Time-dependent matrix cracking in cross-ply laminates

doi:10.1016/0266-3538(90)90029-5

Composites Science and Technology

Volume 39, Issue 1, 1990, Pages 1-12

https://doi.org/10.1016/0266-3538(90)90029-5 Get rights and content

Abstract

The use of fiber-reinforced polymer composites has escalated in recent years, raising numerous questions concerning their long-term durability in both static and transient environments. Time-dependent damage accumulation in cross-ply laminates, specifically in the form of matrix cracking, is discussed. The results of this study show that certain composite materials may display significant time-dependent damage under quasi-static and creep loads even at room temperature.

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There are more references available in the full text version of this article.

Cited by (44)

Time-dependent damage evolution in unidirectional and multidirectional polymer composite laminates
2019, Creep and Fatigue in Polymer Matrix Composites
Damage modes such as fiber cracks, matrix yielding, matrix cracks, and fiber-matrix interfacial debonding can develop within a lamina. These are referred to as intrinsic damage modes to contrast them with the extrinsic damage modes that develop within a laminate, such as delamination between the plies and repeated cracking of a ply (matrix cracks also known as transverse cracks) due to constraints applied by surrounding plies. Due to viscoelasticity and viscoplasticity of the polymer matrices used in structural composites, the evolution as well as sequence of evolution of these damage modes may vary with loading rate (quasistatic loading), time (static loading, i.e., creep), and number of cycles (cyclic loading). These in turn will influence how the properties degrade with loading rate, time, and number of cycles. Due to increasing use of polymer composites in load-bearing structural applications, a comprehensive review of the state of the art in this area is essential and would be timely, to help designers as well as researchers in this area. Hence, this chapter includes (a) an introduction to various intrinsic and extrinsic damage modes, (b) a review of experimental studies of time-dependent evolution of these damage modes during quasistatic, static, and cyclic loading including characterization methods, (c) a review of published criteria to predict the time-dependent initiation and evolution of intrinsic and extrinsic modes, and (d) concluding remarks based on the review.
Model for prediction of simultaneous time-dependent damage evolution in multiple plies of multidirectional polymer composite laminates and its influence on creep
2015, Composites Part B: Engineering
Citation Excerpt :
Dillard et al. [3,4] were the first researchers who highlighted the influence of TDD on creep. Moore and Dillard [5] experimentally recorded the increase in transverse crack density in [90] plies of cross-ply laminates with time at room temperature at the stress levels greater than FPF (First Ply Failure) stress. Raghavan and Meshi [2] showed experimentally that the FPF stress was also time-dependent and the creep of cross-ply laminates increased with the increase in transverse crack density.
A model to predict time-dependent evolution of simultaneous transverse cracking developed in multiple plies during creep loading and its effects on creep of multidirectional polymer matrix composite laminates is presented. The stress states in the intact regions of the plies are determined using the lamination theory during an incremental change in time. The stored elastic energy, determined using this stress state, is compared with a critical stored elastic energy value for damage to determine if a ply would fracture after the increment. If fracture is predicted, variational analysis is used to determine the perturbation in ply stresses due to cracking. This procedure is repeated to determine the crack evolution and creep strain. Model predictions compared well with experimental results for a [±θ_m/90_n]_s laminate.
Influence of time-dependent damage on creep of multidirectional polymer composite laminates
2011, Composites Part B: Engineering
Citation Excerpt :
They recorded extensive damage in their test samples, after testing under constant load, which affected the accuracy of their model’s prediction. Moore and Dillard [3] observed increase in transverse cracking (also known as matrix cracking) in [90] plies of cross-ply laminates with time at room temperature at stress levels greater than FPF (First Ply Failure) stress. Raghavan and Meshii [4] showed that the FPF stress was also time-dependent and that the creep of cross-ply laminates increased with increase in transverse crack density.
An experimental study (Birur et al., 2006 [1]) on time-dependent evolution of various damage modes under constant load was extended; specifically, time-dependent evolution and influence of transverse cracks, in ±45° and 90° plies, on the creep of [±45/90₂]_S multidirectional laminate of a polymer composite (Hexcel F263-7/Toho G30-500) was studied and modeled. The damage evolved with time in both ply groups sequentially and/or simultaneously depending on the test conditions. For the latter case, the two ply groups influenced each other’s damage evolution. The creep of the laminate was due to both the viscoelasticity of the plies and the time-dependent damage. A damaged ply was modeled using an equivalent undamaged ply with an apparent compliance, which was determined as a function of time-dependent transverse crack density. This was used along with a model frame work, based on lamination theory, to predict the creep compliance of the [±45/90₂]_S laminate. The model predictions compared well with experimental results.
A probabilistic static fatigue model for transverse cracking in CFRP cross-ply laminates
2009, Composites Science and Technology
This paper presents a delayed-fracture model for transverse cracking in CFRP cross-ply laminates under static fatigue loading. First, a delayed-fracture model for a crack in a brittle material was established on the basis of the slow crack growth (SCG) concept in conjunction with a probabilistic fracture model using the three-parameter Weibull distribution. Second, the above probabilistic SCG model was applied to transverse cracking in cross-ply laminates under static fatigue loading. The stress and the length of the unit element in the transverse layers were calculated with the aid of a shear-lag analysis, taking the residual stress into account. The transverse crack density was expressed as a function of applied stress and time with the parameters in the Paris law and the Weibull distribution function specified, in addition to the mechanical and geometrical properties. Unknown parameters were determined from experiment data gathered in static tensile and static fatigue tests. The reproduced transverse crack density at various applied loads agreed well with the experiment results.
Effects of nonlinear viscoelastic behaviour and loading rate on transverse cracking in CFRP laminates
2007, Composites Science and Technology
The progressive multiplication of matrix transverse cracks in cross-ply laminates made of long carbon fibre reinforced polymer (CFRP) is addressed in this study. Monotonic tensile tests performed on [0₃/90₃]_S laminates at 120 °C have shown a marked dependence of cracking development on loading rate. This paper aims to assess the impact of the material nonlinearity on the loading rate sensitivity of the damaging process. A “shear-lag” damage analysis, using the nonlinear correspondence principle and appropriate failure criteria, is carried out to numerically predict the cracking evolution. This work shows that, though important, the material nonlinearity of the undamaged material does not significantly enhance the loading rate sensitivity of the cracking process and it cannot explain alone the phenomenon. On the other hand, taking into account the loading rate dependence of the critical strength, together with the R-curve effect, which gives good predicted cracking curves, suggests that the observed rate effect pertains to the viscoelastic character of the damaged material in the process zone close to crack fronts.
A continuum damage model for linear viscoelastic composite materials
2003, Mechanics of Materials
This paper presents a constitutive model for linear viscoelastic orthotropic solids containing a fixed level of distributed cracks. The model is formulated in a continuum damage mechanics framework using internal variables taken as second rank tensors. Use is made of the correspondence principle for linear viscoelastic solids to define a pseudo strain energy function in the Laplace domain. This function is then expressed as a polynomial in transformed strain and tensorial damage variables using the integrity bases restricted by the initial orthotropic symmetry of the material. The constitutive relationships derived in the Laplace domain are then converted to the time domain by using the inverse Laplace transform. The model is applied to the specific case of cross-ply laminates with transverse matrix cracks. The material coefficient functions appearing in the model are determined by a numerical (finite element) method for one cross-ply laminate configuration at one damage level. Predictions of the viscoelastic response are then made for the same laminate at other damage levels and for other cross-ply laminate configurations at different damage levels. These predictions agree well with independently determined time variations of properties by an analytic method (Kumar and Talreja, 2001, Linear viscoelastic behavior of matrix cracked cross-ply laminates. Mechanics of Materials 33 (3), 139–154) as well as with the numerically calculated values. Extension of the model to incorporate effects of transient temperature, physical aging and moisture is outlined.

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Time-dependent matrix cracking in cross-ply laminates

Abstract

Fracture mechanics of sublaminate cracks in composite materials

Composite Technol. Rev.

Characterization and analysis of damage mechanisms in tension-tension fatigue of graphite/epoxy laminates

Multiple transverse fracture in 90° cross-ply laminates of a glass fibre-reinforced polyester

J. Mater. Sci.

Constrained cracking in glass fibre-reinforced epoxy cross-ply laminates

J. Mater. Sci.

Some fundamental aspects of the fatigue and fracture response of composite materials