Given the growing interest in poroelasticity within this forum, I thought I would post the link to "Poronet" -- the poromechanics internet resources network. In particular, there is a nice long pdf chapter on the fundamentals of poroelasticity from Detournay and Cheng, 1993, which has become one of the standard references in the field.
Dear all,
I just joined this group last week. And, I'd like to share some of reading material that I found regarding research directions in computational mechanics. The paper was published in 2003, written by Tinsley Oden, Belytschko, Babuska and Hughes. It's entitled "Research Directions in Computational Mechanics" (Computer Methods in Applied Mechanics and Engineering, 192, pp 913-922, 2003). They outlined six areas with significant research opportunities in CM:
A normalising loading parameter useful in summarising the mechanical response of plane, pin in plate-like contacts is extended to axisymmetric, ball in socket-like contacts. Various diagrams reporting
Graphene is the world's thinnest material.
The one-atom-thick carbon layers have shown remarkable strength and stiffness.
The so-called "graphene-based sheets" can be mixed into polymers, glasses and ceramics, to produce novel composite materials with useful thermal, electrical and mechanical properties.
I recently used focused ion beam to fabricate some small structures, such as free-standing micro-beams, in LIGA Ni thin films and applied cyclic loads to those small micro-beams. In such a way, dynamics of fatigue crack initiation and growth can be revealed. Part of my results has been attached with this post.
Considering the MD (molecualr dynamics) simulation programs, they enable us to define the initial crack and then using different theories they propagate the crack. This process is actually a dynamic feature at least when the sample is going to fail. Here is the question that present in the most modellers assumptions, which will limit the simulation or maybe it is not possible to simulate the process with out these assumptions. One of them which I would like to know your ideas about is the linear velocity which come into conclusions before the simulations start.
A recent string of papers originated from Persson's paper in the physics literature contain a number of interesting new ideas, but compare, of the many theories for randomly rough surfaces, only Persson's and Bush et al, BGT. These papers often assume the original Greenwood and Williamson (GW) theory [1] to be inaccurate, but unfortunately do not test it, assuming BGT to be its better version. The original GW however is, I will show below, still the best paper and method today (not surprisingly, as not many papers have the level of 1300 citations), containing generally less assumptions than any other model, including the constitutive equation which does not need to be elastic! I just submitted this Letter to the Editor: On "Contact mechanics of real vs. randomly rough surfaces: A Green's function molecular dynamics study" by C. Campaña and M. H. Müser, EPL, 77 (2007) 38005. C. Campaña and M. H. Müser also make several questionable statements, including a dubious interpretation of their own results, and do not even cite the original GW paper; hence, we find useful to make some comments.
Experimentally, loading to a mechanical system can be applied either through the displacement control or the force control.
However, the responses of the system can only be measured in displacements, and hence strains.
Determination of Strain Gradient Elasticity Constants for Various Metals, Semiconductors, Silica, Polymers and the (Ir) relevance for Nanotechnologies
Strain gradient elasticity is often considered to be a suitable alternative to size-independent classical elasticity to, at least partially, capture elastic size-effects at the nanoscale. In the attached pre-print, borrowing methods from statistical mechanics, we present mathematical derivations that relate the strain-gradient material constants to atomic displacement correlations in a molecular dynamics computational ensemble. Using the developed relations and numerical atomistic calculations, the dynamic strain gradient constants have been explicitly determined for some representative semiconductor, metallic, amorphous and polymeric materials. This method has the distinct advantage that amorphous materials can be tackled in a straightforward manner. For crystalline materials we also employ and compare results from both empirical and ab-initio based lattice dynamics. Apart from carrying out a systematic tabulation of the relevant material parameters for various materials, we also discuss certain subtleties of strain gradient elasticity, including: the paradox associated with the sign of the strain-gradient constants, physical reasons for low or high characteristic lengths scales associated with the strain-gradient constants, and finally the relevance (or the lack thereof) of strain-gradient elasticity for nanotechnologies.
Thermodynamically consistent plastic deformations at macro and microlevels under thermomechanical loading conditions.
