Applied Mechanics and Materials Vols. 548-549

Abstract: The polishing process plays an important role in the stainless steel cookware since an appearance is one of the prime quality criterions of the product. Typically, there are three sequential steps in the polishing process using abrasive flap wheel, sisal and cloth respectively. The abrasive flap wheel is the first step in the process which aims to rapidly create fine surface finish on the product. Thus, the selection of appropriate flap wheel as well as operating conditions in order to achieve surface finish within the required cycle time i.e. 12 seconds are the key success factor. Therefore, the experimental design is conducted and analyzed. It is found that there are four factors which influence the surface roughness: grits size of flap wheel, polishing time, velocity, and force. It can also be concluded from the analysis that the roughness is directly proportional to grit size and force but it is inversely proportional to velocity. In addition, the optimal condition for the case study can also be obtained.

Abstract: This paper presents the results of an experimental investigation on axially loaded PFRP compression members having double C-sections with pinned-pinned supports. The objectives of this research work are to investigate their structural behaviors and modes of failure and to propose their design equations. The specimens were built from single PFRP C-section, having three cross-sectional dimensions of 76×22×6 mm, 102×29×6 mm and 152×43×10 mm. A total of 42 specimens with slenderness ratios ranging from 21 to 168 were tested. The compression members can be classified as short and long. The short compression members have linear behavior up to 90% to 95% of the ultimate crushing loads. The long compression members have linear behavior up to 80-90% of the flexural buckling loads. By comparing and fitting the test results with the design equations as presented in the ASCE Structural Plastics Design Manual, the design equations that can be used to predict the ultimate compressive stress of the compression members were proposed.

Abstract: The aim of this paper is to develop computer simulation model of railway vehicle using multibody system (MBS) package. ADAMS/Rail was used in modeling and simulating complex realistic railway vehicle system to study their dynamics response to curve and straight track inputs. The Malaya Railway Limited or Keretapi Tanah Melayu Berhad (KTMB) railway vehicle is used as reference model to develop computer simulation model in ADAMS/rail. Curve track input was based on KTMB rail network with maximum curve radius of 1000 m. Straight track input with random vertical irregularity was applied to the 1000 m track to evaluate the vehicle behavior response to track vertical roughness. The results show the roll angle, lateral and vertical acceleration of the carbody was increases with the increases of vehicle speed.

Abstract: The supercritical airfoil has been widely applied to large airplanes for sake of high aerodynamic efficiency. But at transonic speeds, the shock wave on upper surface of supercritical airfoil may induce boundary layer separation, which would change the aerodynamic characteristics. The shock characteristics such as location and intensity are sensitive to Reynolds number. In order to predict aerodynamic characteristics of supercritical airfoil exactly, the Reynolds number effects of shock wave must be investigated.The transonic flows over a typical supercritical airfoil CH were numerically simulated with two-dimensional Navier-Stokes equations, and the numerical method was validated with test results in ETW(European Transonic Windtunnel). The computation attack angles of CH airfoil varied from 0oto 8o, Mach numbers varied from 0.74 to 0.82 while Reynolds numbers varied from 3×10⁶ to 50×10⁶ per airfoil chord. It is obvious that shock location moves afterward and shock intensity strengthens as Reynolds number increasing. The similar curves of shock location and intensity is linear with logarithm of Reynolds number, so that the shock location and intensity at flight condition could be extrapolated from low Reynolds number.

Abstract: In order to research the drag force and balance characteristics of undersea observatory platform during the sinking process. The effect base in different shape and arrangement on the flow field are studied with the help of Fluent, the relationship that how shape and arrangements of base influences drag force and balance characteristic are studied. The results show that pressure drag is the main component of the whole drag force. Round pie base suffer the least drag force, adopting the arrangement that put a round pie base at each vertex of hexagon, undersea observation platform would maintain good stability during the sinking process.

Abstract: Applying the Path Integral Solution Method, the stochastic heave motion of Truss Spar platform was studied in this paper. Taking a platform for example, probability density function of stochastic heave motion amplitude was calculated under the conditions of different wave excitations. The results show that, the changing process of probability density function in the time domain has an obvious periodicity. As the increasing of external excitation, the heave motion amplitude and speed both increases. Meanwhile, as the increasing of excitation amplitude, the probability density function of heave motion has a more pronounced periodicity.

Abstract: Metallic sandwich panels based on lattice truss structure have been developed for a wide range of potential applications with their lightweight and multi-functionality. The study focused on the analytical approach to investigate compression and shear characteristics of pyramidal and tetrahedral truss unit cells. With various unit cell models which have the same weight per unit area but different member angle, analytical solutions for effective stiffness and strength have been predicted and compared with each other. The results showed that there are the most optimal core configuration to maximize effective mechanical properties.

Abstract: The extended finite element is known as the most promising numerical simulation method of crack propagation. In this paper Abaqus software is used to simulate the propagation of the Type I crack and verify the reliability of the numerical methods. With five different vertical distribution of pre-crack established, the paper respectively analyzes the vertical position’s influence on total crack extension form, X direction extension form and Y direction expansion form. By calculating the expansion velocity values, X direction expansion velocity values and Y direction expansion velocity values, the paper also analyzes the influence of crack location on each speed.

Abstract: This paper deals with engineering investigation and equipment design of a new multi-stage distillation system. The facility was designed in UDES center with the objective of increasing its productivity and improving its efficiency. Distillation device consists one of important process to produce fresh and clean water from brackish water that is abundant in many remote areas of south Algeria. In general, the production rate of the conventional solar still shows a daily production of 5 l/m2d which depends strongly on the material used and equipment design together with different factors. In comparison, Multi tray still mounted with four stages is more profitable in term of the output than a simple still. The various results, from which the effect of the boiler temperature T_b is presented in the range 75°C<T_b<95°C. The obtained results show that the first tray of the system produces about 33 liters of fresh water per day when the temperature of the evaporator efficiency is fixed at 96°C. Determinations of the output of each tray of the still are presented in this study. In fact, experimental data suggests that the tray number have a limit number to achieve a highest throughput with a most compact system. The analysis of the distilled water showed that its quality was within the international standards. We notice that water desalination with multi stage equipment is a good solution for a better output.

Abstract: During forming process of sheet metal, friction phenomenon occurs everywhere. Galvanized sheet is the combination of substrate and zinc coating, which are two different materials of different properties. Compared with ordinary cold-rolled steel sheets, friction during forming process of galvanized sheet is more complicated. Factors like load, velocity, etc. have different effects. In this paper, effects of zinc coating, velocity and load on galvanized sheet friction coefficient were researched based on orthogonal tables with using friction wear tester. The results show the following conclusions. Zinc coating has great effect on galvanized sheet friction, friction coefficient of zinc-coated sheet is greater than that of bare board under low load (0.3~1 N), but smaller than that of bare board under high load (1~5 N). Galvanized sheet friction coefficient also changes when load or velocity changes, with load increases, it first increases and then decreases; with velocity increases, it first increases and then decreases. Mechanism of the influence rules above was simply analyzed. Significance of the three factors above could also be seen. Under low load, effect of zinc coating on galvanized sheet friction coefficient is the greatest, followed by that of load, and finally that of velocity, but none of them is significant; under high load, effect of zinc coating is significant, those of velocity and load are not significant.