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Time Domain Inverse Problems in Nonlinear Systems Using Collocation & Radial Basis Functions

Time Domain Inverse Problems in Nonlinear Systems Using Collocation & Radial Basis Functions

by T.A. Elgohary, L. Dong, J.L. Junkins and S.N. Atluri

This paper can be freely downloaded at:


In this study, we consider ill-posed time-domain inverse problems

for dynamical systems with various boundary conditions and unknown controllers.

Dynamical systems characterized by a system of second-order nonlinear ordinary

Acoustic Heating

All -

Are there good references related to acoustic heating?  I am interested in the ability to scale down the effects of this process and looking for ideas in model development to assist.



Abaqus python script: finding an element containing a given point


I have a point with coordinates x,y,z. Is it possible to detemine from python script to which element this point belongs to?


Thank you!

GOPALAERO2000's picture


Hi everybody,


Can anybody help me get the following ASTM SPECS.


1. Test method for poison's ratio at room temperature (ASTM STANDARD E 132)

2. Test method for young's modulus, tangent modulus and chord modulus (ASTM STANDARD E 111)

3. E 1237

4, D 3039

5. D 2584


Thanks and regards

M Gopalakrishnan

Zhigang Suo's picture

Fundamental discoveries in mechanics in recent decade or so

A previous post, Getting Ready for Extreme Mechanics Letters, contained the following paragraph:

“We seek papers from researchers in all disciplines. Mechanics appeals to talents of all kinds. Good mechanics has long been created by people from many fields, by Galileo, Newton, Maxwell and Faraday, as well as by Watt, Darwin, Wright brothers and Whitesides. People make discoveries in mechanics often when doing something else (e.g., in seeking evidence for the existence of God, in building cathedrals, in flying airplanes, in laying transatlantic telegraph cables, in fabricating microprocessors, in watching cells move, in fracking for gas, in inventing optical tweezers, in creating soft lithography, in developing wearable or implantable electronics). Mechanics discovered in one field invariably finds applications in other fields.”

Here I would like to give several examples of papers published in recent decade or so. I will link each paper to its citations on Google Scholar, so that you can have an overview of the influence of the paper on other researchers.

Simpleware Case Study: Total Hip Replacement Implant Positioning

CAD and FE models of hip implants

Positioning hip implants poses a number of challenges, particularly in terms of getting bone and implant contact right. While experimental testing can be costly, image-based modelling can be very effective at predicting the best and worst positions for implants. 

Constitutive modeling of hyperelastic solids reinforced by spheroidal particles under large deformations

This paper presents a homogenization-based constitutive model for the mechanical behavior of particle-reinforced elastomers with random microstructures subjected to finite deformations. The model is based on a recently developed homogenization method (Avazmohammadi and Ponte Castaneda 2013; J. Elasticity 112, 1828–1850) for two-phase, hyperelastic composites, and is able to directly account for the shape, orientation, and concentration of the particles.

Rolling Contact in Ansys Workbench


 Please refer to the figure given below. I want to model this problem using ANSYS WORKBENCH.


R&D engineer opening at Synopsys

This position is for a senior R&D engineer who will work on the development of industry leading Finite Element/Finite Volume simulation tools. Primary responsibilities include developing solid elements and advanced material models.


  (1) Strong mechanics and FEM background

  (2) Solid programming skill in C++

  (3) Ability to work as a team player, as part of a local and globally R&D team

  (4) Good oral and written skills

You can apply online at Synopsys website or forward your resume to me.


fem software at altair

we are looking for a fem software developer. The primary focus is developing implicit structure

dyanmics and  fsi algorithms. If interested send resume to 

Faculty recruitment at Southeast University, China


Faculty recruitment at Southeast University, China


Southeast University is a Key University in China (985,211 project) located at Nanjing City. 

We are searching for new faculty to work in the Department of Mechanics. 

Major needed:  Ph.D.  in Mechanics/Materials Sciences/Physics or related.

Communicate e-mail:


If you are interested, please send us e-mail without hesitation.  




To the Editors of EML

Dear Editors,

The first step of starting EML looks promising and with the help of academic people in this community, I think EML has generated enough heat with lots of interesting view points.

We all know that there has been lots of discussion in the imechanica community regarding open source journals, had any one thought about making EML fully open source?.

Thanks and Regards,


Lance C. Hibbeler's picture

ABAQUS: nice colorbar ranges

I have produced a python script that automates setting up reasonable values in the ABAQUS/CAE colorbar, basically setting up Tecplot functionality.  After executing the script from File->Run Script, you have access to a function that you can call in the built-in interpreter,

>>> SetContourRange(minval, maxval)

problem with Numeric import in abaqus 6.11

Hi, i'm using abaqus 6.11

i am going to link matlab with abaqus using python scripting to perform an iterative analysis

the problem is that i get the error "ImportError: No module named Numeric"

please help me how to solve this problem


Aman Haque's picture

Faculty recruitment at Penn State

Dear Colleagues,

Penn State University Mechanical Engineering is accepting applications for five tenure track faculty positions. Please see the website for details

For the emerging areas - we are looking at themes such as additive manufacturing, metamaterials, 2D materials, data driven modeling, extreme environment mechanics or a fusion of these.

Zhigang Suo's picture

What do we want EML to be? How do we get there?

Starting a new journal is risky.  Starting a new journal in mechanics is particularly risky.  The responses to the two recent posts are encouraging, however.

I'm looking for PhD position [Concrete fracture-FRP bars]


I'm a civil & structural engineer, I got recently my Magister degree in civil engineering. I worked on the numerical modeing of concrete fracture of reiforced concrete elements reinforced with FRP bars. I've used ADINA software in my numerical study (smeared crack model). Now I'm looking for a PhD scholarship to complete my research either in concrete fracture modeling or in the composite materials, please I need your help?. Many thanks

Ideas for a Mechanician

Hello All - 


I am soliciting advice for how to continue to keep mechanics skills sharp while in a more business/leadership role.  


Please advise on techniques you have used or suggestions for ways to stay current.  


Thank you for your input and for your continued development of this discipline.




Luke Porisch


p.s. - if you were Harvard DEAS from 2003-05 please send me a note!

oliver oreilly's picture

Constraint Moments and Constraint Forces in the Mechanics of Rigid Bodies

For those of you preparing to teach a course on Lagrangian Mechanics of Rigid Bodies in the forthcoming semester or quarter, you may be interested to read a new expository paper by Arun Srinivasa at Texas A&M and myself:

 A Simple Treatment of Constraint Forces and Constraint Moments in Rigid Body Dynamics, ASME Applied Mechanics Reviews, To Appear (2014).  

1-3 Piezoelectric Butterfly Curve

Hello Everyone,

I try to plot the butterfly curve for piezoelectric material (strain vs. electric field for different applied stress values). Butterfly curve shows the nonlinear response of the piezoelectric material which is a hysteretic response.

I just want to ask you guys if anybody knows a good way to plot butterfly curve for 1-3 piezoelectric materials in matlab????

mohsenzaeem's picture

TMS 2015 Meet the Candidate Poster Session

The TMS Young Professionals Committee is organizing a "Meet the Candidate Poster Session" in conjunction with the general poster session of TMS 2015. This event is designed to create networking opportunities for young professionals and hopefully help them discover prospects for future employment. 


The Meet the Candidate Poster Session will provide the opportunity for

Gatherin results from multiple points in the parametric study

Hi everybody! 

I am doing a large parametric study of a composite shaft. I am working with 5 variables and the number of simulations and data will be quite big. 

I would like to gather results automatically on a circumferential path around the shaft. (About 60 elements) 
Is it possible to do it with a "gather" command - I think that only one node/integration point can be defined at "gather" command. 

Has anyone already done something like that and how did you solve the problem. 


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