Some Recommendations for Characterization of Composite Panels by Means of Drop Tower Impact Testing

Feraboli, Paolo

doi:10.2514/1.19251

Cited by 40 publications

(44 citation statements)

References 13 publications

(36 reference statements)

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“…This manifested as a more severe impact damage and smaller F max and a shorter t c than those of the original C/BMI composite in Region II. As reported by Feraboli [36], a smaller F max with a longer t c is a result of more compliant combinations of impactor-target in the case of thin laminates, which indicates a reduction of the resistance to impact loading of C/BMI composite caused by 300 cycles. Additionally, the absorbed energy is significantly higher in the cycled C/BMI composite than in the original one, but the increase in the ratio of absorbed energy is much smaller than that of damage area in Region II.…”

Section: Damage Characteristicssupporting

confidence: 52%

“…12). In a previous study, Xu [37] found that there exists an interaction between matrix cracking and free-edge delamination in a glass fiber reinforced BMI composite laminates under static tension. It was shown that matrix cracking could lead to local free-edge delamination and free-edge delamination might induce matrix cracking.…”

Section: Impact Damage Model and Degradation Mechanismmentioning

confidence: 96%

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Low‐velocity impact behavior of a carbon/bismaleimide composite proposed for supersonic flight simulation after hygrothermal cycling

et al. 2018

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The combined high temperature oxidation, humidity exposure, thermal cycling, and a low temperature period were simultaneously performed on a carbon fiber‐reinforced bismaleimide (C/BMI) composite to simulate the supersonic hygrothermal flight‐cycles on long durability of the C/BMI applied in supersonic aircraft. After a hygrothermal cycling for 300 times, the drop‐weight impact test and ultrasonic analysis were carried out to evaluate low‐velocity impact damage behavior of the composite caused by foreign objects during service. The fiber/matrix interface degradation caused by hygrothermal cycling was demonstrated through a parameter proposed by Sarasua (parameter b), which is shown to reflect the level of the interfacial bond by estimating the contribution of the interphase on the damping properties of composites through the dynamic thermomechanical analysis (DMA) test. A secondary increase of delamination area initiated from one long edge was detected for the first time in the hygrothermal cycled C/BMI composite impacted by energy higher than 20 J. After experiencing 300 combined ageing cycles, the damage model of C/BMI composite impacted by more than 20 J changes from the pine tree model to gyro model because of free‐edge delamination, resulting in a serious potential risk to the application of C/BMI composite laminates in aeronautics. POLYM. COMPOS., 40:E1588–E1599, 2019. © 2018 Society of Plastics Engineers

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Section: Damage Characteristicssupporting

confidence: 52%

Section: Impact Damage Model and Degradation Mechanismmentioning

confidence: 96%

Low‐velocity impact behavior of a carbon/bismaleimide composite proposed for supersonic flight simulation after hygrothermal cycling

et al. 2018

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“…The characteristic parameters include F i , F p , D i , D p , D max , E d , E el , the definitions of which are also found in the literature [16,17]. E d2 was also adopted in the discussion of impact properties in this study.…”

Section: Impact Testing Resultsmentioning

confidence: 99%

“…In many cases, these damages are initiated inside the structure and therefore usually go unnoticed. Process parameters such as contact force, energy and projectile deflection, values of which are normally gathered during an impact testing event, are useful for the comparison of the impact properties of laminated composites [15][16][17]. The influence of hygrothermal conditioning on the capacity of PMCs to resist impact loading, however, has not received enough investigation.…”

Section: Introductionmentioning

confidence: 99%

Improved impact response of hygrothermally conditioned carbon/epoxy woven composites

Zhong

Joshi

2015

Science and Engineering of Composite Materials

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The effects of hygrothermal conditioning and moisture on the impact resistance of carbon fiber/epoxy composite laminates were investigated. Specimens were fabricated from carbon fiber/epoxy woven prepreg materials. The fabricated specimens were either immersed in water at 80°C or subjected to hot/wet (at 80°C in water for 12 h) to cold/dry (at -30°C in a freezer for 12 h) cyclic hygrothermal conditions, which resulted in different moisture contents inside the laminates. It was found that the absorbed moisture did not migrate out from composite materials at -30°C. Neither of the hygrothermal conditions in this study had detrimental effects on the microstructure of the laminates. Low-velocity impact testing was subsequently conducted on the conditioned specimens. When attacked by the same level of impact energy, laminates with different moisture levels experienced different levels of impact damage. Moisture significantly alleviated the extent of damage in carbon fiber/ epoxy woven laminates. The elastic response of the laminate under impact was improved after hygrothermal conditioning. The mechanism behind the improved impact resistance after absorbing moisture was proposed and deliberated. NomenclatureD i Projectile deflection corresponding to incipient damage point, mm D max Maximum projectile deflection, mm D p Projectile deflection corresponding to the peak load point, mm D Z Through-the-thickness diffusivity constant, mm 2 /s DI Damping index E d Impact energy dissipated through damage creation and propagation, J E d1 Damage generation energy before the peak load point, J E d2 Damage generation energy after the peak load point, J E el Impact energy absorbed through elastic deformation, J E p Total energy absorbed corresponding to the peak load point, J E total Total impact energy or actual impact energy exerted on specimens, J F i Incipient damage load or load corresponding to the incipient damage point, kN F p Peak contact force between the impactor and the specimen, kN h Thickness of a plate, mm M f Final moisture content of specimens, % M m Effective equilibrium moisture content, % M 1 Moisture content at time t 1 , % M 2 Moisture content at time t 2 , % W i

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“…Instrumented drop-weight tests are very popular because they are simple to perform and easily repeatable [19]. The principal measurement in these tests is the load-time history, which can be integrated to produce the displacement and absorbed energy of the impacted plate.…”

Section: Impact Damage Resistance 221 Impact Testingmentioning

confidence: 99%

Energy absorption characteristics of sandwich structures subjected to low-velocity impact

Foo¹

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This dissertation would not have been possible without Dr. Seah Leong Keey and Dr. Chai Gin Boay, who not only supervised but also encouraged and challenged me through my years at NTU. I am sure I am not even aware of all that I owe to them. I also thank Dr. I. Sridhar for his interest in my work. In addition, I want to acknowledge the generous scholarship received from Agency for Science, Technology and Research (A*STAR), and I thank NTU for permission to use its computing and laboratory facilities. My appreciation also goes to Ms. Chia, Mr. Wong, and Thomas from Strength of Materials Lab, as well as Mr. Teo, Justin, and Chesda from CANES lab, who were always friendly and helpful. I am grateful to Ms. Peh Yin Chee and the numerous FYP students, who had helped to carry out some of the tests. Equally important is the help and support from many colleagues: Lam, Jonathan, Norman, Elson, Nianfeng, Shashi, Kapil, and Shantanu. I am indebted to my family who encouraged me to pursue my dreams and helped me get the best education. Lastly, I thank Bernice for being such a wonderful companion during the period I spent writing this dissertation. Her help with some of the illustrations and editing are truly appreciated.

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Some Recommendations for Characterization of Composite Panels by Means of Drop Tower Impact Testing

Cited by 40 publications

References 13 publications

Low‐velocity impact behavior of a carbon/bismaleimide composite proposed for supersonic flight simulation after hygrothermal cycling

Low‐velocity impact behavior of a carbon/bismaleimide composite proposed for supersonic flight simulation after hygrothermal cycling

Improved impact response of hygrothermally conditioned carbon/epoxy woven composites

Energy absorption characteristics of sandwich structures subjected to low-velocity impact

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