A building block approach to design verification testing of primary composite structure

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

doi:10.2514/6.1983-947

Cited by 13 publications

(7 citation statements)

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“…The current approach to designing safe (avoiding damage) composite structures is the building block approach (BBA). This approach was first demonstrated by Whitehead and Deo [80] when they discussed the necessity of an approach for certification of composite structures in aircraft. The building block approach defines experimental tests along the levels leading up to the final, full-scale component.…”

Section: Design Approachmentioning

confidence: 99%

“…The current levels identified in the literature and used in design are the sub-ply, ply, laminate, sub-element, element, sub-component, and component [2,80,82]. Examples of the levels used in composite engineering are shown in Figure 11.…”

Section: Lengthscales In Compositesmentioning

confidence: 99%

“…These laminates are produced by stacking plies and / or fabric layers to form unidirectional, cross-ply, angleply, quasi-isotropic, or other laminates. The laminate level is traditionally where most coupon testing is conducted [80,[82][83][84]. At the next level, that of the sub-element, structural details (e.g., holes, ply-drops, stiffeners) begin to be included.…”

Section: Lengthscales In Compositesmentioning

confidence: 99%

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Lengthscale Issues in the Mechanical Behavior and Failure of Composite Structures

Lagacé¹,

Chambers²

2011

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Section: Design Approachmentioning

confidence: 99%

Section: Lengthscales In Compositesmentioning

confidence: 99%

Section: Lengthscales In Compositesmentioning

confidence: 99%

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Lengthscale Issues in the Mechanical Behavior and Failure of Composite Structures

Lagacé¹,

Chambers²

2011

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“…The design and certification of a new structure for commercial transport industries is known as certification by analysis supported by test evidence or allowables-based certification. 1 The full process is called Building Block Approach (BBA) and starts from the material design/ certification up to the full structure, as shown in Figure 1. The first step of the pyramid requires a large number of test data at coupon-level for different environmental conditions and testing cases, e.g.…”

Section: Introductionmentioning

confidence: 99%

Design allowables of composite laminates: A review

Cumbo¹,

Baroni²,

Ricciardi³

et al. 2022

Journal of Composite Materials

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The design and certification process of composite structures relies on the building-block approach, which starts from the mechanical characterization of the material at coupon-level. The certification of composite laminates is thus the first challenge and requires the definition of the design allowables, which are statistically defined as established by the Composite Material Handbook. These quantities are strength or strain values indicated as A- or B-basis and an accurate estimation is needed in order to guarantee the integrity of the structure. Given the statistical nature of material allowables, a high number of experimental tests have to be performed for the full mechanical characterization of a material. Notched and unnotched allowables are determined under different testing conditions and in accordance to the standards specified by American Society for Testing and Materials. Different methodologies are presented in literature and explore the combination of simulation-based solutions supported by test-evidence of a reduced number of coupons. In the recent years, several approaches have been explored in the field of uncertainty quantification and Machine Learning demonstrating to be powerful alternatives to full testing-based or simulation-based solutions. A comprehensive literature review is presented in this contribution among the main solutions for the definition of material allowables. This review demonstrates that simulations supported by a reduced number of tests can reach accurate results and the number of simulations can be further reduced by combining the numerical models with predicting theories.

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“…State of art for certification of composite materials in primary aircraft structures to the regulatory requirements of the European Safety (EASA) and Federal Aviation Authority (FAA) is known by analysis supported by “test evidence” or “allowable-based certification” 1 Composite materials are widely used in the aerospace industry in advanced structural applications; however, the wide range of possible failure mechanisms require conservative sizing, and thousands of samples are often used in the design of a structure. For the development of a new concept of composite wing for a tiltrotor a virtual process chain was adopted in order to take into account criteria such as eco-design, low cost, high quality and low weight in order to reduce the number of laboratory tests.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of a virtual allowables approach for the design of composite aircraft structures

Starace¹,

Orlando²,

Guida

et al. 2021

Proceedings of the Institution of Mechanical Engineers, Part C:

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Statistically derived allowables are representative for the behavior of a composite material system in a given structural context where data variability needs to be contemplated. In particular, they define the strength of the material as characterized by various coupon tests according to ASTM standard procedure subjected to the actual manufacturing process and layup stacking sequences. The current paper presents a detailed comparison between virtual allowables predictions obtained using MSC Digimat and the experimentally determined values of a certified material backed up by a 3x2x3 (batch/panel/specimen) stochastic approach. Tests generate the required data for building material model ab initio of carbon fibers reinforced epoxide resin in form of 2x2 twill woven fabric used for qualifying an innovative composite wing for the Next Generation Tilt Rotor (NGCTR). Numerical models of in-plane tension, compression and shear test methods have been assembled along with an associated material model allowing numerical predictions to be validated with the coupon level experimental results as final purpose. Standard statistical model has been adopted in order to include material and manufacturing process variabilities to define B-basis allowables. The calibrated statistical FEM method performed for different layup configurations have been used to fully characterize the mechanical behavior of the analyzed CFRP material and to predict performances for thicker laminates.

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A building block approach to design verification testing of primary composite structure

Cited by 13 publications

References 0 publications

Lengthscale Issues in the Mechanical Behavior and Failure of Composite Structures

Lengthscale Issues in the Mechanical Behavior and Failure of Composite Structures

Design allowables of composite laminates: A review

Experimental study of a virtual allowables approach for the design of composite aircraft structures

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