Structural system based on tensioned wood panels: experimental and numerical validation

Housing in modern societies is a priority need. In the countries of industrial development, there are very sharp contrasts with respect to the housing deficit, affecting the great majority of the families with lower economic resources that solve their problem through subhuman constructions, elaborated, mostly, with residues of construction and disassembly of old buildings, highlighting the importance of the economy, from the financial point of the house built on the architectural quality and comfort. The need to create new building systems based on wood for homes arises when considering the few existing alternatives in developing countries that guarantee an economic, massive and fundamentally sustainable construction. In this sense, this research aims to make a contribution to the implementation of new structural elements for the sustainable construction of wooden houses, which can be manufactured by low technology processes, allowing easy use and appropriation by the general population. The system is called TENSO-WOOD, which is conceived as a system of solid wood plates of Caribbean pine, developed by means of low technology processes that allow an easy appropriation by the population in general. This paper presents a frame structural system using tensioned wood panels as structural elements. It is a lightweight prefabrication system for the construction of two-storey wooden houses. The system consists of bolted wood elements, creating different structural panels such as beam and column. An experimental program was carried out, which allowed knowing the mechanical behavior of each panel of the frame structure. In addition, it permits to know their maximum stress and deformations. The numerical models were compared with the experimental tests to validate and calibrate some parameters in the simulations. Therefore, the numerical models can be able to compute the load capacity and deformation of the wooden elements, obtaining behavior curves.

ANATOMICAL PROPERTIES OF STRAW OF VARIOUS ANNUAL PLANTS USED FOR THE PRODUCTION OF WOOD PANELS

The aim of this study was to determine basic anatomical features of annual plant fibers used as wood substitutes for the production of wood-based panels. For this purpose rye, wheat, triticale, rape and corn straw were used. The determination of the morphological features of the fibers was conducted on the macerated material. Fiber lengths, fiber diameters and lumens were measured, and then the fiber wall thicknesses and slenderness ratios were calculated. The result clearly showed significant differences among all fiber characteristics of the tested plants. The strength and direction of the relationship between the anatomical properties determined in the study and the physicomechanical properties of the boards produced with straw from the tested annual plants were identified.

Efficiency of High-Frequency Pressing of Spruce Laminated Timber Bonded with Casein Adhesives

This study identifies the importance of reducing press times by employing high-frequency pressing of spruce-laminated timber bound with sustainable casein adhesives. Spruce lamellas with dimensions of 12 × 10 × 75 cm were bonded into five-layered laminated timber and then separated into single-layer solid wood panels. Three types of casein (acid casein from two sources and rennin) were used. To compare the effectiveness of the casein formulation, two control samples bonded with polyvinyl acetate (PVAc) adhesive were pressed at room temperature (20 °C) and also with high-frequency equipment. The tests included compression shear strength, modulus of rupture, modulus of elasticity and screw withdrawal resistance on the wood panel surface and in the glue line. The average values of casein-bonded samples compression strengths ranged from 1.16 N/mm2 and 2.28 N/mm2, for modulus of rupture (MOR) were measured 85 N/mm2 to 101 N/mm2 and for modulus of elasticity (MOE) 12,200 N/mm2 to 14,300 N/mm2. The screw withdrawal resistance (SWR) on the surface of the wood panels ranged from 91 N/mm to 117 N/mm and in the adhesive line from 91 N/mm to 118 N/mm. Control samples bonded with PVAc adhesive did not perform better for compression shear strength, MOR and MOE, but for SWR in the adhesive line with 114 N/mm. Casein-bonded spruce timber pressed with HF equipment represents a sustainable new product with reduced press times, hazardous emissions and improved workability.

Purple Dreamscape and Soft Green Haze

>“Soft Green Haze” and “Purple Dreamscape” are two oil paintings on wood panels by Olivia Ross, a Studio Art student at Montana State University. In creating these two works, Olivia looks to examine how narrative and aesthetic choices draw a viewer into a piece. Olivia removed any indication of a clear narrative or recognizable spaces and instead relies on abstraction to prompt an audience to engage. Olivia found even with the absence of these the viewer is enticed to explore further, not only in physical proximity to the work, but in projecting their own ideas onto it. Olivia thinks that this inclination to create one’s own relationship with a piece when there is no clear narrative to grasp makes a nontangible, abstracted space that’s much more reactively powerful.

Purple Dreamscape and Soft Green Haze

“Soft Green Haze” and “Purple Dreamscape” are two oil paintings on wood panels by Olivia Ross, a Studio Art student at Montana State University. In creating these two works, Olivia looks to examine how narrative and aesthetic choices draw a viewer into a piece. Olivia removed any indication of a clear narrative or recognizable spaces and instead relies on abstraction to prompt an audience to engage. Olivia found even with the absence of these the viewer is enticed to explore further, not only in physical proximity to the work, but in projecting their own ideas onto it. Olivia thinks that this inclination to create one’s own relationship with a piece when there is no clear narrative to grasp makes a nontangible, abstracted space that’s much more reactively powerful.

Modeling of Influential Parameters on Bending Strength of Solid Wood Panels Perpendicular to the Grain

The paper presents the results of modeling the bending strength of wood. During the experimental examination and definition of the model, solid wood was taken, where the bending was performed perpendicular to the grain. The experiment was done with thirteen replications and the input values that varied at three levels were wood density and board thickness. The thirteen-repetition experiment also involved four repetitions in the marginal areas, so two more wood densities and two board thicknesses had to be taken. The experimental measurement was performed in the laboratory of the Technical Faculty Bihać. Based on the experimental results, a sufficiently adequate mathematical model of the breaking force of a solid wood panel perpendicular to the grain is obtained.

Surface Detection of Solid Wood Defects Based on SSD Improved with ResNet

Due to the lack of forest resources in China and the low detection efficiency of wood surface defects, the output of solid wood panels is not high. Therefore, this paper proposes a method for detecting surface defects of solid wood panels based on a Single Shot MultiBox Detector algorithm (SSD) to detect typical wood surface defects. The wood panel images are acquired by an independently designed image acquisition system. The SSD model included the first five layers of the VGG16 network, the SSD feature mapping layer, the feature detection layer, and the Non-Maximum Suppression (NMS) module. We used TensorFlow to train the network and further improved it on the basis of the SSD network structure. As the basic network part of the improved SSD model, the deep residual network (ResNet) replaced the VGG network part of the original SSD network to optimize the input features of the regression and classification tasks of the predicted bounding box. The solid wood panels selected in this paper are Chinese fir and pine. The defects include live knots, dead knots, decay, mildew, cracks, and pinholes. A total of more than 5000 samples were collected, and the data set was expanded to 100,000 through data enhancement methods. After using the improved SSD model, the average detection accuracy of the defects we obtained was 89.7%, and the average detection time was 90 ms. Both the detection accuracy and the detection speed were improved.

Color Classification and Texture Recognition System of Solid Wood Panels

Solid wood panels are widely used in the wood flooring and furniture industries, and paneling is an excellent material for indoor decoration. The classification of colors helps to improve the appearance of wood products assembled from multiple panels due to the differences in surface colors of solid wood panels. Traditional wood surface color classification mainly depends on workers’ visual observations, and manual color classification is prone to visual fatigue and quality instability. In order to reduce labor costs of sorting and to improve production efficiency, in this study, we introduced machine vision technology and an unsupervised learning technique. First-order color moments, second-order color moments, and color histogram peaks were selected to extract feature vectors and to realize data dimension reduction. The feature vector set was divided into different clusters by the K-means algorithm to achieve color classification and, thus, the solid wood panels with similar surface color were classified into one category. Furthermore, during twice clustering based on second-order color moment, texture recognition was realized on the basis of color classification. A sample of beech wood was selected as the research object, not only was color classification completed, but texture recognition was also realized. The experimental results verified the effectiveness of the technical proposal.

Analisis Koefisien Serapan (Absorbsi) kebisingan pada Bahan Kayu (Triplek, Papan Kayu dan Kalsiboard)

Noise is a sound that humans do not want and it is an environmental factor that can negatively affect health. To overcome the noise issue, many efforts have been made to reduce noise levels. An example is the manufacture of the walls of a house using materials with sound and absorbent standards. The materials used can also be derived from types of wood such as plywood, wood panels and calciboards. Therefore, the value of its sound absorption coefficient is calculated to find out which active material is to be used in the manufacture of the building. Based on the research results, the value of the sound absorption coefficient of the three types of materials, it can be seen that the shape of the graph and its analysis states that the lowest sound absorption coefficient is most likely at the lower frequencies and the highest value of the sound absorption coefficient tends to be at the higher frequencies. In fact, when viewed as a whole, the magnitude and magnitude of the sound absorption coefficient on the graph is not in line with the increase in the frequency value.