• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.422-422
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• 2009

This paper describes the structural design of small wind turbine blade by using design of experiments. Blade structure consists of skin, spar and foam. The materials for skin and spar are a kind of Glass/Epoxy and form is polyurethane. It has 7 lay-ups with different ply angle. A factorial design is applied to design the ply angles considering manufacturing constraints and to investigate the safety factor which is calculated by structural analysis. In order to perform the structural analysis, the commercial software ABAQUS is used. Tsai-Wu failure criterion is chosen to compute safety factor. The determination of the significance of effects in the experiments is made through the analysis of variance. The results show that ply angle at skin affects the safety factor of wind turbine blade. And from this result, optimal ply angles of composite blade are achieved.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1997.04a
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• pp.42-48
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• 1997

The dynamic response of symmetric cross-ply and angle-ply composite laminated plates under impact loads is investigated using a higher order shear deformation theory. A modified Hertz law is used to predict the impact loads and a four node finite element is used to model the plate. By using a higher order shear deformation theory, the out-of-plane shear stresses, which can be a crucial factor in the failure of composite plates, are determined with significant accuracy. The results compared with previous investigations showed good agreement. The effect of ply sequence and ply angle on the contact force is also studied.

• Steel and Composite Structures
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• v.47 no.4
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• pp.503-511
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• 2023

Stability of laminated plate under thermal load varied linearly along thickness, is developed using a higher order displacement field which depend on a parameter "m", whose value is optimized to get results closest to three-dimension elasticity results. Hamilton, s principle is used to derive equations of motion for laminated plates. These equations are solved using Navier-type for simply supported boundary conditions to obtain non uniform critical thermal buckling and fundamental frequency under a ratio of this load. Many design parameters of cross ply and angle ply laminates such as, number of layers, aspect ratios and E1/E2 ratios for thick and thin plates are investigated. It is observed that linear and uniform distribution of temperature reduces plate frequency.

• Proceedings of the KSME Conference
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• 2001.11a
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• pp.703-709
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• 2001

In this paper, we analyzed the laminated composite sandwich plate structure of truss core with changing values of the designing parameters. As a result, in designing parameters of that, the more height and thickness of the laminated composite plate's core, the more increase of natural frequency. In this type of structure, in the case of applying core of the laminated composite plate and antisymmetric stacking, natural frequency has high value and we calculated the optimum angle-ply making natural frequency maximum. Natural frequency of CFRP is higher than that of GFRP. Both are materials of the laminated composite plate. The mode shapes are various along with the angle-ply of the laminated composite plate.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.109-115
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• 2001

This paper investigates the mechanical characteristics of angle-ply laminates with non-woven carbon tissue. The lami- nates were made by inserting non-woven carbon tissue at the interface. Specimens were rounded near the tabs by grinding and polishing to reduce the stress concentration. Cyclic loads were applied to the specimens and the stress and fatigue life curves were obtained. The matrix crack density was also evaluated to check the effects of non-woven carbon tissue on the fracture resistance of composite laminates. C-Sean technique was used to evaluate the delamination, and SEM was used to understand the fracture mechanisms of the laminates. Experimental results show that the fatigue strength and life of composite laminates were increased by inserting non- woven carbon tissues. The results also show that the matrix crack density and delamination area were reduced by inserting non-woven carbon tissues.

• Steel and Composite Structures
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• v.34 no.1
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• pp.141-154
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• 2020

In the present paper, free vibration analysis of angle-ply laminated composite annular and circular plates is performed by numerical methods. First-order shear deformation plate theory is used for kinematic relations. The related governing equations of motion are discretized via differential quadrature and discrete singular convolution methods. Frequency values are obtained for different lamina scheme, thickness-to-radius ratio, and mode numbers. The advantages and accuracy of these two methods are also tested in detail.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.1
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• pp.28-40
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• 1991

Affine transformation was used to analyze the bending, buckling and vibration behaviors of a thick antisymmetric angle-ply rectangular simply supported laminate. Introducing the generalized parameters, the comprehensive solutions are found. The generalized parameters are a generalized rigidity ratio ( $D^*1), a generalized Poisson's ratio (.epsilon.) and a principal rigidity ratio (.alpha.). Hence, the transverse deflection decreases, the uniaxial buckling load and the fundamental frequency increase with increasing $D^*1 and decreasing .alpha., but the effect of .epsilon. is negligible. With decreasing the thickness ratio, the results by the classical plate theory are more erroneous. The transverse deflection is minimum, the uniaxial buckling load and the fundamental frequency are maximum if the fiber angle is 45.deg., and number of plies is more than 4. The time and efforts can be saved to understand the behaviors of composite laminates because these results can be applied to another composite material easily.sily.

• Steel and Composite Structures
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• v.7 no.3
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• pp.253-262
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• 2007

A methodology to design symmetrically laminated fibre-reinforced structures under transverse loads for minimum weight, with manufacturing uncertainty in the ply angle, is described. The ply angle and the ply thickness are the design variables, and the Tsai-Wu failure criteria is the design constraint implemented. It is assumed that the probability of any tolerance value occurring within the tolerance band, compared with any other, is equal, and thus the approach is a worst-case scenario approach. The finite element method, based on Mindlin plate and shell theory, is implemented, and thus effects like bending-twisting coupling are accounted for. The Golden Section method is used as the search algorithm, but the methodology is flexible enough to allow any appropriate finite element formulation, search algorithm and failure criterion to be substituted. In order to demonstrate the procedure, laminated plates with varying aspect ratios and boundary conditions are optimally designed and compared.

• Structural Engineering and Mechanics
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• v.33 no.6
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• pp.657-674
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• 2009

In this paper a 3-D continuum damage mechanics formulation for composite laminates and its implementation into a finite element model that is based on the layer-wise laminate plate theory are described. In the damage formulation, each composite ply is treated as a homogeneous orthotropic material exhibiting orthotropic damage in the form of distributed microscopic cracks that are normal to the three principal material directions. The progressive damage of different angle ply composite laminates under quasi-static loading that exhibit the free edge effects are investigated. The effects of various numerical modeling parameters on the progressive damage response are investigated. It will be shown that the dominant damage mechanism in the lay-ups of [+30/-30]s and [+45/-45]s is matrix cracking. However, the lay-up of [+15/-15] may be delaminated in the vicinity of the edges and at $+{\theta}/-{\theta}$ layers interfaces.

• Journal of Korean Association for Spatial Structures
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• v.2 no.4 s.6
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• pp.29-36
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• 2002

The responses of composite laminated beams modeled with finite element and excited by stochastic loading are studied. The cantilevered laminated beam having a 5 ply configuration is considered. The beam is 1m long, 0.1m wide, and 0.02m thick, yielding a length to thickness ratio of L/h=50. The laminated beams was assumed to be made of Born Epoxy. The four nodes at the free end of the cantilever were loaded with identical zero-mean white noise excitations. Stress and failure analysis loaded with identical zero-mean white noise excitations is carried out. Along with the obtained results, comparison and discussion are presented for the cases of symmetric-ply, antisymmetric-ply, angle-ply, and cross-ply laminated beams.