Design guidelines for ply drop-off in laminated composite structures

Mukherjee, Abhijit; Varughese, Byji

doi:10.1016/s1359-8368(00)00038-x

Cited by 96 publications

(49 citation statements)

References 7 publications

(8 reference statements)

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“…However, initial studies indicated that the optimized solutions were unlikely to result in thickness gradients exceeding 1/8 (typical design value to limit the inter-laminar stresses in ply-drop regions [10]) or fiber radius of curvature below 0.5m (typical minimum radius for tow-steered laminates using automatic fiber placement methods [17]), due to the relatively wide spacing of the variable control points.…”

Section: Variables Definitionmentioning

confidence: 99%

“…In order to change the stiffness within a component, it is necessary to add or drop plies, which introduces load offsets and fiber discontinuities leading to stress concentrations that can reduce the strength of a laminate. The rate of ply drops is therefore usually constrained [10], such that stiffness changes can only be very gradual over a part, which may reduce the design space available with traditional laminates in terms of aeroelastic tailoring.…”

Section: Introductionmentioning

confidence: 99%

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Aeroelastic Tailoring of a Representative Wing Box Using Tow-Steered Composites

et al. 2017

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Section: Variables Definitionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Aeroelastic Tailoring of a Representative Wing Box Using Tow-Steered Composites

et al. 2017

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“…At last, the "covering ply", of side 55 mm, is placed to encapsulate the sensor inside the monitoring patch. As it can be observed, the patch ply drop-off distance is set on 5 mm, making a drop-off slope of 1/30 as recommended in previous studies [23][24][25][26][27]. Once again, it is underlined that the monitoring patch forms an integration package where the sensor is embedded.…”

Section: Fabrication Of Composite Plates With Monitoring Patchmentioning

confidence: 98%

Mechanical Characterization of an Alternative Technique to Embed Sensors in Composite Structures: The Monitoring Patch

et al. 2011

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Sensor embedding is one of the main operations in dealing with composites incore instrumentation. In this work, an alternative encapsulation technique called "monitoring patch" is proposed to achieve correct sensor embedding, to facilitate the industrialised instrumentation procedure and to adapt the sensors according to the geometry and material heterogeneities required of the composite structures. The monitoring patch is mainly developed with the aim to reduce the variability effects produced if the sensor alone is placed. In this initial study, a first patch's configuration is manufactured with CTMI preimpregnate epoxy-woven glass, hosting two kinds of silicon prism sensors. The monitoring patch is then placed in the thick middle plane of an epoxy-carbon M21 T700GC quasiisotropic plate. The plates are instrumented with strain gauges and tested using digital image correlation (DIC). The strain field maps are calculated to analyse the over-strain zones and to infer fracture paths. At the same time, a FEM model is developed to compare the numerical and the experimental observations. The results show that the mechanical strength of the instrumented plates is not significantly affected by the presence of the patch. The failure path of the instrumented plates with monitoring patch is found along the patch perimeter; therefore, the sensors can be recovered without damage even after the failure of the instrumented structure. The feasibility of the monitoring patch is discussed with other embedding techniques. In further studies, the monitoring patch will host a streaming sensor with an aim to carry out in-core strain measurements.

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“…1 -3 Design guidelines have been developed for ply drop-offs, which occur in tapered regions. 4 While these works focus on the performance of tapered laminates in-service, this paper is concerned with the manufacturability of such laminates. At present, industry uses symmetric stacking sequences extensively; however these can be very restricting, typically following a set of design rules, 5 which also prescribe the manner in which plies should be terminated.…”

Section: Introductionmentioning

confidence: 99%