Advanced Materials Research Vol. 1016

Abstract: This study presents results regarding a numerical simulation of the plastic displacement of a road guardrail. An experimental study of two different guardrails was conducted in order to collect information regarding displacement due to a determined force behavior. These tests were then simulated in Ansys Workbench to recreate the elastic and plastic domain of the material. The guardrails are two meters long, supported by two simple cylinders while being pressed at the center by a third one. In order to explore the software two different mesh sizes were used to compare their efficiency, being concluded with the comparison between the force-displacement curves of numerical and experimental results.

Abstract: This paper investigates the torsional load capacity of three sizes of V-section band clamps when assembled onto rigid flanges by comparing experimental data with a developed theoretical model. This mode of failure is of particular interest for turbocharger applications where, in use, they are subjected to torsional loading via thermal and vibrational effects. The theoretical model developed allows the impact on torsional load capacity of a number of joint parameters to be investigated and good correlation of the results, incorporating variations in coefficients of friction and dimensions, has been shown for the two larger band sizes. For smaller diameter bands, the experimental data suggests that as the band is tightened, contact with the flange is localised rather than being over the full circumference of the band. The coefficients of friction, in particular that between the flanges, and the position of the contact point between band and flange have been shown to have a significant impact on the theoretical torsional load capacity of V-section band clamps.

Abstract: In the continuous casting process, significant amounts of molten steel are left in the ladle during teeming as an established practice to avoid vortexing funnel formation in the end of the teeming process, preventing the ladle slag to be carried over to the tundish. Thus, it was the objective of this work to experimentally and numerically analyze the funnel formation in ladle teeming process. Experiments were designed and carried out to verify the numerical results.

Abstract: A gear-linkage mechanism, composed of a planetary gear mechanism and a four-bar mechanism, has the characteristic of step-cyclical output rotation under a reasonable geometric parameters. The analysis of stepping movement of the base unit and the motion characteristic of the combined mechanism was made, and the parameter equation was figured out. Motion simulation was carried out to analyze the influence of transmission ratio on the variation of the output shaft angular displacement, which proved that the output steps was in correspondence with , and as value of increasing, the rollback of the output motion was more apparent. The gear-linkage mechanism can be applied to engines, pumps and compressors.

Abstract: AZ31 magnesium alloy sheets are usually performed at high temperatures of 200 to 250°C due to their unusual hexagonal close-packed structure and low ductility at room temperature. In this study, to predict the spring-back of AZ31 magnesium alloy sheets in a roll forming process subjected to high temperatures, so the spring-back phenomenon consider in various temperature using an explicit finite element code. Finally, the roll forming process for a magnesium alloy sheet at high temperatures was performed to verify the spring-back angle, which was then compared with the spring-back angle predictions of the FE simulation.

Abstract: Wear resistance of an upper hook, an important fishing net-weaving machine component manufactured from stainless steel, was improved by systematically investigating the influence of molybdenum nitride (MoN) sputtering coating using experimental design. Three factors of MoN coating on upper hooks including DC current, operating pressure, and Ar/N₂ ratio were studied and optimized for minimum wear of the machine component. After conducting wear testing on the fishing net-weaving machine in a participating company, it was found that the three coating factors influenced the wear of the machine component. In addition, the optimal operating condition for MoN sputtering coating that produced the minimum wear was obtained at DC current of 0.45 A, operating pressure of 0.01 mbar, and Ar/N₂ ratio of 0.5.

Abstract: We present two level approach to build accurate approximations for Reserve Factors dependency on loads for composite stiffened panels. Such dependency is continuous non-smooth function with complex form plateaux regions (i.e. regions where function has zero gradient), defined on low dimensional grids. The main problem that arises if one tries to construct global approximation in such case is the occurrence of Gibbs effect (i.e. harmonic oscillations of prediction) near the borders of plateaux that may significantly deteriorate approximation quality. Viable existing solution: approximation based on linear triangular interpolation avoids oscillations, but unlike the proposed approach it provides model that is not smooth outside plateaux regions and generally requires larger sample size to achieve same accuracy of approximation.

Abstract: In this study, the mechanical properties of a weaving machine component made of cast stainless steel are improved by the duplex coatings of electroplated hard-chrome and sputtered metal nitride layers. The effects of the first and second coat layers of three metallic nitrides, including TiN, TiN-Ni and NiN, were comparatively studied. The structural characteristics of the coating materials were studied by scanning electron microscopy, energy dispersive X-ray spectroscopy and X-ray diffraction. Vicker hardness was then measured by nanoindenter. It was found that the duplex coating surfaces gives better surface quality than those of single-layer coated ones. In addition, the hardness of single-layer coating either with hard-chrome or metal nitride was only 2-3 times higher than uncoated ones whereas duplex coating with both layers synergistically increases the hardness by a factor of 7-8. Moreover, duplex coating with TiN exhibits relatively high hardness compared with other metal nitrides.

Abstract: The adhesive structural mechanical performance is influenced by debond flaw. This paper presents a research on the effect of flaws on the mechanical performance of composite scarf joints. The experimental results show that the load-carrying capacity of composite scarf joints changed along with the location of the debond flaw. The location of the flaw in the bondline influences the failure mode. Additionally, the finite element method was employed to obtain the failure mode of the composite scarf joint. The adhesively bonded joints were modeled using ABAQUS software. The computational results show that flaws located at the edge of the bond region result in more pronounced load reduction than which located at the middle of bond region.

Abstract: Severe plastic deformation (SPD), where metals are deformed up to very high strain values, leads to a very small grain size and a high strength of the material. ECAP (Equal Channel Angular Pressing) is one of the SPD methods, and involves the extrusion of a metal billet through two intersecting channels with identical cross-section and forming an angle between them. The material undergoes shearing as it crosses from one channel to the other, but its external dimensions are not altered. Shearing occurs along a single plane, which may lead to anisotropy in the mechanical properties of the material after ECAP. Compression, tension and shearing tests along various directions in the as-processed specimens indicated the presence of mechanical anisotropy in ECAP processed aluminum.