Ying Cheng Hu

Reinforcement Design of Poplar Glulam

Wood is one kind of renewable natural eco-material. Glued laminated timber (glulam) is an engineered wood product made from sawn lumber lamina glued together in horizontal layers. The application of glulam in the construction structure not only has great environmental value, but also reduces energy consumption and carbon emission of the construction. In this study, we evaluated the effects of different factors on the structural properties of glulam and designed several enhancement modes to reinforce the glulam with FRP (Fiber Reinforced Plastic). Then, we measured the mechanical properties of the glulam specimens in the different enhancement modes and selected the optimal reinforcement mode. The reinforcement method obviously increased the value of MOE and MOR of poplar glulam by 5%-15% and 5%-12% respectively. FRP length of 600mm was the optimal and most economic reinforcement length, and finger joint position of 300mm is the optimal position.

Mechanical Performance of a New Coir Fiber Laminated Composites

In order to overcome the uneven distribution of coir fiber density in the materials and the poor forming of the outer surface, a new type of coir fiber hybrid laminated composites has been developed. The non-woven needle felts of coir fiber are added as the core material, wood veneers are as the surface material, and E-type glass fiber felts are as the reinforcement material, the preparation of hybrid laminated composites has been carried out. Through the performance testing and scanning electron microscopy (SEM) analysis, a new type of biomass composite with excellent performance has been successfully developed. The application of coir fiber to obtain good impact toughness of composites has been effectively verified.

Dynamic and Static Properties of Wood-plastic Composites Made of Recycled High-Density Polyethylene

Three different nondestructive testing (NDT) methods were used on the wood-plastic composites (WPC), which were made of either recycled or virgin high-density polyethylene (HDPE) with poplar fibers as filler. The values of dynamic Young’s modulus of WPC based on recycled or virgin HDPE were measured by the different NDT methods, and the values of static bending modulus of elasticity (MOE) were also determined by three point bending test according to ASTM D790-03. The paper analyzed the variability of the dynamic young’s modulus of WPC based on recycled or virgin HDPE obtained with different NDT methods, and the correlativity was also estimated between the dynamic Young’s modulus and the static MOE of WPC based on recycled HDPE. These results suggest that WPC can be made of recycled HDPE, and the NDT methods can be appropriate to estimate the dynamic Young’s modulus of WPC based on recycled HDPE.

Study on Bonding Performances of Air Plasma Treated FRP

This paper reports on the effect of air plasma on the FRP surface wettability via change of the water contact angle. The aim is to alter the surface in a manner and scale resulting in stronger bonding strength between FRP and wood. The specimens are exposed to the direct current discharge. The irradiation time and power are variables. Goniometry is employed to determine the contact angle of FRP surface. The plasma treatment leads to radical generation and activation of such agents as oxygen, thus the surface contact angle decreases significantly. The shear strength of samples of wood reinforced by treated FRP is also given to show the bond quality at the FRP-wood interface.

Reliability Analysis of the Structural Laminated Veneer Lumber

The structural Laminated Veneer Lumber(LVL) is a kind of high-performance eco-material used in the construction engineering structure. It has great significance to analyze the structural reliability for the design and manufacture of the structural LVL. In this paper, the modulus of elasticity and static bending strength of LVL manufactured by birch and poplar veneers were obtained. And the factors were also analyzed, such as wood species, veneer thickness and LVL density. The advanced first order and second moment method (AFOSM) was used to analyze the reliability of LVL. So this paper offered a method to analyze the reliability of structural LVL for designing and using reasonably.

The Optimized Design of Manufacturing Process of Shrub Scrimber

In this study, the optimized manufacturing process of Shrub Scrimber has been researched by using orthogonal experiment. The dynamic mechanical properties of Shrub Scrimber were measured by Fast Fourier Transform (FFT) nondestructive testing method, and the reliability of this method was verified by the linear regression between the static mechanical properties and the dynamic one. The results showed that shrub Scrimber had excellent mechanical properties, and can be used as structure replaced natural wood. The flexural vibration test were confirmed reliable to predict the mechanical properties of Shrub Scrimber.

Research on Tensile Strength of Wood Single Lap Gluing Joint

The tensile strength of joints is one of the most important indexes which can affect joint quality. The effect of gluing length, specimen width and thickness of wood single lap joints on the maximum tensile load and tensile strength has been researched through the experiment method. The maximum tensile load increases with the increase of gluing length, specimen width and thickness, but the increase degrees are different; the tensile strength is consistent with the increase of gluing length, but does not change obviously with the increase of specimen width and even decreases with the increase of specimen thickness. The conclusions of this paper will have guiding significance for the design of wood single lap joints.

Relativity Analysis between Dynamic and Static Modulus of Elasticity on Different Thickness Wood-Plastic Structural Plates

The relativity was evaluated between dynamic modulus of elasticity (MOE) and static MOE, in order to assess the potential of using nondestructive testing (NDT) method as a checking tool for mechanical properties of wood-plastic structural plates. The dynamic MOE was evaluated on a FFT system, and the static MOE was determined by three point bending test. All of specimens were made of polyethylene（PE）and poplar flour. A significant correlation between the dynamic MOE and the static MOE was obtained from relativity analysis. These results suggest that the NDT method could be appropriate to estimate the dynamic MOE of specimens with different thickness.

Non-Destructive Testing and Performance Analysis of Glass Fiber Reinforced Soybean Straw Particleboard

Using the flexural vibration method of Fast Fourier Transform (FFT) non-destructive testing, the dynamic MOE of glass fiber reinforced soybean straw particleboard has been determined. The regression analysis among the dynamic MOE, the static MOE and MOR has been done, the significant correlation exists among the three values. And the prediction model has been built, the dynamic MOE can be used to realize the quality assessment by using the model. Using glass fiber to reinforce the soybean straw particleboard, the structure forms and positions of glass fiber have different effects on particleboard performance.

Effect of Compression Ratio and Lay Angle of Metal Net on the Mechanical Properties of Metal Net-LVL Composite

In order to improve the mechanical strength of LVL, metal net was inserted into the LVL (metal net-LVL composite) made of fast-growing poplar. In this study, the effects of compression ratio and lay angle of metal net (which is lay angle for short in this paper) on the mechanical properties of the metal net-LVL composite was investigated in a comparative way. In order to find out the optimum compression ratio and lay angle, the modulus of rupture (MOR), modulus of elasticity (MOE) and horizontal shear strength of the metal net-LVL composite were tested. The results showed that the effects of the compression ratio on MOR, MOE and horizontal shear strength were significant, with increasing of compression ratio, the values of MOR and MOE showed an earlier raised and later decreased state, and had the maximum values at 31%. The effects of lay angle on MOR and MOE were significant, the values of MOR and MOE increased first and then decreased with lay angle increasing, and the maximum values were obtained at 20°, though there were no significant effects on horizontal shear strength, there were the maximum values at 20°. Therefore, when the compression ratio was 31% and the lay angle was 20°, the metal net-LVL composite could obtain the optimal overall mechanical properties.