Open Access. Powered by Scholars. Published by Universities.®
- Institution
-
- Air Force Institute of Technology (14)
- California Polytechnic State University, San Luis Obispo (6)
- Selected Works (6)
- The British University in Egypt (5)
- University of Nebraska - Lincoln (4)
-
- Clemson University (2)
- Iowa State University (2)
- Michigan Technological University (2)
- University of Massachusetts Amherst (2)
- American University in Cairo (1)
- Embry-Riddle Aeronautical University (1)
- Kennesaw State University (1)
- Old Dominion University (1)
- Southern Methodist University (1)
- The University of Maine (1)
- Union College (1)
- University of Kentucky (1)
- University of Louisville (1)
- University of New Orleans (1)
- University of Tennessee, Knoxville (1)
- West Virginia University (1)
- Keyword
-
- Peridynamics (7)
- Dynamic fracture (5)
- Composites (4)
- Finite element method (4)
- Brittle fracture (3)
-
- Composite materials (3)
- Crack branching (3)
- Damage (3)
- Fracture (3)
- Micromechanics (3)
- Nonlocal methods (3)
- Additive manufacturing (2)
- Aluminum alloys--Cracking (2)
- Ceramic-matrix composites--Fatigue (2)
- Composite (2)
- Crack propagation (2)
- FEA (2)
- Fiber-reinforced composites (2)
- Finite Element Analysis (2)
- Finite element analysis (2)
- Laminates (2)
- Meshfree methods (2)
- Metallic composites--Thermal fatigue (2)
- Strain (2)
- 7075 aluminum alloy (1)
- ABAQUS; Aluminum alloys; Composite materials; Crystallography; Damage detection; Failure (mechanical); Laminated composites; Laminates; Laminating; Mechanisms; Nondestructive examination; Piezoelectric actuators; Piezoelectricity; Power quality; Structural analysis (1)
- ABS (1)
- Abaqus (1)
- Acoustic emission (1)
- Actuators and sensors; Computational technique; Finite element simulations; Finite element solution; Micro-mechanical modeling; Piezoelectric wafer active sensors; Symmetric laminated; Transformation field analysis (1)
- Publication Year
- Publication
-
- Theses and Dissertations (15)
- Centre for Advanced Materials (5)
- Florin Bobaru Ph.D. (5)
- Master's Theses (3)
- Aerospace Engineering (2)
-
- All Dissertations (2)
- Department of Mechanical and Materials Engineering: Faculty Publications (2)
- Dissertations, Master's Theses and Master's Reports (2)
- Electronic Theses and Dissertations (2)
- Masters Theses (2)
- Stephen D. Holland (2)
- Bilge Nazli Altay (1)
- Department of Engineering Mechanics: Dissertations, Theses, and Student Research (1)
- Department of Engineering Mechanics: Faculty Publications (1)
- Doctoral Dissertations (1)
- Graduate Theses, Dissertations, and Problem Reports (1)
- Honors Theses (1)
- International Journal of Aviation, Aeronautics, and Aerospace (1)
- Mechanical & Aerospace Engineering Faculty Publications (1)
- Mechanical Engineering (1)
- Mechanical Engineering Research Theses and Dissertations (1)
- Symposium of Student Scholars (1)
- Theses and Dissertations--Chemical and Materials Engineering (1)
- University of New Orleans Theses and Dissertations (1)
- Publication Type
- File Type
Articles 1 - 30 of 55
Full-Text Articles in Mechanics of Materials
Mechanics Of Pure Bending And Eccentric Buckling In High-Strain Composite Structures, Jimesh D. Bhagatji, Oleksandr G. Kravchenko, Sharanabasaweshwara Asundi
Mechanics Of Pure Bending And Eccentric Buckling In High-Strain Composite Structures, Jimesh D. Bhagatji, Oleksandr G. Kravchenko, Sharanabasaweshwara Asundi
Mechanical & Aerospace Engineering Faculty Publications
To maximize the capabilities of nano- and micro-class satellites, which are limited by their size, weight, and power, advancements in deployable mechanisms with a high deployable surface area to packaging volume ratio are necessary. Without progress in understanding the mechanics of high-strain materials and structures, the development of compact deployable mechanisms for this class of satellites would be difficult. This paper presents fabrication, experimental testing, and progressive failure modeling to study the deformation of an ultra-thin composite beam. The research study examines the deformation modes of a post-deployed boom under repetitive pure bending loads using a four-point bending setup and …
Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams
Cfrp Delamination Density Propagation Analysis By Magnetostriction Theory, Brandon Eugene Williams
All Dissertations
While Carbon Fiber Reinforced Polymers (CFRPs) have exceptional mechanical properties concerning their overall weight, their failure profile in demanding high-stress environments raises reliability concerns in structural applications. Two crucial limiting factors in CFRP reliability are low-strain material degradation and low fracture toughness. Due to CFRP’s low strain degradation characteristics, a wide variety of interlaminar damage can be sustained without any appreciable change to the physical structure itself. This damage suffered by the energy transfer from high- stress levels appears in the form of microporosity, crazes, microcracks, and delamination in the matrix material before any severe laminate damage is observed. This …
Classification Of Electrical Current Used In Electroplastic Forming, Tyler Grimm
Classification Of Electrical Current Used In Electroplastic Forming, Tyler Grimm
All Dissertations
Electrically assisted manufacturing (EAM) is the direct application of an electric current to a workpiece during manufacturing. This advanced manufacturing process has been shown to produce anomalous effects which extend beyond the current state of modeling of thermal influences. These purported non-thermal effects have collectively been termed electroplastic effects (EPEs).
While there is a distinct difference in results between steady-state (ideal DC) testing and pulsed current testing, the very definition of these two EAM methods has not been well established. A "long" pulse may be considered DC current; a "short" pulse may produce electroplastic effects; and even "steady-state" current shapes …
Application Of Multi-Scale Computational Techniques To Complex Materials Systems, Mujan N. Seif
Application Of Multi-Scale Computational Techniques To Complex Materials Systems, Mujan N. Seif
Theses and Dissertations--Chemical and Materials Engineering
The applications of computational materials science are ever-increasing, connecting fields far beyond traditional subfields in materials science. This dissertation demonstrates the broad scope of multi-scale computational techniques by investigating multiple unrelated complex material systems, namely scandate thermionic cathodes and the metallic foam component of micrometeoroid and orbital debris (MMOD) shielding. Sc-containing "scandate" cathodes have been widely reported to exhibit superior properties compared to previous thermionic cathodes; however, knowledge of their precise operating mechanism remains elusive. Here, quantum mechanical calculations were utilized to map the phase space of stable, highly-faceted and chemically-complex W nanoparticles, accounting for both finite temperature and chemical …
Novel Thermal Coating For High-Speed Airplanes, Abinash Satapathy, Lakshay Battu, Liam Watson, Nazanin Rajabi
Novel Thermal Coating For High-Speed Airplanes, Abinash Satapathy, Lakshay Battu, Liam Watson, Nazanin Rajabi
Symposium of Student Scholars
In comparison to various other materials, Carbon Fiber, specifically Carbon Fiber Reinforced Polymers (CFRP), is pre-eminent amongst other materials for use on aeronautical systems. Due to its high specific strength (strength-to-weight ratio), CFRP is prominent for carrying heavy loads while maintaining a lightweight build. However, when influenced by heat resulting from air resistance, CFRP is known to undergo serious degradation that would significantly decrease the effectiveness of the polymers. To prevent this degradation and maintain the strength of the CFRP, thermal protective layers (TPLs) are designed to shield the CFRP from heat exposure. This research is focused on the examination …
Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian
Microscale Transverse Compression Modeling: A Comparative Study Of The Analytical Mac/Gmc Methods To Experimental Results, Emily Zeitunian
Dissertations, Master's Theses and Master's Reports
Composite materials require a multi-scale approach to fully understand its behavior. At the micro level, material behavior analysis is conducted most often using numerical or analytical approaches. These models, however, require validation from experimental data to ensure material predictions are accurate. This study compares a semi-analytical micromechanical analysis tool, MAC/GMC, to experimental results of in-situ microscale transverse compression testing conducted at AFRL facilities. Effective properties, stress-strain curves, stress and strain fields, and damage predictions are compared with experimental outputs. Both generalized method of cells (GMC) and high-fidelity generalized method of cells (HFGMC) theories implemented within MAC/GMC show results that agree …
Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact, Derek G. Spear
Evaluation Of Additively Manufactured Lattices Under High Strain Rate Impact, Derek G. Spear
Theses and Dissertations
Several additively manufactured lattice designs and configurations were evaluated under compression loads under various strain rates from quasi-static to highly dynamic. These experiments examined how the mechanical behavior of the lattice changed based on the lattice design properties and the applied strain rates. The modulus of elasticity, yield strength, plateau stress, and toughness were observed to decrease with an increase in strain rate, revealing that the lattice designs exhibit a negative strain rate sensitivity. A new lattice flow stress model was developed to account for the mechanical response of the lattice and was incorporated into a computational model for simulation. …
Fluid-Structure Interaction Of Nrel 5-Mw Wind Turbine, Mohamed Sayed Elkady Abd-Elhay
Fluid-Structure Interaction Of Nrel 5-Mw Wind Turbine, Mohamed Sayed Elkady Abd-Elhay
Theses and Dissertations
Wind energy is considered one of the major sources of renewable energy. Nowadays, wind turbine blades could exceed 100 m to maximize the generated power and minimize produced energy cost. Due to the enormous size of the wind turbines, the blades are subjected to failure by aerodynamics loads or instability issues. Also, the gravitational and centrifugal loads affect the wind turbine design because of the huge mass of the blades. Accordingly, wind turbine simulation became efficient in blade design to reduce the cost of its manufacturing. The fluid-structure interaction (FSI) is considered an effective way to study the turbine's behavior …
The Effect Of Oxygen On Properties Of Zirconium Metal, Jie Zhao
The Effect Of Oxygen On Properties Of Zirconium Metal, Jie Zhao
Doctoral Dissertations
The influence of oxygen on the thermophysical properties of zirconium has been investigated using MSL-EML (Material Science Laboratory Electromagnetic Levitator) on ISS (International Space Station) in collaboration with NASA (National Aeronautics and Space Administration), ESA (European Space Agency), and DLR (German Aerospace Center). Zirconium samples with different oxygen concentrations was subjected to multiple melt cycles during which the thermophysical properties, such as density, viscosity and surface tension, have been measured at various undercooled and superheated temperatures. Also, there are melt cycles for verifying the solidification mechanism. Similar samples were found to show anomalous nucleation of the solid for certain ranges …
Multiscale Modeling Of Carbon Fibers/Graphene Nanoplatelets/Epoxy Hybrid Composites For Aerospace Applications, Hashim Al Mahmud
Multiscale Modeling Of Carbon Fibers/Graphene Nanoplatelets/Epoxy Hybrid Composites For Aerospace Applications, Hashim Al Mahmud
Dissertations, Master's Theses and Master's Reports
Significant research effort has been dedicated for decades to improve the mechanical properties of aerospace polymer-based composite materials. Lightweight epoxy-based composite materials have increasingly replaced the comparatively heavy and expensive metal alloys used in aeronautical and aerospace structural components. In particular, carbon fibers (CF)/graphene nanoplatelets (GNP)/epoxy hybrid composites can be used for this purpose owing to their high specific stiffness and strength. Therefore, this work has been completed to design, predict, and optimize the effective mechanical properties of CF/GNP/epoxy composite materials at different length scales using a multiscale modeling approach. The work-flow of modeling involves a first step of using …
Investigation Of Fundamental Principles Of Rigid Body Impact Mechanics, Khalid Alluhydan
Investigation Of Fundamental Principles Of Rigid Body Impact Mechanics, Khalid Alluhydan
Mechanical Engineering Research Theses and Dissertations
In impact mechanics, the collision between two or more bodies is a common, yet a very challenging problem. Producing analytical solutions that can predict the post-collision motion of the colliding bodies require consistent modeling of the dynamics of the colliding bodies. This dissertation presents a new method for solving the two and multibody impact problems that can be used to predict the post-collision motion of the colliding bodies. Also, we solve the rigid body collision problem of planar kinematic chains with multiple contacts with external surfaces.
In the first part of this dissertation, we study planar collisions of Balls and …
Structural Health Monitoring Of Composite Parts: A Review, Jacob Pessin
Structural Health Monitoring Of Composite Parts: A Review, Jacob Pessin
Honors Theses
Structural health monitoring has the potential to allow composite structures to be more reliable and safer, then by using more traditional damage assessment techniques. Structural health monitoring (SHM) utilizes individual sensor units that are placed throughout the load bearing sections of a structure and gather data that is used for stress analysis and damage detection. Statistical time based algorithms are used to analyze collected data and determine both damage size and probable location from within the structure. While traditional calculations and life span analysis can be done for structures made of isotropic materials such as steel or other metals, composites …
Fe Modeling Methodology For Load Analysis And Preliminary Sizing Of Aircraft Wing Structure, Jun Hwan Jang, Sang Ho Ahn
Fe Modeling Methodology For Load Analysis And Preliminary Sizing Of Aircraft Wing Structure, Jun Hwan Jang, Sang Ho Ahn
International Journal of Aviation, Aeronautics, and Aerospace
It is a critical part at the basic design phase of aircraft structural design to build a finite element model and it will have a direct impact on time and cost for airframe structure development. In addition, the objective of finite element model will be varied depending on each design review phase and the modelling methodology varied accordingly. In order to build an effective and economic finite element model, it is required to develop adequate level of modelling methodology based on each design phase and its objectives. Therefore, in this paper, the finite element modeling methodology was presented for internal …
Investigation Of The Evolution Of Hydrophobicity And Wettability Of Paper In Multi-Color Printing Process, C Aydemir, A Karademir, S Imamoglu, Bilge N. Altay, Paul D. Fleming, D Tutak
Investigation Of The Evolution Of Hydrophobicity And Wettability Of Paper In Multi-Color Printing Process, C Aydemir, A Karademir, S Imamoglu, Bilge N. Altay, Paul D. Fleming, D Tutak
Bilge Nazli Altay
High Strain Rate Dynamic Response Of Aluminum 6061 Micro Particles At Elevated Temperatures And Varying Oxide Thicknesses Of Substrate Surface, Carmine Taglienti
High Strain Rate Dynamic Response Of Aluminum 6061 Micro Particles At Elevated Temperatures And Varying Oxide Thicknesses Of Substrate Surface, Carmine Taglienti
Masters Theses
Cold spray is a unique additive manufacturing process, where a large number of ductile metal micro particles are deposited to create new surface coatings or free-standing structures. Metallic particles are accelerated through a gas stream, reaching velocities of over 1 km/s. Accelerated particles experience a high-strain-rate microscopic ballistic collisions against a target substrate. Large amounts of kinetic energy results in extreme plastic deformation of the particles and substrate. Though the cold spray process has been in use for decades, the extreme material science behind the deformation of particles has not been well understood due to experimental difficulties arising from the …
Ultrasonic Nondestructive Evaluation Of Metal Additive Manufacturing., Venkata Karthik Nadimpalli
Ultrasonic Nondestructive Evaluation Of Metal Additive Manufacturing., Venkata Karthik Nadimpalli
Electronic Theses and Dissertations
Metal Additive Manufacturing (AM) is increasingly being used to make functional components. One of the barriers for AM components to become mainstream is the difficulty to certify them. AM components can have widely different properties based on process parameters. Improving an AM processes requires an understanding of process-structure-property correlations, which can be gathered in-situ and post-process through nondestructive and destructive methods. In this study, two metal AM processes were studied, the first is Ultrasonic Additive Manufacturing (UAM) and the second is Laser Powder Bed Fusion (L-PBF). The typical problems with UAM components are inter-layer and inter-track defects. To improve the …
Creep Of Hafnium Diboride -20 Vol% Silicon Carbide At 1500°C In Air, Glen E. Pry
Creep Of Hafnium Diboride -20 Vol% Silicon Carbide At 1500°C In Air, Glen E. Pry
Theses and Dissertations
Refractory metal borides, commonly referred to as Ultra High Temperature Ceramics (UHTCs), exhibit a number of unique properties, such as extremely high melting temperature and hardness, chemical stability, high electrical and thermal conductivity and corrosion resistance. It has been demonstrated that the addition of SiC improves the oxidation resistance of ZrB2- and HfB2-based UHTCs above 1200°C by modifying the composition of the oxide scale. Addition of SiC retards the oxidation rate of ZrB2 and HfB2 by forming a protective layer of borosilicate glass. Creep deformation is one of the critical criterion for structural application of ceramics at elevated temperatures. Compression …
Thermal-Fatigue And Thermo-Mechanical Equivalence For Transverse Cracking Evolution In Laminated Composites, Javier Cabrera Barbero
Thermal-Fatigue And Thermo-Mechanical Equivalence For Transverse Cracking Evolution In Laminated Composites, Javier Cabrera Barbero
Graduate Theses, Dissertations, and Problem Reports
Carbon fiber reinforced plastics (CFRP) are potential materials for many aerospace and aeronautical applications due to their high specif strength/weight and a low coeffcient of thermal expansion (CTE) resulting in a high long-term stability. Among candidate structures, the re-entry reusable launch vehicles (RLV), the fuel oxidant storage and transportation at cryogenic temperature, space satellites, and aircraft structure (frame, wings, etc...) can be highlighted. However, CFRP are prone to internal damage as a result of high residual stresses and thermal fatigue loading. In this study, micro-cracking damage evolution in laminated composites subjected to monotonic cooling and thermal cyclic loads is developed …
A Comparison Study Of Composite Laminated Plates With Holes Under Tension, Joun S. Kim
A Comparison Study Of Composite Laminated Plates With Holes Under Tension, Joun S. Kim
Master's Theses
A Comparison Study of Composite Laminated Plates with Holes under Tension
A study was conducted to quantify the accuracy of numerical approximations to deem sufficiency in validating structural composite design, thus minimizing, or even eliminating the need for experimental test. Error values for stress and strain were compared between Finite Element Analysis (FEA) and analytical (Classical Laminated Plate Theory), and FEA and experimental tensile test for two composite plate designs under tension: a cross-ply composite plate design of [(0/90)4]s, and a quasi-isotropic layup design of [02/+45/-45/902]s, each with a single, centered hole of 1/8” diameter, and 1/4" diameter (four sets …
Deployable Antenna For Cubesat, Mackenzie Thomas Lennon, Caleb Andrew Barber, David Matthew Galves
Deployable Antenna For Cubesat, Mackenzie Thomas Lennon, Caleb Andrew Barber, David Matthew Galves
Mechanical Engineering
This project is a proof-of-concept ground model of a large deployable antenna designed for the small space requirements of CubeSats. This small deployment module is designed to fit a 2 m by 1 m reflective antenna inside a storage volume of with the dimensions 20 cm by 20 cm x 40 cm. The reflector will be deployed to a parabolic shape with the goal of modeling the reflector necessary for high frequency communication. Because this module is designed as a proof-of-concept for the deployable parabolic reflector specifically, no electrical components will be incorporated and will just focus on the deployment …
Stressed Oxidation Of Hafnium Diboride In Air At 1500°C, Thomas A. Bowen
Stressed Oxidation Of Hafnium Diboride In Air At 1500°C, Thomas A. Bowen
Theses and Dissertations
Hypersonic vehicles with narrow airfoils produce thin boundary layers and shock temperatures in excess of 2000°C, exceeding the operating limits of traditional aerospace materials. The use of ultra-high temperature ceramics (UHTCs) allows for operating temperatures far exceeding those of metallic alloys. One such UHTC is hafnium diboride (HfB2). Transition metal diborides generally experience significant oxidation degradation at elevated temperatures. The use of additives, such as silicon carbide (SiC) has been shown to reduce the oxidation of transition metal diborides. This research focused on the compressive creep of HfB2 with varying amounts of SiC in air at 1500°C. …
Detecting Laminate Damage Using Embedded Electrically Active Plies – An Analytical Approach, Amany Micheal, Yehia Bahei-El-Din
Detecting Laminate Damage Using Embedded Electrically Active Plies – An Analytical Approach, Amany Micheal, Yehia Bahei-El-Din
Centre for Advanced Materials
Assessment of damage initiation and progression in composite laminates with embedded electrically active plies is modeled. Utilizing electrically active layers embedded in composite laminates as damage sensors is proposed by several researchers and is mainly assessed experimentally. Sensing damage using embedded electrically active plies is generally preferred over the use of surface mounted PZT wafers since the range of the latter is limited to a very narrow area underneath the surface, while multiple damage mechanisms can generally be found in several plies of the laminate. The solution presented invokes two levels of analysis. Firstly, on the laminate level, applied membrane …
Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook
Microstructural Analysis Of Thermoelastic Response, Nonlinear Creep, And Pervasive Cracking In Heterogeneous Materials, Alden C. Cook
Electronic Theses and Dissertations
This dissertation is concerned with the development of robust numerical solution procedures for the generalized micromechanical analysis of linear and nonlinear constitutive behavior in heterogeneous materials. Although the methods developed are applicable in many engineering, geological, and materials science fields, three main areas are explored in this work. First, a numerical methodology is presented for the thermomechanical analysis of heterogeneous materials with a special focus on real polycrystalline microstructures obtained using electron backscatter diffraction techniques. Asymptotic expansion homogenization and finite element analysis are employed for micromechanical analysis of polycrystalline materials. Effective thermoelastic properties of polycrystalline materials are determined and compared …
Finite Element Simulation Of Pzt-Aided Interrogation Of Composite Laminates Exhibiting Damage, Amany Micheal, Yehia Bahei-El-Din
Finite Element Simulation Of Pzt-Aided Interrogation Of Composite Laminates Exhibiting Damage, Amany Micheal, Yehia Bahei-El-Din
Centre for Advanced Materials
Piezoelectricity has proved effective in capturing changes in structures caused by various damage mechanisms. In one approach, piezoelectric wafer active sensors (PWAS) are mounted on the surface of the host structure and utilized as both actuators and sensors to interrogate the structure and monitor its health. This is achieved by subjecting the PWAS to a transient electric pulse and reading the resulting voltage. Changes in the stiffness of the substrate due to structural damage affect the response of the PWAS, which could be correlated to integrity of the structure. Applying this technique to fibrous composite laminates encounters particular challenges due …
A Multi-Scale Based Model For Composite Materials With Embedded Pzt Filaments For Energy Harvesting, A.E. El-Etriby, M.E. Abdel-Meguid, K.M. Shalan, Tarek Hatem, Yehia Bahei-El-Din
A Multi-Scale Based Model For Composite Materials With Embedded Pzt Filaments For Energy Harvesting, A.E. El-Etriby, M.E. Abdel-Meguid, K.M. Shalan, Tarek Hatem, Yehia Bahei-El-Din
Centre for Advanced Materials
Ambient vibrations are major source of wasted energy, exploiting properly such vibration can be converted to valuable energy and harvested to power up devices, i.e. electronic devices. Accordingly, energy harvesting using smart structures with active piezoelectric ceramics has gained wide interest over the past few years as a method for converting such wasted energy. This paper provides numerical and experimental analysis of piezoelectric fiber based composites for energy harvesting applications proposing a multi-scale modeling approach coupled with experimental verification. The multi-scale approach suggested predicting the behavior of piezoelectric fiber-based composites use micromechanical model based on Transformation Field Analysis (TFA) to …
Mode I Fracture Toughness Of Eight-Harness-Satin Carbon Cloth Weaves For Co-Cured And Post-Bonded Laminates, Josh E. Smith
Mode I Fracture Toughness Of Eight-Harness-Satin Carbon Cloth Weaves For Co-Cured And Post-Bonded Laminates, Josh E. Smith
Master's Theses
Mode I interlaminar fracture of 3k 8-Harness-Satin Carbon cloth, with identical fill and weft yarns, pre-impregnated with Newport 307 resin was investigated through the DCB test (ASTM D5528). Crack propagations along both the fill and weft yarns were considered for both post-bonded (co-bonded) and co-cured laminates. A patent-pending delamination insertion method was compared to the standard Teflon film option to assess its applicability to mode I fracture testing. The Modified Beam Theory, Compliance Calibration method, and Modified Compliance Calibration method were used for comparative purposes for these investigations and to evaluate the validity of the proposed Equivalent Stiffness (EQS) method. …
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 …
The Formulation And Computation Of The Nonlocal J-Integral In Bond-Based Peridynamics, Wenke Hu, Youn Doh Ha, Florin Bobaru, Stewart A. Silling
The Formulation And Computation Of The Nonlocal J-Integral In Bond-Based Peridynamics, Wenke Hu, Youn Doh Ha, Florin Bobaru, Stewart A. Silling
Florin Bobaru Ph.D.
This work presents a rigorous derivation for the formulation of the J-integral in bond-based peridynamics using the crack infinitesimal virtual extension approach. We give a detailed description of an algorithm for computing this nonlocal version of the J-integral.We present convergence studies (m-convergence and δ-convergence) for two different geometries: a single edge-notch configuration and a double edge-notch sample.We compare the results with results based on the classical J-integral and obtained from FEM calculations that employ special elements near the crack tip.We identify the size of the nonlocal region for which the peridynamic J-integral value is near the classical FEM solutions.We discuss …
The Meaning, Selection, And Use Of The Peridynamic Horizon And Its Relation To Crack Branching In Brittle Materials, Florin Bobaru, Wenke Hu
The Meaning, Selection, And Use Of The Peridynamic Horizon And Its Relation To Crack Branching In Brittle Materials, Florin Bobaru, Wenke Hu
Florin Bobaru Ph.D.
This note discusses the peridynamic horizon (the nonlocal region around a material point), its role, and practical use in modeling. The objective is to eliminate some misunderstandings and misconceptions regarding the peridynamic horizon. An example of crack branching in a nominally brittle material (homalite) is addressed and we show that crack branching takes place without wave interaction. We explain under what conditions the crack propagation speed depends on the horizon size and the role of incident stress waves on this speed.
Peridynamic Model For Dynamic Fracture In Unidirectional Fiber-Reinforced Composites, Wenke Hu, Youn Doh Ha, Florin Bobaru
Peridynamic Model For Dynamic Fracture In Unidirectional Fiber-Reinforced Composites, Wenke Hu, Youn Doh Ha, Florin Bobaru
Florin Bobaru Ph.D.
We propose a computational method for a homogenized peridynamics description of fiber-reinforced composites and we use it to simulate dynamic brittle fracture and damage in these materials. With this model we analyze the dynamic effects induced by different types of dynamic loading on the fracture and damage behavior of unidirectional fiber-reinforced composites. In contrast to the results expected from quasi-static loading, the simulations show that dynamic conditions can lead to co-existence of and transitions between fracture modes; matrix shattering can happen before a splitting crack propagates. We observe matrix–fiber splitting fracture, matrix cracking, and crack migration in the matrix, including …