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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.

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.

I have some problem in defining the material properties using UMAT. I want to simulate the cubic stress-strain traction-sepration law. Solution doesn't converge after max load is applied (i.e zero slope of stress-strain plot). I am using riks solver. I have written my stress -strain relationship as below in UMAT file. Please tell me how to converge the solution even after zero slope of stress-strain relationship. Can i make my load factor(lambda) negative in riks option.

Professor Ed Berger, Univeristy of Virginia Mechanical Engineering, is featured in the Chronicle of Higher Education for his use of web technologies and, in particular, "video solutions" for teaching undergraduate mechanics courses.

World Scientific Pub. Co. will soon (2008 Winter) publish a new graduate textbook on Micromechanics and Nanomechanics.  The book is based on a lecture notes that have been used in Berkeley for seven years. Reading of book requires minimum knowledge of continuum mechanics and mathematics, and the book is intended for the first year graduate students as well as those practitioners who have no time to read the literature for self-study.