Proceedings of the Korean Society For Composite Materials Conference (한국복합재료학회:학술대회논문집)
The Korean Society for Composite Materials
 Annual
Domain
 Materials ＞ Polymeric Materials
2000.04

This paper addresses a modified arclength method for the nonlinear finite element analysis of a structure which is loaded in incremental and fixed forces, simultaneously. The main idea of the method is to separate the displacement term by the constant force from that by the incremental force. As the illustrative examples of the applicability of the present algorithm, a parametric study is performed on the nonlinear buckling behavior of composite cylindrical panels under the combined load of the incremented compression and the constant lateral pressure.

This paper presents the results of an elastic buckling analysis of orthotropic plate under inplane linearly distributed forces. The analytical solution for the orthotropic plate whose boundaries were assumed to be simply supported was derived in the previous work. In this study the loaded edges of plate are assumed to be simply supported and other two edges are assumed to be fixed. For the buckling analysis RayleighRitz method is employed. Graphical form of results for finding the elastic buckling strength of orthotropic plate under inplane linearly distributed forces is presented.

This paper presents the analytical results of local buckling of orthotropic Ishape compression members. Employing the equilibrium approach, the characteristic equation for local buckling of Ishape compression member is derived. Using the derived equation, the minimum buckling coefficients with respect to the ratio of width to thickness for the Ishape column are suggested as a graphical form. In addition, the dominant plate component initiating the local buckling of Ishape column is also identified by using the approximate solution and the results are plotted with dotted line on the minimum bucking coefficient curve.

Recently Western countries are now beginning to use ACM (Advanced Composites Material), in the construction industry Compared with existing construction materials, ACM possesses many advantages such as lightweight, highstrength, corrosion resistant property. Among other fabrication process of ACM, pultrusion is one of the promising one for civil infrastructure application. In this paper, the structural characteristics of pultruded GFRP strip and structural members of angle and tube type were studied. For the strip, parametric studies of pultrusion process has been carried out. Considered parameters were volume fraction, temperature, pulling speed and fiber orientations. For the pultruded angle and tube, compression test and buckling analysis has been carried out. The results were compared with calculated values using coded formulae

SteelBallImpact fracture Behavior of SodaLime Glass Plates Bonded with Glass Fabric/Epoxy PrepregIn order to study the impact fracture behavior of brittle materials, a steelballimpact experiment was Performed. Five kinds of materials were used in this study : sodalime glass plates, glass/epoxy prepregone layerbonded and unbonded glass plates, glass/epoxy prepregthree layersbonded and unbonded glass plates. Fracture patterns, the maximum stress and absorbed fracture energy were observed according to various impact velocities 40120m/s. With increasing impact velocity, ring crack, cone crack, radial crack and lateral crack took place in the interior of glass plates. The generation of such cracks was largely reduced with glass/epoxy prepreg coating. Consequently, it is thought that the characteristics of the dynamic Impact fracture behavior could be evaluated using the absorbed fracture energy and the maximum stress measured at the back surface of glass plates.

Metal matrix composites(MMCs) are rapidly becoming one of the strongest candidates for structural materials for many high temperature application. Among the high temperature environment, thermal shock is known to cause significant degradation in most MMC system. Therefore, the nondestructive evaluation on thermal shock damage behavior of SiC/A16061 composite has been carried out using ultrasonic surface and SHwaves. For this study, Sic fiber reinforced metal matrix composite specimens fabricated by a squeeze casting technique were thermally cycled in the temperature range 25~
$400^{\circ}C$ up to 1000 cycles. Three point bend test was conducted to investigate the effect of thermal shock damage on mechanical properties. The relationship between thermal shock damage behavior and the change of ultrasonic velocity and attenuation were discussed by considering SEM observation of fracture surface. 
In this study, the low velocity impact behavior of the composite laminates has been described by using 3 dimensional nonlinear finite elements. To describe the geometric nonlinearity due to large deformation, the dynamic contact problem is formulated using the exterior penalty finite element method on the base of Total Lagrangian formulation. The incremental decomposition is introduced, and the converged solution is attained by NewtonRaphson Method. The Newmark's constantacceleration time integration algorithm is used. To make verification of the finite element program developed in this study, the solution of the nonlinear static problem with occurrence of large deformation is compared with ABAQUS, and the solution of the static contact problem with indentation is compared with the Hertz solution. And, the solution of low velocity impact problem for isotropic material is verificated by comparison with that of LSDYNA3D. Finally the contact force of impact response from the nonlinear analysis are compared with those from the linear analysis.

Composite materials have been increasingly used in automotive and aircraft industries, naturally leading to active researches on the materials. The carbonepoxy composite is selected to study its thermal characteristics. During multiple thermal cycles composed of repeated cooling and heating variations of elastic constants are investigated to understand thermal effects on the carbonepoxy composite. In this investigation longitudinal resonance method and flexural resonance method was used to characterize. The values of
$E_1$ show small amount of increases depending on number of cycles of the thermal fatigue processes whereas values of$G_13$ do not indicate noticeable changes. Also, in cases of$E_2$ and$G_23$ their values decrease to a certain extend in initial stages after applications of thermal fatigue processes. However, the number of cycles of the applied thermal fatigue processes does not seem to affect their values. 
A new composite manufacturing technique which combines winding and curing together is studied and analyzed. This method is especially suited to the manufacture of thick composite materials in which thermal spiking is a common problem. An experimental apparatus was designed and built for use with a filament winder to continuously cure a thick composite cylinder. A hoopwound composite cylinder with 152 mm wall thickness was manufactured and embedded thermocouples and strain gages were monitored throughout the cure process. The experimental data were compared with analytical results.

During the curing process of thick glass/epoxy laminates, a substantial amount of temperature lag and overshoot at the center of the laminates is usually experienced due to the large thickness and low thermal conductivity of the glass/epoxy composites. Also, it requires a longer time for full and uniform consolidation. In this work, temperature, degree of cure and consolidation of a 20mm thick unidirectional glass/epoxy laminate were investigated using an experiment and a 3dimentional numerical analysis considering the exothermic reaction. From the experimental and numerical results, it was found that the experimentally obtained temperature profile agreed well with the numerical one and the cure cycle recommended by the prepreg manufacturer should be modified to prevent a temperature overshoot and to obtain full consolidation.

In this study, the distribution of the effective modulus was investigated statistically Plain weave structures were modeled with random stacking phase shift angles and the effective modulus was calculated by the unit cell analysis. The analysis results indicated that the effect of random phase shift angles was significant on the modulus distribution. As the number of layers increased, the coefficient of variation decreased and higher degree of homogeneity was attained.

This paper describes the need for a ductile Fiber Reinforced Plastic(FRP) reinforcement for concrete structures. Using the material hybrid and geometric hybrid, it is demonstrated that the pseudoductility characteristic can be generated in FRP rebar. Ductile hybrid FRP bars were successfully fabricated at 4mm and l0mm nominal diameters using an hand lay up method. Tensile specimens from these bars were tested and compared with behavior of FRP rebar and steel bar

Mechanical properties of (10%
$AI_20_3{\cdot}SiO_2$ +5%Ni)/Al hybrid composites fabricated by the reaction squeeze casting were compared with those of (15%$AI_20_3{\cdot}SiO_2$ )/Al composites. Intermetallic compound formed by reaction between molten aluminum and reinforcing powder was uniformly distributed in the Al matrix. These intermetallic compounds were identified as$Al_3$ NI using EDS and Xray diffraction analysis. Microhardness and flexural strength of hybrid composites were higher than that of (15%$AI_20_3{\cdot}SiO_2$ )/Al Composite. InSitu fracture tests were Conducted on (15%$AI_20_3{\cdot}SiO_2$ )/Al Composites and (10%$AI_20_3{\cdot}SiO_2$ +5%Ni)/Al hybrid composites to identify the microfracture process. It was identified from the insitu fracture test of (10%$AI_20_3{\cdot}SiO_2$ +5%Ni)/Al composites, microcracks were initiated mainly at the short fiber / matrix interfaces. As the loading was continued, the crack propagated mainly along the separated interfacial regions and the well developed shear bands. It was identified from the insitu fracture test of (10%$AI_20_3{\cdot}SiO_2$ +5%Ni)/Al hybrid composites, microcracks were initiated mainly by the short fiber/matrix interfacial debonding. The crack proceeded mainly through the intermetallic compound clusters 
Effects of Stitching Thread on Fatigue Characteristics of Polyurethane foam Cored Sandwich StructureThe effects of stitching thread on fatigue characteristics of polyurethane foam cored sandwich structures are investigated. Fatigue test and static test, being used in four point bending test, are performed with various diameters and distances of stitching thread. The Results show that the maximum load for bending tests is similar to each other, but after
$1O^6$ fatigue cycles, the stiffness degradation of the stitching thread diameter$\emptyset$ 3mm specimen is a much larger than that of the$\emptyset$ 5mm specimen. 
Polymeric composites exhibit highly nonlinear and rate dependent behavior during loading and unloading in offaxis directions. The equilibrium state of stress during loading is lower than the state of stress produced at finite strain rates. The amount of stress relaxation during loading decreases. Interestingly, however, the stress goes up to reach to the equilibrium state of stress for a fixed displacement during unloading. The unloading behavior is quite similar to the loading behavior. The stress relaxation patterns during loading and unloading is also similar, and those depend on the fiber orientation angles and the loading and unloading rates. The AS4/PEEK thermoplastic composite is used to characterize the relaxation behavior for different offaxis angles and loading rates. There exists a transient loading region at the beginning of unloading. The effective stress and effective plastic strain concept is used to establish a master curve of stress recovery pattern for different offaxis angles and unloading rates.

A mesh superposition technique is presented for an efficient analysis of structural behavior. Refined child mesh is superimposed over parent elements for the region of interest. It is a kind of adaptive mesh refinement, which allows locally refined mesh without introducing transition region or multipoint constraints. Proper boundary condition is necessary to avoid redundant rigid body motion and kinematic compatibility between neighbor elements. Delamination buckling analysis is conducted to demonstrate accuracy and efficiency of the present method.


In this paper, an effective procedure is presented for the local recovery of displacements and stresses in multilayered composite panels, which incorporate the local refinement using mesh superposition. The mesh superposition method is used to refine the global coarse mesh by superimposing refined mesh to the localized zone of interest without transition zones. The finite element model used is a solid element based on the HellingerReissner variational principle. The a posteriori computation of the throughthethickness distributions of displacements and stresses is achieved using a predictorcorrector procedure. The procedure utilizes the superconvergent stresses and nodal displacements of the finite element patch. The element patch is generated by locally superimposing a refined local mesh to the coarse global mesh.

The theory of nonprismatic folded plate structures was reported by the senior author in 1965 and 1966. Fiber reinforced composite materials are strong in tension. The structural element for such tension force is very thin and weak against bending because of small bending stiffnesses. Naturally, the box type section is considered as the optimum structural configuration because of its high bending stiffnesses. Such structures can be effectively analyzed by the folded plate theory with relative ease. The "hollow" bending member with uniform crosssection can be treated as prismatic folded plates which is a special case of the nonprismatic folded plates. Tn this paper, the result of analysis of a folded plates with one box type uniform crosssection is presented. Each plate is made of composite laminates with fiber orientation of [ABBCAAB]
$_r$ , with A=B=$45^{\circ}$ , and C=$90^{\circ}$ . The influence of the span to depth ratio is also studied. When this ratio is 5, the difference between the results of folded plate theory and beam theory is 1.66%. is 1.66%. 
A FEA(finite element analysis) model was proposed to study stress and strain distributions in thick composites with various types of fiber waviness under tensile and compressive loadings. Three types of model were considered in this study: uniform fiber waviness, graded fiber waviness and localized fiber waviness models. In the analysis, both material and geometrical nonlinearities due to fiber waviness were incorporated into the model utilizing energy density and incremental method. The strain distributions of uniform fiber waviness model were strongly influenced whereas the stress distributions were little influenced by fiber waviness. The stress and strain distributions of graded and localized fiber waviness models showed more complex distributions than those of uniform fiber waviness model due to the variation of fiber waviness along the thickness and length directions. It was concluded that the stress and strain distributions of composites with fiber waviness were significantly affected by types of fiber waviness.

The general solution of the antiplane shear problem for the curved interfacial crack between viscoelastic foam and composites was investigated with the complex variable displacement function and KelvinMaxwell model. The Laplace transform was applied to treat the viscoelastic characteristics of foam in the analysis. The stress intensity factor near the interfacial crack tip was predicted by considering both anisotropic and viscoelastic properties of two different materials. The results showed that the stress intensity factor increased with increasing the curvature of the curved interfacial crack and it also increased and eventually converged to a specific value with increasing time.


In the present study, (10%
$Al_2O_3$ +5%Si)/AZ91 Mg hybrid composite was fabricated using the squeeze casting method. During squeeze casting, molten Mg was infiltrated into the preform of 10%$Al_2O_3$ +5%Si and reaction product of$Mg_2Si$ intermetallic compound was formed by the reaction between molten Mg and Si powder. Microstructure has been observed and mechanical properties were evaluated for the reaction squeeze cast (RSC) hybrid composite. It was found that Si powder totally reacted with molten Mg to form$Mg_2Si$ . Reinforcement ($Al_2O_3$ ) and the reaction product ($Mg_2Si$ ) are fairly uniformly distributed in Mg matrix for the squeeze cast hybrid composite. Mechanical properties were improved with hybridization of reinforcements, namely higher hardness and enhanced wear resistance comparing squeeze cast (15%$Al_2O_3$ )/AZ91 Mg composite. 
본 연구에서는 온도의 상승에 의하여 부피가 팽창하는 열팽창 고무 치공구의 팽창 특성을 이용하여 열경화성 복합재료를 경화하고 압축하는 과정을 실험과 모델링을 통하여 해석하였으며, 열가소성 복합재료의 함침공정을 연구하였다. 열팽창 고무치공구가 사용되는 닫힌계와 열린계에서 예상되는 압력을 이론적으로 유도하였고, 경화가 수반되는 과정에 있어서는 실험을 통하여 열팽창치공구와 프리프레그가 나타내는 압력을 측정하였다. 온도가 상승하고 경화가 수반되는 경우에 등속도 압축실험에 의하여 얻어지는 응력변형율 곡선은 비선형점탄성 특성을 보여주었는데, 본 연구에서는 Maxwell모델을 KWW(KohlrauschWilliameWatts)식으로 변형시킨 모델식을 이용하여 이를 매우 정확하게 표현할 수 있었다. 또한 고무치공구를 이용하여 열가소성 수지의 복합재료 성형공정을 실험하였고, 중성자 레디오그래피 촬영을 통하여 기공의 분포를 관찰하였다.

A Study on the Vibration Characteristics of the Composite Sandwich Beams for HighSpeed Heddle FrameA heddle frame is the major part of a loom that produces woven cloth by insertion of weft yarns between warp yams. Warp yarns are manipulated by many heddles fixed in a heddle frame. Recently, the up and down speed of heddle frames has been increased much for the increase of productivity, which induces higher inertial stresses and vibrations in the heddle frame. The heddle frame has the rectangular crosssection. For the design of box type beams of rectangular crosssection, extensional stiffness EA, flexural stiffness El, and torsional stiffness GJ as well as the vibration characteristics are important and should be simultaneously considered. Tn this paper, the vibration characteristics of the composite and the composite sandwich beams for highspeed heddle frame were tested by impulse frequency response.

In this study, flutter characteristics of a composite wing have been studied for the variation of laminate angles in the subsonic, transonic and supersonic flow regime. The laminate angles are selected by the aspect of engineering practice such as 0,
$\pm$ 45 and 90 degrees. To calculate the unsteady aerodynamics for flutter analysis, the Doublet Lattice Method(DLM) in subsonic flow and the Doublet Point Method(DPM) in supersonic flow are applied in the frequency domain. In transonic flow, transonic small disturbance(TSD) code is used to calculate the nonlinear unsteady aerodynamics in the time domain. Aeroelastic governing equation has been solved by vg method in the frequency domain and also by Coupled TimeIntegration Method(CTIM) in the time domain. from the results of present study, characteristics of free vibration responses and aeroelastic instabilities of a composite wing are presented for the set of various lamination angles in the all flow range. 
Increased temperature adversely affects the reliability of a device. So, package material should have high thermal diffusion, i.e., high thermal conductivity. And, there are several other physical properties of polymeric materials that are important to microelectronics packaging, some of which are a low dielectric constant, a low coefficient of thermal expansion (CTE), and a high flexural strength. In this study, to get practical maximum packing fraction of AIN (granular type) filled EMC, the properties such as the spiral flow, thermal conductivity, CTE, and water resistance of AINfilled EMC (65vol%) were evaluated according to the size of AIN and the fillersize distribution. Also, physical properties of AIN filled EMC above 65vol% were evaluated according to increasing AIN content at the point of maximum packing fraction (highly loading condition). The high loading conditions of EMC were set
$D_L/D_S$ =12 and$X_S$ =0.25 like as filler of sphere shape and the AIN filled EMC in this conditions can be obtained satisfactory fluidity up to 70vol%. As a result, the AIN filled EMC (70vol%) at high loading condition showed improved thermal conductivity (about 6 W/mK), dielectric constant (2.0~3.0), CTE(less than 14 ppm/$^{\circ}C$ ) and water resistance. So, the AIN filled EMC (70vol%) at high loading condition meets the requirement fur advanced microelectronic packaging materials. 
본 논문에서는 열팽창계수(CTE)가 거의 없는 카본게폭시, PZT 세라믹 박판, 그리고 열팽창계수가 큰 글래스/에폭시 층으로 이루어진 곡면형 복합재료 작동기(LIPCA)의 설계, 제작 및 성능실험에 대한 연구성과를 제시하고 있다. LIPCA의 른 요점은 기존 THUNDER의 성능을 유지하면서 이를 경량화 하기 위하여 THUNDER의 금속 층을 상대적으로 가벼운 섬유 강화 복합재료로 대체하는 것이다. 이러한 경량화 작업으로 LIPCA는 기존 THUNDER 보다 약 30~40% 정도의 무게를 감소시킬 수 있으며, 복합재료의 특성에 따라 설계의 유연성을 가질 수 있는 장점이 있다. 또한, 에폭시 수지를 사용함으로써 접착제 없이 평판 몰드에서 오토클레이브에서 177
$^{\circ}C$ 로 경화되어, 탈형된 후 충분한 곡률을 형성하였다. 작동 성능 실험에서, LIPCA는 기존 THUNDER보다 작동변위가 향상됨을 보였다. 
The SiCp/AC8A composites were fabricated by the pressureless metal infiltration process successfully. The effect of additional Mg, which were mixed with SiC particles to promote interfacial wetting between the reinforcement and matrix alloy, and particle size on the mechanical properties was investigated. By increasing the additional Mg content the hardness of SiCp/AC8A composites was increased due to the hard reaction products, but the bending strength was decreased by the excess reaction of Mg and high porosity level when the additional Mg content is over 7%. The Hardness and bending strength was increased by decreasing the size of SiC particle.

In this article, we presents multiobjective design optimization of laminated composite beam using Fuzzy programming method. At first, the two design objectives are minimizing the structural weight and maximizing the buckling load respectively. Fuzzy multioptimization problem can be formulated based on results of single optimizations. Due to different relative importance of design objectives, membership functions are constructed by adding exponential parameters for different objective's weights. Finite element analysis of composite beam for buckling behavior are carried by Natural mode method proposed by J.Argyris and computational time of analysis can be reduced. With this scheme, a designer can conveniently obtain a compromise optimal solution of a multiobjective optimization problem only by providing some exponential parameters corresponding to the importance of the objective functions.

Substituting composite structures for conventional metallic structures has many advantages because of higher specific stiffness and specific strength of composite materials. In this work, onepiece propeller shafts composed of carbonfepoxy and glass/epoxy composites were designed and manufactured for a rear wheel drive automobile satisfying three design specifications, such as static torque transmission capability, torsional buckling and the fundamental natural bending frequency. Single lap adhesively bonded joint was employed to join the composite shaft and the aluminum yoke. For the optimal adhesive joining of the composite propeller shaft to the aluminum yoke, the torque transmission capability of the adhesively bonded composite shaft was calculated with respect to bonding length and yoke thickness by finite element method and compared with the experimental result. Then an optimal design method was proposed based on the failure model which incorporated the nonlinear mechanical behavior of aluminum yoke and epoxy adhesive. From the experiments and FEM analyses, it was found that the static torque transmission capability of composite propeller shaft was maximum at the critical yoke thickness, and it saturated beyond the critical length. Also, it was found that the onepiece composite propeller shaft had 40% weight saving effect compared with a twopiece steel propeller shaft.

Distributed piezoelectric sensor and actuator system has been designed for the active vibration control of shell structure. PVDF is used for the materials of sensor/actuator. To prevent the adverse effect of spillover, distributed modal sensor/actuator system is established. Although shell structure is threedimensional structure, the PVDF sensor/actuator system can be treated as twodimensional Finite element programs are developed to consider curved structures having PVDF modal sensor/actuator. The ninenode Mindlin shell element with five nodal degree of freedoms is used for finite element discretization. The electrode patterns and lamination angle of PVDF sensor/actuator are optimized to design the modal sensor/actuator system Genetic algorithm is used for optimization. Sensor is designed to minimize the observation spillover, and actuator is designed to minimize the system energy of the control modes under a given initial condition. Modal sensor/actuator for the first and second modes of singly curved cantilevered shell structure are designed using mentioned methods. Discrete LQG method is used as a control law. Experimental demonstrations of the active vibration control with designed sensor/actuator system have been performed successfully.

Interfacial and microfailure properties of carbon fiber/epoxy matrix composites were evaluated using both tensile fragmentation and compressive Broutman tests with acoustic emission (AE). Aminosilane and maleic anhydride polymeric coupling agents were used via the dipping and electrodeposition (ED), respectively. Both coupling agents exhibited higher improvements in interfacial shear strength (IFSS) under tensile tests than compressive cases. However, ED treatment showed higher IFSS improvement than dipping case under both tensile and compressive test. The typical microfailure modes including fiber break, matrix cracking, and interlayer failure were observed during tensile test, whereas the diagonal slippage in fiber ends was observed during compressive test. For both the untreated and treated cases AE distributions were separated well under tensile testing. On the other hand, AE distributions were rather closer under compressive tests because of the difference in failure energies between tensile and compressive loading. Under both loading conditions, fiber breaks occurred around just before and after yielding point. Maximum AE voltage fur the waveform of carbon or basalt fiber breakage under tensile tests exhibited much larger than those under compressive tests.

Fiber Bra99 grating (FBG) sensor, one of the fiber optic sensor (FOS) offers lots of advantages for structural health monitoring due to its multiplexing capability. Also, it is proper to measure the structural vibration with no mass concentration effect. In this paper, we constructed two sensor arrays composed of 9 FBG sensors for the vibration and mode sensing of a composites beam. For an accurate measurement of wavelength shift, a signal processing board with an electric circuit based on timeinterval counting was developed. This sensor system showed a good resolution of dynamic strain (<10
${\mu}{\varepsilon}$ ). Using this sensor system, dynamic strains at 9 points of composite beam was measured and strain measured mode shape of the beam was calculated from the acquired strains and compared with numerical results by ABAQUS. 
The flexural vibration of a sandwich beam with partially inserted viscoelastic layer has been studied using the finite element analysis in combination with an experiment. Effects of length and thickness of partial viscoelastic layers on system loss factor(
${\eta}_s$ ) and resonant frequency(${\omega}_r$ ) were considerably large. The thicker the viscoelastic layer in a sandwich beam, the larger the system loss factor in Mode 1 as compared with that in Mode 2. The loss factor increased almost linearly with increasing the length of partial viscoelastic layer. Effects of thickness of beams were also considered. 
In this paper, impact sound realization of composite structures is performed to investigate the possibility of a new NDE system  Tapping Sound Analysis (TSA). TSA detects the existence of damages inside the structures by comparing tapping sound with precomputed sound data of healthy structures. Tapping on the structures is modeled as impact problem and solved using finite element method. Calculation of sound is formulated based on the coupled finite element and boundary element method. Numerical simulation of impact sound and feature extraction scheme show that the impact sound can be used in the identification of damages of laminated composites.

The internal residual stresses within the multilayered structure with shan interface induced by the difference in thermal expansion coefficient between the materials of adjacent layers often provide the source of failure such as delamination of interfaces and etc. Recent development of the multilayered structure with functionally graded interface would be the solution to prevent this kind of failure. However a systematic thermomechanical analysis is needed fur the customized structural design of multilayered structure. In this study, theoretical model for the thermomechanical analysis is developed for multilayered structures of the Al
$SiC_p$ functionally graded composite for electronic packaging. The evolution of curvature and internal stresses in response to temperature variations is presented for the different combinations of geometry. The resultant analytical solutions are used for the optimal design of the multilayered structures with functionally graded interface as well as with sharp interface. 
Two types of fiberoptic sensors, EFPI(extrinsic FabryPerot interferometer) and FBG(fiber Bragg grating), have been investigated for measurement of thermal strain and temperature. The EFPI sensor is only for measurement of thermal strain and the FBG sensor is for simultaneous measurement of thermal strain and temperature. FBG temperature sensor was developed to measure strainindependent temperature. This sensor configuration consists of a singlefiber Bragg grating and capillary tube which makes it isolated from external strain. This sensor can then be used to compensate for the temperature cross sensitivity of a FBG strain sensor. These sensors are demonstrated by embedding them into a graphite/epoxy composite plate and by attaching them on aluminum rod and unsymmetric graphitelepoxy composite plate. All the tests were conducted in a thermal chamber with the temperature range
$20100^{\circ}C$ . Results of strain measurements by fiberoptic sensors are compared with that from conventional resistive foil gauge attached on the surface. 
The fabrication process and thermal properties of 50∼76vo1% SiCp/Al metal matrix composites (MMCs) were investigated. The 50∼76vo1% SiCp/Al MMCs fabricated by pressure infiltration casting process showed that thermal conductivities were 85∼170W/mK and coefficient of thermal expansion (CTE) were ranged 10∼6ppm/K. Specially, the thermal conductivity and CTE of 71vo1%SiCp/Al MMCs were ranged l15∼156W/mK and 6∼7ppm/K, respectively, which showed a improved thermal properties than the conventional electronic packaging materials such as ceramics and metals.

The process of squeeze casting for metal matrix composites (MMCs) has been simulated numerically by using finite difference method. The governing equations to describe fluid flow through porous medium and heat transfer are applied to two dimensional model which is similar to a real system. A computational code has been developed to solve this problem. The influence on infiltration kinetics and solidification time of several parameters is investigated. Cooling curves and temperature distribution with time and position is also shown. The result can be used to design the squeeze casting for MMCs.

복합재료의 성형 공정 중 하나인 Filament Winding 공정에 열가소성 기지재료인 폴리프로필렌(Polypropylene)과 강화섬유인 유리섬유로 이루어진 Commingled Yarn 을 이용한 연구를 수행하였다. 함침 과정을 해석하기 위한 계산모델을 제시하였다. 그리고 위의 모델링을 해석하는 데 필요한 복합재료 내의 온도 분포를 수치해석을 통해 계산하였고 실험을 통해 이를 검증하였다. 온도계산 결과를 함침도 예측에 이용하였다. 모델링을 통해 Filament Winding 공정의 주요 공정 변수를 찾아내었고 제시한 모델을 검증하기 위해 직접 Filament Winding 실험 장치를 제작하여 제품을 생산하고 모델과 비교하였다. 제작된 시편으로부터 함침도를 계산하는 방법을 제시하였다. 그 결과 함침도에 관해서 실험 결과가 모델과 그 경향이 뚜렷이 일치함을 확인하였다.

Filament wound pressure vessels have been studied for the efficient design tool to consider the variation of fiber angles throughthe thickness direction. Filament winding patterns were simulated from semigeodesic fiber path equation to calculate fiber path on arbitrary surface. Finite element analyses were performed considering fiber angle variation in longitudinal and thickness directions by ABAQUS. For the finite element modeling of the pressure tank, the 3dimensional layered solid element was utilized. From the stress results of pressure tanks, maximum stress criterion in transverse direction was applied to modify material properties for failed region. In the end of each load increment, resultant layer stresses were compared with a failure criterion and properties were reduced to 1/10 for a failed layer. Results of progressive failure analysis were compared with two experimental data.

A both mixing process of electromagnetic stirring and mechanical process technique were used to fabricate particulate metal matrix composites(PMMCs) for variation of particle size. The PMMCs were tested for their tensile test for with and without heat treatment with T6. PMMCs fabrication processing conditions for both electrical and mechanical process are also suggested. In order to thixoforming of PMMCs, fabricated billet are reheated by using the optimal coil designed as a function of length between PMMC billet and coil surface, coil diameter and billet length. The effect of reinforcement distribution on billet temperature variation are investigated with calculated solid fraction theory proposed as a function of matrix alloy and volume fraction of reinforcement.