Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 41 for “"Matrix cracking"”.
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Discrete Damage Mechanics Applied To Transverse Matrix Cracking
… expansion (CTE) reduction due to transverse matrix cracking in laminated composite structures is implemented as a user subroutine in Abaqus. The assumptions of the model are a symmetric laminate under in-plane loads and linear distribution of intralaminar shear stresses. The model was latter …
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Elastic and time dependent matrix cracking in cross-ply composite laminates
… understanding of the effect of time and rate on matrix cracking. The tests were performed on Kevlar/epoxy and graphite/epoxy [0/90₃]₈ laminates. The results indicate that the stress levels required for matrix cracking are a function of how fast the specimens were loaded. Also, significant time …
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Interfacial Mechanics in Fiber-Reinforced Composites: Mechanics of Single and Multiple Cracks in CMCs
… of the interface between the fibers and matrix in ceramic matrix composites (CMCs) are studied. The first issue is the competition between crack deflection and penetration at the fiber/matrix interface. When a matrix crack, the first fracture mode in a CMC, reaches the interface, two …
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Neural Network Burst Pressure Prediction in Composite Overwrapped Pressure Vessels Using Mathematically Modeled Acoustic Emission Data
… data. Thus, amplitude histograms from classified matrix cracking data were mathematically modeled herein using bounded Johnson distributions.</p> <p>A backpropagation neural network (BPNN) was then generated using MATLAB. This BPNN was able to predict the burst pressures of the COPVs using (1) …
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Damage analysis and mechanical response of as-received and heat-treated Nicalon/CAS-II glass-ceramic matrix composites
… in air for 100 hours. Changes at the fiber/matrix interface/interphase due to post-processing heat treatments were also characterized. The combined effect of fiber debonding and transverse matrix cracking in both 90° and 0° plies plays an important role in damage development in [0/90]₄₅ …
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Finite element-based failure models for carbon/epoxy tape composites
… composites. Predictions are challenging because matrix (resin) dominated failure mechanisms such as delaminations and matrix cracking contribute to the structural failure in addition to fiber-dominated failures. A key to rigorous failure predictions for composites is availability of measurements …
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Transmitted light intensity as a nondestructive evaluation technique for glass/epoxy composite laminates
… analysis techniques, damage development due to matrix cracking and delamination, was detected and presented in images that were easy to understand.
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Characterization of damage mechanisms and behavior in two-dimensionally braided composites subjected to static and fatigue loading
… consisting of graphite fibers in an epoxy matrix were tested under static and fatigue loading conditions to determine damage mechanism types and progressions. The braided architectures consisted of straight axial fiber bundles, which were surrounded by braider fiber bundles oriented at ±a 0 …
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Fatigue response of notched graphite--epoxy laminates
… characteristics. Buckling effects as well as matrix cracking and delaminations contribute to stiffness changes.
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The effect of thickness on the fracture behavior of graphite/bismaleimede laminates with central circular holes
… thick laminates. All notched specimens exhibited matrix cracking in the 90° plies around the hole and vertical splitting in the 0° plies at the edge of the hole.
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Analysis of Composite Laminates with Matrix Cracks
Analysis of the effects of matrix cracking on composite laminates is a well-known problem which has attracted considerable attention for the past decade. An approximate analytical solution is introduced in this thesis to study this type of problem. The subjects of primary concern are the …
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Mechanical behavior and damage mechanisms of woven graphite-polyimide composite materials
… different than in non-woven graphite-epoxy. Matrix cracking was denser and delamination less extensive in the graphite-polyimide material system, and as a result, increases in notched residual tensile strength were much lower. A ply level failure theory was used to successfully predict the …
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Damage Development in Static and Dynamic Deformations of Fiber-Reinforced Composite Plates
… layers, and damage due to fiber breakage, fiber/matrix debonding, and matrix cracking. The three damage modes are modeled using the theory of internal variables and the delamination by postulating a failure envelope in terms of the transverse stresses; the damage degrades elastic moduli. The …
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Simulation of low-velocity impact damage in sandwich composites
… including delaminations, fibre fracture and matrix cracking were simulated and implemented into ABAQUS/Explicit through user-defined subroutines VUMAT. Numerical simulations were assessed and validated by a series of experimental analyses carried out through low-velocity impact tests (using …
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An investigation of stiffness reduction as an indicator of fatigue damage in graphite epoxy composites
… essentially unchanged following fatigue loading. Matrix cracking and delamination appears to contribute to the stiffness reductions that occur in the [0,90,±45]<sub>s</sub> laminate.
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X-ray Micro-Computed Tomography and Deep Learning Segmentation of Progressive Damage in Hierarchical Nanoengineered Carbon Fiber Composites
… have been identified generally as polymer matrix cracking within (intralaminar) and between (interlaminar, termed ‘delamination’) plies, fiber fracture, fiber bundle microbuckling, and fiber/matrix interfacial debonding. Two emerging solutions aiming to suppress or delay such mechanisms …
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The development of a systematic experimental method for damage identification
… that can be classified as fiber breaking and matrix cracking were supposed to be identified through the dynamic experimental techniques. The tests of the frequency response functions (FRFs) of the investigated objects were conducted first to provide a general understanding of the dynamic …
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A micromechanics-based method for off-axis strength prediction of unidirectional laminae - Approach for a nonlinear rubber based lamina
… linear elastic laminae. These composites fail by matrix cracking along a plane parallel to the fiber direction. The stresses in the matrix are calculated using a local stress analysis based on a concentric cylinder model. This model consists of a unique fiber embedded in matrix; both constituents …
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Thermophysical properties of glass and glass-ceramic composites
… twice that of the normal orientation and of the matrix. Heating the composite to above 600°C resulted in permanent decrease in thermal conductivity due to void formation by relaxation of the elastically bent fibers by viscous flow of the matrix. Thermal conductivity of iniaxial carbon fiber …
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Solvent-based self-healing approaches for fiber-reinforced composites
… survive high temperature processing, reside in matrix interstitial regions to retain a high fiber volume fraction, and have minimal impact on the mechanical properties of the host material. This dissertation explores several microencapsulated solvent-based self-healing approaches for …
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