• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.314-319
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• 2004

Many of researches regarding mechanical properties of composite materials are associated with humid environment and temperature. Especially the temperature is a very important factor influencing the design of thermoplastic composites. However, the effect of temperature on impact behavior of reinforced composites have not yet been fully explored. An approach which predicts critical fracture toughness GIC was performed by the impact test in this work The main goal of this work is to study effects of temperature in the impact test with glass fiber/polypropylene(GF/pp) composites. The critical fracture energy and failure mechanisms of GF/PP composites are investigated in the temperature range of $60^{\circ}C\;to\;-50^{\circ}C$ by impact test. The critical fracture energy shows a maximum at ambient temperature and it tends to decrease as temperature goes up or goes down. Major failure mechanisms can be classified such as fiber matrix debonding, fiber pull-out and/or delamination and matrix deformation.

• Journal of the Korean Society for Precision Engineering
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• v.15 no.3
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• pp.119-126
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• 1998

유리섬유 강화 열가소성 복합재료는 고상성형법에 의해 저렴한 가격으로 큰 부피의 제품의 제조에 널리 사용될 수 있어 아주 좋은 전망을 가지고 있다. 그러나 이러한 재료의 성형성이나 재료거동의 특성은 아직 잘 파악되지 않았다. 본 연구의 주안점은 이러한 재료의 단순 굽힘에서의 굽힘성형성을 연구하는데 두었다. 실험에 사용된 재료는 임의의 방향으로 위치한 유리섬유를 중량비로 20 %, 35 %, 40 % 함유한 폴리프로필렌이다 굽힘시험은 75 $^{\circ}C$에서 150 $^{\circ}C$ 사이의 온도에서 25 $^{\circ}C$ 씩 증가하면서 행했고, 편치속도는 2.54 mm/sec와 0.0254 mm/sec에서 행했다. 단순 굽힘시험에서 측정된 굽힘성형성은 해석적 모델로 예측한 결과와 비교하였다. 실험결과와 예측결과가 비교적 잘 일치함을 보였으며, 굽힘성 map으로써 성형 온도와 펀치반경의 좌굴에 대한 효과를 가시화 함은 물론 좋은 성형조건을 선정할 수 있는 좋은 도구로써 나타내었다.

• Journal of Ocean Engineering and Technology
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• v.10 no.4
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• pp.58-66
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• 1996

The purpose of this investigation is to estimate the strength with the variations of the notch shape and the adgesive condition at the fiber/matrix micro interface of E-glass/PP laminates. To promote the degradation of the adhesive condition at the fiber/matrix micro interface without matrix dissolution loss, low-, hot-wet and spiking tests were carried out. The absorpotion properties and the tensile properties were compared accrding to the fiber orientation and the content. The results show that, firstly, saturated moisture absorption was reached at 5cycles and their absorptions of RD-40, UD-42 and UD-50 are 0.68%, 0.63%, 0.60%, respectively. Secondly, all the specimens investigated were mostly degraded at 5cycle, whereas UD-50 having ellipse shaped notch the least decrement of strength.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2004.05a
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• pp.326-330
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• 2004

Thermosetting matrix composites have disadvantages in terms of moulding time, repairability and manufacturing cost. Thus the high-performance thermoplastic composites to eliminate such disadvantages have been developed so far. As a result of environmental and economical concerns, there is a growing interest in the use of thermoplastic composites. However, since their mechanical properties are very sensitive to the environment such as moisture, temperature etc., those behaviors need to be studied. Particularly the temperature is a very important factor influencing the mechanical behavior of thermoplastic composites. The effect of temperature have not yet been fully quantified. Since engineering applications of reinforced composites necessitate their fracture mechanics characterization, work is in progress to investigate the fracture and related failure behavior. An approach which predicts the tensile strength was perpormed in the tensile test. The main goal of this work is to study the effect of temperature on the result of tensile test with respect to GF/PE composite. The tensile strength and failure mechanisms of GF/PE composites were investigated in the temperature range $60^{\circ}C\;to\;-50^{\circ}C$. The tensile strength increased as the fiber volume fraction ratio increased. The tensile strength showed the maximum at $-50^{\circ}C$, and it tended to decrease as the temperature increased from $-50^{\circ}C$. The major failure mechanisms was classified into the fiber matrix debonding, the fiber pull-out, the delamination and the matrix deformation.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2000.04a
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• pp.157-163
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• 2000

The application as the parts of an automobile, using the property of GMT-Sheet, is increasing. In order to exchange the parts of an automobile for GMT-Sheet, at first, the establishment and joining problem of exact joining strength must be determined. We have studied it using composites which is not same each other fiber oriented condition so as to determine joining strength and joining condition of GMT-Sheet. In this study, the result of experiment of forming condition concerned joining problem of GMT-Sheet is this ; joining efficiency of GMT-Sheet, increases as lap joint length L increases. Increase of compression ration cause decrease of joining efficiency after of GMT-Sheet, joining. In the viewpoint of recycling, randomly oriented composite of GMT-Sheet is desirable more than unidirectional oriented composite. We have better design the structure so as not occur to stress centralization on the joining part.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.71.5-71
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• 2001

This paper presents the vibration control of a flexible intelligent beam with added mass. The materials which is a glass fiber reinforced(GFR) thermoplastic composite is employed to achieve vibration characteristics according to added mass induced end of composite beam. In the experiments of forced vibration control, the -controller are employed to achieve vibration suppression in forced vibration situations. Also, in the controller design, 1st and 2nd´s natural frequencies are considered in the modeling, because robust control theory which has robustness to structured uncertainty is adopted to suppress the vibration. By designing a controller using mu-synthesis, robust performance against measurement noise, various modeling.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.2
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• pp.158-163
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• 2003

Thermosetting matrix composites have disadvantages in terms of moulding time, repairability and manufacturing cost. Thus the high-performance thermoplastic composites to eliminate such disadvantages have been developed so far. As a result of environmental and economical concerns, there is a growing interest in the use of thermoplastic composites. However, since their mechanical properties are very sensitive to the environment such as moisture, temperature etc., those behaviors need to be studied. Particularly the temperature is a very important factor influencing the mechanical behavior of thermoplastic composites. The effect of temperature have not yet been fully quantified. Since engineering applications of reinforced composites necessitate their fracture mechanic characterization, work is in progress to investigate the fracture and related failure behavior. An approach which predicts the tensile strength was perpormed in the tensile test. The main goal of this work is to study the effect of temperature on the result of tensile test with respect to GF/PE composite. The tensile strength and failure mechanisms of GF/PE composites were investigated in the temperature range 6$0^{\circ}C$ to -5$0^{\circ}C$. The tensile strength increased as the fiber volume fraction ratio increased. The tensile strength showed the maximum at -5$0^{\circ}C$, and it tended to decrease as the temperature increased from -5$0^{\circ}C$. The major failure mechanism was classified into the fiber matrix debonding, the fiber pull-out, the delamination and the matrix deformation.

• Composites Research
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• v.14 no.1
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• pp.1-7
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• 2001

In this study, damage evaluation of glass fiber reinforced thermoplastic composites was investigated with acoustic emission method. Specimens of 1.7mm thickness laminate were made from PET and 7 layers o171ass fabrics. Notch and impact loading were added to the specimen and normal tensile test and tensile test with the dead load were carried out. AE signal was measured as the functions of notch ratio to the width0 and impact energy in order to find out the correlation between fracture mode and AE parameters. The result has shown that low amplitude of AE signal was due to the microcrack of matrix and its growth, whereas the amplitude in the mid range was the response to the delamination and interfacial separation. In the range of high amplitude above 90dB. the fracture of glass fabric was found. Tensile strength decreased with increasing notch ratio to the width and impact energy because of tile effect or delamination, the cracking of matrix and stress concentration. In proportion to the size of damaged area. AE signal showed its wider range of frequency and energy as well as increased number of hits.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.39 no.3
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• pp.167-173
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• 2003

Many of researches regarding mechanical properties of composite materials are associated with humid environment and temperature. Especially the temperature is a very important factor influencing the design of thermoplastic composites. However, the effect of temperature on impact behavior of reinforced composites have not yet been fully explored. An approach which predicts critical fracture toughness G$_{IC}$ was performed by the impact test in this work. The main goal of this work is to study the effect of temperature and span of specimen supports on the results of Charpy impact test for GF/PE composite. The critical fracture energy and failure mechanism of GF/PE composites were investigated in the temperature range of $60^{\circ}C;to;-50^{\circ}C$ by the Charpy impact test. The critical fracture energy showed the maximum at the ambient temperature, and it tended to decrease as the temperature increased or decreased from the ambient temperature. The major failure mechanisms are the fiber matrix debonding, the fiber pull-out and/or delamination and the matrix deformation.n.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.553-553
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• 2000

The application as the parts of an automobile, using the property of GMT-Sheet, is increasing. In order to exchange the parts of an automobile for GMT-Sheet, at first, the establishment and joining problem of exact joining strength must be determined. We have studied it using composites which is not same each other fiber oriented condition so as to determine joining strength and joining condition of GMT-Sheet. h this study, the result of experiment of forming condition concerned joining problem of GMT-Sheet is this ; joining efficiency of of GMT-Sheet, increases as lap joint length L increases. Increase of compression ratio causes decrease of joining efficiency after of GMT-Sheet joining. In the viewpoint of recycling, randomly oriented composite of GMT-Sheet is desirable more than unidirectional oriented composite. We has better design the structure so as not to occur to stress centralizatien on the joining part.