Abstract Delamination of composite laminates under mode I loading is usually accompanied by large scale fiber bridging. Characterization of the bridging-traction law is of significant importance in delamination simulations to account for the effect of fiber bridging in such situation. This paper proposed a semi-analytical methodology to determine the bridging-traction law of composite laminates under mode I loading. The enhanced beam theory is physically improved by considering the bending-extension coupling to model the delamination in angle-ply laminates. The strain energy release rate as well as the opening displacement of the initial crack tip, from which the bridging-traction law is derived, are characterized as a function of the crack advance and some integration constants. The effectiveness and applicability of the proposed method are validated by comparing the obtained results with those numerically and experimentally achieved. The proposed approach can conveniently determine the mode I bridging-traction law using only the fundamental material properties and experimental load-displacement data of DCB specimen, which provides some guidelines in bridging-traction law determination of composite laminates under extreme conditions requiring the environmental chambers.
Abstract Delamination is one common type of damage in composite laminates. To avoid structural failure and catastrophic events, detecting delamination is vital. Vibration-based delamination detection methods, which employ changes in structural dynamic properties such as natural frequencies, have been extensively investigated. However, natural frequency is generally considered as a global dynamic property and as such cannot identify local locations of delamination. This study analyzes delaminatio...
#1Rafiullah Khan(IIUI: International Islamic University, Islamabad)H-Index: 9
Abstract Fiber reinforced composites are quickly replacing their metal counterparts in the structural applications due to their higher specific strength and stiffness. The fiber bridging increases the fracture toughness of the composites several times. At the same time, the characterization of the composites is challenging due to fiber bridging. Large number of studies has been devoted to investigate various aspects of fiber bridging phenomenon in the composites. This paper is a comprehensive re...
#2Qian Zhang(Hefei University of Technology)H-Index: 1
Last. Zhongrong Niu(Hefei University of Technology)H-Index: 1
view all 5 authors...
Abstract In this paper, moisture parameters of adhesive SY-14M-III and composite T800/AC531 were firstly measured, which were used for the following moisture diffusion investigations. Then, double cantilever beam (DCB) tests and end notched flexure (ENF) tests were conducted in four environments, and relevant progressive damage models considering cohesive zone models were established. The results show that the models are efficient by comparison of experimental and numerical results, and eight pa...
#1C. Blondeau(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 2
#2G. Pappas(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 8
Last. John Botsis(EPFL: École Polytechnique Fédérale de Lausanne)H-Index: 37
view all 3 authors...
Abstract Laminated composites are prone to fracture at layer interfaces. Such damage impairs their structural response and engenders important constraints in design. In this work, the influence of ply orientation on crack growth resistance was studied for three different antisymmetric interfaces and compared to a unidirectional reference one, using double cantilever beam specimens with equivalent stiffness, loaded under mode I conditions. Fracture toughness at initiation was found interface-inde...
#1T. Shojaee(IUST: Iran University of Science and Technology)H-Index: 4
#2Bijan Mohammadi(IUST: Iran University of Science and Technology)H-Index: 31
Last. Davood Salimi-Majd(IUST: Iran University of Science and Technology)H-Index: 10
view all 4 authors...
Abstract One of the main methods for improving the strength of the notched laminates, which are commonly used in the engineering structures, is to employ a stringer in a proper configuration. To optimize the design of these perforated laminates under compression loading, accurate characterization of the effects of various parameters on the instability behavior plays a significant role. For this purpose, after a review on the main previous researches, a semi-energy finite strip method (SE-FSM) is...
#1A. Arrese(UPV/EHU: University of the Basque Country)H-Index: 10
#2N. Insausti(UPV/EHU: University of the Basque Country)H-Index: 2
Last. Jordi Renart(University of Girona)H-Index: 16
view all 5 authors...
Abstract This study presents a novel method to determine the mode II cohesive law of unidirectional carbon fiber reinforced polymer laminates, employing the End Notched Flexure (ENF) test. The fracture toughness in mode II (G) and crack shear displacement (Δt) are determined based on a compliance variation data reduction method (BTBR) by processing the global load displacement curve, without monitoring the crack length and the crack shear displacement during the test. The procedure is validated ...
Abstract Cohesive Zone Models (CZMs) have been increasingly used for the fracture prediction of adhesively bonded joints. In order to better understand the relation between the fracture behaviors of the different geometry/adhesive combinations and the shape of CZMs, the butt-joint uniaxial tension, shear and the double cantilever beam (DCB) fracture experiments were conducted using two distinct adhesives, an epoxy-based brittle adhesive and a VHBTM tape ductile adhesive. Three shapes of CZMs wer...
Last. Jianyu Zhang(Chongqing University)H-Index: 25
view all 4 authors...
Abstract Low velocity impact (LVI) has always been a potential threaten to composite structures. This out-of-plane dynamic impact load easily leads to a dramatic increase of the strain state in the material transverse plane, which can affect the dynamic stress state and damage evolution of the composite laminate, especially for LVI with a relatively high energy. However, the strain rate effect was always neglected in existing investigations, thus introducing inevitable errors in numerical predic...
#1M.D. Thouless(UM: University of Michigan)H-Index: 55
Abstract In this paper, the concepts of root rotations and phase angles in laminated structures are reviewed, with particular reference to how the presence of a shear force affects the fracture mechanics of an interface. It is shown that it is possible to combine all the effects of shear into an effective root rotation, rather than the usual approach of invoking root rotation as a correction to a clamped Timoshenko beam. This simplifies the mechanics of the phenomenon, as root rotation is a gene...
Abstract Large-scale fiber bridging can significantly enhance delamination resistance, which makes the use of traditional delamination propagation criterion failed to accurately evaluate the delamination behavior in multidirectional laminates. This paper proposed an improved power law criterion to take account for the effect of fiber bridging on the delamination behavior. The key of the improved criterion lies on the introducing of R-curves, which can typically be determined by the standard dela...
Last. Jianyu Zhang(Chongqing University)H-Index: 25
view all 5 authors...
Abstract Large scale fiber bridging in composite laminates is one of the most common toughening mechnisms, exerting a close-force on the crack surfaces to restrain the delamination propagation. To account for the effect of the fiber bridging in delamination simulation, a physically semi-analytical method based on the Euler-Bernoulli beam theory considering the bridging stress is presented. The mode I energy release rate for every crack length is explicitly expressed in terms of the external load...
Abstract R-curve and traction-separation relation are commonly used to characterize the fiber bridging, which is significant toughening mechanism in composite laminates. Current investigations are mainly focused on unidirectional laminates. However, the dependence of the R-curve and traction-separation relation on the stacking sequence is still lack of comprehensive studies. Here, the effect of stacking sequence on the R-curve and traction-separation relation in unidirectional and multidirection...
Abstract For composite multidirectional laminates widely used in engineering, there is still no effective model to characterize the fatigue delamination behavior with the combined effects of fiber bridging and stress ratio. A new fatigue delamination model was thus proposed in this study to deal with this problem. The model was established based on the fatigue driving force and fatigue delamination resistance, which characterized the effects of stress ratio and fiber bridging, respectively. A se...
Last. Sue Ren(Arkansas Electric Cooperative Corporation)
view all 6 authors...
Abstract Non-planar composite π joints are receiving increasing attention in marine engineering. Efficient two-dimensional (2D) finite element (FE) methods, which can accurately predicted the failure behavior of this kind of joint, are critically meaningful for structural design emphasizing low computational time and easy operation. A material model is developed here, from which the equivalent engineering constants of plies with various angles can be obtained. Based on the material model, a 2D F...