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Full-Text Articles in Engineering
Wrinkling Of Functionally Graded Sandwich Structures Subject To Biaxial And In-Plane Shear Loads, Harold Costa
Wrinkling Of Functionally Graded Sandwich Structures Subject To Biaxial And In-Plane Shear Loads, Harold Costa
Masters Theses
"Benefits of a functionally graded core increasing wrinkling stability of sandwich panels have been demonstrated in a recent paper [1] where a several-fold increase in the wrinkling stress was observed, without a significant weight penalty, using a stiffer core adjacent to the facings. In the present paper wrinkling is analyzed in case where the facings are subject to biaxial compression and/or in-plane shear loading and the core is arbitrary graded through-the-thickness. Two issues addressed are the effect of biaxial or in-plane shear loads on wrinkling stability of panels with both graded and ungraded core and the verification that functional grading …
Modeling Of Debonding And Crack Propagation In Fibrous Composites Using A Discontinuous Galerkin Approach, Wesley Michael Hicks
Modeling Of Debonding And Crack Propagation In Fibrous Composites Using A Discontinuous Galerkin Approach, Wesley Michael Hicks
Masters Theses
A recently proposed Discontinuous Galerkin (DG) method for modeling debonding and fracture within the context of the finite element method is investigated for problems relating to fiber reinforced composites, namely fiber-matrix interfacial debonding which progresses to matrix fracture. The results are then compared against an existing intrinsic cohesive zone method and a hybrid Discontinuous Galerkin method. The results show that the method can eliminate the problem of artificial compliance that is associated with intrinsic cohesive zone models. Eliminating this stiffness has the positive effect of removing user-defined numerical parameters that are not actually present in the physical system. A key …
Fabrication Of Out-Of-Autoclave Bismaleimide Based Composite Laminates With Embedded Fiber Optic Sensors, Sudharshan Anandan
Fabrication Of Out-Of-Autoclave Bismaleimide Based Composite Laminates With Embedded Fiber Optic Sensors, Sudharshan Anandan
Masters Theses
"Composites are becoming the material of choice in applications where weight savings are critical, like aerospace structures. The common composites used are- Carbon/Epoxy and Carbon/Bismaleimide (BMI). BMI based systems are preferred in applications which involve operating temperatures higher than conventional epoxies. Carbon/BMI laminates are traditionally fabricated in an autoclave, which is associated with high operating costs. In this work, a low cost out of autoclave (OOA) process is evaluated. It is desirable to have BMI OOA prepreg systems cure at reasonably low temperatures with sufficient degree of cure and green strength to maintain rigidity for subsequent freestanding post cure Carbon/BMI …
Investigation Of Composite Patch Performance Under Low-Velocity Impact Loading, Geoffrey Roy Goodmiller
Investigation Of Composite Patch Performance Under Low-Velocity Impact Loading, Geoffrey Roy Goodmiller
Masters Theses
Bonded fiber composite repair on damaged metal structures can be an effective method to restore load carrying capacity or increase damage resistance. Low velocity impacts can cause barely visible damage to the interior structure of laminated composites. Delamination between plies is of particular concern in these composites. Impacts may also create disbonds between the patch and metal substrate. A building-block approach was suggested to model impact damage to composite patches. Composite, adhesive, and metal substrate damage models were separately validated and then combined. Cohesive Zone theory modeled interlaminar composite damage and adhesive damage. Hashin failure criteria with energy dissipation based …
An Automated Finite Element Analysis Framework For The Probabilistic Evaluation Of Composite Lamina Properties, Jonathan Phillips Weigand
An Automated Finite Element Analysis Framework For The Probabilistic Evaluation Of Composite Lamina Properties, Jonathan Phillips Weigand
Masters Theses
This thesis outlines the development of computational modeling tools used to predict the elastic properties of composite lamina from representative volume elements (RVE) using numerical methods. The homogenization approach involves the use of Gauss’s Theorem to simply the average volumetric strain integral into a surface integral containing which is defined by surface displacements and their direction. Simulations of RVEs under specific loading conditions (longitudinal tension or shear and transverse tension or shear) are then performed in the software package ABAQUS to obtain the surface displacements. It was found that obtaining quality meshes and applying periodic boundary conditions for each RVE …