Thermal Residual Stress

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Dai Gil Lee - One of the best experts on this subject based on the ideXlab platform.

  • Smart cure cycles for the adhesive joint of composite structures at cryogenic temperatures
    Composite Structures, 2008
    Co-Authors: Kwan-ho Lee, Dai Gil Lee
    Abstract:

    Adhesive joints are employed for composite structures used at the cryogenic temperatures such as LNG (liquefied natural gas) insulating tanks and satellite structures. The strength of the adhesive joints at the cryogenic temperatures is influenced by the property variation of adhesive and the Thermal Residual Stress generated due to the large temperature difference (??T) from the adhesive bonding process to the operating temperature. Therefore, in this work, the strength and Thermal Residual Stress of the epoxy adhesive at cryogenic temperatures were measured with respect to cure cycle. Also, the cure cycles composed of gradual heating, rapid cooling and reheating steps were applied to the adhesive joints to reduce the Thermal Residual Stress in the adhesive joints with short curing time. Finally, a smart cure method was developed to improve the adhesive joint strength and to reduce the cure time for the composite sandwich structures at cryogenic temperatures. ?? 2008 Elsevier Ltd. All rights reserved.

  • Smart cure cycle with cooling and reheating for co-cure bonded steel/carbon epoxy composite hybrid structures for reducing Thermal Residual Stress
    Composites Part A: Applied Science and Manufacturing, 2006
    Co-Authors: Hak-sung Kim, Sang-wook Park, Dai Gil Lee
    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. © 2005 Elsevier Ltd. All rights reserved.

Sang-wook Park - One of the best experts on this subject based on the ideXlab platform.

  • smart cure cycle with cooling and reheating for co cure bonded steel carbon epoxy composite hybrid structures for reducing Thermal Residual Stress
    Composites Part A-applied Science and Manufacturing, 2006
    Co-Authors: Sang-wook Park
    Abstract:

    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.

  • Smart cure cycle with cooling and reheating for co-cure bonded steel/carbon epoxy composite hybrid structures for reducing Thermal Residual Stress
    Composites Part A: Applied Science and Manufacturing, 2006
    Co-Authors: Hak-sung Kim, Sang-wook Park, Dai Gil Lee
    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. © 2005 Elsevier Ltd. All rights reserved.

Hak-sung Kim - One of the best experts on this subject based on the ideXlab platform.

  • In situ monitoring of the strain evolution and curing reaction of composite laminates to reduce the Thermal Residual Stress using FBG sensor and dielectrometry
    Composites Part B: Engineering, 2013
    Co-Authors: Hak-sung Kim, Seong Hwan Yoo, Seung-hwan Chang
    Abstract:

    Generally, a large, Thermal Residual Stress is generated during the curing process for composite laminates due to differences in the coefficients of Thermal expansion of the respective layers. The Thermal Residual Stress during fabrication greatly decreases the fatigue life and dimensional accuracy of the composite structures. In the present study, through a fiber bragg grating (FBG) sensor and dielectrometry in an autoclave, the strain evolution and curing reaction in composite laminates with a stacking sequence of [0 5/90 5] S were monitored simultaneously during a conventional cure cycle and a modified cure cycle to reduce the Thermal Residual Stress. From the study, it was verified that about 50% of the Thermal Residual Stress during fabrication could be reduced in a composite laminate by adjusting the cure cycle; this improved the static strength and fatigue life by 16% and up to 614%, respectively, for a peak ratio of 0.9. © 2012 Published by Elsevier Ltd.

  • Smart cure cycle with cooling and reheating for co-cure bonded steel/carbon epoxy composite hybrid structures for reducing Thermal Residual Stress
    Composites Part A: Applied Science and Manufacturing, 2006
    Co-Authors: Hak-sung Kim, Sang-wook Park, Dai Gil Lee
    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. © 2005 Elsevier Ltd. All rights reserved.

Seung-hwan Chang - One of the best experts on this subject based on the ideXlab platform.

  • In situ monitoring of the strain evolution and curing reaction of composite laminates to reduce the Thermal Residual Stress using FBG sensor and dielectrometry
    Composites Part B: Engineering, 2013
    Co-Authors: Hak-sung Kim, Seong Hwan Yoo, Seung-hwan Chang
    Abstract:

    Generally, a large, Thermal Residual Stress is generated during the curing process for composite laminates due to differences in the coefficients of Thermal expansion of the respective layers. The Thermal Residual Stress during fabrication greatly decreases the fatigue life and dimensional accuracy of the composite structures. In the present study, through a fiber bragg grating (FBG) sensor and dielectrometry in an autoclave, the strain evolution and curing reaction in composite laminates with a stacking sequence of [0 5/90 5] S were monitored simultaneously during a conventional cure cycle and a modified cure cycle to reduce the Thermal Residual Stress. From the study, it was verified that about 50% of the Thermal Residual Stress during fabrication could be reduced in a composite laminate by adjusting the cure cycle; this improved the static strength and fatigue life by 16% and up to 614%, respectively, for a peak ratio of 0.9. © 2012 Published by Elsevier Ltd.

  • in situ monitoring of the strain evolution and curing reaction of composite laminates to reduce the Thermal Residual Stress using fbg sensor and dielectrometry
    Composites Part B-engineering, 2013
    Co-Authors: Seung-hwan Chang
    Abstract:

    Abstract Generally, a large, Thermal Residual Stress is generated during the curing process for composite laminates due to differences in the coefficients of Thermal expansion of the respective layers. The Thermal Residual Stress during fabrication greatly decreases the fatigue life and dimensional accuracy of the composite structures. In the present study, through a fiber bragg grating (FBG) sensor and dielectrometry in an autoclave, the strain evolution and curing reaction in composite laminates with a stacking sequence of [0 5 /90 5 ] S were monitored simultaneously during a conventional cure cycle and a modified cure cycle to reduce the Thermal Residual Stress. From the study, it was verified that about 50% of the Thermal Residual Stress during fabrication could be reduced in a composite laminate by adjusting the cure cycle; this improved the static strength and fatigue life by 16% and up to 614%, respectively, for a peak ratio of 0.9.

Makoto Kanai - One of the best experts on this subject based on the ideXlab platform.

  • study on the curing process for carbon epoxy composites to reduce Thermal Residual Stress
    Composites Part A-applied Science and Manufacturing, 2012
    Co-Authors: Hideaki Murayama, Kazuro Kageyama, Kiyoshi Uzawa, Makoto Kanai
    Abstract:

    Abstract In this work, a cure monitoring system using dielectrometry and a fiber Bragg grating (FBG) sensor, was devised to measure the dissipation factor and Thermal Residual Stress of carbon fiber-reinforced epoxy composite materials. Three rapid-cooling points, which were based on the cure initiation point, were chosen as test variables to investigate the effect of cure cycle on process-induced internal strain. The internal strains generated in the composite specimens were measured using embedded FBG sensors. Three-point bending tests were conducted to investigate the effect of Thermal Residual Stress on the flexural strength of the composite specimens.

  • Study on the curing process for carbon/epoxy composites to reduce Thermal Residual Stress
    Composites Part A-applied Science and Manufacturing, 2012
    Co-Authors: Hideaki Murayama, Kazuro Kageyama, Kiyoshi Uzawa, Makoto Kanai
    Abstract:

    Abstract In this work, a cure monitoring system using dielectrometry and a fiber Bragg grating (FBG) sensor, was devised to measure the dissipation factor and Thermal Residual Stress of carbon fiber-reinforced epoxy composite materials. Three rapid-cooling points, which were based on the cure initiation point, were chosen as test variables to investigate the effect of cure cycle on process-induced internal strain. The internal strains generated in the composite specimens were measured using embedded FBG sensors. Three-point bending tests were conducted to investigate the effect of Thermal Residual Stress on the flexural strength of the composite specimens.