Parameters optimization for ultrahigh-pressure pure water and abrasive water jet of Pterocarpus macarocarpus kurz processing

This work optimizes the parameters of ultrahigh-pressure water jet, with or without abrasives, for the cutting of Pterocarpus macarocarpus Kurz wood, a precious species. Parametric factors of cutting pressure, target distance and feed rate were analyzed with respect to the resultant surface roughness of the cuts on specimens using an orthogonal experiment. The optimal machining schemes were elected for water jets either with or without added abrasives based on microscopic evidences. The results showed that the impacts on the resultant surface-roughness of the factors with a given water jet, i.e. either with or without added abrasives, from the most to the least, are both in the order of water jet pressure>feed rate>target distance. Water jets with no added abrasives have lower cutting capacity, which was evidenced by the worse surface roughness of cuts resulted from rebound jet. Raising their kinetic energy, the probabilities of fracture from tearing would also rise, thus, inducing corrugation in the bottom with exacerbated overall surface roughness of cuts. Abrasive water jet has the feature of many ripples, decreasing the surface integrity of specimens. Therefore, to improve product quality of Pterocarpusma carocarpus Kurz wood, is to increase the portion that is smooth in the sections from water jet cuts by choosing carefully the process parameters. The investigation of water jet cutting in this work throws some light on the configuration of process parameters while applying ultra high-pressure water jets, both with and without added abrasives, to the cutting of wood products of precious species.

Optimization and analysis of processing parameters of wooden crafts based on ultra-high pressure water jet method

The investigation and application of computer-numeric-control (CNC)-based ultra-high pressure water jet technology used in the field of wood processing have been paid increasing attention. In order to further optimize the technique of processing parameters in wooden crafts processing, medium density fiberboard (MDF) and solid wood of Italian poplar (Populus euramericana cv.) were taken as he experimental materials. The orthogonal experiment method was applied and the influence of several processing parameters including sand regulating speed, air-dry density, water jet pressure, feeding speed and target distance was considered to analyze the surface roughness. The water jet experiments were conducted based on the patterns designed by AutoCAD software with aid of numerical control working system. By the measurement of surface roughness and calculations, the influence of each processing parameter was investigated and the optimal scheme was then proposed. This work could provide optimization of processing parameters to the manufacturing of wooden crafts including fancy wood floors, indoor decorative boards of timber structure and mahogany furniture et al., which has high application value and practical significance.

Testing and analysis of hemlock cross laminated timber

In this paper, the three-layer Canadian hemlock CLT panel was designed to test the elastic modulus and bending strength of CLT specimens by four-point bending method. The interlaminar shear of CLT specimens was tested by short-span three-point bending method. Strength, the shear strength and wood breaking rate of the CLT specimens were tested by the stair shear method. At the same time, the failure mode of the CLT board was analyzed. The main conclusions indicate that the test values of bending and shear performance of Hemlock CLT can meet the relevant grade requirements of standard ANSI APA PRG320: 2012. During the bending process, the CLT specimen firstly exhibits a rolling shear failure of vertical layer after reaching the non-elastic deformation phase. After that, the damage extends gradually to the interface layer. The final failure mode is shear failure of interface layer or tensile failure of parallel layer. The interlaminar shear performance is partly relevant to the converted timber performance of parallel layer of CLT under the short-span three-point bending test conditions. The position of interlaminar shear failures is concentrated near support points of specimens and the position is generally located at the interface between parallel and vertical layers, inclining to the parallel ones. CLT at Grade 1 has significantly higher interlaminar shear strength than CLT at Grade 2. There is a certain variability in the test results of wood failure rate of CLT. The overall mechanical properties of the hemlock specification material and the hemlock CLT can meet the relevant grade requirements of Standard ANSI APA PRG320: 2012. The above can provide reference for the optimization design and application work of CLT heavy-duty timber structure.

Study and analysis on sound absorbing and noise reducing performance of timber construction wall based on acoustic spiral matasurface

Based on acoustic spiral metasurface, a spiral structural layer was designed to apply to timber construction interior wall. The sound absorption coefficient was measured by impedance tube method and compared with Helmholtz resonance structural layer, solid structural layer and air layer in traditional wall. The results show that the combination of the spiral structural layer and the wall can optimize the sound absorption performance of the wall in the medium and low frequency. Without reducing the overall sound-absorbing performance of the wall, can achieve perfect sound absorption in some medium and low frequency sound bands.