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Full-Text Articles in Mechanical Engineering

Peridynamic Modeling Of Dynamic Fracture In Bio-Inspired Structures For High Velocity Impacts, Sneha Akula May 2018

Peridynamic Modeling Of Dynamic Fracture In Bio-Inspired Structures For High Velocity Impacts, Sneha Akula

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

Bio-inspired damage resistant models have distinct patterns like brick-mortar, Voronoi, helicoidal etc., which show exceptional damage mitigation against high-velocity impacts. These unique patterns increase damage resistance (in some cases up to 3000 times more than the constituent materials) by effectively dispersing the stress waves produced by the impact. Ability to mimic these structures on a larger scale can be ground-breaking and could be used in numerous applications. Advancements in 3D printing have now made possible fabrication of these patterns with ease and at a low cost. Research on dynamic fracture in bio-inspired structures is very limited but it is crucial ...


Peridynamic Models For Fatigue And Fracture In Isotropic And In Polycrystalline Materials, Guanfeng Zhang May 2017

Peridynamic Models For Fatigue And Fracture In Isotropic And In Polycrystalline Materials, Guanfeng Zhang

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

To improve design and reliability, extensive efforts has been devoted to understanding damage and failure of materials and structures using numerical simulation, as a complement of theory and experiment. In this thesis, peridynamics is adopted to study fatigue and dynamic failure problems.

Fatigue is a major failure mode in engineering structures. Predicting fracture/failure under cyclic loading is a challenging problem. Classical model cannot directly be applied to problems with discontinuities. A peridynamic model is adopted in this work because of important advantages of peridynamics in allowing autonomous crack initiation and propagation. A recently proposed peridynamic fatigue crack model is ...


Magnetic Properties Study Of The Mn-Al System With Additions Of B Or C And Mechanical Milling Techniques, Timothy E. Prost Aug 2012

Magnetic Properties Study Of The Mn-Al System With Additions Of B Or C And Mechanical Milling Techniques, Timothy E. Prost

Engineering Mechanics Dissertations & Theses

Recently a shift in the focus of permanent magnetic research has moved from Rare Earth (RE)-based alloys to those made from more readily available elements. Because of their relatively large magnetocrystalline anisotropy, L10 compounds have the potential for use as permanent magnet materials. One particular alloy that is readily available and inexpensive is near equi-atomic manganese and aluminum (Mn50-Al50). First characterized in 1958, it did not receive much attention until more recently when RE supply chain issues made the alloy more attractive for commercial and research applications. The ferromagnetic (FM) τ-phase (L10) is metastable ...


Structural And Magnetic Properties Of Neodymium - Iron - Boron Clusters, Jeremy J. Anderson Jul 2010

Structural And Magnetic Properties Of Neodymium - Iron - Boron Clusters, Jeremy J. Anderson

Mechanical (and Materials) Engineering -- Dissertations, Theses, and Student Research

Using inert gas condensation techniques the properties of sputtered neodymium-iron-born clusters were investigated. A D.C. magnetron sputtering source created vaporous Nd-Fe-B which was then condensed into clusters and deposited onto silicon substrates. A composite target of Nd-Fe-B discs on an iron plate and a composite target of Nd-(Fe-Co)-B were utilized to create clusters. The clusters were coated with a carbon layer through R.F. sputtering to prevent oxidation.

Samples were investigated in the TEM and showed a size distribution with an average particle diameter of 8.11 nm. The clusters, upon deposition, were amorphous as indicated by ...