The Carbon Fiber Reinforced Plastic(CFRP) is used in many industrial areas owing to its excellent specific strength. In order to be utilized for machine parts, it is needed to have the hole drilling machining that presents the excellent surface. For the excellent hole machining of CFRP, this study evaluated the cutting force and remaining burr in accordance with changes in temperature by cooling down the temperature of the machining part. It could be used for other machining of composite materials produced by laminating fabric.

본 연구에서는 이수의 유동 특성을 분석하기 위한 기초 연구로서 상용 코드인 ANSYS CFX 14.5를 이용하여 고체-액체 2상 유동 에 대한 수치해석적 연구를 수행하였다. 고체-액체 2상 유동 현상을 모사하기 위해서 균질류 모델과 분리류 모델을 사용하였다. 분리류 모델에서는 Gidaspow의 항력모델을 적용하였으며, 고체 입자에 운동 이론 모델을 적용하였다. 기존의 실험 결과를 기반으로 본 연구에서 사용한 수치해석 모델의 유효성을 검토하였으며, 수치해석은 직경 54.9 mm, 길이 3 m의 수평관에서 체적 분율 0.1~0.5, 속도 1~5 m/s 범위에서 수행되었다. 그리고 압력강하와 고체 입자의 체적 분율 분포를 확인하였으며, 압력강하는 균질류 모델과 분리류 모델이 각각 MAE 17.04%, 8.98 % 이내에서 실험결과를 잘 예측하였다. 관의 하부에서 높은 체적 분율이 나타나며, 상부로 갈수록 체적 분율은 감소하였다. 그리고 속도가 증가할수록 높이 변화에 따른 체적 분율 분포의 변화는 감소하였으며, 수치해석 결과는 이러한 유동 특성을 잘 예측하였다.

The paper concerns numerical study of fully developed laminar flow of a Newtonian water and non-Newtonian fluids, 0.2% aqueous of sodium carboxymethyl cellulose(CMC) solution in eccentric annuli with combined bulk axial flow and inner cylinder rotation. Pressure losses and skin friction coefficients have been measured when the inner cylinder rotates at the speed of 0～200 rpm. A numerical analysis considered mainly the effects of annular eccentricity and inner cylinder rotation. The present analysis has demonstrated the importance of the drill pipe rotation and eccentricity. In eccentricity of 0.7 of a Newtonian water, the flow field is recirculation dominated and unexpected behavior is observed. it generates a strong rotation directed layer, that two opposing effects act to create two local peaks of the axial velocity. The influences of rotation, radius ratio and working fluid on the annular flow field are investigated.

The paper concerns an experimental and numerical study of fully developed laminar flow of a Newtonian, water and non-Newtonian fluids, 0.2% aqueous of sodium carboxymethyl cellulose(CMC) solution in concentric and eccentric annuli with combined bulk axial flow and inner cylinder rotation. Pressure losses and skin friction coefficients have been measured when the inner cylinder rotates at the speed of 0～300 rpm. The influences of rotation, radius ratio and working fluid on the annular flow field are investigated.

The experimental data from the central composite design runs were utilized for mathematical models far the drilling characteristics containing linear, quadratic and interactive effects of the parameters such as volume fraction of TiC in the composites, drill speed, feed rate and drill diameter. The models were developed via stepwise selection where the insignificant effects were removed using t-test. The models were subjected to optimization of maximizing drill life and satisfying the other constraints.