Engineering expressions for thermo-elastic constants of laminates with high density of transverse cracks

Loukil, Mohamed Sahbi; Vārna, Jānis; Ayadi, Z. Ben

doi:10.1016/j.compositesa.2012.12.012

Cited by 26 publications

(17 citation statements)

References 27 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Thereby the actual laminate was replaced by a cross-ply with orthotropic or monoclinic constraint layers. Limitations of this particular realization of ''the equivalent constraint model'' were revealed in Loukil et al (2013) showing that homogenization over all non-damaged layers not always leads to good description of the constraint. For example, a very stiff closest neighbor alone is responsible for the constraint and homogenization over all layers to find the constraint is not correct.…”

Section: Introductionmentioning

confidence: 97%

Variational models for shear modulus of symmetric and balanced laminates with cracks in 90-layer

Katerelos

Krasņikovs

Vārna

2015

International Journal of Solids and Structures

View full text Add to dashboard Cite

a b s t r a c tThree analytical models with increasing complexity, all based on minimization of complementary energy, are compared in their ability to predict shear modulus reduction of laminates with intralaminar cracks in 90-layer. The very elegant and simple (and the less accurate) model by Hashin assumes linear out-of-plane shear stress distribution across the ply in all layers. The second model assumes exponential shape of these stresses in the constraint layer keeping linear assumption in the cracked layer. The model developed in the present paper accounts for nonlinear out-of-plane shear stress thickness distribution in all layers described by shape functions determined in the procedure of minimization. Increasing the complexity of the model the predicted shear modulus of the damaged laminate increases approaching to value obtained using finite elements (FE). Results show that for laminates with relatively thick cracked layers the stress state description in the cracked layer should be refined whereas for laminates with constraint layer thicker than the cracked layer more accurate stress description in the constraint layer is necessary. More accurate solutions could be derived using the described methodology, but the involved complexity and the numerical routines required for their application diminish their value comparing with direct FE solution.

show abstract

Section: Introductionmentioning

confidence: 97%

Variational models for shear modulus of symmetric and balanced laminates with cracks in 90-layer

Katerelos

Krasņikovs

Vārna

2015

International Journal of Solids and Structures

View full text Add to dashboard Cite

show abstract

“…A very detailed study on the interaction effect on u2an for cracks in surface ply was presented in Loukil et al. (2013).…”

Section: Determination Of Thermo-elastic Constants In Glob-loc Formulmentioning

confidence: 99%

“…When the crack density is high (interactive cracks) the in-plane stresses between cracks are much weaker than in an undamaged laminate and they cannot deform the crack surface as for non-interactive cracks. The crack interaction effect on COD was studied (Loukil et al., 2013; Lundmark and Varna, 2011) and described by simple functions. The effect on COD is strong.…”

Section: Introductionmentioning

confidence: 99%

Crack face sliding displacement (CSD) as an input in exact GLOB-LOC expressions for in-plane elastic constants of symmetric damaged laminates

Loukil

Vārna

2019

International Journal of Damage Mechanics

Self Cite

View full text Add to dashboard Cite

The crack opening and crack sliding displacements of both faces of an intralaminar crack are the main parameters defining the significance of each crack in laminate stiffness degradation, according to the previously published GLOB-LOC approach for symmetric laminates with an arbitrary number of cracks in all plies. In the exact stiffness expressions of this approach, the crack density is always multiplied by crack opening displacement and crack sliding displacement. The dependence of crack opening displacement on geometrical and elastic parameters of adjacent plies was studied previously and described by simple fitting functions. The crack sliding displacement has been analyzed for low-crack densities only and the proposed finite element method-based fitting expressions are oversimplified not including the out-of-plane ply stiffness effects. Based on finite element method analysis, more accurate expressions for so-called non-interactive cracks are suggested in the presented article. For the first time the shear stress perturbations are analyzed and interaction functions are presented with the feature that they always lead to slightly conservative predictions. The presented simple fitting functions, when used in the GLOB-LOC model, give predictions that are in a good agreement with finite element method results and with experimental data for laminates with damaged off-axis plies in cases when crack face sliding is of importance. The significance of including crack sliding displacement in stiffness predictions is demonstrated.

show abstract

“…In the literature, many efforts have been devoted to the relationship of the laminate elastic properties to the matrix cracks. The most common of them could be classified as: finite element (FE) analysis of cracked laminates [9,10], crack faces displacement (CFD) or crack opening displacement (COD) models [11,12], synergistic damage mechanics (SDM) models [13,14], variational analysis [15,16], generalized plane strain analysis (McCartney’s models) [17] and shear lag (SL) analysis [18,19]. In most of the research, the laminates were modeled in the presence of regular crack arrays which means the cracks were pre-located or pre-existing.…”

Section: Introductionmentioning

confidence: 99%

A Simplified Computational Strategy Focused on Resin Damage to Study Matrix Cracking of The Cross-Ply Laminates Under Uniaxial Tension Load

Sun

Wang

et al. 2019

Materials

View full text Add to dashboard Cite

Transverse cracking is probably the first and most dominant mode of damage in composite materials. In this paper, transverse cracking of cross-ply [02/90n]s (n = 2,3,4) laminates under uniaxial tension load was studied by means of experimental and numerical methods. In the numerical simulations, a simplified computational strategy only focusing on the damage of the resin was proposed and the mechanical response of the cracking cross-ply laminates was studied by finite element analysis of multi-scale representative volume elements (RVEs). In the RVEs, the longitudinal 0° plies were represented by macro-scale, homogeneous, orthotropic elastic solids while the 90° plies were modeled by the discrete fibers and the surrounding matrix resin in micro-scale. Based on researching the critical longitudinal mechanical strain ε x which initiates the cracks, the in-situ transverse ply strength and the stiffness degradation of the transverse plies, the simplified computational strategy proposed was proven correct. In addition, the crack initiation is sensitive to residual stress. Higher process-induced residual stress levels are dangerous to laminates, leading to early crack initiation.

show abstract

Engineering expressions for thermo-elastic constants of laminates with high density of transverse cracks

Cited by 26 publications

References 27 publications

Variational models for shear modulus of symmetric and balanced laminates with cracks in 90-layer

Variational models for shear modulus of symmetric and balanced laminates with cracks in 90-layer

Crack face sliding displacement (CSD) as an input in exact GLOB-LOC expressions for in-plane elastic constants of symmetric damaged laminates

A Simplified Computational Strategy Focused on Resin Damage to Study Matrix Cracking of The Cross-Ply Laminates Under Uniaxial Tension Load

Contact Info

Product

Resources

About