Applied Mechanics and Materials Vol. 392

Abstract: Previous studies on corrugated metal gaskets have established that the contact width, contact stress, and surface roughness are important design parameters for optimizing gasket performance. However, the metal gaskets studied previously required a high axial force for the tightening process; in addition that metal gaskets tend to corrode easily. In this study, we examined the deformation mode of a thin stainless gasket using a finite element method (FEM) analysis. A final evaluation was made using a compression examination. The analysis based on the dimension of flat and convex portion. The load, deformation mode, and contact stress were obtained through a simulation. Based on the deformation of the flat and convex portions, the deformation modes were divided into three types. The deformation mode of the thin stainless gasket material has a higher probability of deformation in mode I when the aspect ratio of the length of the flat portion to the length of the convex portion, L/D, increases.

Abstract: In this paper, preliminary investigation of a new cement-sand based piezoelectric composite was conducted for potential structural engineering applications. PZT ceramic powder has been incorporated into cement material to form composite smart materials in earlier studies and showed promising outcome. However, the previous studies were limited to using only PZT and cement. In this study, PZT powder mixed with cement and sand, which is more realistic in civil engineering applications. The compressive strength of the composites with different PZT volume ratios was investigated. The results showed that embed PZTs increased the strength of the composites. Modified Sawyer-Tower circuit was applied to pole the composites in order to obtain the desired electrical properties of the composites. The mechanical and electrical properties of this type of new smart material had been investigated experimentally. Through a series of MTS compression tests, feasibility of using cement-sand based PZT composite materials in civil engineering is evaluated.

Abstract: Through flotation recovery of Silver (Ag) from Zinc acid-leaching residue (ZALR) was investigated in this study. The study adopted the single factor and orthogonal test reveal interactions among all considerable influence factors including sodium sulphide (SS) as regulator, ammonium butyl dithiophosphate (ABD) as major collector, GC as minor collector, interaction between ABD and GC, OC as flotation carrier, and pulp density. The experimental results show the flotation of the circuit composited of one rougher, one cleaner, one scavenger and middlings being back to the next rough flotation together is practical way and that the concentrate containing Ag 10890.0g/t, recovery77.43% can be obtained from the residue (Ag grade 340g/t). The optimum roughing flotation process is: the pH value of flotation pulp is 3.0~4.0, the pulp density is about 45wt.%, ABD dosage is 900g/t, GC dosage is 50g/t, OC dosage is 2000g/t, and BK201 dosage is 100g/t.

Abstract: The objective of the present work is to study the effect of sintering temperature on the formability and pore closure behavior of the Al-SiC composites. Aluminium matrix composites reinforced by 10% and 20% SiC by weight were produced by powder metallurgy technique and sintered at 605°C in different time duration namely 90, 180 and 270 minutes. A complete cold upsetting test was performed on the as-sintered preforms to evaluate the effects of SiC addition and the sintering temperature on the forming behaviour of the Al-SiC composites. The formability stress index was evaluated and discussed in terms of geometric and matrix work-hardening. It was observed that the formability stress index reaches very high value for higher amount of SiC addition. Also with increasing sintering time the formability stress index increases due to a decreased pore size.

Abstract: Fine blanking is a press-working process that permits the production of precise finished components which are cleanly sheared through the whole cutting surface. It can be eliminated secondary operations, such as milling, grinding, etc. Recently, many studies on the weight reduction of automobile for fuel saving were underway. Especially, there are many examples in which light metal like Al were applied for automotive parts. Eco-Al is the new material which is replaced Mg of aluminum alloy with Mg+Al2Ca, therefore Eco-Al material has improved mechanical properties and formability. The clearance between the punch and die of a fine blanking tool is an important design factor that affects the sheared surface of a product. In a fine blanking process, the clearance is typically assigned a 0.5% material thickness. If the clearance is too big, a fractured surface would occur in the product while if it is too small, bulging would occur. In this study, a setting for optimum clearance was proposed for inner corner shapes by checking shear characteristics and bulging effects according to various clearances. After designing a special part with various corner shapes possessing Eco-Al5052 (thickness: 4 mm), a fine blanking tool was constructed and fine blanking experiments were conducted. The result could be usefully applied in fine blanking processes for Eco-Al automobile parts with corner shapes in the future.

Abstract: This paper deals with finite element modeling (FEM) and simulation of machining of titanium alloy and H-13 tool steel. Titanium alloys are very suitable for airframe manufacture and aircraft as H-13 uses forging dies and machined die casting. The machinability of both metals was evaluated by high temperature and tool wear. Finite element simulation was performed with ABAQUS explicit software to predict cutting temperature and stress distribution during metal cutting process. The purpose of this study was evaluation the performance of PCBN cutting tool material on machining of titanium alloy and H-13. It was found that PCBN tool can resistant well against high thermal shocks, high temperature and stress distribution when machining difficult to cut materials. The results can give a better understanding of cutting tool material for metal cutting process.

Abstract: In order to study the impact of nanoZnO on the mechanical properties of PLA, nanoZnO modified with different surface treatment agents (titanium ester NDZ-201,silane coupling agent KH550 ) was added to PLA matrix. The samples were examined by fourier transform infrared (FT-IR) spectroscopy, mechanical properties and SEM. The results show that infrared spectra of nanoZnO modified with different treatment agents include two peaks at 2852cm^-1 and 2925 cm^-1, which are corresponding to C-H stretching vibration, peak at 1735cm^-1 which is corresponding to NH₂, and peak at 964cm^-1 which is corresponding to P-O-Ti.when the addition of nanoZnO reaches to 1wt.%, the tensile strength of PLA/ZnO nanocomposites have the maximum values of 47.43MPa, increase to 9.64% by pure nanoZnO. The mechanical properties of PLA/ZnO nanocomposites can be improved modified with different treatment agents, and the dispersion of nanoZnO has been significantly improved.

Abstract: This paper investigates the tensile properties and fracture toughness of a liquid rubber-modified highly crosslinked epoxy cured using 4,4 diaminodiphenyl sulphone (DDS/LR). The results for DDS/LR epoxy in relation to rubber and matrix properties are also compared with those of rubber-modified lowly crosslinked epoxy systems, namely, liquid rubber-modified piperidine cured epoxy (Piperidine/LR) and core-shell-rubber modified piperidine cured epoxy (Piperidine/CSR). It was found that highly crosslinked DDS/LR epoxy has a higher tensile strength than that of either Piperidine/LR or Piperidine/CSR epoxy, while it shows only a moderate increase in the fracture toughness.

Abstract: Al matrix composites (Al-MMC) were reinforced with SiC and flyash particulate. The effects on the variation of SiC (5 %, 10 % and 15 %) were investigated by dry sliding method, whereas the flyash content was maintained at 14 %. Effect on the SiC on the mechanical and tribology was discussed in detail. Friction wear properties SiC reinforced was investigated. Coefficient of friction was estimated and is discussed for the various SiC compositions. Powder X-ray diffraction (XRD) was carried out to identify the homogeneous formation of the composites. Surface morphology was investigated by the use of optical microscope and scanning electron microscopic probe. Hardness of the prepared samples was subjected to Vickers microhardness test.