Effect of Knots and Related Grain Deviation on the Rolling Shear in Dimension Lumber Used in Cross-Laminated Timber Transverse Core Layers

2019 ◽  
Vol 69 (1) ◽  
pp. 81-86
Author(s):  
Thibault Grandvuinet ◽  
Lech Muszyński
Keyword(s):  
Core Layer ◽  
Shear Capacity ◽  
Measurable Effect ◽  
Rolling Shear ◽  
Cross Laminated Timber ◽  
Three Point Bending ◽  
The Core ◽  
Loading Direction ◽  
Dimension Lumber ◽  
Product Standard

Abstract Cross-laminated timber (CLT) technology has the potential for utilization of lower grades and underused species of lumber, because the core layers perpendicular to the principal loading direction transfer loads through shear, which is not correlated to the grade of lumber. Currently the product standard specifies the minimum grade requirements for all lumber to be used as CLT laminations. In this study, the effect of the presence of knots in the transverse core layer of CLT billets was examined in matched CLT samples where the heavy presence of knots and the related grain disturbance in the transverse core layer were the only variables compared with knot-free reference. All samples were tested as short beams in three-point bending and all failed in rolling shear in the transverse core layer. The presence of knots had no measurable effect on the shear capacity or stiffness of the tested CLT beam samples.

scholarly journals Bolt-Bearing Yield Strength of Three-Layered Cross-Laminated Timber Treated with Phenol Formaldehyde Resin

Forests ◽  
2020 ◽  
Vol 11 (5) ◽  
pp. 551 ◽  
Author(s):  
Wengang Hu ◽  
Jilei Zhang
Keyword(s):  
Yield Strength ◽  
Pinus Taeda ◽  
Phenol Formaldehyde ◽  
Core Layer ◽  
Phenol Formaldehyde Resin ◽  
Formaldehyde Resin ◽  
Low Molecular Weight ◽  
Southern Pine ◽  
Cross Laminated Timber ◽  
Loading Direction

The effect of impregnation treatment of low molecular weight phenol formaldehyde (MWPF) resin on the bolt-bearing yield strength (BBYS) of a three-layered cross-laminated timber (CLT) composed of two face layers of southern pine (Pinus taeda) and one core layer of sweetgum (Liquidambar styraciflua) was investigated together with two additional factors of material type and loading direction. Experimental results indicated that the amount of low MWPF resins penetrating into sweetgum was more than the ones into southern pine. Sweetgum had more uniform distribution of low MWPF resins penetrating longitudinally than southern pine. Impregnation treatment using a low MWPF resin at a concentration of 20% can enhance the BBYS of three-layered CLTs with a 60% increase. The BBYS of a core layer material in three-layered CLTs can significantly alter the overall BBYS of the three-layered CLTs.

Static and dynamic response of sandwich beams with lattice and pantographic cores

2021 ◽  
pp. 109963622110338
Author(s):  
Yury Solyaev ◽  
Arseniy Babaytsev ◽  
Anastasia Ustenko ◽  
Andrey Ripetskiy ◽  
Alexander Volkov
Keyword(s):  
Mechanical Performance ◽  
Lattice Structure ◽  
Unit Length ◽  
Experimental Tests ◽  
Plane Geometry ◽  
Sandwich Beams ◽  
Static Tests ◽  
Three Point Bending ◽  
The Core ◽  
The Impact

Mechanical performance of 3d-printed polyamide sandwich beams with different type of the lattice cores is investigated. Four variants of the beams are considered, which differ in the type of connections between the elements in the lattice structure of the core. We consider the pantographic-type lattices formed by the two families of inclined beams placed with small offset and connected by stiff joints (variant 1), by hinges (variant 2) and made without joints (variant 3). The fourth type of the core has the standard plane geometry formed by the intersected beams lying in the same plane (variant 4). Experimental tests were performed for the localized indentation loading according to the three-point bending scheme with small span-to-thickness ratio. From the experiments we found that the plane geometry of variant 4 has the highest rigidity and the highest load bearing capacity in the static tests. However, other three variants of the pantographic-type cores (1–3) demonstrate the better performance under the impact loading. The impact strength of such structures are in 3.5–5 times higher than those one of variant 4 with almost the same mass per unit length. This result is validated by using numerical simulations and explained by the decrease of the stress concentration and the stress state triaxiality and also by the delocalization effects that arise in the pantographic-type cores.

Face Wrinkling and Core Strength in Sandwich Construction

1960 ◽  
Vol 64 (591) ◽  
pp. 164-167 ◽  
Author(s):  
S. Yusuff
Keyword(s):  
High Stress ◽  
Core Layer ◽  
High Strength ◽  
Bending Rigidity ◽  
Core Strength ◽  
Surface Smoothness ◽  
Lightweight Material ◽  
The Core ◽  
Sandwich Construction ◽  
Strength Material

The effect of initial waviness on the wrinkling of faces in sandwich construction is studied. Formulae are derived to determine the failing stress when the faces wrinkle due to failure of the core in tension, compression or shear. The importance of core strength requirements in maintaining surface smoothness is noted. A comparison of theory with experiments is made, and the agreement between the two is found to be reasonably good.A sandwich construction consists of two thin face layers of high-strength material and a thick core layer of lightweight material. The function of the core is twofold. Firstly, it increases the bending rigidity of the faces and second, it stabilises them so that they will not wrinkle until high stress is reached.

Free Vibration Analysis of Symmetric Sandwich Beams

2017 ◽  
Vol 872 ◽  
pp. 399-404
Author(s):  
Zakaria Ibnorachid ◽  
Khalid El Bikri ◽  
Lhoucine Boutahar
Keyword(s):  
Sandwich Beam ◽  
Free Vibration Analysis ◽  
Core Layer ◽  
Equation Of Motion ◽  
Geometrical Parameters ◽  
Symmetric Vibration ◽  
Materials Properties ◽  
The Core ◽  
Validation Of Results ◽  
Good Agreement

The aim of the present work is to study the linear free symmetric vibration of three-layer sandwich beam using the energy method. The zigzag model is used to describe the displacement field. The theoretical model is based on the top and bottom layers behave as Euler-Bernoulli beams while the core layer as a Timoshenko beam. Based on Hamilton’s principle, the governing equation of motion sandwich beam is obtained in order to calculate the linear frequency parameters. Two types of boundary conditions simple supported-simple-supported (SS-SS) and clamped-clamped (C-C) under the influence of materials properties and geometrical parameters are studied. The validation of results is done by comparing with another studies, which available in the literature and found good agreement between the studies.

An attempt to use „Tetra Pak” waste material in particleboard technology

2021 ◽  
Vol 114 ◽  
pp. 70-75
Author(s):  
Radosław Auriga ◽  
Piotr Borysiuk ◽  
Alicja Auriga
Keyword(s):  
Mechanical Properties ◽  
Water Absorption ◽  
Bending Strength ◽  
Physical And Mechanical Properties ◽  
Core Layer ◽  
Waste Material ◽  
Thickness Swelling ◽  
The Core ◽  
Tetra Pak ◽  
The Impact

An attempt to use „Tetra Pak” waste material in particleboard technology. The study investigates the effect of addition Tetra Pak waste material in the core layer on physical and mechanical properties of chipboard. Three-layer chipboards with a thickness of 16 mm and a density of 650 kg / m3 were manufactured. The share of Tetra Pak waste material in the boards was varied: 0%, 5%, 10% and 25%. The density profile was measured to determine the impact of Tetra Pak share on the density distribution. In addition, the manufactured boards were tested for strength (MOR, MOE, IB), thickness swelling and water absorption after immersion in water for 2 and 24 hours. The tests revealed that Tetra Pak share does not affect significantly the value of static bending strength and modulus of elasticity of the chipboard, but it significantly decreases IB. Also, it has been found that Tetra Pak insignificantly decreases the value of swelling and water absorption of the chipboards.

Partial Gaussian-Approximation Soft Demapper for the Core Layer of MIMO-LDM in ATSC 3.0

2021 ◽  
pp. 1-9
Author(s):  
Yulong Shang ◽  
Seunghyeon Kim ◽  
Hojun Kim ◽  
Jaehyun Seo ◽  
Namho Hur ◽  
...  
Keyword(s):  
Gaussian Approximation ◽  
Core Layer ◽  
The Core

PERFORMANCE OF CONNECTED PRECAST LIGHTWEIGHT SANDWICH FOAMED CONCRETE PANEL UNDER FLEXURAL LOAD

2015 ◽  
Vol 75 (9) ◽  
Author(s):  
Noridah Mohamad ◽  
Abdul Aziz Abdul Samad ◽  
Noorwirdawati Ali ◽  
Josef Hadipramana ◽  
Norwati Jamaluddin
Keyword(s):  
Failure Modes ◽  
Ultimate Load ◽  
Core Layer ◽  
Crack Pattern ◽  
Control Panel ◽  
Structural Behaviour ◽  
The Core ◽  
Steel Bar ◽  
Mode Of Failure ◽  
Foamed Concrete

This paper investigates the structural behaviour of two connected Sandwiched Precast Lightweight Foamed Concrete Panel (PLFP) in term of their load bearing capacities and failure modes. Three (3) connected PLFP panels were cast using foamed concrete as the wythe and polystyrene as the core layer. Each connected panel were cast from two single panels connected using L-bar connection. The panels were strengthened with steel bar reinforcement embedded in both wythes which were connected to each other by the steel shear truss connectors. The connected PLFP panels were tested under flexural load. A single PLFP panel was cast as a control panel and tested under axial load. The results were analysed in term of the panel’s ultimate load, crack pattern and mode of failure. Results showed that the two connected PLFP panels were able to sustain slightly lower ultimate load compared to single PLFP panel. Crack at 45 degree angle at top half of panel and small crack at surface between joint of the connection were observed.

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