Blog posts

I want to model a viscoelastic material using UMAT in Abaqus. I am facing two problems:

At the invitation of David Clarke on behalf of the UCSB/Los Alamos Institute of Multiscale Materials and Structures, I gave the following three lectures:

1. Large deformation and instability in dielectric elastomers
2. Large deformation and instability in swelling polymeric gels
3. Mechanics and electrochemistry of polyelectrolyte gels

The abstracts follow, and the slides are attached at the end of this post.

Here is a position for University lecturership in Engineering Science(Solid or Structural Mechanics)in association with a Tutorial fellowshiip at Pembroke College. 

Im trying to model a rotating uniform beam for 12 rotational speeds in Abaqus using c3d20 elements. As expected, "step 1 to step 5" the frequencies increase as the rotational speed is increased. However, for some strange reason, the frequencies stop varying from the fifth speed. I do get warning messages when running the input file but i cant intepret them well since Im new to Abaqus.

I believe the problem is elementary but i cant figure it out. Can anyone review or run the attached input file to let me know what I  am not doing or what exactly is wrong.

People sometimes complain that reading iMechanica takes time.  This is because iMechanica has a large number of pages, and new pages are added frequently.  If you go directly to iMechanica, you have to load individual pages one by one.  

Scaling of fracture strength, fracture energy and toughness is an important issue when it comes to predicting the behaviour of large-scale structures on the basis of laboratory scale measurements. Historically the work of Leonardo da Vinci and Gallileo is well known, followed by the statistical weakest link theory derived by Weibull in 1939. Weibull scaling is a statistical approach assuming instantaneous failure when the weakest link in a material structure fails.

In honor of its two recent National Medal of Science recipients, Jan Achenbach and Tobin Marks, Northwestern University held a National Medal of Science Symposium on May 14.