Models for Intralaminar Damage and Failure of Fiber Composites - A Review

Abstract

In order to fully exploit the potential of structures made from fiber composites, designers need to know how damage occurs and develops and under what conditions the structure finally fails. Anisotropy and inhomogeneity cause a rather complex process of damage development which may be one reason for an exceptionally large number of existing models. This paper intends to provide an overview over those models and give some hints about current developments. As such it is an updated version of a recent publication [1]. The survey is limited to laminates from unidirectional layers out of straight continuous fiber polymer composites under quasi-static loading. Furthermore, focus is laid on intralaminar damage.Many failure models smear out the inhomogeneity between fibers and the matrix. Simply limiting each stress component separately can lead to surprisingly good results as documented in the first World-Wide Failure Exercise. Interpolation criteria consider mutual influence of normal and shear stresses, predominantly through a quadratic failure condition. Traditionally one distinguishes between interpolation criteria and physically based ones. As an important physical effect the difference between fiber failure and inter-fiber failure is considered. Furthermore, stress invariants are taken as a basis, increased shear strength under compression is accounted for, and characteristic failure modes are captured. Fibers and the matrix material are characterized by a large disparity in stiffness and strength. Micromechanical models consider this inhomogeneity but suffer from the difficulty to determine relevant material properties. Compressive strength in fiber direction has attracted special attention. However, the role of kink band formation, which is observed in the failure process, seems to be not yet fully understood.In summary it must be concluded that despite the tremendous effort which has been put into the model development the damage and failure simulation of fiber composites are not in a fully satisfying state. That is partly due to lack of accurate and reliable test results.

Damage Characterization of Nano-Interleaved CFRP under Static and Fatigue Loading

“…According to these methods, the nano-interleaved samples have shown a 120-140% increase of G IC , compared to the virgin samples. The results are coherent with similar researches as reported in [27,28]. The fracture toughness is improved at both crack initiation and propagation for the fatigue tests as illustrated in Figure 4.…”

Effects of Aggregate Types on the Stress-Strain Behavior of Fiber Reinforced Polymer (FRP)-Confined Lightweight Concrete

“…Zhou and Wu’s [ 59 ] four-parameter expression ( E 1 , f o , E 2 , and n ) was adopted to fit the stress-strain curves of the FRP-confined FLWAC, and this expression is monotonic, continuous, and capable of integration and derivation. This expression [ 59 ] has been successfully applied to describe the stress-strain behavior of FRP-confined NC subject to different conditions regarding concrete columns with different cross-sectional shapes, load-induced damaged concrete, environmentally impacted concrete, and eccentric loads [ 14 , 20 , 42 , 50 ]. The FRP-confined LWAC also can be described by the stress-strain model, which is given as: where E 1 and E 2 are the first and second slopes concerning the stress-strain curve.…”

“…Thus, FRP application can make it an effective method to reduce self-weight in structural design. The advantage of composite structure is that they can fully use the characteristics of the multi-materials [ 41 , 42 , 43 ]. However, it also brings more complicated damage mechanism or confinement mechanism of the composite materials.…”

Quasi-Static Indentation Behavior of GFRP With Milled Glass Fiber Filler Monitored by Acoustic Emission

“…Fiber-reinforced composites, made of glass, carbon or even natural fibers, have found their application in several industries such as aerospace, automobile, marine, wind turbines production, etc., due to their high specific stiffness/strength, chemical resistance and fatigue properties, which makes them a suitable alternative for metals [1][2][3]. On the other side, the composites are susceptible to delamination due to poor mechanical properties through their thickness [4]. This effect is evident, in particular, when adhesion between the fibers and the matrixes is not initially perfect or has deteriorated with use [5].…”