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B. Pradhan - One of the best experts on this subject based on the ideXlab platform.
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Delamination Damage Analyses of FRP Composite Spar Wingskin Joints with Modified Elliptical Adhesive Load Coupler Profile
Applied Composite Materials, 2008Co-Authors: S. K. Panigrahi, B. PradhanAbstract:Three-dimensional non-linear finite element analyses (FEA) for Delamination damage onset and its growth in Graphite Fiber Reinforced Plastic (GFRP) composite Spar Wingskin Joints (SWJ) with modified elliptical adhesive load coupler profile for varied ratios of base width to height of the spar have been presented in this paper. Both in-plane and out-of-plane normal and shear stress variations on the interfacial surface of the wingskin between the spar and the wingskin have been evaluated. Coupled stress failure criterion has been used to predict the locations of initiation of failures due to Delamination induced damages. Based on the stress and Delamination damage analyses, suitable geometry of the modified elliptical adhesive load coupler profile of the SWJ has been recommended. The Delamination damage has been observed to be initiated from the toe-end of the interfacial surface of the spar and the wingskin of the SWJ. Subsequently, the Delamination propagations have also been studied by calculating the individual and the total Mode of Strain Energy Release Rate (SERR) along the Delamination Front using Modified Crack Closure Integral (MCCI) technique based on Linear Elastic Fracture Mechanics (LEFM) approach. It is seen that SERR variations along the Delamination Front i.e. across the width of the SWJ are not uniform. Therefore, a straight Delamination Front may grow into a curved Delamination Front as the Delamination propagates. Also, it is found that Mode I SERR ( G _I) governs the Delamination propagation predominantly for the SWJ. Accordingly, suitable Delamination arresting mechanism has been suggested.
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Thermoelastic effects on mixed-mode Delamination growth emanating from circular holes in laminated FRP composites
Composite Structures, 2008Co-Authors: P. Ramesh Babu, B. PradhanAbstract:Abstract This paper deals with the thermoelastic effects on mixed-mode Delamination growth behaviour emanating from circular holes in laminated Fiber-Reinforced Polymeric (FRP) composites. Two sets of full three-dimensional analyses have been performed (one with the thermal residual stresses developed while curing the laminate and the other without thermal residual stresses i.e., with mechanical loading only) to calculate the displacements and interlaminar stresses along the annular shaped delaminated interface responsible for Delamination onset and propagation. Modified Crack Closure Integral (MCCI) method based on the concept of linear elastic fracture mechanics has been followed to calculate the three modes of Strain Energy Release Rates (SERR). The strain energy release rate components GI, GII and GIII along the annular shaped Delamination Front due to thermal residual stresses developed while curing the laminate (i.e., cooling from an elevated temperature of thermosetting to the room temperature) and the subsequent mechanical loading have been obtained by superimposing their respective effects. Numerical calculations are carried out for multi-layered cross-ply and angle-ply glass/epoxy FRP composite laminates and the strain energy release rate plots demonstrate large asymmetries along the Delamination Front due to the interaction of residual curing stresses and superimposed mechanical loading. It is observed that the residual curing stresses have the effect of enhancing the behaviour of Delamination growth. On subsequent mechanical loading this can be a potential source of causing premature failure due to the superimposed thermomechanical effects.
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Influence of Ply Sequence and Thermoelastic Stress Field on Asymmetric Delamination Growth Behavior Emanating From Elliptical Holes in Laminated FRP Composites
Journal of Engineering Materials and Technology, 2007Co-Authors: B. Pradhan, Poosa Ramesh BabuAbstract:The present study encompasses the influence of ply sequence and thermoelastic stress field on asymmetric Delamination growth behavior emanating from elliptical holes in laminated fiber reinforced polymeric composites. Results, emphasizing the effect of thermal residual stresses on Delamination growth behavior of the composite laminates subjected to two different loading conditions, i.e., in-plane tensile and compressive loadings, are presented. Two sets of full three-dimensional finite element analyses have been performed to calculate the displacements and interlaminar stresses along the delaminated interfaces responsible for the Delamination onset and propagation. Modified crack closure integral methods based on the concepts of linear elastic fracture mechanics have been followed to evaluate the individual modes of strain energy release rates along the Delamination Front. In each case, the Delamination is embedded at a different depth along the thickness direction of the laminates. It is observed that the fiber orientation of the plies bounding the Delamination Front significantly influences the distribution of the local strain energy release rate. Also, the residual thermal stresses have a detrimental effect on the laminates subjected to compressive loading and more so in the case of laminates with Delaminations existing closer to the top and bottom surfaces of the laminate.
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Mixed-mode analysis of superimposed thermo-elastic effects in fiber-reinforced composites with embedded interface Delaminations
Composite Structures, 2007Co-Authors: Subrata Kumar Panda, B. PradhanAbstract:This paper deals with the 3D finite element analysis of superimposed thermo-elastic effect on embedded interfacial Delamination crack growth characteristics in fiber-reinforced laminated composites. Interlaminar fracture at the Delamination Front is found to be a mixed-mode phenomenon due to the anisotropy and heterogeneity of thermo-physical properties of composite materials. This leads to the requirement of finite element evaluation of energy release rates, based on the principles of linear elastic fracture mechanics. The strain energy release rate components along the Delamination Front due to a uniform temperature drop, during the manufacturing stages of composite laminates, to room temperature and subsequent mechanical loading is obtained by superimposing their respective effects based on the assumptions of linear elasticity. Numerical calculations are carried out for multi-layered cross-ply and angle-ply composite laminates and energy release rate plots demonstrate large asymmetries along the Delamination Front due to the interaction of residual stresses and superimposed transverse loading.
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Characterization of Curing Stress Effects on Fracture Behavior of FRP Laminated Composites with Embedded Delaminations
Journal of Reinforced Plastics and Composites, 2006Co-Authors: B. Pradhan, Saroja Kanta PandaAbstract:A detailed study on the effect of curing stresses on interlaminar Delamination crack growth behavior in fiber-reinforced polymeric (FRP) composites is presented. At a given applied load or displacement, the strain energy release rate distribution along the Delamination Front with and without considering the effects of curing stresses are compared. In this analysis, results are presented for elliptical Delaminations embedded between plies of different orientations in the laminate. A full three-dimensional coupled-field finite element analysis has been conducted to study the Delamination crack growth behavior due to curing stress effects. A superposition procedure along with the modified crack closure integral technique based on the concepts of linear elastic fracture mechanics is employed to evaluate the individual modes of strain energy release rates during Delamination propagation. It has been observed that the residual thermal stresses developed during the curing stages in manufacturing of FRP laminated composites significantly affect the onset and growth of Delamination. The asymmetric behavior of interlaminar fracture energy along the Delamination Front is found to depend upon the stacking sequence, neighboring ply orientation, thermoelastic anisotropy, and material heterogeneity at the interface of laminated composites.
Subrata Kumar Panda - One of the best experts on this subject based on the ideXlab platform.
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Mixed-mode thermo elastic Delamination fracture behavior of composite skin stiffener containing interface Delamination
Journal of Materials Research and Technology, 2019Co-Authors: Saumya Shah, Pardeep Kumar, Subrata Kumar Panda, Sandeep KumarAbstract:Abstract This paper presents the thermo-elastic effect on materials having anisotropic behavior and stresses developed due to residual temperature on interlaminar Delamination fracture characteristics of composite skin stiffener. For the preexisting interlaminar Delaminations subjected to uniaxial loading and three-point bending of three-dimensional coupled field thermo-elastic finite element analyses have been accomplished. The individual mode of strain energy release rate along the Delamination Front has been evaluated by modified crack-closure integral method based on the concept of mechanics of linear elastic fracture. Qualitative comparison has been illustrated for the individual modes of energy release rate along the Delamination Front of skin stiffener for both the loadings. The influence of coupled field thermo-elastic material anisotropy of the constituting laminae has been reasoned for the asymmetric variation of total strain energy release rate along Delamination Front. This was found to be significantly higher for the case of residual thermal stresses compared to mechanical loading.
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Mixed-mode analysis of superimposed thermo-elastic effects in fiber-reinforced composites with embedded interface Delaminations
Composite Structures, 2007Co-Authors: Subrata Kumar Panda, B. PradhanAbstract:This paper deals with the 3D finite element analysis of superimposed thermo-elastic effect on embedded interfacial Delamination crack growth characteristics in fiber-reinforced laminated composites. Interlaminar fracture at the Delamination Front is found to be a mixed-mode phenomenon due to the anisotropy and heterogeneity of thermo-physical properties of composite materials. This leads to the requirement of finite element evaluation of energy release rates, based on the principles of linear elastic fracture mechanics. The strain energy release rate components along the Delamination Front due to a uniform temperature drop, during the manufacturing stages of composite laminates, to room temperature and subsequent mechanical loading is obtained by superimposing their respective effects based on the assumptions of linear elasticity. Numerical calculations are carried out for multi-layered cross-ply and angle-ply composite laminates and energy release rate plots demonstrate large asymmetries along the Delamination Front due to the interaction of residual stresses and superimposed transverse loading.
Sandeep Kumar - One of the best experts on this subject based on the ideXlab platform.
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Mixed-mode thermo elastic Delamination fracture behavior of composite skin stiffener containing interface Delamination
Journal of Materials Research and Technology, 2019Co-Authors: Saumya Shah, Pardeep Kumar, Subrata Kumar Panda, Sandeep KumarAbstract:Abstract This paper presents the thermo-elastic effect on materials having anisotropic behavior and stresses developed due to residual temperature on interlaminar Delamination fracture characteristics of composite skin stiffener. For the preexisting interlaminar Delaminations subjected to uniaxial loading and three-point bending of three-dimensional coupled field thermo-elastic finite element analyses have been accomplished. The individual mode of strain energy release rate along the Delamination Front has been evaluated by modified crack-closure integral method based on the concept of mechanics of linear elastic fracture. Qualitative comparison has been illustrated for the individual modes of energy release rate along the Delamination Front of skin stiffener for both the loadings. The influence of coupled field thermo-elastic material anisotropy of the constituting laminae has been reasoned for the asymmetric variation of total strain energy release rate along Delamination Front. This was found to be significantly higher for the case of residual thermal stresses compared to mechanical loading.
Kiran K. Simon - One of the best experts on this subject based on the ideXlab platform.
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Assessment of split-beam-type tests for mode III Delamination toughness determination
International Journal of Fracture, 2014Co-Authors: Allison L. Johnston, Barry D. Davidson, Kiran K. SimonAbstract:Four split-beam-type tests are proposed for determining the mode III Delamination toughness of laminated composite materials. Each test is first assessed via three dimensional finite element analysis. Experimental evaluations are then conducted, for which two different unidirectional carbon/epoxy materials are considered. For either material, it is shown that the same mode III toughness is obtained by the four different tests, provided that specimens with the same Delamination length are tested. However, when a single test configuration is utilized to investigate the effect of Delamination length, the apparent mode III toughness is observed to decrease with increasing Delamination length. In order to understand the mechanisms behind this, transverse section cuts were taken at the Delamination Front of tested specimens. Photomicroscopic examinations of these cross sections revealed matrix cracks at the Delamination Front that were oriented at an inclination of $$45^{\circ }$$ 45 ∘ to the plane of the Delamination. Based on previous observations of mode III crack initiation in homogeneous materials, it is hypothesized that these matrix cracks initiate prior to or concurrent with Delamination advance, and therefore are responsible for the observed geometry-dependence of the mode III Delamination toughness in laminated polymeric composites.
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Assessment of split-beam-type tests for mode III Delamination toughness determination
International Journal of Fracture, 2014Co-Authors: Allison L. Johnston, Barry D. Davidson, Kiran K. SimonAbstract:Four split-beam-type tests are proposed for determining the mode III Delamination toughness of laminated composite materials. Each test is first assessed via three dimensional finite element analysis. Experimental evaluations are then conducted, for which two different unidirectional carbon/epoxy materials are considered. For either material, it is shown that the same mode III toughness is obtained by the four different tests, provided that specimens with the same Delamination length are tested. However, when a single test configuration is utilized to investigate the effect of Delamination length, the apparent mode III toughness is observed to decrease with increasing Delamination length. In order to understand the mechanisms behind this, transverse section cuts were taken at the Delamination Front of tested specimens. Photomicroscopic examinations of these cross sections revealed matrix cracks at the Delamination Front that were oriented at an inclination of $$45^{\circ }$$ 45 ∘ to the plane of the Delamination. Based on previous observations of mode III crack initiation in homogeneous materials, it is hypothesized that these matrix cracks initiate prior to or concurrent with Delamination advance, and therefore are responsible for the observed geometry-dependence of the mode III Delamination toughness in laminated polymeric composites.
Mgd Marc Geers - One of the best experts on this subject based on the ideXlab platform.
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Interface Integrity in Stretchable Electronics
Experimental and Applied Mechanics Volume 6, 2011Co-Authors: Jan Neggers, Jpm Johan Hoefnagels, Olaf Van Der Sluis, O Sedaghat, Mgd Marc GeersAbstract:Stretchable electronic devices enable numerous futuristic applications. Typically, these devices consist of a (metal) interconnect system embedded in a stretchable (rubber) matrix. This invokes an apparent stretchability conflict between the interconnect system and the matrix. This conflict is addressed by shaping the interconnects in mechanistic patterns that bend and twist to facilitate global stretchability. Metal-rubber type stretchable electronic systems exhibit catastrophic interface Delamination, which is investigated in this research. The fibrillation process occurring at the Delamination Front of the metal-rubber interface is investigated through in-situ SEM imaging of the progressing Delamination Front of peel tests of rubber on copper samples. Results show that the interface strength is dependent on the Delamination rate and the interface roughness. Additionally, the fibril geometry seems highly dependent on the interface roughness, while being remarkably independent on the Delamination- rate.
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Copper–rubber interface Delamination in stretchable electronics
Scripta Materialia, 2010Co-Authors: Jpm Johan Hoefnagels, Jan Neggers, Phm Peter Timmermans, Van Der O Olaf Sluis, Mgd Marc GeersAbstract:Interface Delamination in metal–rubber-type stretchable electronic systems leads to early failure. This paper reports an investigation of metal–rubber interfaces through in situ scanning electron microscopy imaging of the progressing Delamination Front of 90° peel tests of rubber on copper samples. The results show that the energy dissipated in the forming, elongation and rupture of ∼50 μm long fibrils constitutes the major part of the work of separation. The experiments are characterized and modeled using a cohesive zone-enriched finite-element model.
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A combined numerical-experimental approach to characterize Delamination in polymer coated steel
2005Co-Authors: Van Den Mj Marco Bosch, Pjg Piet Schreurs, Mgd Marc GeersAbstract:Methods A Finite Element model is used to simulate industrial forming processes, such as bending and deep-drawing. Between the polymer layer and the metal substrate interface elements are present to simulate the Delamination of the polymer layers. Experiments are needed to determine parameters for the simulations. Results Delamination experiments are conducted inside a Scanning Electron Microscope (SEM). The Delamination Front is observed (see figure 3) and the force is measured.