• Journal of the Korean Wood Science and Technology
• /
• v.19 no.3
• /
• pp.19-26
• /
• 1991

This study was carried out to investigate the solid wood bending properties of red pine(Pinus densiflora S. et Z.)naturally grown in Korea by boiling treatment The specimens were green and their dimension was $15\times15\times350mm$. The optimum conditions for solid wood bending processing of pine lumber are shown in Table 6 and the minimum solid bending radius was 240 mm in boiling treatment. The effects of knot on the degradation of bending processing properties were very severe and the failures of diagonal and torn grained wood were 20% and 30% respectively.

• Steel and Composite Structures
• /
• v.18 no.1
• /
• pp.29-50
• /
• 2015

With a quasi-three point bending apparatus, ratcheting deformation is studied experimentally on a pressurized austenitic stainless steel Z2CND18.12N pipe under bending load and vertical displacement control, respectively. The characteristic of ratcheting behavior of straight pipe under both control methods is achieved and compared. The cyclic bending loading and internal pressure influence ratcheting behavior of pressurized straight pipe significantly under loading control and the ratcheting characteristics are also highly associated with the cyclic displacement and internal pressure under displacement control. They all affect not only the saturation of the ratcheting strain but the ratcheting strain rate. In addition, ratcheting simulation is performed by elastic-plastic finite element analysis with ANSYS in which the bilinear model, Chaboche model, Ohno-Wang model and modified Ohno-Wang model are applied. By comparison with the experimental data, it is found that the CJK model gives reasonable simulation. Ratcheting boundaries under two control modes are almost same.

• Interaction and multiscale mechanics
• /
• v.4 no.4
• /
• pp.321-336
• /
• 2011

This paper presents the results of static vertical load tests carried out on a model building frame supported by pile groups embedded in cohesionless soil (sand). The effect of soil interaction on displacements and rotation at the column base and also the shears and bending moments in the columns of the building frame were investigated. The experimental results have been compared with those obtained from the finite element analysis and conventional method of analysis. Soil nonlinearity in the lateral direction is characterized by the p-y curves and in the axial direction by nonlinear vertical springs along the length of the piles (${\tau}-z$ curves) at their tips (Q-z curves). The results reveal that the conventional method gives the shear force in the column by about 40-60%, the bending moment at the column top about 20-30% and at the column base about 75-100% more than those from the experimental results. The response of the frame from the experimental results is in good agreement with that obtained by the nonlinear finite element analysis.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
• /
• 1998.10a
• /
• pp.140-145
• /
• 1998

In this study, analysis for fatigue crack propagation behavior of interface and aroud interface under rotary bending stress. Though K values are nearly the same in around interface by BEM 2-D, fatigue crack propagated H.A.Z. Around Interface crack propagation speed is m=0.678 in H.A.Z by Paris' law. In this case(friction welded materials: STS304, SM15C), fatigue crack growth is considered SM15C metal microstructure and elastic flow from this result. Result is more metal microstructute dependence than stress dependence by analysis (BEM 3-D, BEM 2-D) and fatigue crack propagation

• Computers and Concrete
• /
• v.16 no.4
• /
• pp.625-642
• /
• 2015

Prestressed concrete bridges with corrugated steel webs have emerged as one of the promising bridge forms. This structural form provides excellent structural efficiency with the concrete flanges primarily taking bending and the corrugated steel webs primarily taking shear. In the design of this type of bridges, the flexural ductility and deformability as well as strength need to be carefully examined. Evaluation of these safety-related attributes requires the estimation of full-range behaviour. In this study, the full-range behaviour of beam sections with corrugated steel webs is evaluated by means of a nonlinear analytical method which uses the actual stress-strain curves of the materials and considers the path-dependence of materials. In view of the different behaviour of components and the large shear deformation of corrugated steel webs with negligible longitudinal stiffness, the assumption that plane sections remain plane may no longer be valid. The interaction between shear deformation and local bending of flanges may cause additional stress in flanges, which is considered in this study. The numerical results obtained are compared with experimental results for verification. A parametric study is undertaken to clarify the effects of various parameters on ductility, deformability and strength.

• Journal of the Korea Furniture Society
• /
• v.11 no.2
• /
• pp.45-53
• /
• 2000

This study was carried out to determine the suitability of 3 months old bamboo species of Phyllostachys bambusoides S. et Z., Phyllostachys Pubescens Mazel and Phyllostachys nigra var henonis Stapf as raw materials for the manufacture of strandboard. Total of 108 strandboards were made using urea-formaldehyde resin content level of 12% and one percent of liquid wax emulsion. The strandboard consisted of three layers the top and the bottom layer of which were oriented to the same direction and weighted 25% of the strandboard each. The middle core layer weighed 50% of the board and was perpendicular to the outer top and bottom layers. Analysis was performed to determine the effect of strand lengths and Uowing years of 3 months, 2 years and 3 years on strandboard properties. The physical and mechanical properties of bamboo species and boards were measured and compared to the standard requirements of strandboards. The results are as follows; 1. The more the growing years the higher the density of bamboo. Top part of bamboo indicated higher density value than that of bottom part. 2. Bamboo showed higher static bending strength compared to the main wood species. Longer growing years of bamboo generally inclosed the static tending strength out there were no statistical significancies for Phyllostachys bmbusoides S. et Z. and Phyllostachys pubescens Mazel. 3. Strand length indicated no difference on density and moisture content of strandboard. 5 cm of strand length gave the best static bending strength and internal bonding strength. Bamboo strandboard exhibited lesser extents of thickness swelling than that of CSA standard. 4. 3 months old bamboo gave higher static bending strength of strandboard than those of 2 years and 3 years old bamboo. In case of Phyllostachys nigra var henonis Stapf, 3 months old bamboo indicated higher internal bonding strength than those of 2 years and 3years old bamboo. but in Phyllostachys bambusoides S. et Z., Phyllostachys pubescens Mazel, there were no difference among growing years. Growing years showed no different physical properties of bamboo strandboard.

• Journal of the Korean Wood Science and Technology
• /
• v.29 no.2
• /
• pp.118-125
• /
• 2001

In this study, it was examined the characteristics of bending property of red pine(Pinus densiflora S, et Z.) related to slope of grain. At first, we have investigated the characteristics of wood species for bending property. At second, it was examined the relationships between grain angle and its related bending property. Specimens were made following to grain angle $0^{\circ}$, $30^{\circ}$, $45^{\circ}$, $60^{\circ}$, $90^{\circ}$, respectively. Dimension of wood materials was $10mm(T){\times}20mm(R){\times}350mm(L)$. Microwave irradiation time for bending process was 30, 60, 90, 120 seconds. The result of this study were as follows ; 1. Grain angle of wood was closely related to Young's modulus on bending process. In the process of bending with various grain angle, wood bending was easily proceed on the high grain angle range. 2. However, the strength of bent wood was very weak when the grain angle was high. Therefore, it was considered suitable grain angle for bending was existed. 3. The characteristics of wood properties for wood bending were very different among wood species.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.40 no.3
• /
• pp.267-273
• /
• 2016

This study evaluated the mechanical properties and crack-healing abilities of zirconia composite ceramics. The six kinds of specimens used were: partially stabilized zirconia (Z) and five zirconia composite (ZS, ZST1, ZST2, ZST3, and ZST5) with SiC and $TiO_2$. There was not a large difference between the Vickers hardness of the six types of zirconia ceramics. The bending strength of the ZS specimen degraded rapidly, but the zirconia specimens with $TiO_2$ (ZST1, ZST2, ZST3, and ZST5) showed improved strength. Therefore, it was determined that the bending strength is affected by the crystallization, which is due to the addition of SiC and $TiO_2$. From the crack-healing conditions having the highest bending strength, monolithic zirconia retained its cracks, while the specimens of four types with SiC healed their cracks.

• Transactions of Materials Processing
• /
• v.18 no.1
• /
• pp.67-72
• /
• 2009

This paper covers finite element simulations to evaluate tube bending process of auto chassis component i.e. trailing-arm product. The rear of the auto chassis structure is primarily composed of CTBA and trailing-arm. When a car rolls into a corner, the trailing arm reacts to roll in the same degree as the car body. During the bending process of trailing arm the tube undergoes significant deformation. Thus forming defects such as excessive thinning and flattening of the tube will be formed in the outside of the tube. In this paper, we analyzed the effect of process parameters in rotary draw bending process and searched the optimized combination of process parameters using orthogonal arrays method to minimize the forming defects. In this process we analyzed several parameters which are displacement of pressure die, boosting force, initial position of mandrel bar, dimensions of mandrel in regarding to the thinning and flattening of the tube.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.20 no.5
• /
• pp.533-541
• /
• 2007

The Zienkiewicz-Zhu(Z/Z) error estimate is slightly modified for the hierarchical p-refinement, and is then applied to L-shaped plates subjected to bending to demonstrate its effectiveness. An adaptive procedure in finite element analysis is presented by p-refinement of meshes in conjunction with a posteriori error estimator that is based on the superconvergent patch recovery(SPR) technique. The modified Z/Z error estimate p-refinement is different from the conventional approach because the high order shape functions based on integrals of Legendre polynomials are used to interpolate displacements within an element, on the other hand, the same order of basis function based on Pascal's triangle tree is also used to interpolate recovered stresses. The least-square method is used to fit a polynomial to the stresses computed at the sampling points. The strategy of finding a nearly optimal distribution of polynomial degrees on a fixed finite element mesh is discussed such that a particular element has to be refined automatically to obtain an acceptable level of accuracy by increasing p-levels non-uniformly or selectively. It is noted that the error decreases rapidly with an increase in the number of degrees of freedom and the sequences of p-distributions obtained by the proposed error indicator closely follow the optimal trajectory.