WOOD RESEARCH Volume 62, Number 4, 2017
Wen-Gang Hu and Hui-Yuan Guan

Experimental and numerical study on optimization design of stretcher positions

In this study, the withdrawal strength of T-shaped joint was investigated through using Finite Element Method (FEM) and Analytic Method (AM). Firstly, the mechanical properties of wood were measured by conducting the experiment. In addition, the influence of friction coefficient between wood interfaces was studied with various size of contact area, direction of grain and pressure. Then, a mathematical model of oval mortise and tenon joint withdrawal strength was established based on linear elastic mechanics. Subsequently, the withdrawal strength of T-shaped joint was analyzed on the basis of numerical method with Finite Element Method (FEM) software. Finally, with the application of the experimental method, comparison and analysis were made between numerical method and analytic method. The results demonstrated that the consistency level between the numerical method and experiment was 83 %, which is more accurate than that between analytic method and experiment 80 %. As a results, the mathematical model was applicable to calculate the withdrawal strength of mortise and tenon joint which can also meet the engineering requirements of wood construction and wooden products structure design. In addition, the FEM applied in the study was more precise than analytic method while the latter was comparatively simple and convenient. These two methods were capable of evaluating the withdrawal strength of mortise and tenon joint, which can also be applied to structure design and optimization of wood construction and wooden products in order to make the design more scientific and reasonable.

WOOD RESEARCH Volume 63, Number 3, 2018
Wen-Gang Hu, Wei-Lian Fu, and Hui-Yuan Guan

Optimal design of stretchers positions of mortise and tenon joint chair

The chair joined by oval mortise-and-tenon was taken as a case. Then influences of two adjacent sides (side A and side B) stretcher positions on mechanical properties of chairs, including ultimate loading capacity, stiffness and strain distributions, were investigated through using experimental and numerical methods. Firstly, two factors and three levels experiments were conducted and analyzed by Finite Element Method (FEM) . The results showed that ultimate loading capacity of chairs decreased firstly and then increased with the growth of the height of stretchers positions. In addition, the stress concentration occurred at middle of side rails and joints of side rails, especially at the side B, while the stress at the middle of the leg was minimum. Besides, the higher the stretcher position of the side A was, the more harmonious the stress distributions of chair was, and the higher ultimate loading capacity and stiffness were. Moreover, the results of FEM were well consistence with those of experiments, and the errors were within 10%. Secondly, two factors and five levels numerical analysis was conducted to optimize the stretcher positions of chair by the FEM, and the results showed more boadly that the best stretchers positions of chair owning the highest loading capacity was not the only one. Finally, the relationship between ultimate loading capacity and stretcher positions was generated by using the response surface method, and the correlation coefficient was nearly 88%.

WOOD RESEARCH Volume 65, Number 3, 2020
Wen-Gang Hu, Na Liu, Lu Xu, and Huiyuan Guan

Study on cold/warm sensation of materials used in desktop of furniture

The aim of this study was to investigate the cold/warm sensations of materials used in desktop when forearms touching desktop. Both experimental tests and subjective evaluations were conducted in this study. A device was developed used to simulate forearm in order to replace subjects. Five men and five women were selected and introduced to six types of materials and two types of environmental temperatures in the tests. The results showed that the effects of environmental temperature on contact temperature of all tested materials were statistically significant, and the differences among wood and wood based materials, plastic materials, and artificial stone were also statistically significant. The device developed in this study was qualified to measure the contacting temperature between forearm and desktop sustainably and steadily, which can reduce the error introduced by subjects. Although qualitative relation was found between contact temperature and subjective evaluations, no quantitative correlation was proved.