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Full-Text Articles in Engineering
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 …
Thermal Analysis Of Carbon Nanofiber Reinforced Isotactic Polypropylene, Anna Alicia Hernandez
Thermal Analysis Of Carbon Nanofiber Reinforced Isotactic Polypropylene, Anna Alicia Hernandez
Theses and Dissertations - UTB/UTPA
Isotactic Polypropylene (IPP) is a commonly known thermoplastic that has unique properties include being light weight, high performance, impact strength, tensile strength, elongation, and high temperature properties. The use of vapor grown carbon nanofiber (VGCNF) reinforcements on polypropylene has shown to produce high specific modulus, strength, electrical and thermal properties on specimens. Thermogravimetric (TGA) investigations on the thermal degradation of isotactic polypropylene – vapor grown carbon nanofibers composites in nitrogen were reported. The mass evolution as a function of temperature is a single sigmoid for both polypropylene and polypropylene loaded with VGCNF. The inflection temperature of these sigmoids increases as …
Experimental And Finite Element Studies Of Shock Transmission, Eldon Jerry Goddard
Experimental And Finite Element Studies Of Shock Transmission, Eldon Jerry Goddard
UNLV Theses, Dissertations, Professional Papers, and Capstones
Composite materials are more widely used today in engineering products than ever before. Shock transmission in jointed composite sections needs to be investigated to understand the affect of composite materials on the dynamic response of the system. There exists limited published work on transient shock propagation through composite sections. The aim of this study is to analyze the transient behavior of joints in composite materials subjected to low impact loads and to develop a computational model that provides an improved physics based shock model. The jointed connection will be investigated experimentally and using Finite Element Analysis (FEA). The bolted joint …
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 …
Simplifying The Testing And Calculation Of Fracture Toughness Of Thermoplastic And Thermoset Matrix Composite Materials, James Shedden
Simplifying The Testing And Calculation Of Fracture Toughness Of Thermoplastic And Thermoset Matrix Composite Materials, James Shedden
Materials Engineering
Fracture toughness, or the ability of a material to resist fast fracture by crack propagation is an important property in the use of composite materials for structural designs. Other mechanical tests such as tensile, flexure, and compression are more established and practical than testing fracture toughness. Fracture toughness testing is less commonly used because it requires specific specimens and non-conventional test methods. In composite materials specifically, delamination of the plies of materials is tested for GIC and GIIC values to find the critical strain energy release rate of the two types of fracture modes. The common two tests …
Drape Forming Machine, Adam Johnson, Will Schlosser, Brian Miller
Drape Forming Machine, Adam Johnson, Will Schlosser, Brian Miller
Mechanical Engineering
The goal of this project was to build a prototype machine that formed multiple sheets of debulked pre-preg OOA carbon fiber into a 2-foot long trapezoidal shape. The machine was required to do this process semi-automatically.
Nano-Particles In Multi-Scale Composites And Ballistic Applications, Jason Gibson
Nano-Particles In Multi-Scale Composites And Ballistic Applications, Jason Gibson
Electronic Theses and Dissertations
Carbon nanotubes, graphene and nano sized core shell rubber particles have all been extensively researched for their capability to improve mechanical properties of thermoset resins. However, there has been a lack of research on their evaluation for energy absorption in high velocity impact scenarios, and the fundamental mechanics of their failure mechanisms during highly dynamic stress transfer through the matrix. This fundamental research is essential for laying the foundation for improvement in ballistic performance in composite armor. In hard armor applications, energy absorption is largely accomplished through delamination between plies of the composite laminate. This energy absorption is accomplished through …
Low Strain Rate Studies Of Alumina Epoxy Composites Using Piezospectroscopy, Ashley Jones
Low Strain Rate Studies Of Alumina Epoxy Composites Using Piezospectroscopy, Ashley Jones
Electronic Theses and Dissertations
Particulate composites are widely used in many aerospace and military applications as energetic materials, armor materials or coatings and their behavior under dynamic loads have gained increasing significance. The addition of modifiers such as alumina nanoparticles generally facilitates the improvement of the mechanical strength to density ratio due to high specific area and particle rigidity. This allows for sufficient particlematrix bonding and therefore improved stiffness and load transfer in the composite. Photo-luminescent α-alumina nanoparticles when embedded in an epoxy matrix allow for the added benefit of in situ measurements at low strain rates to provide stress-sensitive information using the particle …