Numerical evidence of persisting surface roughness when deposition stops

Do evolving surfaces become flat or not with time evolving when material deposition stops? As one qualitative exploration of this interesting issue, modified stochastic models for persisting roughness have been proposed by Schwartz and Edwards (2004 Phys. Rev. E 70 061602). In this work, we perform numerical simulations on the modified versions of Edwards–Wilkinson (EW) and Kardar–Parisi–Zhang (KPZ) systems when the angle of repose is introduced. Our results show that the evolving surface always presents persisting roughness during the flattening process, and sand dune-like morphology could gradually appear, even when the angle of repose is very small. Nontrivial scaling properties and differences of evolving surfaces between the modified EW and KPZ systems are also discussed.

A FEA Method for Mathematical Calculation and Prediction Analysis Cross-sectional Ovalization of Tubes under Rotary Straightening

The section flattening phenomenon (namely Bazier effect) will occur in the large bending deformation stage of thin-walled pipe in the continuous straightening process. The maximum section flattening amount and the residual section flattening amount are important process parameters, which are the basis for calculating the subsequent process parameters of the flattening circle, and directly determine the roundness of the final pipe and the product quality. However, it is hard to be obtained by the theoretical or experimental methods. Therefore, based on the structure and process parameters of the leveler, a finite element model was built to simulate the section flattening process. Then, ANSYS/LS-DYNA software was used to dynamically simulate the bending flattening phenomenon of thin-walled pipe in the continuous straightening process, and the stress and strain nephographic of the flattening deformation zone was obtained. By recording the position curve of the key nodes in the preventing process, the section flattening amount of the thin-walled pipe in the large bending deformation stage in the continuous straightening process was determined. The simulation results show that the dynamic simulation method can effectively predict the section flattening of thin-walled pipe in the process of continuous straightening.

Kajian eksperimental mekanisme rol pemipih pada prototipe mesin pemipih emping beras

Rice quaker are traditional food from the Sambas regency. The manufacture of rice quaker has been traditionally done by pounding it. Economically, the production capacity of traditionally made rice quaker is so low that it needs to be increased by changing the manual to mechanical flattening system. The purpose of this research is designing a prototype machine for flattening rice quaker as well as conducting experimental studies on the flattening process. The research stages were to design, manufacture, and test the performance of the flattening rice quaker. The independent variables of the study were the gap width and the number of flattening, while the dependent variables of the study were thickness and percentage damage of rice quaker. The width of the gap was varied into 0.4 mm, 0.6 mm, 0.8 mm, and 1.0 mm, while the number of flattening was varied to 1, 2, and 3 times the flattening. The result of the construction of the prototype rice quaker machine is in accordance with the initial design, and can work to flatten rice quaker. The engine test was carried out at a flat roller speed of 360 rpm. The thickness of the rice quaker made traditionally, 0.98 mm, can be approached by flattening using a machine at a gap width of 0.8 mm with 2 flakes resulting in a thickness of 0.96 mm quaker with a percentage of damage of 38.52%. In general, the level of damage to the resulting rice quaker is still very high, so further analysis is needed.Keywords: Rice quaker, gap width, flattening machine, flat rollers.

Effect of NaOH treatment on mechanical strength of banana/epoxy laminates

The present study is focused on studying the effect of alkali treatment on the mechanical properties of banana fiber-reinforced epoxy composites. Four batches of samples were prepared with respect to the percentage of sodium hydroxide (NaOH) in the treatment solution (0%, 2.5%, 4.5%, and 6.5%). Later mechanical tests such as tensile, compressive, and interlaminar shear tests were conducted on the prepared composite specimens to determine the influence of alkali treatment on the mechanical characteristics. The test results indicate an overall improvement in all the mechanical properties due to the fiber treatment. Moreover, the samples made from the fiber treated with 4.5% of NaOH solution indicated the highest tensile strength and compressive strength, with an overall increment of 24.2% and 34.8% in tensile and compressive strengths, respectively, when compared with the untreated sample. A linear increment in interlaminar strength is observed with a maximum value of 25.4 N/mm2 for the sample made from the fiber treated with 6.5% of NaOH solution. This increase is due to the fiber flattening process which increases the bonding surface at the interface.