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Hierarchical Mechanics of Diatom Algae: From Atoms to Organism and Weakness to Strength

This month’s iMechanica Journal Club theme is the hierarchical structure and mechanics of diatom algae, silicified organisms that use silica (“sand”) – abundantly available in the ocean – to construct strong, tough and stiff structures [1-10]. The interest in this area has been revived recently given recent advances in the combined measurement, modeling and synthesis of these materials, leading to exciting research being conducted at the interface of mechanics and biology.

Dear all,

I am in the process of developing an FE code, and doing the analysis, for a class of highly nonlinear, dynamic problems in elasticity using Total Lagrangian formulation.  It is well-known that for the accuracy purposes, we need to use a small timestep size (stability is not an issue for me as I am using an unconditionally stable implicit scheme for timestepping).

My doubt is whether I can use arbitrarily/extremely small time steps in the analysis for a given mesh?

Mechanically active single-crystal structures can now be fabricated with size scales of less than 100 nm in all three dimensions. These engineered structures have fundamental mechanical resonance frequencies approaching 1 GHz, with very little mechanical dissipation. Using such structures, we are developing a new class of devices with applications in electrometry, magnetometry, surface physics, and investigations of the physics of phononmediated processes. The methods used to fabricate these devices, combining electron-beam

Hi

Dear all,

I am new to abaqus and I have to model a fatigue crack growth using xfem.

I have searched for a tutorial for that and I could not find anything useful. 

Does anybody know where can I find the tutorial or smth helpful?

tnx in advance,

Hi everyone,

      We know that crack or wedge problems are discussed in the porlar coordinate system which centered at the crack tip. Analytical solution (Irwin's) in an expanding form with unkown constants exist for crack or wedges with any open angle in isoptropic materials. The analytical solutions are always employed as enrichments in FEM, MM, XFEM. When the problem moves to anisotropic materials, does the analytcial solution exist?

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