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The lateral enlargement perpendicular to the compressive direction for small thin boards of Cryptomeria japonica was investigated to evaluate the effects of density and compressive directions to the radial (plane-sawn board) and 45 degrees of tilt to the radial (45º sawn board). Samples were impregnated with 200 and 20,000 molecular weight polyethylene glycol (PEG). The enlargement perpendicular to the fiber direction with deformation was obtained for heartwood and sapwood specimens treated only with PEG20,000. The compression ratio of specimens treated with PEG 20,000 exceeded the void volumes regardless of the wood density. Enlarged specimens of both sapwood and heartwood showed the inflection points in the force-compression ratio curve and no correlation between the compressive directions and lateral enlargement of specimens. In the local area showing the largest deformation, however, a weak positive correlation from plane-sawn boards and weak negative correlation from 45º sawn boards between the angles of compressive direction to growth ring and lateral enlargement were derived. Microfocus X-ray computer tomography in these areas showed the different morphological compressive deformations. The cells in the 45º sawn board were forced out due to each cell moving, whereas the radially arranged ones in the plane sawn board buckled under compression.

The distal part of the vastus medialis (VM) (VM obliquus: VMO) muscle acts as the medial stabilizer of the patella. However, it has been known to facilitate VMO contraction during training of the quadriceps femoris muscle in knee joint rehabilitation. This study aimed to examine the contribution degree of VMO as a knee joint extension torque generator. Sixteen healthy male volunteers participated in this study. Electrical muscle stimulation (EMS) was performed on VMO at 60° knee angle for 20 min to induce muscle fatigue. Knee extension twitch torques (TT) at 90° and 30° knee angle evoked by femoral nerve stimulation were measured before and after EMS. Although each TT at 90° and 30° knee angle significantly decreased after EMS, the decreased TT rate in both joint angles showed no significant difference. Our results show that VMO might contribute to the generation of the knee joint torque at the same level in the range from flexion to extension. Therefore, it was suggested that the facilitating the neural drive for VMO is important during the quadriceps femoris muscle strengthening exercise.

Objective: Elderly people with hallux valgus have decreased gait speed, which can result in reduced capacity to perform the activities of daily living. Therefore, this study examined the gait ability and related factors of patients with hallux valgus. Methods: The study participants were 10 patients with hallux valgus and 10 without. Ground reaction forces were measured as front–rear (X), lateral (Y), and vertical (Z) components from the early to late stance phases. Three-dimensional motion analysis was used to measure gait speed; touchdown distance; release distance; the angles of the limb joints and trunk at heel contact, toe-off, and peak ground reaction force; and the center of mass (COM) displacement in the sagittal plane. The height of the COM was calculated as a percentage of the body height. The hallux valgus and control groups were compared using the Mann–Whitney U-test. Results: In the hallux valgus group, the ground reaction force showed a significant increase in the Y component in each stance phase and in the Z component in the late stance phase. The lowest COM position in the hallux valgus group was significantly higher than that in the control group, resulting in a smaller difference in COM height over a gait cycle. Conclusions: The hallux valgus group was found to have reduced gait speed because of a shortened touchdown distance. Moreover, the continued high COM position in the hallux valgus group meant that potential energy could not efficiently be converted to kinetic energy.

[Purpose] The purpose of this study was to clarify fundamental changes induced by lower trunk muscle contraction during single-leg standing. [Subjects and Methods] Ten healthy normal males participated in this study. All subjects could accurately perform lower trunk muscle contraction-type Abdominal Expansion (AE), Abdominal Bracing (AB), and Abdominal Cave-in (AC). The alignment and position of the center of foot pressure (COP) during single-leg standing with SLR and step position after rotating the body from single-leg standing with maximum SLR were measured in each lower trunk muscle contraction type. [Results] When AC was performed during single-leg standing with SLR, the SLR angle increased, COP shifted backward, and the posterior tilt angle of the trunk and cross step distance decreased. [Conclusion] It was assumed that AC during wind-up increases the angle of lower limb elevation and decreases the posterior tilt angle of the trunk and cross step distance.

The failure behavior of wood with a short crack was examined by conducting the single-edge-notched bending tests of a radial-longitudinal system on Agathis specimens. In the test, the mode I critical stress intensity factor was measured, and its validity was checked by the result from double cantilever beam testing method. The mode I critical stress intensity factor decreased when the crack length approached zero. With crack length correction, a constant critical stress intensity factor was obtained over a wide range of crack length including crack-free specimen.

Asymmetric four-point bending tests of agathis specimens with a short crack along the neutral axis in a tangential–longitudinal system were conducted onto analyse the failure behaviour of wood with a short crack. The nominal shear strength and Mode II critical stress intensity factors of the specimens with various crack lengths were measured, and the influence of crack length on these properties was examined. The nominal shear strength of the cracked specimens was significantly lower than the strength of a crack-free specimen, even when the crack was extremely short. This finding suggests that the fracture mechanics theory is effective for analysing the failure behaviour of wood with a very short crack in this loading condition. However, the Mode II critical stress intensity factor still depends on the crack length. When the crack length was corrected with considering the formation of fracture process zone ahead of the crack tip, the critical intensity factor could be predicted effectively as well as the nominal shear strength.

Part I of this article described the treatment of specimens of fast-growing poplar (Populus ×euramericana NL-95) with styrene (ST) and glycidyl methacrylate (GMA) monomers. It detailed the results of tests for water absorption, dimensional stability, and termite and fungus resistance. This part continues the previous work. It examines the static and dynamic mechanical properties, as well as the thermal stability, of polymer-infused wood (PIW). Static mechanical properties of PIWs were assessed in terms of bending strength, compressive strength, and Brinell hardness. Our results showed that, as a result of the treatment, these properties were significantly increased. Moreover, the PIW treated with GMA-ST showed greater mechanical strength than PIW treated with ST alone. We believe that this is due to the formation of cross-linked bonds between the GMA-ST and the hydroxyl groups of the wood's cell walls. Dynamic mechanical analysis (DMA) demonstrated that, at normal temperatures, storage modulus E′ and mole...

Fast-growing poplar (Populus Xeuramericana NL-95) has been extensively cultivated in China. However, because of its poor quality, poplar wood is commonly used only in the manufacture of low-grade wood products. If the wood could be improved by postharvest treatment, it would be more useful and more saleable. Such modification is possible. Our team has developed a protocol to modify fast-growing poplar by impregnating poplar wood with styrene (ST) and glycidyl methacrylate (GMA); this treatment is followed by in situ polymerization by means of thermal treatment. Experimental results show that the treated wood absorbed only one-fifth of the water absorbed by untreated wood when both were submerged in water for 1 week. The treated wood was also two times as dimensionally stable. When treated and untreated wood specimens were exposed to termites and to the fungi that cause dry rot, the treated wood was 9.3 times as resistant to termites and 3.8 times as resistant to fungi. Specimens of treated wood were examined using Fourier transform infrared spectroscopy, which showed that a grafting reaction and copolymerization had occurred, bonding the hydroxyl groups of the wood cell walls to the GMA and ST. Scanning electron microscope observation of the treated wood showed that the cell lumens had been filled with polymers and that the interfaces between wood cell walls and polymer were hard to distinguish.

Single-edge-notched tests of a tangential–radial system were conducted on agathis specimens to analyze the failure behaviour of wood with a short crack. The nominal bending strength and mode I critical stress intensity factors of the specimens with various crack lengths were measured, and the influence of the crack length on these properties was examined. The nominal bending strength of the cracked specimens was significantly lower than that of a crack-free specimen, even when the crack was extremely short. This finding suggests that the fracture mechanics theory is essential for analyzing the failure behaviour of wood with a very short crack. However, the mode I critical stress intensity factor still depended on the crack length. When considering the fracture process zone developing at the crack tip, the critical intensity factor could be predicted effectively.

3次元の拡散方程式を差分法で解き，乾燥過程の構造材の含水率を計算した。その際，拡散係数の温度依存性に必要な材温については，含水率を相対湿度に変換し，その湿球温度が材温に相当するとして計算を行った。材全体の温度の平均値を用いて含水率の変動を計算した結果，中温乾燥の過程における様々な温度での拡散係数が最も一定の値となった。また，高温乾燥の過程においては，材温の実験結果と良く一致する結果が得られた。

A new education system for the mechanical design and manufacturing based on the conventional education system has been proposed. The proposed system is considered as a main subject of the specialized subjects of the mechanical engineering department in Kurume National College of Technology. In the proposed system, students could master the way to use 3D-CAD due to making 3D models of a hand-powered winch. The students also learned way of the optimum design for strength due to making the winch handle using CAE/CAM and due to estimating its strength. As the results of analysis of education system, it was seen that the education of the conventional manual drawing and graphics is very important for the new design and manufacturing education.

This study investigated the relationship between the initial shape of the stress (σ)-strain (e) curve of a Chamaecyparis obtusa wood specimen subjected to repeated combined compression and vibration stresses at various angles between the fiber direction and load direction and the piezoelectric behavior. The main findings of the study are: (1) the σ-e curve became convex initially, and then the stress was proportional to the strain. The σ-e curve had almost the same shape during both loading and unloading. (2) The σ-piezoelectric voltage (P) curve was nonlinear, with a maximal point or cusp on the curve, which had almost the same shape during both loading and unloading, as was also observed for the σ-e curve. (3) The plot of the first derivative of the stress [dσ/de (= σ′)] against e was nonlinear. The σ′-e and P-e curves at various angles were fairly similar. (4) The stress at the maximal point (or cusp) of the σ-P curve decreased with an increase in the angle between the fiber direction and load direction. The tendency of the stresses was very similar to that of Young’s modulus and compression strength calculated from Hook’s law and Hankinson’s law, respectively.

This study investigated the relationship between the cellulose crystal lattice strain (crystalline region) and the macroscopic surface strain in specimens of Chamaecyparisobtusa wood under repeated uniaxial tension stress in the fiber direction. Changes in the strain of the crystal lattice were measured from the peak of (004) reflection using the transit X-ray method. The macroscopic surface strain of each specimen was measured with a strain gauge. In both loading and unloading, the surface strain changed linearly with changes in stress. However, crystal lattice strain was not linear but exhibited changes along a curve with changing stress. Under stressed conditions, the crystal lattice strain was always less than the surface strain, regardless of the frequency of repetition in the loading and unloading cycle. The ratio of the crystal lattice strain to the surface strain showed a negative correlation for stress in both loading and unloading. That is, the ratio decreased with increasing stress, and finally tend to converge to a specific value. The ratio (I/I0) between the diffracted intensity (I0) in the (004) plane in the unloaded condition and the diffracted intensity (I) in the (004) plane in the loaded condition tend to converge on a specific value with increasing frequency of repetition. When the substantial tension Young’s modulus of the wood in the longitudinal direction decreased, the ratio of the strain of the crystal lattice to the surface strain also decreased. Moreover, the ratio decreased with increasing microfibril angle of the specimen.

The relationship between sap flow rates and diurnal fluctuation of stems was investigated in cloned 3-year-old saplings of Cryptomeria japonica D. Don grown in a phytotron with irrigation every 2 days. The improved stem heat balance method and a strain gauge were used to measure sap flow rate and diurnal fluctuation of the stem. The sap flow rate reacted to lighting conditions, increasing and decreasing immediately after lights-on and lights-off, respectively. The tangential strain on the surface of the inner bark exhibited a reaction that followed but opposed the reaction of the sap flow rate to lighting conditions. Based on the changes in sap flow rate, there seemed to be four phases in diurnal sap flow: phase A1 began with lights-on, when the sap flow rate increased, and lasted about 2 hours. In the following phase, A2, the sap flow rate remained almost constant at 1.3 g/min for about 10 h, and then declined for about 2 h as lights-off approached. In phase B, the early period of darkness, the sap flow declined quickly and then more slowly, for about 4 h, until the start of the second dark period, phase C, when the sap flow rate became almost constant at 0.05 g/min for about 6 h. The first derivative of each sap flow rate and the corresponding tangential strain were calculated, and the results indicated a negative correlation between the two variables in all periods. In particular, the relationship between the first derivative values exhibited a highly negative correlation in phases A1 and B, expressed as a primary formula. Sap flow rate was found to continue for some time after lights-off, and this compensated for reduced evaporative effects, albeit at a slow rate, over 4 h. The total amount of sap flow in the dark was only about 9% of that in the light, disregarding transpiration in the dark for simplicity. Thus, the total amount of sap flow responsible for swelling of the stem was about 9% of that consumed in transpiration during the light period.

The effects of grain angle, thickness of face veneer, and shelling ratio on dynamic modulus of elasticity (E) of veneer-overlaid particleboard composite (VOP) were examined by using nondestructive test. In this study, the possibility that E of VOP can be predicted by means of some empirical formula was also discussed. This study has shown that grain angle, thickness of face veneer, and shelling ratio have substantial effects on E of VOP. The E at 0° of grain angle of face veneer was the largest, decreasing rapidly with increase in the grain angle. The lowest value of E occurred at 90° of grain angle of face veneer. The relationship between grain angle of face veneer and E of VOP can be expressed in the form of Jenkin’s and Hankinson’s equations. The orthotropic properties of wood and VOP defined as the ratio E0/ E90 were 25.7 for wood and 4.7 for VOP. When the grain direction of face veneer was parallel to the length of the specimens, the E of VOP increased with increasing shelling ratio. VOP increased E from 125 to 179% over that of the particleboard and veneer thickness from 2.1 upto 3.6 mm. However, when the grain direction of face veneer was perpendicular to the length of the specimens, the E of VOP decreased with increasing shelling ratio. VOP decreased E from 23 to 41% over that of the particleboard and veneer thickness from 2.1 upto 3.6 mm. The relationship between E of VOP and face veneer thickness can be expressed in the form of a second-order parabolic equation. Rule of Mixture (ROM) can be used to predict E of VOP from the E of wood element and particleboard element.

The effects of grain angle of face veneer on surface wave velocity and dynamic shear modulus of three types of wood-based composites were examined using a surface wave propagation method. It was found that grain-angle dependence of surface wave velocity and dynamic shear modulus indeed exists for wood-based composites. Grain angles of face veneer were found to have substantial effects on the surface wave velocities and dynamic shear moduli of wood–plastic composite (WP), wood–fiberboard composite (WF), and wood–metal composite (WM). The orthotropic properties of the three composites were defined as the ratio of surface wave velocities at 0° and 90° grain angles (V0/V90), which were 3.7, 2.2, and 2.0 for WP, WF, and WM, respectively. For WP, WF, and WM, the dynamic shear moduli in the 90° grain angle of face veneer were approximately 7%, 19%, and 25% of that in the 0° grain angle, respectively. The relationships between grain angles of face veneer and the shear moduli of the three types of wood-based composites could be represented by Hankinson’s equation, and their optimal n values were 2.1, 1.2, and 1.3 for WP, WF, and WM, respectively.

We investigated the relationship between the crystal lattice strain and the piezoelectric response in Japanese cypress (Chamaecyparis obtusa Endl.) wood fibers subjected to tension stress in the fiber direction. As a result, the piezoelectric voltage was very sensitive to the mechanical behavior (deformation) of the wood crystalline regions obtained from the x-ray stress measurement. Thus, by investigating the behavior of piezoelectric voltage, it was possible to simply estimate the mechanical behavior of the crystalline regions in the wood.

This study used a vibration test method to show that grain angles of face veneer have substantial effects on sound velocities and dynamic Young’s moduli of three types of wood-based composites. The sound velocity at 0° grain angle of face veneer was the highest, and it decreased with increasing grain angle in the range of 0° to 90°. This tendency was similar to that for dynamic Young’s modulus. The relationship between the grain angle of face veneer and the sound velocity of three types of wood-based composites can be expressed in the form of Hankinson’s equation or a second-order parabolic equation. This study also showed that the application of orthotropic elasticity theory was valid for the three types of wood-based composites. The relationship between the grain angle of the face veneer and the Young’s modulus of three types of wood-based composites can be expressed in the form of the Jenkin equation, Hankinson’s equation, or a second-order parabolic equation. Rule of mixture can also be used to predict the Young’s modulus of wood-based composite from the Young’s moduli of the two elements.

This study was performed to investigate the relationship between the cellulose crystal lattice strain (crystalline region) and the macroscopic surface strain in specimens of Chamaecyparis obtusa wood under repeated uniaxial tension stress in the fiber direction. Changes in the strain of the crystal lattice were measured from the peak of (004) reflection using the transit X-ray method. The macroscopic surface strain of each specimen was measured with a strain gauge.In both loading and unloading, the surface strain changed linearly with changes in stress. However, crystal lattice strain was not linear but exhibited changes along a curve with changing stress.Under stressed conditions, the crystal lattice strain was always less than the surface strain, regardless of the frequency of repetition in the loading and unloading cycle.The ratio of the crystal lattice strain to the surface strain showed a negative correlation for stress in both loading and unloading. That is, the ratio decreased with increasing stress, and finally tended to converge to a specific value.The ratio (I/I0) between the diffracted intensity (I0) in the (004) plane in the unloaded condition and the diffracted intensity (I) in the (004) plane in the loaded condition tended to converge on a specific value with increasing frequency of repetition.When the substantial Young's modulus of the wood in the longitudinal direction decreased, the ratio of the strain of the crystal lattice to the surface strain also decreased. Moreover, the ratio decreased with increasing microfibril angle of the specimen.

The bending properties of particleboards with various density profiles were analyzed by calculating their modulus of elasticity (MOE) using two-dimensional finite element method (FEM). The calculation was based on the fundamental properties of homo-profile particleboards (board with flat density profile) produced from lauan (Shorea spp.) particles and an isocyanate resin. The results are summarized as follows: 1. The calculated MOE fit very well with the experimental values, with a deviation of below 5%. 2. Increment in peak density (PD) results in a proportional increase in MOE, while core density (CD) determines the optimum slope gradient between the peak and core regions. 3. The counteractive effect arising from increment in PD and simultaneous reduction in peak width resulted in merely 9% improvement in MOE, when PD was increased from 1.0 to 1.5 g/cm 3 . 4. Increment in peak distance (Pdi) results in a proportional reduction in MOE. When Pdi was doubled from 1 mm to 2 mm, MOE was reduced by about 11%. 5. In idealized density profile models, when peak and core densities remain unchanged, the maximum peak area does not necessarily result in the highest MOE. 6. Multiple regression analysis shows that the overall MOE of particleboard depends basically on the board mean density (MD), PD and Pdi.

Short carbon fibers, a reinforced material in wood veneer composites, were used to investigate the effects of fiber length and orientation of fibers on the elasticity of plywood. The technical feasibility, elasticity, and strength of the reinforced plywood with short carbon fiber were evaluated. In a short fiber reinforcement system, the fiber length does not directly influence the reinforcement in Cox's theory when the fiber length exceeded a certain length. When the length of short carbon fiber is beyond 3 mm, the high reinforced result was obtained in the experiment. However, if fiber length was too long, the reinforced result was less owing to the bridge between fibers and the increase of holes. The optimum fiber length must be considered. The orientation of fibers has a strong influence on the reinforcement. Unidirectional, perpendicular, and random orientation displayed different influence on the elasticity. Experimental results were discussed with Cox's method. Reinforced plywood with short carbon fibers in random orientation has a higher shear modulus and bending strength than the controls, in addition to other mechanical properties.

The rolling shear strength of plywood was evaluated using a flexural vibration test. Test specimens were lauan and Douglas fir three-ply plywoods made from thick veneers. The dynamic shear and Young's moduli were determined using the flexural vibration method, which involved in-plane and out-of-plane flexural vibration. The rolling shear strength was determined using the static destructive method, which is dependent on the direction of the lathe check in the core veneer. Before and after accelerated aging treatments were conducted, there were relations between out-of-plane dynamic properties (out-of-plane shear and Young's moduli) and its rolling shear strength. It was concluded that the rolling shear strength is related not only to the shear property of the core but the flexural stiffness of two faces when the deformation of out-of-plane plywood was not restrained.

In this paper, we present data on the electrical properties of 50 gm thick space silicon BSFR cells irradiated with 10 MeV protons with a fluence exceeding 1 x 1013 p/cm2 and irradiated with 1 MeV electrons with a fluence exceeding 1 x 1016 e/cm2, and discuss the anomalous degradation which was found in these large-fluence regions. These data show an increase of saturation current density and a decrease of diffusion voltage of the pn junction, and a decrease of majority carrier density and an increase of series resistance of the p-substrate as a result of the formation of a large amount of carrier traps by the large-fluence irradiation.

By using stress function methods and the conversion theories from isotropy to anisotropy, the torsional rigidity was analyzed, and the theoretical formulas for the anisotropic shear moduli in width and thickness directions were given for 3-ply composite. According to the theoretical analysis, the anisotropic shear moduli in width and thickness directions, and the anisotropic coefficients were obtained from Eq. (36), (37) and (41). The shear modulus in width direction was not related to that in the thickness direction of each ply, and could be calculated by Eq. (42) including secondary moment. There was an effect of the shear moduli in width direction of each ply on the shear modulus in thickness direction for composite, but it was little.In addition, the variations of shear stress distribution factors, which appear as the correction coefficient to shear modulus in the Timoshenko's beam theory including secondary shear deformation effects, were estimated for the composite materials. Using the mixture law of shear modulus obtained herein and the well-known mixture law of Young's modulus in bending, the shear stress distribution factors in thickness direction for 3-ply composite were about 1.0-1.35 except for 90° plywood. There were still the errors between the theoretical shear moduli and the those estimated from the distribution factors (κ44).

Following a previous paper, another type of diffusion equation accounting for the Coulomb friction is proposed in this paper. For the drying experiments Sitka spruce bars were used with dimensions L×R×T=10×2×2 cm, and the density was 0.4 g/cm3. The specimens were prepared at 20°C and 60% R.H., and were dried in the desiccator with silica gel at 20°C. After 1,200 h, the specimens were cut in half and dried in the desiccator again. The moisture contents were determined by using the oven-dry method and were also calculated from the above theories. The results considering friction are in good agreement with the experimental results.

Lumbers of sapwood of western hemlock (Tsuga heterophylla Sarg.) were impregnated with CCA wood preservatives. The treated lumbers and their ash obtained after burning them were extracted by cold water. The concentrations of copper, chromium, and arsenic in the extracts were determined by using an atomic absorption analyzer. The extracts were given to mice for three months to observe their effect on the living body.Copper, chromium and arsenic were detected in the extracts from the preserved wood, and chromium and arsenic were detected in the extracts from the ash. The results showed that the concentrations of arsenic and chromium flown out from CCA treated wood or its ash exceeded the criteria specified in the law. However, no significant difference was observed in the weight increase and the serum biochemical properties between the mice that took the water extracts of the treated wood or its ash, and the mice that took the water extracts of the untreated wood or its ash.

A possibility was investigated to calculate the surface roughness of woods by band sawing by using the acoustic emission count rate, the cutting force and the specific gravity of woods. Five different softwoods, four different ring-porous woods and eight different radial- and diffuse-porous woods were used as workpieces. Ripsawing was carried out. The acoustic emission count rate was measured by the ring down method using a measuring system with a microphone. The cutting force in the cutting direction was measured using a load cell attached to the feed table. The surface roughness of a wood measured by a contact instrument with a stylus of 0.25mm curvature was described by ten point height of irregularities. The results obtained in this study are summarized as follows: The surface roughness of softwoods and ring-porous woods can be calculated by the multiple regression of the specific gravity of woods, and the AE count-rate or the cutting force. The multiple regression using the AE count-rate is more precise than using cutting force for the calculation of softwoods and ring-porous woods. The surface roughness of radial- and diffuse-porous woods can be calculated by the linear regression of the AE count-rate when they are classed by the similar characteristics of their structures. Moreover, it can be calculated by the multiple regression of the specific gravity of woods and the cutting force.

An adaptive control optimization system was developed to produce a desired surface finish roughness by automatic control of the work-piece feed-rate in circular sawing. The system developed in this study consists of the interconnection of an adaptive controller with a numerically controlled circular saw. The AE signals and cutting forces were measured to monitor the machining process continuously in this system. The signals were provided to the adaptive controller to evaluate the surface finish roughness and adjust the workpiece feed-rate automatically in the machining process.