Assessment of damage tolerance in composites

Demuts, E.; Whitehead, R. S.; Deo, R. B.

doi:10.1016/0263-8223(85)90019-4

Cited by 38 publications

(12 citation statements)

References 2 publications

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“…( 1 ) Predict delamination onset thresholds using f r a c t u r e mechanics ( 2 ) Assume complete propagation o c u r r s immediately a f t e r t h e d e l a m i n a t i o n threshold i s exceeded [31], and is summarized i n the next section to provide a specific case study for the implementation of the Damage-threshold/Fail-safety approach. However, in most structural applications real-time monitoring of stiffness l o s s may not be practical, so the conservative approach outlined in step 2 would be applied.…”

Section: Damace-'l"heshoi D/f a 1 L-s Afety Approachmentioning

confidence: 99%

“…Recent government programs have focused heavily on this issue in developing damage tolerance criteria that will satisfy thp safety requirements of current military aircraft [2,3]. At the same time, research has been conducted on low velocity impact; both in the prediction of damage accumulation during the impact [4,5], and in the assessment of t h e influent(: of impact damage on compression s t r e n g t h 1 6 -1 3 ] .…”

mentioning

confidence: 99%

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Towards a Damage Tolerance Philosophy for Composite Materials and Structures

O’Brien

1990

Composite Materials: Testing and Design (Ninth Volume)

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A damage-threshold/fail-safety approach is proposed for ensuring that composite structures are both sufficiently durable for economy of operation, and adequately failsafe or damage tolerant for flight safety. Matrix cracks are assumed to exist throughout the off-axis plies. Delamination onset is predicted using strain energy release rate thresholds. Delamination growth is accounted for in one of three ways: either analytically, using delamination growth laws in conjunction with strain energy release rate analyses incorporating delamination resistance curves: experimentally, using measured stiffness loss; or conservatively, assuming delamination onset corresponds to catastrophic delamination growth. Fail safety is assessed by accounting for the accumulation of delaminations through the thickness. A tension fatigue life prediction for composite laminates is presented as a case study to illustrate how this approach may be implemented. Suggestions are made for applying the damage threshold/fail-safety approach to compression fatigue, tension/compression fatigue, and compression strength following low-velocity impact.

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Section: Damace-'l"heshoi D/f a 1 L-s Afety Approachmentioning

confidence: 99%

mentioning

confidence: 99%

Towards a Damage Tolerance Philosophy for Composite Materials and Structures

O’Brien

1990

Composite Materials: Testing and Design (Ninth Volume)

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“…Fatigue failures occurred under fatigue testing conducted at the 73% of CAI strength, which agrees with the data described in some reports. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] Weibull statistics were adopted for fatigue lifetime distribution under the same peak compressive stress S min . [11,18,21]…”

Section: Cai Fatigue Strength Distributionsmentioning

confidence: 99%

Fatigue behavior and lifetime distribution of impact-damaged carbon fiber/toughened epoxy composites under compressive loading

Ogasawara

Sugimoto

Katoh

et al. 2013

Advanced Composite Materials

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This paper presents fatigue lifetime data of impact-damaged carbon fiber/toughened epoxy composites under compressive loading to elucidate the lifetime prediction methodology based on statistical approaches. Drop-weight impact damage was induced to a composite specimen with impact energy of 6.7 J/mm in accordance with ASTM D7136. Postimpact fatigue tests were conducted using a test fixture defined in ASTM D7137 under compression-compression loading (R = 10) at room temperature. The maximum compressive stress (S min ) was 200, 210, 220, 230, and 240 MPa, and the total number of specimens was 31. The compression-after-impact strength and fatigue lifetime show considerable scattering. This result is apparently derived from the variation in impact damage size. A simple statistical model based on the weakest link theory was proposed for predicting the lifetime of impact-damaged composite laminates. Results show that the experimentally obtained data were confirmed consistently using this model. The ratio between the endurance limit at 10 6 and 10 7 cycles and the initial static strength was estimated as 0.74 and 0.68 as B-basis allowable values.

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“…Among the damage modes, delamination has been found to be the most serious for all cases of loading. This form of damage can be induced by relatively low energy impacts and is particularly insidious as it can reduce the tensile strength of the material by as much as 25% and the static compressive strength by amounts in excess of 60% with very little visible surface damage [3]. This has given rise to the commonly used acronym, BVID, for Barely Visible Impact Damage.…”

Section: Mechanisms Of Composite Failure and Conventional Nde Sys1emsmentioning

confidence: 99%

45585 Damage assessment for composite smart structures

1994

NDT & E International

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Assessment of damage tolerance in composites

Cited by 38 publications

References 2 publications

Towards a Damage Tolerance Philosophy for Composite Materials and Structures

Towards a Damage Tolerance Philosophy for Composite Materials and Structures

Fatigue behavior and lifetime distribution of impact-damaged carbon fiber/toughened epoxy composites under compressive loading

45585 Damage assessment for composite smart structures

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