Key Engineering Materials Vol. 863

Abstract: The application of bamboo by-products such as bamboo branches, chips to recycle and produce pressed bamboo pulp is an urgent task in Vietnam. It perfectly replaces natural wood with artificial wood embryos from bamboo powder, which has both economic benefits of reserving the source of raw materials, environmental protection... The paper presents a study of the influence of technological parameters on the water absorption and swelling thickness of pressed bamboo pulp plywood in order to ameliorate the quality of pressed bamboo pulp plywood in production of new materials for civil engineering with environmentally friendly bamboo wood pulp materials.

Abstract: Single Point Incremental Forming (SPIF) technology has become popular and familiar for forming sheet, especially in single, small and prototype batch production in many fields such as medicine, aviation, automobile... However, sheet materials with high hardness and durability are difficult to deform and shape because of their high properties. In that case, if we determine a set of logical suitable technological parameters such as temperature T (°C), speed of forming V_xy (mm/min), vertical tool feed z (mm) and tool diameter D (mm) for single point incremental forming at high temperature (Hot SPIF) technology we will get high precision dimension product. The paper presents a study to optimize the main technological parameters when processing non-alloy Titanium sheet materials by HOT SPIF technology to get the smallest error in the radial direction of the product.

Abstract: The application of bamboo by-products such as bamboo branches, debris... to recycle and produce bamboo powder plywood, perfectly saves high price natural resource of national wood with artificial wooden boards made from bamboo powder that ensures the reservation of natural source of raw materials and protecting of environment. Plywood that is made from bamboo powder has both economic and environmental benefits. It is an urgent task for providing a new version of material for civil engineering in Vietnam. The paper presents a study of the effect of technological parameters on the bending strength of pressed bamboo pulp plywood in order to enhance the mechanical properties of a new domestic product of construction in Vietnam.

Abstract: Single Point Incremental Forming (SPIF) technology has become popular and familiar in sheet materials forming, especially in single manufacturing, prototype manufacturing and in the medical field.... However, sheet materials with high hardness and durability are difficult to deform and shape because of their high properties. In that case, when we determine the main logical technological parameters such as forming temperature T (°C), speed of forming V_xy tool (mm/min), depth tool feeding z (mm) and tool diameter D (mm) tool, it is possible to apply HOT SPIF technology at high temperature to form these materials. The paper presents a study of optimization the main technology parameters when processing non-alloy Titanium sheet materials with HOT SPIF technology to get the smallest depth dimension error ΔH.

Abstract: Nowadays, Fused Deposition Modelling (FDM) method has been growing rapidly, which can be used to fabricate complex parts within a reasonable time. The fabrication principle of FDM method is “layer by layer” so that the previous layer and subsequent layer don’t deposit each other to create the interface between two adjacent layers. Thus, the tensile strength of FDM product along building direction depends on various process parameters. In this study, five important process parameters such as layer thickness, build orientation, build style, infill density, and print temperature are considered. The effect on tensile strength is evaluated based on the tensile test of Polylactic Acid (PLA) part. The Design of experiment (DOE) based on the Central Composite Design (CCD) to consider the relationship between the process parameters and their response through the experimental data are gathered. The suitability of model is validated by Analysis of Variance (ANOVA) and t-test. Moreover, Artificial Neural Network (ANN) is also applied to predict the response for experimental model and compared with regression equation obtained from Response surface analysis (FCCCD). The results show that the predict value of ANN model is approximate to experiment value (R² = 0.964), and the mean absolute error (MAE) of ANN model is smaller than those of FCCCD model. It is proved that ANN model is applicable to predict accurately the relationship between the process parameters and their response.

Abstract: The objective of this paper is to select a set of technological forming parameters including vertical feed Δz, feeding rate of V_xy of the tool (a kind of pestle but no-cutting edges), the diameter of tool D and the revolutions per minute of tool n to achieve the highest forming ability of aluminum sheet A1050 H14 (according to JIS G3101Japanese standard) when forming metal sheet by Single Point Incremental Forming Technology-SPIF. The content of the article consists of 3 processes: Pre-design of experiment (Pre-DOE) to select of a set of reasonable limited parameters when forming aluminum sheet A1050 H14 models when forming on the existent specialized SPIF machine in the National Key Laboratory of Digital Control and System Engineering laboratory (DCSELAB); Performing aluminum sheet A1050 H14 models on the Pre-DOE to obtain the forming angle values; Evaluating the experimental results by analysis of variance; Setting up the regression equation of the angle of deformability with influence parameters; Optimization the regression equation to select an optimal set of forming parameters to gain the highest deformability of aluminum sheet A1050 H14.

Abstract: The objective of this paper is to select a set of technological forming parameters including vertical feed Δz, feeding rate of V_xy of the tool (a kind of pestle but no-cutting edges), the diameter of tool D and the revolutions per minute of tool n to achieve the highest forming ability of stainless steel sheet SUS304 (according to JIS Japanese standard) when forming metal sheet by Single Point Incremental Forming Technology-SPIF. The content of the article consists of 3 processes: Pre-design of experiment (Pre-DOE) to select of a set of reasonable limited parameters when forming SUS304 stainless steel models when forming on the existent specialist SPIF machine in the National Key Laboratory of Digital Control and System Engineering laboratory (DCSELAB); Performing SUS304 models on the Pre-DOE to obtain the forming angle values; Evaluating the experimental results by Analyzing of the variance; Setting up the regression equation of the angle of deformability with influence parameters Optimization the regression equation to select an optimal set of forming parameters to gain the highest deformability of stainless steel sheet SUS304.

Abstract: Polycarbonate (PC) has the high impact strength, whereas Polymethylmethacrylate (PMMA) possesses the high tensile strength. Both of them have been widely used for optical elements in illumination. This paper aims to investigate mechanical properties including tensile and impact strengths of PMMA/PC blend with 50 percent of PC concentration by injection molding process. Tensile and impact specimens were designed following ASTM, type V and were fabricated by injection molding process. Taguchi technique was employed to figure out the optimal process conditions for maximum tensile and impact strengths. The processing conditions such as melt temperature, mold temperature, packing pressure and cooling time were applied and each factor has three levels. As a results, melt temperature has been found to be the most significant parameter for both tensile and impact strengths and cooling time is the least significant parameter for the mechanical properties.

Abstract: The fabrication of Fresnel focusing lenses operating at frequencies of 100 and 200 MHz was investigated in order to enhance the focusing efficiency of ultrasonic energy. The effects of process parameters on the four-level Fresnel lens profiles were discussed to find a most feasible fabrication procedure through these experiments. The quality of Fresnel lenses was improved when two-and three-mask processes using SiO2 film as the hard mask were employed. Besides, a better side-wall profile of Fresnel lens was obtained by using the three-mask process as compared to the two-mask one.