The results of dynamic finite element simulation are presented for stress distributions in a bar-plate friction welded joints steel alloy subjected to impact loading.This paper examines the effects of different location of contact area and massof pendulum on the penetration of bar-plate friction welded joints steel alloy at impact loading.Accurate approach of mechanical behavior such as stress distribution, stress concentration for bar-plate friction welded joints steel product subjected to impact loading is needed to experimental design. This approach is based on the finite element simulation. In the finite element simulation, the ANSYS code was employed. It was found that the impact response of bar-plate friction welded joints steel alloy is significantly influenced by location of contact areaand mass of pendulum. Advanced finite element simulation approach must be applied for impact assessments of friction welded structure under impact loading, to avoid unsafe designed obtained from the static criteria.
Department of Mechanical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia
In this work, response surface methodology was used to optimize the conditions for the transesterification of oil-palm off grade with methanol, using CaO from chicken eggshell as catalyst. By experimental design a quadratic polynomial equation was obtained for biodiesel yield. Multiple regression analysis and verification experiments confirmed the validity of the predicted model. The studied variables were reaction temperature (50, 60 and 70 °C), catalyst weight base oil (2,4 and 6%) and methanol to oil-palm off grade molar ratio (7:1; 9:1 and 11:1). Results from the optimation study showed that reaction temperature and molar ratio methanol to oil-palm off grade can be optimized. Catalyst characterization was carried out by X-ray Diffraction. Biodiesel with highest methyl ester content (87.41%) was obtained at 70 °C, 1:11 methanol to oil-palm off grade molar ratio and 2% catalyst concentration. The produced biodiesel was found to fulfill the specifications of the SNI-2012 regarding viscosity, flash point and acid value.
Department of Chemical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia
School of Chemical Engineering, University Sains Malaysia, 14300, NibongT ebal, Penang, Malaysia
The objective of this work is to investigate the influence of hydroxyapatite (HA) on physical properties of porous alumina bodies fabricated through protein foaming-consolidation method. Hydrothermal derived HA powder was used as bioactive ceramic. Alumina and HA powders were mixed with yolk, starch and darvan 821 A at an adjusted mass ratio to make slurry. HA-to-alumina mass ratio was in the range of 0.0 to 0.8 w/w. The slurries were cast into cylindrical shaped molds and then dried for foaming and consolidation process. Subsequently, the dried bodies were burned at 600°C for 1 h, followed by sintering at temperatures of 1,300°C for 2 h. The porous alumina-HA composites with pore size in the range of 50-500 µm and densities of 2.7 – 2.9 g cm-3 were obtained. Porosity of bodies decreased from 35.9 to 31.7% when HA-to-alumina mass ratio increased from 0.0 to 0.8 w/w. Compressive strength of sintered body was 0.8 MPa at 35.9% porosity and 2.9 MPa at 31.7% porosity. Intensity of tricalcium phosphate (TCP) phase in bodies increased with HA loadings.
Department of Chemical Engineering, Universitas Riau, Pekanbaru, 28293, Indonesia
In literature, there are extensive amounts of experimental and numerical studies in refrigeration system, this paper presents natural convection numerically investigated in refrigeration at Difussion Absorption Refrigeration (DAR) system. Object of this study is a 3D model of refrigeration cabin, with source of the cold temperature came from the evaporator that adheres at the back side of the cabin’s wall. The model forms a closed system with no inlet or outlet. Numerical method is finite volume computational fluid dynamics simulations, using the discrete ordinates (DO) laminar model. It is expected to know the flow characteristic and the temperature distribution inside the refrigeration cabin numerically.
Departement of Mechanical Engineering, Institut Teknologi Sepuluh Nopember, 60111 Surabaya, Indonesia