Vignesh Sekar^1,*, Se Yong Eh Noum¹, Azma Putra², Sivakumar Sivanesan¹, Kok Chun Chin¹, Yi San Wong¹, Dg Hafizah Kassim³

Sound & Vibration, Vol.55, No.4, pp. 343-352, 2021, DOI:10.32604/sv.2021.014916

Abstract This paper presents the development and performance of micro-perforated panels (MPP) from natural fiber reinforced composites. The MPP is made of Polylactic Acid (PLA) reinforced with Oil Palm Empty Fruit Bunch Fiber (OPEFBF). The investigation was made by varying the fiber density, air gap, and perforation ratio to observe the effect on the Sound Absorption Coefficient (SAC) through the experiment in an impedance tube. It is found that the peak level of SAC is not affected, but the peak frequency shifts to lower frequency when the fiber density is increased. This phenomenon might be due to the presence of porosity… More >

Ting Jiang^1,3, Chunmei Yang^1,2,*, Yueqiang Yu³, Bakary S. Doumbia^1,2, Jiuqing Liu^1,*, Yan Ma^1,2

Journal of Renewable Materials, Vol.9, No.1, pp. 119-128, 2021, DOI:10.32604/jrm.2021.011490

Abstract

As a natural and environmentally friendly renewable material, Northeast China ash wood (NCAW) (Fraxinus mandshurica Rupr.) was cut by water-jet assisted CO₂ laser (WACL), the surface quality was evaluated by surface roughness of cut section. The surface roughness was measured by three-dimensional (3D) profilometry. Furthermore, the micromorphology of machined surface was observed by scanning electronic microscopy (SEM). Carbon content changes of machined surface were measured by energy dispersive spectrometer (EDS). A relationship between surface roughness and cutting parameters was established using response surface methodology (RSM). It is concluded that the cutting speed, laser power and water pressure played an important… More >

Qingwei Liu^1,2, Chunmei Yang^1,2,*, Qian Miao^1,2, Yifan Liu^1,2, Jiuqing Liu^1,*, Wenji Yu³

Journal of Renewable Materials, Vol.8, No.12, pp. 1681-1689, 2020, DOI:10.32604/jrm.2020.012031

Abstract Based on the LOM (Laminated Object Manufacturing) process, an inert gas-assisted laser method for wood cutting was proposed. The carbonization degree of wood surface was improved by the introduction of helium (He) gas, and the influence of process parameters on the carbonization layer of wood surface was solved, it was significance to reduce the post-processing of LOM and improve the quality of forming workpiece. The cherry wood veneer was used as the experimental material, under the condition of the same process parameters, the wood was cut with or without inert gas-assisted, and the influence factors of kerf quality were studied… More >

S. Aggoune¹, C. Abid², E.H. Amara^1,3

FDMP-Fluid Dynamics & Materials Processing, Vol.11, No.2, pp. 115-125, 2015, DOI:10.3970/fdmp.2015.011.115

Abstract This paper focuses on the vortex formation effect during the application of a laser-fusion cutting technique. This industrial technique is typically associated with the ejection of a film of molten stainless steel blown off by a subsonic laminar jet of nitrogen gas used to assist the process. Without taking into account the transverse movement of the workpiece, we consider a 4 mm thick stainless steel plate. The resulting molten metal flow is assumed to be laminar, steady, viscous and incompressible. The numerical results reveal vortex structures adjacent to the walls at the entrance of the kerf, and a pair of… More >