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

2021 ◽  
Vol 1208 (1) ◽  
pp. 012020
Author(s):  
Damir Hodžić ◽  
Nedim Hurem ◽  
Atif Hodžić
Keyword(s):  
Mathematical Model ◽  
Bending Strength ◽  
Solid Wood ◽  
Breaking Force ◽  
Experimental Examination ◽  
Wood Panel ◽  
Marginal Areas ◽  
Wood Panels ◽  
Definition Of ◽  
Influential Parameters

Abstract 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.

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

Forests ◽  
2021 ◽  
Vol 12 (10) ◽  
pp. 1419
Author(s):  
Yutu Yang ◽  
Honghong Wang ◽  
Dong Jiang ◽  
Zhongkang Hu
Keyword(s):  
Wood Surface ◽  
Feature Detection ◽  
Surface Defects ◽  
Detection Efficiency ◽  
Solid Wood ◽  
Detection Accuracy ◽  
Single Shot ◽  
Wood Panel ◽  
Data Set ◽  
Wood Panels

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.

Einfluss des Plattenaufbaus und des Pressdrucks auf die Eigenschaften dreischichtiger Massivholzplatten | Influence of layering arrangement and compression level on the characteristics of three-layered solid wood panels

2004 ◽  
Vol 155 (11) ◽  
pp. 505-513
Author(s):  
Benjamin Steiger ◽  
Peter Niemz ◽  
Andreas Hurst
Keyword(s):  
Tensile Strength ◽  
Bending Strength ◽  
Middle Layer ◽  
Longitudinal Axis ◽  
Solid Wood ◽  
Diffusion Resistance ◽  
Covering Layer ◽  
Wood Panels ◽  
Layered Solid

The level of compression and the arrangement of layers were varied on layered solid wood panels, produced in the laboratory using technical methods and glued with polyurethane(PUR). Measurements were subsequently carried out on the Emodule,bending strength, diffusion resistance level, changes in length caused by changes ambient climate, as well as the warping in a fluctuating climate. Following results were recorded. The level of compression with the PUR glue used in the experiment had no influence on the tensile strength or the E-module. When the proportion of middle layer wood is increased in the panel, the tensile strength of the covering layer falls when stressed parallel to the direction of the fibre. It rises when the covering layer lies at a right angle to the direction of the fibre. The quality of the panel can be influenced by varying the quality of the wood used in the covering and middle layers, e.g. by sorting. Slitting the middle layer leads to a clear reduction of shearing strength (rolling shear) when the panel is stressed, and the covering layer is parallel to the longitudinal axis of the sample. On the other hand, with the longitudinal axis lies at right angles to the covering layer (stressing of the middle layer parallel to the fibre), the influence of slitting is slight because the weakening of the cross-section is considerably less. Warping in a fluctuating climate can be clearly improved with rift cut in the covering layer. Diffusion resistance only continues to increase between pressures of 1 to 2 bars,and subsequently remains constant. Differential longitudinal swelling is influenced by the arrangement in construction.

Untersuchungen zum Diffusionswiderstand von Holzwerkstoffen | Diffusion resistance of timber materials

2005 ◽  
Vol 156 (3-4) ◽  
pp. 100-103
Author(s):  
Rudolf Popper ◽  
Peter Niemz ◽  
Gerhild Eberle
Keyword(s):  
Relative Humidity ◽  
Water Vapour ◽  
Middle Lamella ◽  
Solid Wood ◽  
Diffusion Resistance ◽  
Water Vapour Diffusion ◽  
Wood Panels ◽  
Vapour Diffusion ◽  
Wet Climate ◽  
Panel Thickness

The water vapour diffusion resistance of timber materials were tested in a wet climate (relative humidity ranging from 100%to 65% at 20 °C) and in a dry climate (relative humidity ranging from 0% to 65% and from 0% to 35% at 20 °c) with variation by relative humidity and vapour pressure gradient. The diffusion resistance of multilayer solid wood panels lies under or within the range of the solid wood (spruce), tending even to a lower range. This can be attributed to the loosely inserted middle lamella of the used solid wood panels, which were not correctly glued by the manufacturer. The diffusion resistance of the solid wood panels increases with decreasing moisture content and decreasing panel thickness, as well as with increasing water vapour gradient from 818 to 1520 Pa. There were clear differences between the tested timber materials. The diffusion resistance of particle composites is strongly dependent on the specific gravity. Due to laminar particles OSBs(Oriented Strand Boards) have a larger diffusion resistance than chipboards. The water vapour diffusion resistance of OSBs lies within the range of plywood.

Tra ruralizzazione ed urbanizzazione: progetti integrati cittŕ-campagna

TERRITORIO ◽  
2009 ◽  
pp. 171-177
Author(s):  
Alessandra Giannini
Keyword(s):  
Urban Agriculture ◽  
Agricultural Production ◽  
Urban Areas ◽  
Rural Life ◽  
Rural Living ◽  
Marginal Areas ◽  
Country Life ◽  
The Subject ◽  
Definition Of ◽  
The Relationship

- Country life is (and has been) the object of utopian visions, set against the rise of urban living. The paradigms of the myth of rural life can be traced back to Howard's Garden City and to Frank Lloyd Wright's Broadacre City. These examples of the paradigm blend into a broader and trans-disciplinary contemporary discourse on the myth of rural living. Since the end of the 1990s, the subject of the relationship between the rural and the urban has developed into plans that could be called ‘country utopias'. The system of agricultural production and the countryside is evolving today towards new forms of integration and hybridisation with urban areas. Planning practices are emerging today in the definition of the characters and traits of urban agriculture designed to create town and country interaction particularly in marginal areas, strips located on the borders between town and country. These modifications are leading to the definition of new rural figures, together with plans capable of giving new life to liminal and marginal areas between town and country by creating new models of ‘rururban' living.

scholarly journals Immediately mathematical model of maneuverability of the items of the administration

2019 ◽  
Vol 9 (3) ◽  
Author(s):  
Volodymyr Kotsyuruba ◽  
Ruslan Cherevko
Keyword(s):  
Mathematical Model ◽  
Traditional Approach ◽  
Armed Forces ◽  
Control Points ◽  
Military Operations ◽  
The Reformation ◽  
Definition Of ◽  
The Cost ◽  
Military Units ◽  
Current Stage

At the current stage of the reformation of the Armed Forces of Ukraine in the context of the operation of the United Nations (Anti-Terrorist Operation (ATO)), there was a need to increase the effectiveness of the use of troops without increasing the cost of the resource. In the context of increasing capabilities of the armies of the leading countries in the world to investigate and defeat the forces of the opposite side, the problem of maintaining and restoring combat capability in the course of hostilities is very acute. One of the important components that determines combat capability is the maneuverability of the control points (PU). In the course of the defense, the problem of increasing the survivability of the PU system is important because the forces of the opposite side, with the onset of aggression, will try, first of all, to dismantle the PU using modern means of defeat and the massive use of high-precision weapons (WTZ), as well as aircraft and artillery strikes, electronic information and information fight, the use of sabotage and reconnaissance groups and tactical airborne troops to disrupt the control of defending troops. Important importance of the ability to timely carry out maneuver (organized movement) of PU and its elements into a new area in the preparation and in the course of military operations. The traditional approach to ensuring the survivability of PU does not allow to ensure the proper stability of their functioning. There is an objective necessity in the development of such a mathematical model of maneuverability, which in its characteristics would meet the dynamically increasing requirements of the control system of troops in the difficult conditions of projected operations. To ensure the quality management of military units, various measures to ensure the survivability of PU are considered. The article outlines approaches to the definition of indicators of estimation of maneuverability of PU and methods of their calculation. The research is carried out in modern conditions of combat operations, taking into account the movement of the line of the combat collision of the parties and the disclosure of the PU to the enemy's intelligence.

scholarly journals Development of a mathematical model for calculating the process of crushing hard rocks by explosions of cylindrical charges of explosives

2020 ◽  
Vol 5 ◽  
pp. 30-32
Author(s):  
Norov Yunus Dzhumaevich ◽  
Mehmonov Maksud Rabbonokul ugli
Keyword(s):  
Mathematical Model ◽  
Rock Mass ◽  
Mechanism Of Action ◽  
Mathematical Description ◽  
Granulometric Composition ◽  
Rock Fragmentation ◽  
Hard Rocks ◽  
Definition Of ◽  
The Relationship

The article presents a developed mathematical model for calculating the granulometric composition of the blasted rock mass based on the mechanism of action of an explosion in rocks, a mathematical description of the determination of natural units (blocks) in the rock mass, the relationship between the degree of rock fragmentation and the size of the units and the definition of sections of the controlled pressure zone.

Gear root bending strength: a comparison between Single Tooth Bending Fatigue Tests and meshing gears

2021 ◽  
pp. 1-17
Author(s):  
Luca Bonaiti ◽  
Ahmed Bayoumi Mahmoud Bayoumi ◽  
Franco Concli ◽  
Francesco Rosa ◽  
Carlo Gorla
Keyword(s):  
Failure Modes ◽  
Bending Strength ◽  
Gear Tooth ◽  
Fatigue Tests ◽  
Bending Fatigue ◽  
Gear Design ◽  
Single Tooth ◽  
Actual Strength ◽  
Meshing Gears ◽  
Definition Of

Abstract Gear tooth breakage due to bending fatigue is one of the most dangerous failure modes of gears. Therefore, the precise definition of tooth bending strength is of utmost importance in gear design. Single Tooth Bending Fatigue (STBF) tests are usually used to study this failure mode, since they allow to test gears, realized and finished with the actual industrial processes. Nevertheless, STBF tests do not reproduce exactly the loading conditions of meshing gears. The load is applied in a pre-determined position, while in meshing gears it moves along the active flank; all the teeth can be tested and have the same importance, while the actual strength of a meshing gear, practically, is strongly influenced by the strength of the weakest tooth of the gear. These differences have to be (and obviously are) taken into account when using the results of STBF tests to design gear sets. The aim of this paper is to investigate in detail the first aspect, i.e. the role of the differences between two tooth root stress histories. In particular, this paper presents a methodology based on high-cycle multi-axial fatigue criteria in order to translate STBF test data to the real working condition; residual stresses are also taken into account

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