Applied Mechanics and Materials Vol. 606

Abstract: In this work, the effects of room temperature deposition on the structural properties of Al-Cu bilayers thin films were investigated. The bilayers were sputter deposited by RF magnetron sputtering on Si {100} wafers without substrate heating. The thickness of each layer is approximately 500 nm thick. Characterization were performed with grazing incidence X-ray diffraction (XRD) cross-sectional field emission scanning electron microscope (FE-SEM) with chemical analysis by energy dispersive X-ray (EDX) and atomic force microscope (AFM). It was found polycrystalline Al and Cu thin films have been grown with {111} preferred growth orientation with very fine crystallites size (less than 20 nm). The bilayers were in non-strained condition, but each layer shows different morphologies between the columnar and non columnar structure. AFM analysis revealed that the bilayers top surface appears to have higher surface roughness (R_a = 20 nm) due to low adatoms surface mobility during room temperature deposition.

Abstract: Modeling the spring-back requires tool-laminate interaction to be taken into account. In this study, an interface based on orthotropic linear behavior coupled with an out-of-plane shear stress failure was proposed to simulate the tool-laminate interaction. The results from this particular model captured the out-of-plane shear stress distribution. The model allows predicting the warpage displacement in function of interface properties; shear modulus and shear stress failure which leads to the construction of Chart Design. Additionally, the influence of the number of plies was studied as well and the evolution of the maximum warpage agreed with the literature.

Abstract: This research work was focused on the application of powder metallurgy technology to the production of high-quality products from Ti10V2Fe3Al alloy. For the purpose of investigations hot compaction and hot closed-die forging processes were used. As an initial material a mixture of elemental powders was applied. As a result of hot densification, fully densified semi-products were obtained (99.4 % relative density). Numerical modelling of forging of a selected forging was performed using finite element method. Various options of forging process conditions were applied. The designed parameters of forging technology were verified by means of trials performed in industrial conditions. The quality of the product was estimated by microstructure observations. It was found that hot forging of compacted mixture of elemental powders resulted in obtaining defect-free gear wheel showing the relative density of 99.8 ±0.2 %.

Abstract: In the rapid new automobile development, the use of simulation technology is highly demanded due to shorter time to market and fashionable product styling that go beyond the rule-of-thumb in the manufacturing technology. In stamping simulation, the expected predictions rest with the part formability, spring back, blank optimization, and other vehicle integration works. These predictions are conducted concurrently during detailed product design, and intensive product validation is performed based on such predictions. In current work, it has established the experimental mechanical properties and flow curve data for thin galvanized sheet metal. Furthermore, the true prediction of part formability is investigated with established data and standard material database embedded in commercial simulation software. The tensile experiments were carried out on a uniaxial hydraulic tensile test machine with sheet metal specimen and in accordance to ASTM requirements. Three different sheet metal specimens were prepared from the longitudinal, transverse and 45⁰ degrees from the rolling direction. From experimental works and formulation, the mechanical properties, anisotropy and flow curve had been obtained. Further improvement in the embedded material database increases the prediction accuracy of FEM analysis for Body-in-White structure and crash performance.

Abstract: Milling is one of the most common manufacturing processes for automotive component, but its productivity is limited by chatter. This form of chatter is undesirable because it results in premature tool wear, poor surface finish on the machined component and the possibility of serious damage to the machine itself. Modal testing is a form of vibration testing which is able to determine the Frequency Response Function (FRF) of the mechanical test structures. In this paper, the main focus is to obtain natural frequency values for machine tool components in order to establish better conditions in the cutting process on the machine tool. For this purpose, a 3D model of the machine tool’s part is made using design software and exported to analysis software. Later on, the Finite Element Method (FEM) modal analysis was used to obtain the natural frequencies. The model is evaluated and corrected through an experimental modal test. In the experiment, the machine tool vibration is excited by impact hammer and the response of excited vibration is recorded. In the end, the result of both FEM and experimental shows a good consistency in comparison.

Abstract: Top spray granulation process is a common technique used widely in pharmaceutical, food and special chemical modification for fertilizer manufacturing. Nevertheless, there is still a lack of studies regarding to the description of controlled parameters with dynamic correlation in targeting to produce urea granules. Thus, this research was carried out to introduce the crucial applied process parameters using top spray technique for paddy urea fertilizer production.The acquisition process parameter readings were verified by obtained yield of urea granules (UG) which featured as an optimum particle diameter size from 2 mm to 6 mm with reasonable hardness (crush strength) in range 2.0 kg/granule to 4.0 kg/granule, these criteria were required as a slow - release mechanism during soil adsorption interaction in paddy field to reduce amount of fertilizer consumption. Three significant parameters have been selected namely as air inlet temperature, the viscosity of binder solution and rate of top spraying from starch liquid binder to generate greater UG size from wet granulation interaction with smooth coalescence and consolidation growth . The data classification was screened by One-Factor-at-a-Time (OFAT) 101 method and supported by 2 levels and 3 factors (2³ ) of full factorial design for clear description to vindicate the critical parameter required during urea granulation using fluidized bed granulator corresponds to low energy consumption and economical process. The obtained parameter readings and findings of UG features were useful to be applied further for detail investigation on next stage regarding to agglomeration profile and mechanism using CCD camera and PDA monitoring devices.

Abstract: High gloss plastics part in injection molding industries were widely used in Malaysia. However the high rejection rate in this industries were major problem affecting the economic aspects. Therefore this paper presents an approach of implementing six sigma method to reduce the rejection rate in a plastic injection molding process for high gloss plastics part. Define, Measure, Analyze Improve and Control (DMAIC) methodology was applied as basis of the study. By using current process, the average of rejection is 40.6% and the aim of this study is to reduce the rejection rate to less than 10 % . All potential factors were taken into account to identify the significant factors. The improvement process was made base on the analysis output. This study was successful with increment in sigma level from 1.74 σ to 3.00 σ. .

Abstract: Bispectral analysis is one of the relatively more recent tools in signal processing used for detection and identification of higher harmonics in a signal. It is also acknowledged to be one of Higher Order Spectral Analysis (HOSA) effective tools for detecting nonlinear behavior in mechanical systems. In this study, vibration sources in a hydraulic machine which may have features of nonlinear behavior were investigated. An experimental study was undertaken to formulate a more sensitive and effective method using Bispectral analysis to diagnose cavitation in a centrifugal pump facility. Cavitation was induced on the suction side of the pump. The cavitation signal was analyzed with and without induced cavitation conditions at different locations on the pump, and analyzed using FFT and bispectrum methods. It was observed that bispectral analysis could be used as an early indicator of cavitation with changes for severity of cavitation.

Abstract: The dynamic characteristics of the Polypropylene honeycomb (PPHC) sandwich composites have been investigated under various temperatures (30°,35°,40°,45°,50°,55°,60°, 65°,70°,75° and 80°C) and different orientations (0° and 90°) of the glass fibers in the composites. Since the thermal properties of the constituent materials (glass fiber, epoxy resin and PPHC core) of the PPHC sandwich composites are different and the in-plane effect of the composites varies with the two different orientations (0° and 90°) of the fibers, the variation of the loss factor under the various temperatures are also different for these orientations. A two stage layup technique has been used to fabricate the sandwich composite specimens. Impulse technique associated with the half power bandwidth method, has been used to evaluate the natural frequency and damping values of the sandwich composite under different temperatures.

Abstract: In the present work, the mode I delamination behaviour of a quasi-isotropic quasi-homogeneous carbon/epoxy composite laminate with adjacent plies of 0^o//45^o is studied numerically. To describe the R-curve behaviour observed during crack propagation, a linear-exponential traction-separation law is proposed, where the fracture toughness and the increment in the fracture energy could be considered separately in the model. This model is then implemented in the finite element simulation of the delamination process in the composite laminate. Numerical results indicate that with the incorporation of the fibre bridging effect leads to a well-predicted force-displacement response of the composite laminates.