• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.11a
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• pp.249-250
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• 2008

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.333-340
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• 2011

We evaluated the stress-reduction effect for different shapes of a composite adherend with or without a spew fillet. Six different single-lap joint specimens were modeled and assessed using nonlinear finite element analysis. Moreover, we investigated the effect of the stiffness ratio of the adherend and adhesive. The single-lap joint with normal tapering had the highest stress values, and the single-lap joint with reverse tapering and a spew fillet had the lowest stress values. The composite adherends with higher stiffness had lower stress values, and the adhesives with lower stiffness had lower stress values.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2007.04a
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• pp.487-492
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• 2007

The enhancement of the service life of damaged or cracked structures is a major issue for researchers and engineers. The hierarchical void element with the integrals of Legend polynomials is used to characterize the fracture behavior of unpatched crack as well as repaired crack with bonded composite patches by computing the stress intensity factors and stress contours at the crack tip. The numerical approach is based on the v-version degenerate shell element including the theory of anisotropic laminated composites. Since the equivalent single layer approach is adopted in this study, the proposed element is necessary to represent a discontinuous crack part as a continuum body with zero stiffness of materials. Thus the aspect ratio of this element to represent the crack should be extremely slender. The sensitivity of numerical solution with respect to energy release rate, displacement and stress has been tested to show the robustness of hierarchical void element as the aspect ratio is increased up to 2000. The stiffness derivative method and displacement extrapolation method have been applied to calculate the stress intensity factors of Mode I problem.

• JSTS:Journal of Semiconductor Technology and Science
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• v.16 no.2
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• pp.153-158
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• 2016

The elastic material constants, stiffness constants ($c_{11}$, $c_{12}$, and $c_{44}$), are three unique coefficients that establish the relation between stress and strain. Accurate knowledge of mechanical properties and the stiffness coefficients for silicon is required for design of Micro-Electro-Mechanical Systems (MEMS) devices for proper modeling of stress and strain in electronic packaging. In this work, the stiffness coefficients for silicon as a function of temperature from $-150^{\circ}C$ to $+25^{\circ}C$ have been extracted by using the experimental measurements of Poisson's ratio (${\nu}$) of silicon in several directions.

• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.941-946
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• 2001

The objectives of this study are to investigate effective stiffness of Rectangular reinforced concrete bridge columns. It is reasonable to use yielding effective stiffness of columns in seismic bridge design, especially in case that plastic hinges form at the bridge columns. In this study, the material nonlinear analysis was conducted for 3, 240 column sections of which variables were the concrete compressive stress, the steel yielding stress, the longitudinal steel location parameter, the longitudinal steel ratio, the axial load level, and the diameter of section. Based on the analytical results, an effective stiffness including two variables(longitudinal steel ratio and axial load ratio) was proposed by regression analyses, and it is compared with test results and the proposed equation for yielding effective stiffness of circular bridge columns.

• Journal of the Korean Society of Safety
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• v.32 no.3
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• pp.60-65
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• 2017

This study examined the effect of rotational stiffness of joints between vertical and horizontal members in system supports. In order to prevent repeated disasters of system supports, it is important to examine the accurate behavior of system supports. Among various factors affecting the complex behavior of system supports, this study focused on the stiffness of joints between vertical and horizontal members. The considered joint was modelled by a rotational spring, but the translational displacements were fixed. The stiffness of rotational spring was calculated by utilizing the usable experimental data. In addition, the hinge connection condition, which is generally considered in design and only restrict the translational displacements, was modelled to compare the results. The case with the rotational stiffness in joints showed 3.5 times buckling loads compared to the case without the rotational stiffness. Thus, the structural behavior of the vertical member in system supports was similar to the vertical member with the fixed condition. For the combined stresses of vertical members, the combined stress ratios were reduced 5~6% by considering the rotational stiffness of connecting parts. However, for the horizontal member where showed relatively small stress range, the stresses were increased 2.3~7.6 times by considering the rotational stiffness in connecting parts.

• Geomechanics and Engineering
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• v.33 no.1
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• pp.101-112
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• 2023

When a submerged floating tunnel is connected to the ground, there is a risk of stress concentration at the shore connection owing to the displacement imbalance caused by low confinement pressures in water and high confinement pressures in the ground. Here, the effects of the boundary condition and stiffness of the joints installed at the shore connection on the behaviors of a submerged floating tunnel and its shore connection were analyzed using a numerical method. The analysis results obtained with fixed and ground boundaries were similar due to the high stiffness of the ground boundary. However, the stability of the shore connection was found to be improved with the ground boundary as a small displacement was allowed at the boundary. The effect of the joint stiffness was evaluated by investigating the dynamic behavior of the submerged floating tunnel, the magnitude of the load acting on the bored tunnel, and the stress distribution at the shore connection. A lower joint stiffness was found to correspond to more effective relief of the stress concentration at the shore connection. However, it was confirmed that joints with low stiffness also increase the submerged floating tunnel displacement and decrease the frequency of the dynamic behavior, causing a risk of increased resonance when wave loads with low frequency are applied. Therefore, it is necessary to derive the optimal joint stiffness that can achieve both stress concentration relief and resonance prevention during the design of shore connections to secure their dynamic stability.

• Journal of the Korea Concrete Institute
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• v.18 no.5 s.95
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• pp.695-702
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• 2006

The stress distribution and the critical stresses in concrete pavements were analyzed using formulations in the transformed field domains when dual-wheel single-, tandem-, and tridem-axle loads were applied. First the accuracy of the transformed field domain analysis results was verified by comparing with the finite element analysis results. Then, the stress distribution along the longitudinal and transverse directions was investigated, and the effects of slab thickness, concrete elastic modulus, and foundation stiffness on the stress distribution were studied. The effect of the tire contact pressure related to the tire print area was also studied, and the location of the critical stress occurrence in concrete pavements was finally investigated. From this study, it was found that the critical concrete stress due to multi-axle loads became larger as the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The number of axles did not tend to affect the critical stress ratio except for a small foundation stiffness value with which the critical stress ratio became significantly larger as the number of axles increased. The critical stress location in the transverse direction tended to move into the interior as the tire contact pressure increased, the concrete elastic modulus increased, the slab thickness increased, and the foundation stiffness decreased. The critical stress location in the longitudinal direction was under the axle for single- and tandem-axle loads, but for tridem-axle loads, it tended to move under the middle axle from the outer axles as the concrete elastic modulus and/or slab thickness increased and the foundation stiffness decreased.

• Journal of Korean Neurosurgical Society
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• v.52 no.5
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• pp.435-440
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• 2012

Objective : The purpose of this study is to find the optimal stiffness and volume of bone cement and their biomechanical effects on the adjacent vertebrae to determine a better strategy for conducting vertebroplasty. Methods : A three-dimensional finite-element model of a functional spinal unit was developed using computed tomography scans of a normal motion segment, comprising the T11, T12 and L1 vertebrae. Volumes of bone cement, with appropriate mechanical properties, were inserted into the trabecular core of the T12 vertebra. Parametric studies were done by varying the volume and stiffness of the bone cement. Results : When the bone cement filling volume reached 30% of the volume of a vertebral body, the level of stiffness was restored to that of normal bone, and when higher bone cement exceeded 30% of the volume, the result was stiffness in excess of that of normal bone. When the bone cement volume was varied, local stress in the bony structures (cortical shell, trabecular bone and endplate) of each vertebra monotonically increased. Low-modulus bone cement has the effect of reducing strain in the augmented body, but only in cases of relatively high volumes of bone cement (>50%). Furthermore, varying the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies. Conclusion : The volume of cement was considered to be the most important determinant in endplate fracture. Changing the stiffness of bone cement has a negligible effect on the stress distribution of vertebral bodies.

• Journal of Power System Engineering
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• v.16 no.6
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• pp.45-51
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• 2012

In this paper, the algorithm for the static analysis of an axisymmetric cylindrical shell by using the finite element-transfer stiffness coefficient method (FE-TSCM) is suggested. TE-TSCM combining both the modeling procedure of the finite element method (FEM) and the transfer procedure of the transfer stiffness coefficient method (TSCM) has the advantages of FEM and TSCM. After computational programs are made by both FE-TSCM and FEM for the stress analysis of the axisymmetric cylindrical shell, we compare the numerical results by FE-TSCM with those of FEM for two computational models in order to confirm the trust of FE-TSCM.