• Journal of the Korean Society of Propulsion Engineers
• /
• v.11 no.1
• /
• pp.34-42
• /
• 2007

Ultrasonic inspection method is more profitable than X-ray radiographic inspection in cost and effect of defect detection such as debond, damage, and it doesn't need special constructions. The method can also be a possible real time inspection with safety. This report explains 1)the experiment and analysis of ultrasonic property of solid propellant, 2)the inspection methods of propellant/liner debond by inside or outside inspection, and 3)the inspection methods of propellant microcrack by damage. From the results, it is possible to detect the defect of propellant/liner debond by inside or outside inspection. Futhermore, it can be possible to detect the propellant microcrack caused by damage using the ultrasonic attenuation.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.04a
• /
• pp.17-21
• /
• 2007

Ultrasonic inspection method is more profitable than X-ray radiographic inspection in cost and effect of defect detection such as debond, and it doesn't need special facilities. The method can also be a possible real time inspection with safety. This report explains the experiment and theoretical modeling analysis of the inspection methods of propellant/liner debond using ultrasonic multi-reflection in rocket motor. From the results, it is possible to detect the defect of propellant/liner debond and its signal is distinguishable with normal. And, it is approximately coincide with both experimental signal and modeling.

• Proceedings of the Korean Geotechical Society Conference
• /
• 1996.10a
• /
• pp.81-90
• /
• 1996

• Transactions of the Korean Society of Mechanical Engineers
• /
• v.18 no.12
• /
• pp.3202-3218
• /
• 1994

Mode shapes and natural frequencies of vibrating laminated composite plates are taken using real-time and time-average holographic interferometry. Debonds and delamination in the laminated plates are measured nondestructively. During holographic testing of composite plates, it has been found that the conditions for the local resonance in debonds are strongly dependent on the frequency of excitation. A membrane resonance model was proposed to describe this behavior. Relations between characteristic length according to the size, shape of debonds and membrane resonance frequency are presented. Several experiments were performed to verify the membrane resonance model. The agreements between the predicted excitation frequency and the observed resonance frequency are good. The experimental results show that higher stresses and strains due to local resonance lead to the debond detection.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.24 no.6 s.177
• /
• pp.1456-1469
• /
• 2000

Mechanical behaviors of uniaxially fiber-reinforced metal matrix composites under transverse loading conditions were studied at room and elevated temperatures. A mono-filament composite was selecte d as a representative analysis model with perfectly bonded fiber/matrix interface assumption. The elastic-plastic and visco-plastic models were investigated by both theoretical and numerical methods. The product of triaxiality factor and effective strain as well as stress components and strain energy was obtained as a function of location to estimate the failure sites in fiber-reinforced metal matrix composite. Results showed that fiber/ matrix interfacial debond plays a key role for local failure at the room temperature, while void creation and growth in addition to the interfacial debond are major concerns at the elevated temperature. It was also shown that there would be an optimal diameter of fiber for the strong fiber-reinforced metal matrix composite.

• Journal of the Korean Society of Propulsion Engineers
• /
• v.12 no.2
• /
• pp.40-47
• /
• 2008

It is known that the adhesive interface testing of the rocket motor using the ultrasonic wave is superior to the other testing methods about the ability to economical detect the defects. But, the signal analysis of the ultrasonic wave takes a lot of time and efforts because the time interval of the transmitted pulse and the received pulse is too short to separate the reflected signals due to the multi-layers of the rocket motor. The ultrasonic testing of rocket motor have only applied to the automatic system about extremely limited areas like the debond in adhesive interface between the motor case and the insulator. In this study the new technique to detect the debond between the liner and the propellant using the property of the resonance and the lamb waves instead of the existing ultrasonic testing was described.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2007.11a
• /
• pp.55-59
• /
• 2007

It is known that the adhesive interface testing of the rocket motor which using the ultrasonic wave iS superior to the other testing methods about the economically detectable abiliη of the defects. But, the signal analysis of the ultrasonic wave takes too much time and effort that the time interval of the transmitted pulse and the received pulse is too short to be separated the reflected signals because the structure of the rocket motor is multi-layers. The ultrasonic testing of rocket motor have been only applied with automatic system about extremely limited area like the debond in adhesive interface between the motor case and insulator. In this study the new technique to detect the debond between the liner and the propellant using the property of the resonance and Lamb waves was described as comparing the existence ultrasonic testing.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.21 no.3
• /
• pp.299-306
• /
• 2001

In this paper, artificial and real defects(delamination and debond) in composite structures were detected by using ESPI system. Three types of specimens, that is, composite laminates, honeycomb structures, and adhesive joints, were used to study the applicability of ESPI to composite structures. To detect defects in specimens, we selected thermal loading method that can easily induce the surface deformation of specimen. Experimental results show that defects in composite structures could be easily detected by ESPI. Moreover, it shows that ESPI could be usefully applied to the detection of defects in various composite structures.

• Composites Research
• /
• v.15 no.5
• /
• pp.19-26
• /
• 2002

Real defects in composite structures were detected by using laser measuring system. Four types of real defects, that is, impact-induced delamination in a composite laminate, debond in a honeycomb structure, free-edge delamination in a composite laminate and debond in an adhesive joint, were made by applying several types of loads to the specimens. Laser measuring system such as ESPI and shearography technique were used to detect those defects. Thermal loading method, which can easily induce the surface deformation of specimen, was used to detect the defects. Experimental results show that the defects in composite structures could be easily detected by ESPI and shearography technique. Moreover, it shows that ESPI and shearography technique could be usefully applied to the detection of defects in various kinds of composite structures.

• Korean Journal of Materials Research
• /
• v.3 no.2
• /
• pp.140-144
• /
• 1993

Abstract To modify brittleness among the properties of thermosetting epoxy resin, a reactive additive. succinonitrile(SN) was introduced to Diglycidyl ether of bisphenol A(DGEBA)-4, 4'-methylene dianiline (MDA) system. Fracture behavior was microscopically studied during breaking of composite materials. As a result, post debond friction energy was the most significant for breaking the composite having glass fibres, pull-out energy was the next significant and debonding energy was the last. It was observed that shear stress between glass fibre and epoxy matrix was main factor for fracture behavior. Reactive additive, SN made shear stress deteriorated.