WOOD RESEARCH Volume 67, Number 1, 2022
Juraj Gigac and Mária Fišerová

Effect of smoothing in calender and hot stamping machine on the properties of coated paperboards for printed electronics

The methods of coated paperboards smoothing with a hot stamping machine using a smooth metal die and a conventional calender were compared. The printing roughness required for printing electrical and electronic components was achieved by both smoothing methods. The printing roughness of the coated paperboards decreased after hot stamping by 18 to 42% and after calendering by 22 to 41% depending on the grade of coated paperboard. The stiffness of coated paperboards decreased after hot stamping by only 4 to 21%, while by up to 38 to 51% after calendering. The ratio of specific stiffness and printing roughness of coated paperboards after hot stamping ranged from 2.5 to 8.1 mN. μm-2 and after calendering from 2.0 to 6.7 mN. μm-2. The stiffness of the coated paperboards decreased less after hot stamping, and that only in the printed electronics area, while after calendering the stiffness decreased significantly more in the whole profile. It can be assumed that packaging made from coated paperboards smoothed by hot stamping will have a lower weight and thus lower costs than packaging from calendered coated paperboards.

WOOD RESEARCH Volume 66, Number 6, 2021
Yifan Liu, Ziyin Yao, Feibin Wang, Hui Huang, and Zeli Que

Effect of edge distances on stiffness of shear-tension mode in glulam connections with inclined screws

The effects of edge distances on stiffness in glulam connections with inclined selftapping screws were studied in this paper. Under four anchorage angles (A-45°, A-60°, A-75°, A-90°) and three edge distances (EG-2D, EG-4D, EG-6D) conditions, the shear-tension tests were carried out on the timber structure connections with inclined self-tapping screws, and the stiffness and other properties of the connections were tested. Based on the results, the effects of edge distances on stiffness in joints were quantified using the equivalent energy elastic-plastic (EEEP) model. The results showed that the edge distances had a certain impact on the yield mode and load-carrying performance of the joints. Within a certain range of variation, as the edge distance increased, the stiffness of the connections increased gradually, showing a positive correlation. The stiffness of specimen EG-2D is 4.41 kN·mm-1. The stiffness of specimen EG-4D is 10.04 kN·mm-1, which increases by 128% compared with the specimen EG-2D. The stiffness of specimen EG-6D is 12.08 kN·mm-1, which increases by 174% compared with the specimen EG-2D. However, the ductility coefficient, yielding load, and energy dissipating have no significant change. Within a reasonable edge distance, only ductile damage occurred.

WOOD RESEARCH Volume 62, Number 1, 2017
Roger Moya and Carolina Tenorio

Strength and displacement under tension and compression of wood joints fastened with nails and screws for use in trusses in Costa Rica

The objective of the present study is to determine the behaviour of two typical types of fastener (nails and screws) used in trusses made of Gmelina arborea and Hieronyma alchorneoides timber. Wood joints with metal fasteners (nails and screws) and five angles (0°, 30°, 45°, 60° and 90°) were subjected to tension and compression loads in order to establish values of displacement in relation to applied loads, strength, stiffness values, mode of failure and a model for prediction of stiffness for intermediate orientations. Results indicate that the differences in loads and displacements appear among species in the compression test, whereas those differences appear among fasteners in the tension test. The results obtained for stiffness indicate that jointsofH. alchorneoides wood present the highest values. Models for prediction of stiffness for truss joints of intermediate orientations were: in compression, while for tension the model was.

WOOD RESEARCH Volume 65, Number 2, 2020
Xiaojun Yang, Qi Zhao, Dan Hao, Jiayang Wang, Shuai Fu, and Lan Ma

Flexural behavior of osb reinforced wood truss

In this paper, oriented strand board (OSB) on both sides of the wood truss was used to strengthen the wood truss. The flexural behavior of the reinforced wood truss was studied. The results showed that OSB was an effective technical member to improve the flexural bearing capacity of wood truss. Besides, wood truss and OSB can be firmly combined by using glue bonding and screw connections. The screws served only to apply pressure to the glued joint. And the reinforced wood trusses had good synergy and overall stability. The initial bending stiffness and ultimate bending load of the reinforced wood trusses were increased by 203.20% and 234.39% respectively. Ultimate bending load and initial bending stiffness were improved a little by making the wood truss wider. Compared with the traditional wood truss, the reinforced wood truss had the advantages of simple connection mode, less wood consumption, no rolling machine and easy fabrication.