• 한국산학기술학회논문지
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• 제9권3호
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• pp.580-586
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• 2008

본 연구는 재료 특성에 있어 미세구조의 연속성을 예측한 것이다. 예측은 미세구조에서 사용되는 제작 재료의 동적 응답 분포를 측정해서 만들어졌다. 분포되는 재료 특성들이 미세구조의 기계적 성능을 평가하는데 사용될 때, 미세구조에 대한 컴퓨터 시뮬레이션과 실험결과의 차이를 줄일 수 있고 신뢰성 설계가 이루어질 수 있다.

• 대한기계학회논문집
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• 제15권2호
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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.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.684-689
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• 2008

In this study, homogenization method combined with the effective interface model for the characterization of properties of the nanoparticulate composites is developed. In order to characterize particle size effect of nanocomposites, effective interface model has been developed. The application range of analytical micromechanics approach is limited because a simple analytical approach is valid only for simple and uniform geometry of fiber particles. Therefore this study focuses on the analysis of mechanical properties of the effect interface through the continuum homogenization method instead of using analytical micromechanics approach. Using the homogenization method, elastic stiffness properties of the effective interface are numerically evaluated and compared with the analytically obtained micromechanics solutions. The suggested homogenization method is expected to be applied to optimization problems for nanocomposite design.

• 항공우주시스템공학회지
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• 제14권4호
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• pp.25-31
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• 2020

The development of manufacturing technology for braided composites has led to farther extension of the applications in aerospace structures. Since the mechanical characteristics of braided composites are affected by various materials and manufacturing parameters, it is important to determine the parameters required to appropriately design the braided composite structures. In this study, we proposed a geometric model of RUC (repeating unit cell) for 2D braided composites, and predicted the mechanical properties according to the change of fiber volume fraction, fiber filament size, braiding angle, and gap between adjacent yarns by the yarn slicing technique and stress averaging method. Finally, we analyze the characteristics of mechanical properties according to each manufacturing parameter of the braided composite material.

• Journal of Mechanical Science and Technology
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• 제19권11호
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• pp.2025-2031
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• 2005

Eshelby type micro mechanics model with a newly developed piezoelectric Eshelby tensor is proposed for predicting the effective electroelastic properties of the piezoelectric composite. The model is applied for piezoelectric solids containing both porosities and metal inhomogeneities. The effective electroelastic moduli of the composites such as stiffness, piezoelectric constants, and dielectric constants are predicted by the present model, which are extensively compared with the existing experimental results from the literatures. The validity of Eshelby type model for predicting the effective properties of the composite is thoroughly examined. It can be concluded from this study that a new mechanism is needed to compute correctly the dielectric constants among the effective properties of the composites.

• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2004년도 학술대회지
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• pp.228-233
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• 2004

The characteristics of the probability distribution for mechanical properties, e.g. tensile strength, reduction of area ana elongation, for STS304 stainless steel in elevated temperature were investigated from tensile test performed by constant cross head speea controls with 1mm/min, Recently, in order to clarify the strengthening mechanisms at high temperature, a new scheme to improve high temperature mechanical properties is desired. Therefore, the test ,technique development of high temperature creep behaviors for this material is very important. In this paper, the creep praperties and creep life prediction by Larson-Miller parameter method for STS304 stainless steel to be used for other high temperature components were presented at the elevated temperatures of 600, 650 and $700^{\circ}C$.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2004년도 추계학술발표대회 논문집
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• pp.151-154
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• 2004

A procedure of predicting mechanical properties of braided composites was developed. Mechanical behaviors of yams and resin in the composites were represented by elastoplastic constitutive relations. The mechanical properties of the hybrid braided composites were calculated using Method of cells and finite element method. Predictions of finite element method showed good agreement with experimental data but Method of cells predicted lower values than those of the experiment.

• Fibers and Polymers
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• 제2권4호
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• pp.196-202
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• 2001

In order to investigate the relationship between subjective sensation for fabric sound and touch and the objective measurements, eight different apparel fabrics were selected as specimens. Sound parameters of fabrics including level pressure of total sound (LPT), level range (ΔL), and frequency differences (Δf) and mechanical properties by Kawabata Evaluation System (KES) were obtained. For subjective evaluation, seven aspects of the sound (softness, loudness, pleasantness, sharpness, clearness, roughness, and highness) and eight of the tough (hardness, smoothness, fineness, coolness, pliability, crispness, heaviness, and thickness) were rated using semantic differential scale. Polyester ultrasuede was evaluated to sound softer and more pleasant while polyester taffeta to sound louder and rougher than any other fabrics. Wool fabric such as worsted and woolen showed similar sensation for sound but differed in some touch sensation in that woolen was coarseast, heaviest, and thickest in touch. In the prediction model for sound sensation, LPT affected positively subjective roughness and highness as well as loudness, while ΔL was found as a parameter related positively with softness and pleasantness. Touch sensation was explained by some of mechanical properties such as surface, compressional, shear, and bending properties implying that a touch sensation could be expressed by a variety of properties.

• 한국재료학회지
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• 제17권5호
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• pp.250-255
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• 2007

The alloying effects on the electronic structures of Zinc are investigated using the relativistic $DV-X{\alpha}molecular$ orbital method in order to obtain useful information for alloy design. A new parameter which is the d obital energy level(Md) and the bonder order(Bo) of alloying elements in Zinc was introduced and used for prediction of the mechanical properties. The Md correlated with the atomic radius and the electronegativity of elements. The Bo is a measure of the strength of the covalent bond between M and X atoms. First-principles calculations of electronic structures were performed with a series of models composed of a MZn18 cluster and the electronic states were calculated by the discrete variational- $X{\alpha}method$ by using the program code SCAT. The central Zinc atom(M) in the cluster was replaced by various alloying elements. In this study energy level structures of pure Zinc and alloyed Zinc were calculated. From calculated results of energy level structures in MZn18 cluster, We found Md and Bo values for various elements of Zn. In this work, Md and Bo values correlated to the tensile strength for the Zn. These results will give some guide to design of zinc based alloys for high temperature applications and it is possible the excellent alloys design.

• 대한기계학회논문집
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• 제11권5호
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• pp.717-724
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• 1987

본 연구에서는 한국중공업에서 실제로 제작한 터어빈 로우터를 시험편으로 하 여 -150.deg. C에서 +150.deg. C에 걸쳐 인장시험, 충격시험 및 파괴인성시험을 실시하여 각 온 도에서 기계적 성질과 파괴인성치를 시험적으로 구하고 Begley-Logsdon의 방법에 따라 파괴인성치를 예측하여 예측방법의 유용성 여부를 조사하고 또한 파단면의 양상을 함 께 검토하였다.