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Jizhou Song's picture

Caltech: secrets of the world’s number one university

Good International news on Caltech and engineering. Ares Rosakis, chair of the Division of Engineering and Applied Science,describes Caltech as “a unique species among universities…a very interesting phenomenon”.More can be found in the attachment or at the link below

http://www.timeshighereducation.co.uk/features/caltech-secrets-of-the-wo...

low reynolds number flow over a capsule in fluent

I've been trying to simulate flow conditions at 100 km altitude over a re entry capsule in fluent.

Conditions are

Temperature:
168.7219
K

Density = 0.000000577 Kg/m3

Pressure = 0.0289 N/m

I tried using laminar and k-w model. The solution does not converge even after 50000 iterations using the density based solver and ideal gas equation.

Is there a way to go about it?

Please let me know. 

Zhigang Suo's picture

Inglis (1913) vs. Griffith (1921)

I have updated my notes on the Griffith paper.  I added more description on the experimental determination of surface tension of solids.  Griiffith himself determined the surface tension of glass by an experimental setup.  Udin et al (1949) described a setup based on the same principle.  This setup is now known as the zero creep experiment.

Zhigang Suo's picture

The toughest hydrogel in the world

The class started today.  I'll be teaching fracture mechanics this semester.  I'll be mostly using the class notes I wrote in 2010, but will post updated ones. 

In today's class I covered "Trouble with linear elastic theory of strength."  I have just posted updated notes of the lecture.  The new notes begin with the follwoing paragraphs.

Intermediate Mechanics of Materials Online For Free Viewing

I recently posted a free, online, and
condensed version of my book Intermediate Mechanics of Materials, Second
Edition. It is posted on my  website madhuvable.org
and can be used for reference or by self-learners. In addition to the
online book, there is a glossary of mechanics terms, brief reviews of
Statics, Matrix Algebra, Numerical Methods, and Mechanics of Materials.

Zhigang Suo's picture

Massvolume vs. Spacetime

Apples and oranges. Each element in a set is a pile containing some number of apples and some number of oranges.  Adding two piles means putting them together, resulting in a pile in the set. Multiplying a pile and a real number r means finding in the set a pile r times the amount.  We model each pile as a vector, and the set as a two-dimensional vector space over the field of real numbers.

Paul Calvert's picture

NMT Biomechanics Why is it better to be seaweed better than to be phytoplankton?

This is an introductory post to a discussion on the advantages of multicellular organisms over single-celled eukaryotes from an energy harvesting viewpoint.  It is intended for the New Mexico Tech biomechanics class but others can play.

As engineers we should seek for a numerical measure (or some measures) that allows us to decide how close an organism is to the optimum.  Consider two cases: a seaweed in comparison to a single-cell photosynthetic eukaryote and a herbivore in comparison to a single-celled eukaryotic animal.

Julian J. Rimoli's picture

Common questions about developing educational apps

This afternoon, I had an extremely pleasant Google hangout with Daniel Suo, and Professors Zhigang Suo and Teng Li . Our main focus was on brainstorming ideas on how to improve the user experience on iMechanica. After an hour or so our conversation drifted towards educational topics including novel ways of incorporating technology in STEM education.

DMIG

can i include mechanisms while creating DMIG in FEA?

Vlado A. Lubarda's picture

Joining a discussion on Linear Algebra

I read with interest an excellent discussion about Linear Algebra in Mechanics. I am attaching Chapter I: Tensor Preliminaries from my book Elastoplasticity Theory, which includes Hill's analysis of induced tensors mentioned in the discussion.

kishore_cadcam's picture

Marine propellers

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How to consider a pretwisted tapered propeller balde either as beam orplate

Zhigang Suo's picture

Scalar done wrong

Update on 9 April 2016.  At the bottom of this post, I attach a pdf file of my notes on scalar.

Notes on scalars now forms part of my notes on linear algebra.

Creep in porous material

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Hello

I'm working on a project & I'm in a trouble. I need to know creep relations for a porous material under undrained condition and constant stress. I'll be gratefull if you help me.

Amit Acharya's picture

Carlson - Mathematical Preliminaries and Continuum Mechanics 1991

I attach some class notes developed by the late Professor Donald Carlson from which many generations of students at the University of Illinois learnt Continuum Mechanics.

Zhigang Suo's picture

Textbook on linear algebra

Linear algebra is significant to many aspects of mechanics.  For some years I have been using the book by Shilov.  But this book may or may not be a good one to recommend to a student, depending on his or her prior experience.  On StackExchange Mathematics, there are several excellent threads discussing textbooks of linear algebra.  A particular recommendation was made for

Residual stresses 2D to 3D

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Hello,

i have simulated welding in 2D model for beam attached with cover plates at both the flanges using Abaqus, now i want to use the same residual stress distribution for whole 3D cover plated beam with same cross-section,so that i can find load carring capacity of beam.

Mismatch between built-in linear-elastic material behaviour and tutorial VUMAT in ABQ/Explicit using truss elements

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Hello dear all,

for my master's thesis I'd like to write a simple VUMAT for a material with nearly zero compression stiffness.

So for a better understanding of VUMAT subroutines I did the ABQ tutorial for a VUMAT with isotropic, isothermal elastic material behaviour and compared the results with the built-in material definition.

There is a discrepancy of almost 35% of the S11 stress. ABQ Manual says that both times the Green-Naghdi stress-rate formulation is used.

Why are the results not the same? After hours of trying I still could not find the solution!

beam-column joint

finish
/clear
/title,study of beam-column joint
/prep7

! define element type & real constants
ET,1,link8 ! element type 1
R,1,0.000153938 ! real constant 1
R,2,5.02654e-005 ! real constant 2

ET,2,solid65 ! element type 2
R,3 ! real constant 3

ET,3,solid45 ! element type 3

! define material properties

Faculty Positions - Mechanical Engineering

Faculty Positions
Mechanical Engineering

The Physical Sciences and Engineering (PSE) Division at King Abdullah University of Science and Technology (KAUST) invites qualified applicants to apply for faculty positions at all ranks (Assistant, Associate, and Full Professor) in the Mechanical Engineering Program.

vrh59ir's picture

opprecunity study

 I am a Vahid Reza Hosseini PHD student  in China. My major is mechanic  and I am working on fractions and mesh method and meshless method. I have been looking for opprecunity study for 6 months or more. If you have a position for me,please let me know 

with best Regards  

Vahid

 

Email: V.r.hosseini@gmail.com

Julian J. Rimoli's picture

Educational iPad app on structural mechanics

I would like to share with fellow mechanicians an educational iPad app I recently developed. The name of the app is Truss Me! and the main goal is to help students, all the way from high school to college, to build intuition on how truss structures behave. The video below highlights some features of the app:

Jiang Chen's picture

How to get the update the local material coordinate in large deformation for hyperelasitc rubber-like materials?


Hello, 


I want to ask things about the updation of local material coordinate in large deformation. 


Does there exist two ways for this?


1. Polar decomposition of Gradient Deformation Tensor F to get the rotation tensor.


2. Update each basis vector of local material coordinate system using modified Gradient Deformation Tensor F_bar = F*J^(-1/3).

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