Abstract A new method for obtaining energy release rate by the Double Cantilever Beam test for angle-ply laminates is proposed. Two different sequences, symmetric and anti-symmetric, have been studied. The fact that the layers are oriented at different angles and the residual stresses, causes the existence of mixed mode fracture. The analytical model presented, based on the complementary energy of a laminated beam, is an extension of a previous model for unidirectional laminates and includes hygrothermal effects. Experimental results of the energy release rate obtained by means of the area method agree with those determined by the proposed approach.
#1Ana Boyano(UPV/EHU: University of the Basque Country)H-Index: 7
#2J. De Gracia(UPV/EHU: University of the Basque Country)H-Index: 4
Last. Faustino Mujika(UPV/EHU: University of the Basque Country)H-Index: 15
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Abstract The crack propagation performance of the End Notched Flexure with inserted roller test is analyzed. An equivalent energy release rate is proposed taking into account the interaction of the modes I and II, based on the linear failure criterion. Experimental results obtained with specimens of F593/T300 carbon/epoxy unidirectional composite show a good agreement with the proposed approach. The stability condition is theoretically developed based on the derivative of the equivalent energy r...
#1J. De Gracia(UPV/EHU: University of the Basque Country)H-Index: 4
#2Ana Boyano(UPV/EHU: University of the Basque Country)H-Index: 7
Last. Faustino Mujika(UPV/EHU: University of the Basque Country)H-Index: 15
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Abstract A new method for obtaining the R-curve point to point by the Double Cantilever Beam test is proposed. Besides the determination of new compliance and energy release rate equations, the analytical model presented leads to calculate the crack length for every pair of load and displacement values, without any optical measurement. In addition, a simple trigonometric approximation is proposed for the calculation of large displacement effects. The approach is checked with experimental results...
#1Mahmood M. Shokrieh(IUST: Iran University of Science and Technology)H-Index: 53
#2Afshin Zeinedini(IUST: Iran University of Science and Technology)H-Index: 7
Last. A. Zeinedini(IUST: Iran University of Science and Technology)H-Index: 3
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In this research, a novel data reduction method for calculation of the strain energy release rate (SERR) of asymmetric double cantilever beams (ADCB) is presented. For this purpose the elastic beam theory (EBT) is modified and the new method is called as the modified elastic beam theory (MEBT). Also, the ADCB specimens are modeled using ABAQUS/Standard software. Then, the initiation of delamination of ADCB specimens is modeled using the virtual crack closure technique (VCCT). Furthermore, magnit...
#1J.M. Romera(UPV/EHU: University of the Basque Country)H-Index: 4
#2M.A. Cantera(UPV/EHU: University of the Basque Country)H-Index: 3
Last. Faustino Mujika(UPV/EHU: University of the Basque Country)H-Index: 15
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Abstract A top-down approach has been proposed to achieve the free-edge stresses in a [ θ /− θ ] s rectangular laminate under a longitudinal tensile load. At the first stage, the laminate is subdivided into two antisymmetric parts and the upper one is analyzed by including an unknown twisting moment. This problem has been solved by extending an analytical solution for torsion of orthotropic laminates to antisymmetric laminates. At the second stage, the upper lamina was analyzed alone by includin...
Abstract A cohesive zone model was developed for mode I delamination in composite beams. The present model is an extension of a beam on elastic foundation analysis similar to the one that led to the well-known corrected beam theory data reduction scheme. In particular, it is demonstrated that the shear foundation considered in most formulations can actually be discarded, thereby allowing a much simpler model implementation. The present model agrees very well with finite element analyses of doubl...
#1M.A. Cantera(UPV/EHU: University of the Basque Country)H-Index: 3
#2J.M. Romera(UPV/EHU: University of the Basque Country)H-Index: 4
Last. Faustino Mujika(UPV/EHU: University of the Basque Country)H-Index: 15
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This work evaluates the influence of geometric properties, the length-to-width ratio, named Aspect Ratio, on curvatures in [θ − 90/θ]T carbon/epoxy composite laminates at room temperature due to thermal residual stresses. A new method to determine experimentally thermal residual curvatures in composites laminates by defining small-length increments on the surface of deformed plate has been exposed. [–454/454]T was considered to obtain a simple analytical expression of twisting curvature. A new w...
#1Mahmood M. Shokrieh(IUST: Iran University of Science and Technology)H-Index: 53
#2M. Heidari-Rarani(IUST: Iran University of Science and Technology)H-Index: 16
Last. S. Rahimi(IUST: Iran University of Science and Technology)H-Index: 1
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Abstract Mode I delamination toughness ( G Ic ) of a laminated composite depends not only on the stacking sequence or indirectly coupling parameter of D c = D 12 2 D 11 D 22 , but also on specimen geometrical ratios a 0 / b and a 0 / h . In this study, a non-uniformity ratio, β = ( G Imax − G Iavg )/ G Iavg %, is introduced to take into account the influence of above factors on the energy release rate distribution along the width of double cantilever beam (DCB) specimens simultaneously. Results ...
#1Faustino Mujika(UPV/EHU: University of the Basque Country)H-Index: 15
The complementary energy of a multidirectional laminate is obtained as a function of mechanical and hygrothermal force and moment resultants. Three-point flexure is then analysed assuming that the specimen is in contact with the support rollers at four points. As this problem is statically indeterminate, the redundant force is obtained by applying Engesser's second theorem. Lift-off at supports is assumed to occur when the redundant unknown is zero. The displacement field of a multidirectional l...
#1Mahmood M. Shokrieh(IUST: Iran University of Science and Technology)H-Index: 53
#2M. Heidari-Rarani(IUST: Iran University of Science and Technology)H-Index: 16
Last. Majid R. Ayatollahi(IUST: Iran University of Science and Technology)H-Index: 65
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Abstract A novel theoretical approach is presented to calculate the mode I interlaminar fracture toughness ( G Ic ) of double cantilever beam (DCB) specimens with low ratio of initial crack length-to-thickness ( a 0 /2 h ). This method is based on a sixth-order beam theory, namely Reddy-Bickford beam (RB), on Winkler elastic foundation (WEF) to account for both transverse shear deformation of the beam and local effects at the delamination front (root rotation). RB with only two generalized displ...
Abstract A new analysis was developed for the Double Cantilever Beam (DCB) test. Its main objective is to compute mode I critical strain energy release rates G Ic unaffected by fibre bridging. In fact, the latter phenomenon often observed in standard unidirectional specimens is not considered representative of most structural applications. The analysis developed applies a relatively simple numerical procedure to experimental load–displacement data for the initial crack propagation stages. Moreov...
Last. Xiaojing Gong(University of Toulouse)H-Index: 1
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Abstract Strain energy release rate (SERR) along a linear crack front of a multidirectional composite DCB specimen shows an obviously non-uniform distribution, which causes the fracture toughness GIavg measured by experiments smaller than the real GIC, and so leading to a lower estimation of fracture toughness. In this study, based on the numerical model a novel semi-empirical closed-form formula was proposed for determination of pure mode I fracture toughness of a multidirectional composite DCB...
This paper presents an experimental evaluation of influence of the elastic couplings on the fracture toughness as well as on delamination initiation and propagation in carbon/epoxy composite laminates. For this purpose the mode I double cantilever beam (DCB) tests according to the American Society for Testing and Materials (ASTM) D5528 Standard were performed on specimens with different delamination interfaces and specific lay-ups composition exhibiting the bending-twisting (BT) and the bending-...
#2Kalyan Singh(IITs: Indian Institutes of Technology)H-Index: 17
AbstractInterlaminar fracture toughness had been the subject of great interest for several years and is still interesting to the research community. In this article, a comprehensive analysis of fra...
Abstract The aim of this work is to investigate the effect of the loading rate on the crack growth behavior in carbon fiber reinforced polymer composites, under mode I monotonic tensile loading. For such objective, inter-laminar fracture toughness tests were performed on double cantilever beam (DCB) specimens, according to the ASTM-D5528 standard. The initial crack tip opening displacement (CTOD) was obtained by employing the digital image correlation (DIC) technique. Then, the strain energy rel...