User login

Navigation

You are here

research

Fang Wang's picture

BIOMECHANICAL STUDY OF GOLF BALL IMPACT ON CHILD’S HEAD USING THE FINITE ELEMENT METHOD

Head traumatic injury due to the impact of a flying golf ball is one of the severest injuries sustained on a golf course. This paper presents numerical simulation results based on the finite element (FE) method to investigate head injuries in children due to impacts by flying golf balls.

Ying Li's picture

How to characterize the interface?

Recently, I am interested in the interface between two different masses. But, I don’t know how to characterize the interface between them, especially the adhesive strength and the mechanics model.

huang peng's picture

Impact and explosion mechanics in China

Choose a channel featured in the header of iMechanica: 

Impact and explosion mechanics in China

Impact and explosion mechanics is a muti-discipline subject , which concern mechanics, physics, and chemistry. As you know, explosive wave propagation and penetration problems are researched in impact and explosion mechanics.

How to simulate corrosion layer using ABAQUS

Dear Forum Members:

Does anyone have a chance to simulate a corrosion layer using ABAQUS? If yes, could you please explain to me what type of constitutive model you use; i.e. UMAT?

Thank you and best regards,

information needed

Would anyone have spec sheets for the load cell of the LIDO multijoint systemII?

I want to convert the torque readings from volts to newton-meter. I know LIDO dynamometer gives output as torque. But, our lab does not have any spec sheets or manuals, as this system is an old donated system.

Xiaodong Li's picture

On the uniqueness of measuring elastoplasticproperties from indentation

Indentation is widely used to measure material mechanical properties such as hardness, elastic modulus, and fracture toughness (for brittle materials). Can one use indentation to extract material elastoplastic properties directly from the measured force-displacement curves? Or simply, is it possible to obtain material stress-strain curves from the corresponding indentation load-displacement curves? In an upcoming paper in JMPS titled "On the uniqueness of measuring elastoplastic properties from indentation: The indistinguishable mystical materials," Xi Chen and colleagues at Columbia University and National Defense Academy, Japan show the existence of "mystical materials", which have distinct elastoplastic properties yet they yield almost identical indentation behaviors, even when the indenter angle is varied in a large range. These mystical materials are, therefore, indistinguishable by many existing indentation analyses unless extreme (and often impractical) indenter angles are used. The authors have established explicit procedures of deriving these mystical materials. In many cases, for a given indenter angle range, a material would have infinite numbers of mystical siblings, and the existence maps of the mystical materials are also obtained. Furthermore, they propose two alternative techniques to effectively distinguish these mystical materials. The study in this paper addresses the important question of the uniqueness of indentation test, as well as providing useful guidelines to properly use the indentation technique to measure material elastoplastic properties.

Ashkan Vaziri's picture

Flexible Probes for Characterizing Surface Topology: From Biology to Technology

In nature, several species use flexible probes to actively explore their environment, and acquire important sensory information, such as surface topology and texture, water/air flow velocity, etc. For example, rats and other rodents have an array of facial vibrissae (or whiskers) with which they gather tactile information about the external world.  The complex mechanisms, by which mechanical deformations of the probe lead to neuronal activity in the animal’s nervous system are still far from being understood. This is due to the intricacy of the deformation mechanics of the flexible sensors, the processes responsible for transforming the deformation to electrical activity, and the subsequent representation of the sensory information by the nervous system. Understanding how these mechanosensory signals are transduced and extracted by the nervous system promises great insight into biological function, and has novel technological applications. To understand the mechanical aspect of sensory transduction, here we monitored the deformation of a rat’s vibrissa as it strikes rigid objects with different topologies (surface features) during locomotion, using high-speed videography. Motivated by our observations, we developed detailed numerical models to study the mechanics of such flexible probes. Our findings elucidate how active sensation with vibrissae might provide sensory information and in addition have direct implications in several technological areas. To put this in perspective, we propose strategies in which flexible probes can be used to characterize surface topology at high speeds, which is a desirable feature in several technological applications such as memory storage and retrieval. (The full article is attached)

Amit Acharya's picture

Toward averaging nonlinear dynamics

Attached is a paper outlining ideas for averaging autonomous dynamics, based on a dynamical systems point of view.

People interested in computational multiscale modeling, especially of the sequential kind, as well as nonequilibrium statistical mechanics may find these ideas useful.

fengliu's picture

From self-bending of nanofilms to fabrication of nanotubes

We demonstrate, by theoretical analysis and molecular dynamics simulation, a mechanism for fabricating nanotubes by self-bending of nanofilms under intrinsic surface stress imbalance due to surface reconstruction. A freestanding Si nanofilm may spontaneously bend itself into a nanotube without external stress load, and a bilayer SiGe nanofilm may bend into a nanotube with Ge as the inner layer, opposite of the normal bending configuration defined by misfit strain.

Lakshmana B K's picture

Fluid-Structure Interaction study on artery help needed

I am now doing my project on "Fluid-Structure Interaction study on artery", using ANSYS-9.0, I am doing 3-D FSI analysis using fluid142 & solid185 using FSI solver. I have written a macro as per the help file specified in FSI, ANSYS under coupled field approach.

Henry Tan's picture

Journal of the Mechanics and Physics of Solids, 2007

This blog focuses on the papers in Journal of Fluid Mechanics, 2007.

Is it possible to obtain (without modeling) the fracture strength of defect-free nanotubes or nanowires by tensile loading?

What boundary conditions would allow failure to occur in the gauge length and not at or near the clamps? One is not allowed (in suggesting ways of overcoming stress concentation at the clamps) to create defects in the nanotube or nanowire, to configure the region where failure will occur.  Thus, it is not possible (or is it?)  to create an analog of dog-bone specimens by, e.g., milling away part of the nanowire with a focused ion beam, etc., because this creates defects in the nanowire.

Plastic Deformation Recovery in Freestanding Nanocrystalline Aluminum and Gold Thin Films


Science 30 March 2007:
Vol. 315. no. 5820, pp. 1831 - 1834
DOI: 10.1126/science.1137580
Jagannathan Rajagopalan, Jong H. Han, M. Taher A. Saif*
In nanocrystalline metals, lack of intragranular dislocation sources leads to plastic deformation mechanisms that substantially differ from those in coarse-grained metals. However, irrespective of grain size, plastic deformation is considered irrecoverable. We show experimentally that plastically deformed nanocrystalline aluminum and gold films with grain sizes of 65 nanometers and 50 nanometers, respectively, recovered a substantial fraction (50 to 100%) of plastic strain after unloading. This recoverywas time dependent and was expedited at higher temperatures. Furthermore, the stress-strain characteristics during the next loading remained almost unchanged when strain recovery was complete.These observations in two dissimilar face-centered cubic metals suggest that strain recovery might be characteristic of other metals with similar grain sizes and crystalline packing.

Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801, USA.

Jinglei Yang's picture

Self-healing polymers - an introduction

I'm now working on the preparation and characterization of self-healing polymers, a promising branch in materials science. The following is a general conception of this kind of materials system. (Pasted from our group website http://www.autonomic.uiuc.edu.) I may introduce some of my current work later.

Mohsin Hamzah's picture

Boundary Element Method for Hyperelastic Materials

I am interested in using the Boundary Element Method for the hyperelastic materials. The objective of this work  is to simulate the behaviour of elastomeric or rubber-like materials parts. I am now in the derivation stage, and I intened to use Ogden constitutive model with this derivation.

Ph.D. Studentships in Spacecraft Design, Dynamics and Control

The Department of Aerospace Engineering at Ryerson University has a strong and vibrant research programme involving the development of pico- and femto-satellites (weighing less than 1 kilogram) under Dr.

Pages

Subscribe to RSS - research

Recent comments

More comments

Syndicate

Subscribe to Syndicate