Showing papers by "Dai Gil Lee published in 2006"
TL;DR: In this paper, a laminate with stacking sequence of [± θ /0 8 ] S was proposed to increase the efficiency of composite bolted joints under general load, such as bending, compressive, and tensile load.
55 citations
TL;DR: In this paper, a smart cure cycle with cooling and reheating for co-cure bonded steel/carbon epoxy composite hybrid structures was developed to reduce the fabricational thermal residual stress between the steel and carbon epoxy composites material.
Abstract: In this work, a smart cure cycle with cooling and reheating for co-cure bonded steel/carbon epoxy composite hybrid structures was developed to reduce the fabricational thermal residual stress between the steel and carbon epoxy composite material. The thermo-mechanical properties of the high modulus carbon epoxy composite were measured by a Differential scanning calorimetry (DSC) and rheometer to obtain the optimal time to apply the cooling operation. The static lap shear strength of the co-cure bonded steel/composite lap joints and tensile strength of the composite specimen were measured to investigate the effect of cure cycle on the thermal residual stress. Also, the deflection of the hybrid structures was measured to measure the actual cure temperature with respect to various cure cycles. From the experiments, it was found that the smart cure cycle with cooling and reheating not only reduced the fabricational thermal residual stress but also improved the strength and dimensional accuracy of the hybrid structures.
52 citations
TL;DR: In this article, the dielectric properties of unidirectional E-glass fiber reinforced epoxy composites were tested with the free space method, from which theoretical models and mixture equations for estimating its Dielectric constant were proposed with respect to the fiber volume fractions.
52 citations
TL;DR: In this article, a smart cure method with cooling and reheating was developed to reduce residual stresses in thick-wound composite cylinders made of carbon phenolic woven composite, and the optimal cure cycle was obtained to reduce the residual stresses without increasing processing time.
51 citations
TL;DR: In this paper, a model for the effect of wear debris on the friction and wear of carbon composites with micro-groove was proposed. And the wear characteristics of carbon/epoxy composite materials with microgrooves were investigated by dry sliding test with respect to applied pressure.
46 citations
TL;DR: In this paper, a simple air slit levitating conveyor was devised to lower the equipment cost and to reduce the air consumption, and the air consumptions between the air conveyor with the air slit and that with the porous pad were compared.
42 citations
TL;DR: In this article, the E-glass/epoxy composite and single dipole FSS element was fabricated by printed circuit board (PCB) manufacturing process, and their EM transmission characteristics, such as a resonant frequency, a minimum transmission loss, and a transmission bandwidth, were measured in the X-band frequency range by the free space method with respect to the size of dipole element and its periodicity of array.
37 citations
TL;DR: In this article, the wear characteristics of carbon fiber phenolic composites were experimentally investigated both under dry sliding and oil-lubrication conditions, where nano-size particles were mixed in the surface layers of composite specimens to improve their wear characteristics.
33 citations
TL;DR: In this paper, a hybrid composite hemispherical bearing (CHB) composed of carbon-phenolic composite and aluminum back-up for the suspension of high mobility tracked vehicles, is developed.
31 citations
TL;DR: In this paper, the effect of wear debris on the tribological behavior of flat composite surfaces was investigated and the worn out surfaces were observed, from which the friction and wear mechanisms considering the compacted wear debris were proposed.
30 citations
TL;DR: In this paper, the effect of design parameters for co-cured joint, such as fiber stacking sequence, stiffness ratio of composite to aluminum on the static tensile load capabilities and dynamic fatigue characteristics were experimentally investigated.
TL;DR: In this paper, a hybrid composite journal bearing (HCJB) composed of carbon/phenolic laminated composite bush and steel housing was designed for marine vessels because it reduces the possibility of the seizure problem between the journal and bearing.
TL;DR: In this article, a smart cure cycle composed of cooling and reheating cycles was applied to reduce the thermal residual stresses generated during co-cure bonding stages due to the difference of coefficients of thermal expansions (CTE) of the composite and the aluminum tube.
TL;DR: In this article, a composite spherical bearing (CSB) composed of carbon-phenolic composite race and steel ball is developed to solve the seizure of conventional metal-metal spherical bearings for the elevation driving mechanism (EDM) of a future battle tank.
TL;DR: In this article, a hybrid steel/composite circular plate cutting tool was analyzed by finite element method with respect to material types such as composite and foam, stacking angles of the composite, adhesive bonding thickness, and dimensions of the cutting tool.
TL;DR: In this paper, polyetheretherketone (PEEK) powders were mixed near the surface plies to make a functionally gradient material, because the PEEK powder lowers not only the friction coefficient but also the strength of the composite.
TL;DR: In this paper, a smart cure cycle with cooling, polymerization and reheating was devised to nearly completely eliminate thermal residual stresses in the bonding layer of the co-cure bonded hybrid structure.
Abstract: In this work, a smart cure cycle with cooling, polymerization and reheating was devised to nearly completely eliminate thermal residual stresses in the bonding layer of the co-cure bonded hybrid structure. In situ dielectrometry cure monitoring, DSC experiments and rheometric measurements were performed to investigate the physical state and the cure kinetics of the neat epoxy resin in the carbon fiber/epoxy composite materials. From the experimental results, an optimal cooling point in the cure cycle was obtained. Also, process parameters such as cooling rate, polymerization temperature and polymerization time in the curing process were investigated. Then, the thermal residual stresses were estimated by measuring the curvatures of co-cure bonded steel/composite strips and their effects on the static lap-shear strengths of co-cure bonded steel/composite lap joints were measured. Also, the effects of thermal residual stresses on the tensile strength, the interlaminar shear strength and the interlaminar frac...
TL;DR: In this article, a new micro-multi-functional actuator was designed using a spring (music) wire which has a high fatigue endurance limit because the surface of music wire is finely surface-finished.
Patent•
10 Feb 2006
TL;DR: In this article, a method for manufacturing a spherical bearing assembly with a composite material eliminates the need to forcedly insert a spherical journal into the spherical bearing, while acquiring required strength and enhancing a lubrication characteristic.
Abstract: A method for manufacturing a spherical bearing assembly with a composite material eliminates the need to forcedly insert a spherical journal into a spherical bearing, while acquiring required strength and enhancing a lubrication characteristic. The method includes a step of producing a spherical journal and a step of molding a spherical bearing with a composite material by using the spherical journal as a core. The spherical journal may be produced with the composite material, in which case the step of producing the spherical journal includes molding the spherical journal with the composite material and coating a metal film on an outer surface of the spherical journal molded.