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About piezoelectric resonance.

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For 31 mode piezoelectric plate. I have measured it's electric impedance spectrum (curve of Log IZI~ Frequency). I found that, when I used this plate for a piezoelectric sensor to receive mechanic signals. the maximum output  occured at antiresonance frequency;   For example, for piezoelectric hydrophone or receiving-type piezoelectric transducers, It works at antiresonance frequency (at the maximum electric impedance). 

Introduction to Cohesive Zone and Modelling DCB Test using Cohesive Elements

I am currently working on a project to model DCB test in ABAQUS. My current problem lies in understanding cohesive zone modelling. I was wondering if anyone can forward me a couple of  materials regarding the introduction of cohesive zones?

 This would help me understand the material greatly and help me in modelling the DCB test.

 Another question in ABAQUS:  how do you implement the material properties for cohesive elements? in particular, what values should i be using for them? e.g. E, G1, G2?

Ji Wang's picture

An Introduction Course on Mechanics


We are currently offerring an introductory course on mechanics for junior students for all fields and subjects.  It is a so called general knowledge course for students to know more on certain subjects and fields before a decision on choice of a major is made.  Since the Mechanics Department in our University has not been popular for so long, we have decided to evangalize our field with more glorious history of Mechanics: Newton, Bernoulli, Euler, Clausius, Faraday, and Einstein.

Finalists for 2008 Robert J. Melosh Competition

Six finalists for the 20th Annual Melosh Competition for the Best Student Paper in Finite Element Analysis have been announced.  They are:

Ludovic Chamoin, University of Texas at Austin

Irina Kalashnikova, Stanford University

Christian Linder, University of California, Berkeley

Ajaykumar Rajasekharan, Stanford University

Saurabh Srivastava, SUNY Buffalo

Tim Wildey, University of Texas at Austin 

Mark E. Walter's picture

Symposium Honoring Professor J. W. Hutchinson at IMECE'08 (Boston)

To coincide with this year’s IMECE in Boston, the Fracture and Failure Mechanics Technical Committee is organizing a series of sessions to honor Professor John W. Hutchinson’s seminal contributions as he moves into semi-retirement. The organizers request abstracts in contemporary research related to fracture and failure mechanics. Topics that relate to Professor Hutchinson's many past and present research activities in other areas are also welcome.

What is the difference between RVE and Unit Cell ?

I have been working in composites for sometime now. In the literature I have found that the words  "Representative Volume Element" (RVE) and "Unit Cell" (UC)  are  used frequently.  Some  authors treat them differently and some treat them  same. I am little bit confused can anyone PLEASE clarify the situation or suggest some good papers to read.


Thanks In Advance. 

Jintegral and Umat subroutine

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Rui Huang's picture

A symposium on Mechanical Instabilities in Polymer Films, Interfaces and Nanostructures

This symposium is part of the Spring 2008 ACS National Meeting and Exposition , to be held at New Orleans, Louisiana, from Sunday, April 6 to Thursday, April 10, 2008.

Organizers: Christopher M. Stafford (NIST), Adam J. Nolte (NIST), Rui Huang (UT Austin)

Sponsors: ACS Division of Polymeric Materials: Science and Engineering (PMSE) and National Science Foundation

Technical Program:

Masayuki Wakamatsu's picture

Cutting Mica Sheet

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Hi iMechanica,

PLASTICITY 2009: Mini-symposium on ‘Routes to Bulk Nanomaterials’

We would like to inform you that we are organizing a mini-symposium on ‘Routes to Bulk Nanomaterials’  as part of the International Symposium PLASTICITY 2009 to be held at the Frenchman's Reef and Morning Star Marriott Beach Resort (St. Thomas, US Virgin Islands), on January 3-8, 2009.

One Postdoctoral/Research Scientist Position in Geometric Modeling and Mesh Generation

A position of postdoctoral fellow or research scientist is available immediately in the group

of Jessica Zhang at Department of Mechanical Engineering, Carnegie Mellon University. 

We are looking for someone with strong software design and development skills coupled

Stress concentration at a corner of varying angles, mode I and mode II

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I was looking at the stress concentration at a corner for both a mode I and mode II loading situation.

For reference, see: Carpenter, 1984. Mode I and mode II stress intensities for plates with cracks of finite opening. International Journal of Fracture. V. 26. 201-214. 1984.

vikulp sharma's picture

you tube Video lectures on Finite element methods, Dynamics and Kinematics of machines by NPTEL India

Here is very good chain of full course lectures on - This will be very helpfull for someone new and beginner in this areas.

Finite element methods :-

 Dynamics of machines:-

 Advance strength of materials:-

Wei Hong's picture

Prof. Zhigang Suo and Prof. Frans Spaepen elected to the National Academy of Engineering

Prof. Zhigang Suo and Prof. Frans Spaepen, of the Harvard School of Engineering and Applied Sciences, have just been elected to the National Academy of Engineering.  They are among 65 new members elected to the NAE in 2008.  Update:  Also elected this year is another mechanician, Robert Dodds, of the University of Illinois.

ASME 2008 Conference Track on Mechanics of Solids, Structures and Fluids

The ASME International Mechanical Engineering Congress (IMECE 2008) will be held on October 31 - November 6, 2008, in Boston, Massachusetts. A wide range of mechanics-related symposia (topics) are being organized in Track 12 Mechanics of Solids, Structures and Fluids. The Executive Committee of the ASME Applied Mechanics Division (AMD) believes that this track will provide a good platform for mechanics-related presentations.

Material model of Kevar composite for Impact problem

I am looking for material model of Kevlar composite for Ballistic impact simulation. Presently i am using ANSYS. Can any body suggest material model for kevlar composite for fracture and penetration phenomina.


Helix is a very interesting structure. There are many biopolymers that have a helical structure. 

  • How can someone model the helix in mechanics?
  • How can the helix reinforce a rod? 
  • How does this structure reflect the mechanical properties of biopolymers?
Joseph P. Cusumano's picture

Postdoctoral Position at Penn State University in Multiscale Computational Dynamics

We have an immediate opening in the Department of Engineering Science and Mechanics for a postdoctoral research associate in multiscale modeling and computational mechanics. The focus of this position is on the modeling, simulation, and analysis of the nonlinear evolution of coupled macro/microstructure in failure processes, with an emphasis toward structural health monitoring. Coupled-field models using continuum damage variables will be used to study the fundamental spatiotemporal features of damage evolution, particularly regarding the nature and origin of unpredictability in damage processes. The candidate must have a solid general background in theoretical mechanics and dynamics, and be familiar with nonlinear finite element analysis

Physics programmer position in Boston

The person in this position will be responsible for developing finite element-based soft tissue representations that supportreal-time interaction with surgical tools. The successful candidate should befamiliar with the extensive prior work in the field of surgical simulationincluding finite element formulations (both traditional nonlinear approaches aswell as various real-time approximations), real-time collision detection andresponse between rigid and deformable objects, multi-processor/coreimplementations, and integration with haptics devices.

Stresses and Strains

In classical elasticity, we know that at the interface of two different materials, traction stresses and non-traction strains are cotinuous. Traction stresss are continuous according to Newton's third law, but why non-traction strains are continuous?


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