• Proceedings of the Korean Society of Precision Engineering Conference
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• 2010.11a
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• pp.327-328
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• 2010

• Proceedings of the Korean Society For Composite Materials Conference
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• 2000.11a
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• pp.177-182
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• 2000

This paper predicted the equivalent stiffness of spatially reinforced composites (SRC) using the volume average of a fiber rod and matrix stiffness, and the strength of SRC using the stiffness reduction and the modified Tsai-Wu composite failure theory. Those equivalent engineering constants are used to analyze the mechanical behavior and the failure of SRC structures. Because the distribution of equivalent engineering constants is varying with the change in SRC shape, we made a program that predicts engineering constants of SRC. Both 3-D and 4-D SRC show the smallest tensile modulus and the largest shear modulus at the maximum rotated direction from each rod. Also the strength properties show the same tendency.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.18 no.2
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• pp.58-64
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• 2019

This paper describes the analysis of dynamic characteristics and prediction of the stiffness for the joint between structural members. In the process of deriving the governing equations, the stiffness values responsible for the moment and shear force were modelled by using linear and torsional springs in the middle of a clamped-clamped beam. The sensitivities of the natural frequency and modal assurance criterion were investigated as a function of the dimensionless linear and torsional spring stiffness. The reliability of the predictions for the linear and torsional stiffness values was verified by the inverse computations of the stiffness matrix. The predictive and exact theoretical stiffness values were compared for the stiffness element in the finite element formulation, and their results show an excellent correlation. It is strongly anticipated that although the proposed methodology is currently limited to the analytical utilization, it will provide a useful tool to estimate unknown joint stiffness values based on the experimental natural frequency and mode shape.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2012.05a
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• pp.597-598
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• 2012

• Journal of Aerospace System Engineering
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• v.18 no.1
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• pp.21-28
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• 2024

In this paper, two prediction models based on deep neural network that could predict cross-sectional stiffness of a rotor blade were proposed. Herein, we employed structural and material information of cross-section. In the case of a prediction model that used material properties as the input of the network, it was designed to predict the cross-sectional stiffness by considering elastic modulus of each cross-sectional member. In the case of the prediction model that used structural information as a network input, it was designed to predict the cross-sectional stiffness by considering the location and thickness of cross-sectional members as network input. Both prediction models based on a deep neural network were realized using data obtained by cross-sectional analysis with KSAC2D (Konkuk section analysis code - two-dimensional).

• Advances in aircraft and spacecraft science
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• v.11 no.1
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• pp.1-21
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• 2024

The stiffness reduction of cross-ply composite laminates featuring a transverse cracking and delamination within the mid-layer is predicted through utilization of a modified shear-lag model, incorporating a stress perturbation function. Good agreement is obtained by comparing the prediction models and experimental data. The material characteristics of the composite are affected by fluctuations in temperature and transient moisture concentration distribution in desorption case, based on a micro-mechanical model of laminates. The transient and non-uniform moisture concentration distribution induces a stiffness reduction. The obtained results demonstrate the stiffness degradation dependence on factors such as cracks density, thickness ratio and environmental conditions. The present study underscores the significance of comprehending the degradation of material properties in the failure progression of laminates, particularly in instances of extensive delamination growth.

• Journal of Ocean Engineering and Technology
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• v.36 no.4
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• pp.243-250
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• 2022

Subsea power cables are subjected to various external loads induced by environmental and mechanical factors during manufacturing, shipping, and installation. Therefore, the prediction of the structural strength is essential. In this study, experimental and theoretical analyses were performed to investigate the axial stiffness of subsea power cables. A uniaxial tensile test of a 6.5 m three-core AC inter-array subsea power cable was carried out using a 10 MN hydraulic actuator. In addition, the resultant force was measured as a function of displacement. The theoretical model proposed by Witz and Tan (1992) was used to numerically predict the axial stiffness of the specimen. The Newton-Raphson method was employed to solve the governing equation in the theoretical analysis. A comparison of the experimental and theoretical results for axial stiffness revealed satisfactory agreement. In addition, the predicted axial stiffness was linear notwithstanding the nonlinear geometry of the subsea power cable or the nonlinearity of the governing equation. The feasibility of both experimental and theoretical framework for predicting the axial stiffness of subsea power cables was validated. Nevertheless, the need for further numerical study using the finite element method to validate the framework is acknowledged.

• Journal of the Korean Geosynthetics Society
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• v.9 no.2
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• pp.21-31
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• 2010

This paper describes research on the prediction of the vertical displacement of surface, horizontal displacements and bending moments in two anchored retaining wall for an excavation by a finite element program. It is very important to consider the appropriate constitutive model for the numerical analysis in excavation behavior. It is shown in this paper that the analyses of excavation considering small strain stiffness gives the more reasonable prediction of the vertical displacement of surface. and the parametric study on the small strain stiffness parameters for excavation analysis has been analysed.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.2
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• pp.611-617
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• 1991

Effective stiffness of short fiber composite with a three-dimensional random orientation of fibers is derived theoretically and compared with available experimental data. The laminate analogy and transformed laminate analogy are used for modulus prediction of 2-D and 3-D random composites, respectively. The effective stiffness of random oriented fiber composite can be expressed in terms of longitudinal and transverse stiffnesses of unidirectional composites. The result of transformed laminate analogy is more accurate than other approaches such as, Christensen-Waals equational and Lavengood-Goettler equation, etc. Also the effective properties of random oriented fiber composite can be expressed in terms of fiber and matrix properties such as elastic modulus, shear modulus and Poisson's ratio.

• Composites Research
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• v.17 no.5
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• pp.25-38
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• 2004

In this study, the stiffness of spatially reinforced composites (SRC) are predicted by using superposition of a rod and matrix stiffnesses in an arbitrary direction. To confirm the predicted values, the material properties of SRC are measured. The predicted values from the volume average of stiffness matrix are consistent with the tested values in a rod direction, but are inconsistent in an off-rod direction while reverse is true fur the volume average of compliance matrix. Therefore, the harmony function from superposition of stiffness and compliance matrix is introduced. The predicted values from the harmony function are consistent with the tested values in both the rod and the off-rod directions.