Recovering critical stresses in sandwiches using through-the-thickness reinforcement

Icardi, Ugo; Sola, Federico

doi:10.1016/j.compositesb.2013.05.027

Cited by 11 publications

(13 citation statements)

References 37 publications

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“…Modelling of stitching (Icardi and Sola (2013)) could be applied, but as it represents an uncertainty source that could prevent from the assessments of (i)-(iv), it is left to a future study.…”

Section: Numerical Results and Discussionmentioning

confidence: 99%

Impact Damage Analysis with Stress Continuity Constraints Fulfilment at Damaged-Undamaged Regions and at Layer Interfaces

Icardi

Urraci

2017

Lat. Am. j. solids struct.

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Low-velocity impacts have a relevant importance for safety of laminated and sandwich composite structures, because they are highly susceptible to damage. In this paper, a 3D cost effective zig-zag model is developed in order to efficiently simulate such impacts. It a priori fulfills the continuity of out-of-plane stresses at layer interfaces, the continuity of stresses under in-plane variation of properties across undamaged and damaged regions and it is suitable for general boundary conditions. Its main advantage is its capability to accurately predict stresses from constitutive equations at a low cost, along with being refined across the thickness keeping fixed the number of unknowns. A modified Hertzian contact law that forces the target to conform to the shape of the impactor and the Newmark's implicit time integration scheme are used for computing the contact force time history. The progressive damage analysis is carried out using stress-based criteria. Non-classical feature, a continuum damage mesomechanic model is employed that accounts for the effects of local failures in homogenized form by modifying the strain energy expression. Fiber, matrix and delamination failures are predicted using stress-based criteria, and then the modified strain energy expression is employed for computing stresses. Such modeling options enable to account for the residual properties as they are in the reality, as shown by the comparison with the damage experimentally detected. As shown by the comparison with experiments, a closed-form solution by the Galerkin's method, obtained as a series expansion of trial displacement functions, accurately simulates the contact force and the damage progressively accumulated. The results show the importance of in-plane stress continuity for obtaining accurate predictions.Keywords Impact-induced damage; 3D variable-kinematics zig-zag model; undamaged/damaged stress continuity; interlayer stress continuity; fixed d.o.f; mesomechanic damage model.

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Section: Numerical Results and Discussionmentioning

confidence: 99%

Impact Damage Analysis with Stress Continuity Constraints Fulfilment at Damaged-Undamaged Regions and at Layer Interfaces

Icardi

Urraci

2017

Lat. Am. j. solids struct.

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“…Previous studies (see, e.g., [53,[55][56][57][58]71]) have proven that the OM model is able to accurately and efficiently treat local geometry, loading and material variations. In particular, a successful application to adhesively bonded joints was presented in [71] that demonstrated its capability of satisfying the quite complex stress-boundary conditions at the end of the overlap.…”

Section: Numerical Applications and Discussionmentioning

confidence: 99%

“…Applications to test cases (see, e.g., [53,[55][56][57][58]71]) have proven that the present model can be used elsewhere, no special models being required for treating local geometry, loading and material variations. An applications to bonded joints having already been presented in [71], in the numerical applications a sample case with clamped edges (Tessler, Di Sciuva and Gherlone [72]) will be considered in order to show how non-classical boundary conditions can be easily satisfied.…”

Section: Variable In-plane Representation δ C_ipmentioning

confidence: 99%

“…As a consequence, an always correct representation of the strain energy is obtained, from which accurate stresses are predicted directly from constitutive equations. Because the enforcement of the physical constraints is satisfied without increasing the number of unknowns, accurate results are obtained with a computational effort not considerably larger than for equivalent single-layer models, thus considerably lower than for the available discrete-layer and high-order layerwise models, as shown in [55][56][57][58][59] and also by the results reported hereafter, where the processing time by the present model is compared to that by the first-order shear deformation theory-FSDPT. In many sample cases [43,[51][52][53][54][55][56], a successful application to variable stiffness composites was shown, which proven the progressively refined "adaptive" zigzag models based on enforcement of physical conditions suited to find solutions in closed form of static and dynamic cases.…”

Section: Introductionmentioning

confidence: 99%

“…Because the transverse normal stress has a significant bearing for keeping equilibrium when temperature gradients across the thickness cause thermal stresses and when describing the core's crushing behavior of sandwiches, Icardi and coworkers [43,[51][52][53][54][55][56][57][58][59] incorporated into zigzag models a variable kinematic representation of displacements across the thickness that can adapt to the variation of solutions, where a progressively refined description of the piecewise variation of the transverse displacement was also considered. Accordingly, the representation can be refined like with discrete layer models, though the functional d.o.f.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

C0 Layerwise Model with Fixed Degrees of Freedom and Variable In- and Out-of-Plane Kinematics by Strain Energy Updating Technique

Icardi

Sola

2015

Aerospace

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Abstract:Physically based zigzag models have the merit of giving accurate stress predictions for laminates and sandwiches keeping fixed the functional degrees of freedom, though at the expense of the introduction of their derivatives. In the present paper, a technique that enables deleting these derivatives is developed. The objective is finding a priori corrections of displacements, which make the energy of the model with all the derivatives neglected equivalent to that of its initial counterpart model containing all the derivatives. Numerical applications show that this technique can obtain accurate results, even for strongly asymmetrical lay-ups, keeping low the computational cost.

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Mechanical properties of foam sandwich with chopped‐glass‐fiber/carbon nanotube reinforced hierarchical structure interlayer

Chen

Jiang

et al. 2020

Polymer Composites

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A chopped‐glass fiber/multi‐walled carbon nanotubes (MWCNTs) hierarchical reinforcing structure was used to toughen the core‐face interlayer of sandwich materials. Chopped‐fiber mats modified by MWCNTs‐COOH were inserted at the face‐core interface before resin infusion. Sandwich beams were prepared by vacuum‐assisted resin transfer molding, containing a Polyvinylchloride (PVC) foam core covered with two glass fiber/epoxy composite face sheets. The mechanical properties were characterized using quasi‐static three‐point‐bending, Charpy impact, and asymmetric double cantilever beam. Improvement in mechanical properties and interlayer toughness was achieved in the sandwich structure with negligible weight increase and processing variations. The interfacial characteristics between chopped glass fibers, carbon nanotubes, and underlying energy absorption mechanisms were discussed and analyzed using scanning electron microscopy.

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Recovering critical stresses in sandwiches using through-the-thickness reinforcement

Cited by 11 publications

References 37 publications

Impact Damage Analysis with Stress Continuity Constraints Fulfilment at Damaged-Undamaged Regions and at Layer Interfaces

Impact Damage Analysis with Stress Continuity Constraints Fulfilment at Damaged-Undamaged Regions and at Layer Interfaces

C0 Layerwise Model with Fixed Degrees of Freedom and Variable In- and Out-of-Plane Kinematics by Strain Energy Updating Technique

Mechanical properties of foam sandwich with chopped‐glass‐fiber/carbon nanotube reinforced hierarchical structure interlayer

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