and micron’s Coatings are finding more and more applications in industry such as aerospace, automotive, and naval industries. The present article has a purpose. Firstly, it intends to explore the influence of four industrial coatings, namely, hardened chromium, embellished chromium, hardened nickel, and warm galvanizing, all of which have the thickness value at micron levels on fatigue specimens. Moreover, it aims to find the most convenient coating. To achieve these purposes, the abovementioned coatings with the thickness of 13 & 19 were coated on standard specimens who were made of CK45 steel under the same conditions. Then, the S-N curve of each sample was attained empirically according to the standard fatigue testing. Specimens are simulated in the finite element analysis according to experimental conditions and then S-N curve of each sample was attained. Finally, comparing the S-N curves, the most appropriate coating is introduced for the delineated conditions and based fatigue results may be predicted damage of coating.

Abstract: For the damage process of rock is a kind of energy-consuming process in nature, it should conform to the least energy consumption principle. Here, a new damage evolution model based on the least energy consumption principle is proposed. With real experiments of granite specimens, the new model is verified. It can be seen that, the stress-strain curves (part before the peak) of the theoretical curve is coincided with the test curve well. So, this new method is suitable to describe the evolution process of rock damage.

Abstract: Oxide dispersion strengthened (ODS) ferritic alloys of composition Fe-19Cr-0.5Y₂O₃ have been prepared by mechanical alloying at various heat-treatment conditions to produce a range of grain sizes and dispersed oxide particle size. Fine oxide particles appear to pin grain boundaries and result in inhibition of grain growth in the alloy matrix. Particle strengthening is shown to be a larger component of the material strength, rather than grain boundary strengthening or matrix strength, indicating that the finely dispersed oxide particles contribute very significantly to the total strength of 19Cr-ODS ferritic alloy.

Abstract: Vector control system is dependent of parameters of motor, and rotor time constant usually changes with temperature. Through analyzing the influence of rotor time constant variations on the control system performance, a novel identification method based on adaptive flux observer is presented. Different with traditional pole assignment method, it implies robust control theory and Lyapunov stability theory, by solving a linear matrix inequality (LMI) to obtain the feedback gain matrix. The simulation results show that this method can identify the rotor time constant of induction motor accurately, and it has rapid converge, good indiscrimination degree and strong robustness.

Abstract: A load test was performed on reinforced concrete beams that were strengthened with carbon fibers. Seventy five thousands blocks were placed in four stages. A quality and management team worked continuously in the testing process. No creep effects were noticed with the use of carbon fiber plates, an interesting observation.