The Experts below are selected from a list of 810 Experts worldwide ranked by ideXlab platform
Bijan Mohammadi - One of the best experts on this subject based on the ideXlab platform.
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Prediction of Outer-Ply matrix crack density at saturation in laminates under static and fatigue loading
International Journal of Solids and Structures, 2018Co-Authors: Hamed Pakdel, Bijan MohammadiAbstract:Abstract The onset of dominant damage mode transition from matrix cracking to induced delamination in laminates containing Outer-Ply matrix cracks is experimentally and analytically investigated. Stress states of a [ θ m ( o ) / θ n ( i ) ] s laminate containing staggered Outer-Ply matrix cracks with or without induced delaminations are derived implementing a developed unit-cell based analysis in the framework of variational principles. A damage mode competition criterion is implemented to predict crack density at saturation which is argued to be a characteristic damage state (CDS) independent from loading conditions. Several carbon/epoxy specimens of type [θm/0n]s are prepared with different off-axis Ply orientation, θ, and thickness. Optical microscopy is used to identify matrix crack density during both static and fatigue loading with different loading conditions. The analytically predicted crack densities at saturation are shown to be in acceptable agreement with experimental observations and saturated crack density is confirmed to be a characteristic damage state (CDS) identical during both static and fatigue loading.
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experimental observation and energy based analytical investigation of matrix cracking distribution pattern in angle Ply laminates
Theoretical and Applied Fracture Mechanics, 2017Co-Authors: Hamed Pakdel, Bijan MohammadiAbstract:Abstract An energy based criteria is developed to predict the leading distribution pattern of matrix cracks in the damage mode competition in angle-Ply laminates of type θ m 1 / θ n 2 s subject to uniaxial tensile loading. For the first time in the literature, all plausible matrix crack distribution patterns, namely mid-Ply or staggered/symmetric Outer-Ply cracking are considered and energy release rate for initiation of each case is derived. Different geometrical effects such as Ply orientation, thickness ratios and scale effects are investigated on the initiation distribution pattern of matrix cracks. The results show that distribution pattern of matrix cracks is directly affected by geometrical factors. Test specimens with different geometrical characteristics are prepared from unidirectional carbon-epoxy and an experimental test setup is prepared to capture the distribution pattern of matrix cracks during tensile loading. The predicted matrix crack distribution patterns of all specimens are verified by experimental observations.
Hamed Pakdel - One of the best experts on this subject based on the ideXlab platform.
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Prediction of Outer-Ply matrix crack density at saturation in laminates under static and fatigue loading
International Journal of Solids and Structures, 2018Co-Authors: Hamed Pakdel, Bijan MohammadiAbstract:Abstract The onset of dominant damage mode transition from matrix cracking to induced delamination in laminates containing Outer-Ply matrix cracks is experimentally and analytically investigated. Stress states of a [ θ m ( o ) / θ n ( i ) ] s laminate containing staggered Outer-Ply matrix cracks with or without induced delaminations are derived implementing a developed unit-cell based analysis in the framework of variational principles. A damage mode competition criterion is implemented to predict crack density at saturation which is argued to be a characteristic damage state (CDS) independent from loading conditions. Several carbon/epoxy specimens of type [θm/0n]s are prepared with different off-axis Ply orientation, θ, and thickness. Optical microscopy is used to identify matrix crack density during both static and fatigue loading with different loading conditions. The analytically predicted crack densities at saturation are shown to be in acceptable agreement with experimental observations and saturated crack density is confirmed to be a characteristic damage state (CDS) identical during both static and fatigue loading.
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experimental observation and energy based analytical investigation of matrix cracking distribution pattern in angle Ply laminates
Theoretical and Applied Fracture Mechanics, 2017Co-Authors: Hamed Pakdel, Bijan MohammadiAbstract:Abstract An energy based criteria is developed to predict the leading distribution pattern of matrix cracks in the damage mode competition in angle-Ply laminates of type θ m 1 / θ n 2 s subject to uniaxial tensile loading. For the first time in the literature, all plausible matrix crack distribution patterns, namely mid-Ply or staggered/symmetric Outer-Ply cracking are considered and energy release rate for initiation of each case is derived. Different geometrical effects such as Ply orientation, thickness ratios and scale effects are investigated on the initiation distribution pattern of matrix cracks. The results show that distribution pattern of matrix cracks is directly affected by geometrical factors. Test specimens with different geometrical characteristics are prepared from unidirectional carbon-epoxy and an experimental test setup is prepared to capture the distribution pattern of matrix cracks during tensile loading. The predicted matrix crack distribution patterns of all specimens are verified by experimental observations.
Narasimalu Srikanth - One of the best experts on this subject based on the ideXlab platform.
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Effect of delamination on the flexural response of [+45/−45/0]2s carbon fibre reinforced polymer laminates
Composite Structures, 2019Co-Authors: Zhe Liu, Narasimalu SrikanthAbstract:Abstract The damage arising in the manufacturing or service operation can result in the degradation in mechanical properties or even structural failure in composite laminates. This work investigated the flexural behaviour of [+45/−45/0] 2s carbon fibre reinforced polymer laminates with the artificially embedded delamination (pre-delamination) at different interfaces. After static flexural experiments, the internal 3D damage including various failure modes was characterised and quantified in the X-ray microtomography. It was found that regardless of the pre-delamination, similar in-Ply (fibre failure, matrix cracking and fibre/matrix debonding) and interlaminar (delamination) failure modes occur dominantly in the Outer Ply group of the compression zone in all the laminates. However, the pre-delamination and its location have the influence on both the distribution and size of the 3D damage, and thus on the flexural properties. The flexural strength that is reduced by pre-delamination is the most (least) sensitive to the pre-delamination embedded at the third (ninth) interface.
Quade Derek - One of the best experts on this subject based on the ideXlab platform.
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The Effects of Fiber Orientation and Adhesives on Tensile Properties of Carbon Fiber Reinforced Polymer Matrix Composite with Embedded Nickel-Titanium Shape Memory Alloys
2018Co-Authors: Morscher Gregory, Mccorkle Linda, Jana Sadhan, Kannan Manigandan, Quade DerekAbstract:Tensile tests of Nickel-titanium (NiTi) shape memory alloys (SMA) embedded within carbon fiber reinforced polymer matrix composite (CFRP/PMC) laminates were evaluated with simultaneous monitoring of modal acoustic emissions (MAE). Three different layup configurations utilizing two different thin film adhesives were applied to bond the materials. Ultimate tensile strengths, strains, and moduli were obtained along with cumulative AE energy of events and specimen failure location. Scanning electron microscopy was used to examine the break areas of the specimens post-test. Microscopy was used to validate failure locations revealed from MAE analysis. A unique finding within this research showed that 90 plies in the Outer Ply gave the strongest acoustic signals as well as the cleanest fracture of the specimens tested. Overlapping 0 Ply layers surrounding the SMA was found to be the best scenario to prevent failure of the specimen itself
Jana, Sadhan C. - One of the best experts on this subject based on the ideXlab platform.
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The Effects of Fiber Orientation and Adhesives on Tensile Properties of Carbon Fiber Reinforced Polymer Matrix Composite with Embedded Nickel-Titanium Shape Memory Alloys
2017Co-Authors: Mccorkle, Linda S., Kannan Manigandan, Morscher, Gregory N., Quade, Derek J., Jana, Sadhan C.Abstract:Nickel-titanium (NiTi) shape memory alloy (SMA) sections were embedded within carbon fiber reinforced polymer matrix composite (CFRPPMC) laminates and their tensile properties were evaluated with simultaneous monitoring of modal acoustic emissions. The test specimens were fabricated in three different layup configurations and two different thin film adhesives were applied to bond the SMA with the PMC. A trio of acoustic sensors were attached to the specimens during tensile testing to monitor the modal acoustic emission (AE) as the materials experienced mechanical failure. The values of ultimate tensile strengths, strains, and moduli were obtained. Cumulative AE energy of events and specimen failure location were determined. In conjunction, optical and scanning electron microscopy techniques were used to examine the break areas of the specimens. The analysis of AE data revealed failure locations within the specimens which were validated from the microscopic images. The placement of 90 deg plies in the Outer Ply gave the strongest acoustic signals during break as well as the cleanest break of the samples tested. Overlapping 0 deg Ply layers surrounding the SMA was found to be the best scenario to prevent failure of the specimen itself
