• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2009.11a
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• pp.429-432
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• 2009

The deformation and burst pressure of composite motor case highly depends on fiber material properties. Therefore, measuring exact fiber material properties is a priority item to develop a advanced composite motor case. However, the fiber material properties in composite motor case is very sensitive on the various processing variables (equipment, operator and environmental condition etc..)and size effect, so the fiber material properties can't be measured exactly from the existing specimen test method. This paper suggests a newly developed test method, hoop ring test, that is capable of pressure testing with ring specimens extracted from real composite motor case. The results of hoop ring test showed excellent agreement with measured fiber material properties from hydro-burst test with full scale composite motor cases.

• Journal of the Korean Society of Propulsion Engineers
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• v.16 no.2
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• pp.65-72
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• 2012

A defect analysis program for a composite motor case was developed to apply the ultrasonic signal processing method, based on the ultrasonic pulse-echo method. With the proposed defect analysis program, defects of FRP delamination and FRP/Rubber disbond in the composite motor case could be quantitatively measured. The defects detected in the composite motor case were in good agreement with the results measured with the computed tomography and video microscope. This paper described the development process of the defect analysis program to convert the ultrasonic test data into the C-Scan images.

• Composites Research
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• v.25 no.3
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• pp.82-89
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• 2012

This paper investigated the composite materials application examples and trends in the future to the solid rocket motor cases. The motor case must be stiff and tolerate at the high pressures, and light weight. In accordance to these kind of requirements, the composite materials showed the adaptable efficiency, and glass fibers, aramid, carbon fibers are applied to orderly. The comparison of the motor case efficiencies of the D6AC steel alloy, aramid, carbon fibers results in the carbon fibers best. Also the capacity of the payload will be increased more than 20% by using the high strength ones.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2007.04a
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• pp.193-196
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• 2007

The motor case for the KSLV-I KM is the first satellite launch vehicle ever to be developed by Korea to deliver the 100 kg class satellite into Earth's low orbit. This SLV is made of two stages, and the 2nd stage is made of solid rocket motor. The motor case of the KM is made of all composite materials except for the interface structures. Manufacturing process for the motor case such as insulation, filament winding for the motor case, fabrications for the interface structures will be discussed in this paper.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.393-399
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• 2011

A defect analysis program of the composite motor case was developed to apply the ultrasonic signal processing method on basis of the ultrasonic pulse-echo method and the defects of FRP delamination and FRP/Rubber disbond in the composite motor case could be quantitatively measured. The defects detected in the composite motor case were in agreement with the results measured with the computed tomography and video microscope. This paper was described about the development process of the defect analysis program to convert the ultrasonic test data into the C-Scan image.

• Journal of the Korean Society of Propulsion Engineers
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• v.2 no.1
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• pp.50-58
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• 1998

Water vapor transmission was tested in water bath controlled by $20^{\cire}C$, 90%RH for T800/AD6005 based composite motor case which made by filament winding method. We detected internal relative humidity of composite motor case by inserting the humidity detector through the head of motor case for the study of humidity transmission through the wall of composite motor case. We found out that this composite material appears the water vapor flux of 2.88${\times}$$10^{-9}$g/$\textrm{m}^2$sec and diffusivity of 7.98${\times}$$10^{-7}$$\textrm{mm}^2$/sec at $20^{\cire}C$, 90%RH water vapor condition.

• Journal of the Korean Society of Propulsion Engineers
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• v.23 no.4
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• pp.21-27
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• 2019

Composite motor cases fabricated by the filament winding method are structurally weak in the dome when they are required to withstand the internal pressure of the combustion gas. In this study, a finite element analysis is conducted to compare the burst pressure of a composite dome according to the variation of the pressure distribution ratio(PDR). The performance of the composite motor case was compared quantitatively by calculating the stress on the inner and outer dome surfaces and metal boss volume. As a result, the critical point of the failure mode was observed at a PDR between 2.5 and 3.0. A design at a PDR of 2.5­-3.5 can reduce the weight of metal boss without fluctuation in the burst pressure of the combustion motor case. Moreover as the design reference value changes according to the dome shape and opening size, further analysis and testing are necessary.

• Journal of the Korean Society for Nondestructive Testing
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• v.18 no.3
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• pp.191-204
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• 1998

One of the key issues in acoustic emission (AE) during hydroproof test of filament-wound composite rocket motor cases is the determination of the optimal component of elastic wave to be monitored. To solve this problem, broadband ultrasonic wave was generated into a symmetrically filament-wound composite motor case, and was received at 105 different locations after the propagation through the composite case with different distances and directions. By analysis of the received signals, characteristics of elastic wave propagation such as frequency components, the maximum propagating distance, and velocity surface were investigated. This analysis was performed for two different conditions of the motor case; air-filled and hydraulically pressurized. Based on these information, the effect of hydraulic pressure on the wave propagation characteristics was investigated and furthermore, the optimal component of elastic wave for AE during hydroproof test of the motor case was successfully determined.

• Journal of the Korean Society of Propulsion Engineers
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• v.1 no.2
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• pp.1-11
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• 1997

During hydroproof test of composite pressure vessel, acoustic emission signal was measured and analyzed to evaluate structural integrity of composite motor case. When pressure was held for 1 min. at constant pressure from low pressure level to high pressure level, the pattern of hit rate of good composite pressure vessel is increased with higher value than that of bad composite pressure vessel. This report also presents detection possibility of burst location approximately in the range of 25∼36％ of burst pressure using energy rate. In case that it is difficult to detect burst location of composite motor case, it is possible to detect burst location, i.e. structurally weak location of composite pressure vessel with applying same pressure lower than maximum expected operating pressure(MEOP) repeatedly.

• Journal of the Korean Society for Nondestructive Testing
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• v.23 no.5
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• pp.488-496
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• 2003

To establish nondestructive test method for rocket motor assembly with rubber and aerospace composite materials, practicable quality control acoustic emission test method is presented. Structural analysis for motor assembly is performed by ABAQUS code and analysis output result is confirmed by strain gage and AE data. Various specimens were tested and analyzed using strain gage and acoustic emission data. The hit rate of acoustic emission was closely related with case/rubber debonding. This report also describes practicable acoustic emission nondestructive method for evaluating motor case assembly quality assurance in the industrial field.