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Articles 1 - 14 of 14
Full-Text Articles in Mechanical Engineering
Optical Detection Of Acoustic Emission Signals, C Harvey Palmer, Robert E. Green Jr
Optical Detection Of Acoustic Emission Signals, C Harvey Palmer, Robert E. Green Jr
Robert A. Green
Piezoelectric transducers, long used in the generation and detection of ultrasonic waves, have more recently been the detector of choice for acoustic emission signals. Optical probing methods, however, have several important advantages for acoustic emission studies: (1) they have an inherent broad frequency response, free from mechanical resonances, (2) they do not interfere with the acoustic waves. (3) since the focused optical beam diameters are typically only a few hundredths of a millimeter, optical methods can probe very close to a crack or a twin, (4) they can probe internally in transparent media, and (5) they can be used over …
Effects Of Temperature Change On Interfacial Delamination In Thermal Barrier Coatings, Hossein Ebrahimi, Soheil Nakhodchi
Effects Of Temperature Change On Interfacial Delamination In Thermal Barrier Coatings, Hossein Ebrahimi, Soheil Nakhodchi
Hossein Ebrahimi
No abstract provided.
Single-Layer Graphene Oxide Reinforced Metal Matrix Composites By Laser Sintering: Microstructure And Mechanical Property Enhancement, Dong Lin
dong lin
No abstract provided.
Experimental Investigation Of Worm Gears Performance, Part I: Contact Pattern And Worm Wheel Teeth, Alireza Nezamabadi, Ehsan Soury, Arash Houshmand
Experimental Investigation Of Worm Gears Performance, Part I: Contact Pattern And Worm Wheel Teeth, Alireza Nezamabadi, Ehsan Soury, Arash Houshmand
Arash Houshmand
This paper is focused on the performance of worm gears influenced by the position of the contact pattern. By decreasing in size of the contact pattern area the lubricant film thickness between worm and worm wheel teeth will be decreased and lubricant temperature as a criterion for worm gears performance will be increased. In this experiment by designed tests, the effect of Contact Pattern Position of the Worm Wheel Teeth on the Lubricant Temperature behavior had been investigated. By considering the performed studies on statistical results of the amount of percentage of contact area in every tooth of under experiment …
Optimization Of Contact Pattern Position On The Worm Wheel Teeth By Axial Shift In Worm Wheel Axis, Ehsan Soury, Arash Houshmand, Alireza Nezamabadi
Optimization Of Contact Pattern Position On The Worm Wheel Teeth By Axial Shift In Worm Wheel Axis, Ehsan Soury, Arash Houshmand, Alireza Nezamabadi
Arash Houshmand
In industrial applications Lubricant temperature decrease is a desired aim in the case of lubricant and gears performance. In this paper the procedure of optimization of worm gears performance by considering the proper contact pattern position had been performed. In accordance with required axial shift in worm wheel axis the contact pattern optimized and as a result the lubricant temperature decreased. This procedure leads to increase gears efficiency and their effective life.
Morphological Instability Leading To Formation Of Porous Anodic Oxides, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya
Morphological Instability Leading To Formation Of Porous Anodic Oxides, Ömer Çapraz, Kurt Hebert, Pranav Shrotriya
Ömer Özgür Çapraz
No abstract provided.
Impact Damage On A Thin Glass Plate With A Thin Polycarbonate Backing, Wenke Hu, Yenan Wang, Jian Yu, Chian-Fong Yen, Florin Bobaru
Impact Damage On A Thin Glass Plate With A Thin Polycarbonate Backing, Wenke Hu, Yenan Wang, Jian Yu, Chian-Fong Yen, Florin Bobaru
Florin Bobaru Ph.D.
We present experimental and computational results for the impact of a spherical projectile on a thin glass plate with a thin polycarbonate backing plate, restrained in a metal frame, or in the absence of the frame. We analyze the dependence of the damage patterns in the glass plate on the increasing impact velocities, from 61 m/s to 200 m/s. Experimental results are compared with those from peridynamic simulations of a simplified model. The main fracture patterns observed experimentally are captured by the peridynamic model for each of the three projectile velocities tested. More accurate implementation of the actual boundary conditions …
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.
Convergence, Adaptive Refinement, And Scaling In 1d Peridynamics, Florin Bobaru Ph.D., Mijia Yabg Ph.D., Leonardo F. Alves M.S., Stewart A. Silling Ph.D., Ebrahim Askari Ph.D., Jifeng Xu Ph.D.
Convergence, Adaptive Refinement, And Scaling In 1d Peridynamics, Florin Bobaru Ph.D., Mijia Yabg Ph.D., Leonardo F. Alves M.S., Stewart A. Silling Ph.D., Ebrahim Askari Ph.D., Jifeng Xu Ph.D.
Florin Bobaru Ph.D.
We introduce here adaptive refinement algorithms for the non-local method peridynamics, which was proposed (in J. Mech. Phys. Solids 2000; 48:175–209) as a reformulation of classical elasticity for discontinuities and long-range forces. We use scaling of the micromodulus and horizon and discuss the particular features of adaptivity in peridynamics for which multiscale modeling and grid refinement are closely connected. We discuss three types of numerical convergence for peridynamics and obtain uniform convergence to the classical solutions of static and dynamic elasticity problems in 1D in the limit of the horizon going to zero. Continuous micromoduli lead to optimal rates of …
Influence Of Van Der Waals Forces On Increasing The Strength And Toughness In Dynamic Fracture Of Nanofibre Networks: A Peridynamic Approach, Florin Bobaru Ph.D.
Influence Of Van Der Waals Forces On Increasing The Strength And Toughness In Dynamic Fracture Of Nanofibre Networks: A Peridynamic Approach, Florin Bobaru Ph.D.
Florin Bobaru Ph.D.
The peridynamic method is used here to analyse the effect of van der Waals forces on the mechanical behaviour and strength and toughness properties of three-dimensional nanofibre networks under imposed stretch deformation. The peridynamic formulation allows for a natural inclusion of long-range forces (such as van der Waals forces) by considering all interactions as ‘long-range’. We use van der Waals interactions only between different fibres and do not need to model individual atoms. Fracture is introduced at the microstructural (peridynamic bond) level for the microelastic type bonds, while van der Waals bonds can reform at any time. We conduct statistical …
Crack Nucleation In A Peridynamic Solid, S. Silling, O. Weckner, E. Askari, Florin Bobaru
Crack Nucleation In A Peridynamic Solid, S. Silling, O. Weckner, E. Askari, Florin Bobaru
Florin Bobaru Ph.D.
A condition for the emergence of a discontinuity in an elastic peridynamic body is proposed, resulting in a material stability condition for crack nucleation. The condition is derived by determining whether a small discontinuity in displacement, superposed on a possibly large deformation, grows over time. Stability is shown to be determined by the sign of the eigenvalues of a tensor field that depends only on the linearized material properties. This condition for nucleation of a discontinuity in displacement can be interpreted in terms of the dynamic stability of plane waves with very short wavelength. A numerical example illustrates that cracks …
Studies Of Dynamic Crack Propagation And Crack Branching With Peridynamics, Youn Doh Ha Ph.D., Florin Bobaru Ph.D.
Studies Of Dynamic Crack Propagation And Crack Branching With Peridynamics, Youn Doh Ha Ph.D., Florin Bobaru Ph.D.
Florin Bobaru Ph.D.
In this paper we discuss the peridynamic analysis of dynamic crack branching in brittle materials and show results of convergence studies under uniform grid refinement (m-convergence) and under decreasing the peridynamic horizon (δ-convergence). Comparisons with experimentally obtained values are made for the crack-tip propagation speed with three different peridynamic horizons.We also analyze the influence of the particular shape of themicro-modulus function and of different materials (Duran 50 glass and soda-lime glass) on the crack propagation behavior. We show that the peridynamic solution for this problem captures all the main features, observed experimentally, of dynamic crack propagation and branching, as well …
Reverse Logic - Safety Of Spent Nuclear Fuel Disposal, Antti Lempinen, Marianne Silvan-Lempinen
Reverse Logic - Safety Of Spent Nuclear Fuel Disposal, Antti Lempinen, Marianne Silvan-Lempinen
Antti Lempinen
No abstract provided.