Delamination threshold loads for low velocity impact on composite laminates

Schoeppner, G. A.; Abrate, Serge

doi:10.1016/s1359-835x(00)00061-0

Cited by 463 publications

(240 citation statements)

References 17 publications

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“…While Figure 2a represents the different curves obtained for the first impact on control samples and for the distances of 10 mm and 0 mm, Figure 2b shows the typical evolution of the curves for the control samples subjected to multi-impacts. These curves contain oscillations as consequence of the vibrations promoted by the samples [27,29,30].…”

Section: Resultsmentioning

confidence: 99%

Effects of external patch configuration on repaired composite laminates subjected to multi-impacts

Coelho

Reis

Ferreira

et al. 2017

Composite Structures

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Please cite this article as: Santos, R.A.M., Reis, P.N.B., Santos, M.J., Coelho, C.A.C.P., Effect of distance between impact point and hole position on the impact fatigue strength of composite laminates, Composite Structures (2017), doi: http://dx.doi.org/10. 1016/j.compstruct.2017.02.045 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. In terms of multi-impacts, the damage severity is also very influenced by the distance. For small distances the damage progresses quickly, while three stages can be found for the control samples and for the distance of 20 mm. Effect of distance between impact

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Section: Resultsmentioning

confidence: 99%

Effects of external patch configuration on repaired composite laminates subjected to multi-impacts

Coelho

Reis

Ferreira

et al. 2017

Composite Structures

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“…Moreover, the existence of an optimal value of the interlaminar fracture toughness corresponding to maximum energy absorption has been theoretically proven by Lear and Sankar [37], but not experimentally verified. Delamination, and therefore the energy absorbing capability, of composite laminates has been also successfully promoted by other techniques, such as the introduction of fibre orientation change between adjacent layers [32], the modification the target stiffness [38], or the introduction of ply grouping [39].…”

Section: Introductionmentioning

confidence: 99%

Experimental optimization of the impact energy absorption of epoxy–carbon laminates through controlled delamination

Pegoretti

Cristelli

Migliaresi

2008

Composites Science and Technology

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Experimental optimization of the impact energy absorption of epoxy-carbon laminates through controlled delamination. Composites Science and Technology, Elsevier, 2010, 68 (13) ACCEPTED MANUSCRIPT 2 ABSTRACTIn this paper, the correlation between interlaminar fracture toughness and impact energy absorption for the fracture of epoxy-carbon laminates was studied. Carbon fibres-epoxy cross-ply prepreg layers were interleaved with thin (26 microns) poly(ethylene-terephthalate) (PET) films. Before the composite preparation, circular holes 1 mm in diameter were drilled in the PET films at several densities (from 0 up to 44 holes/cm 2 ) in order to selectively increase the interlaminar contact area between the epoxycarbon laminae. In this way, the interlaminar contact area was gradually varied from 0%, corresponding to the case in which non-perforated PET films were used, up to 100% in the case of

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“…Therefore, the choice of the quasi-static perforation test is a way of defining an absolute reference test. It is in any case worthwhile saying that results presented in [11] suggest that, even in the presence of significant strain-rate effects on the delamination threshold load (DTL), the displacement value measured at DTL remains almost constant. Indeed, at least for the laminates investigated in the study, the s MAX of perforation tests was constant regardless of the impact velocity and equal to the s QS value.…”

Section: From the Damage Degree To The Damage Indexmentioning

confidence: 99%

A new damage index to monitor the range of the penetration process in thick laminates

Belingardi

Cavatorta

Paolino

2008

Composites Science and Technology

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A damage variable (damage degree DD) representing the ratio between the absorbed energy and the impact energy was introduced in 1998 by Belingardi and Vadori to assess damage accumulation caused by low-velocity impacts. More recently, repeated impact tests carried out on thick laminates pointed out the significance and extent of the penetration process in thick laminates, which the DD is unable to monitor as, by definition, it reaches the value of one at penetration to remain unchanged over the entire penetration process. In the present paper, a new damage variable (damage index DI) is proposed to overcome shortcomings of the DD with respect to thick laminates. By introducing the displacement of the impactor into the definition of the DI, the depth of the penetration process is taken into account. Normalization by the displacement of the quasi-static perforation test allows for a non-dimensional damage variable which is shown to reach the value of one at perforation. Validity of the approach is proven against impact data obtained for different fibre-matrix architectures and laminate thickness. Results show that the DI can effectively differentiate between penetration and perforation thresholds, increasing monotonically within the range of the penetration process. In particular, the DI is shown to increase linearly with the impact energy up to penetration and to rise quite abruptly within the range of the penetration process. Results for repeated impact tests prove that at first the DI increases quite linearly impact after impact, owing to a steady accumulation of damage. A few impacts before penetration a sudden rise in the DI value points out a change in the rate of damage accumulation.

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Delamination threshold loads for low velocity impact on composite laminates

Cited by 463 publications

References 17 publications

Effects of external patch configuration on repaired composite laminates subjected to multi-impacts

Effects of external patch configuration on repaired composite laminates subjected to multi-impacts

Experimental optimization of the impact energy absorption of epoxy–carbon laminates through controlled delamination

A new damage index to monitor the range of the penetration process in thick laminates

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