I love my MoM

Some mechanical-engineering programs, like ours here at the University of Utah, use the phrase “Strength of Materials” to refer to what the majority of other mechanical engineers more accurately refer to as “Mechanics of Materials” (often locally shortened to “MoM”).   The latter designation is more appropriate because this class typically is focused on an introduction to elementary elasticity with only very lightweight coverage of failure criteria (and almost never any post-failure theories, which are typically covered in upper-division and grad courses). Our University of Utah class, ME EN 3300, is locally called “Strengths” even though strength is barely covered (and only at an idealized level such as Tresca and von Mises criteria).

The following infographic furthermore shows that engineering textbooks appropriately and overwhelmingly favor MoM over Strengths (to see details, click to open in separate page and then zoom to fit the page):


Thanks go to Dr. Ashley Spear for stimulating this commentary/flame.

Simulation of sand/soil/clay thrown explosively into obstacles

Here are a couple of cool movies created by CSM researcher, Biswajit Banerjee, in preparation for our project review this week:

  1. Clods of soil impact a plate:  A major advantage of the Material Point Method (developed as part of this research effort) is that it automatically allows material interaction without needing a contact algorithm.
  2. Extrapolated buried explosive ejecta. The sample is in a centrifuge to get higher artificial gravity, so the particles move to the side because of the Coriolis effect!

PUBLICATION: Continuum effective-stress approach for high-rate plastic deformation of fluid-saturated geomaterials with application to shaped-charge jet penetration


AUTHORS: Michael A. Homel · James E. Guilkey · Rebecca M. Brannon

ABSTRACT: A practical engineering approach for modeling the constitutive response of fluid-saturated porous geomaterials is developed and applied to shaped-charge jet penetration in wellbore completion. An analytical model of a saturated thick spherical shell provides valuable insight into the qualitative character of the elastic– plastic response with an evolving pore fluid pressure. However, intrinsic limitations of such a simplistic theory are discussed to motivate the more realistic semi-empirical model used in this work. The constitutive model is implemented into a material point method code that can accommodate extremely large deformations.Consistent with experimental observations, the simulations of wellbore perforation exhibit appropriate dependencies of depth of penetration on pore pressure and confining stress.



@article{  year={2015},  issn={0001-5970},  journal={Acta Mechanica},  doi={10.1007/s00707-015-1407-2},  title={Continuum effective-stress approach for high-rate plastic deformation of fluid-saturated geomaterials with application to shaped-charge jet penetration},  url={http://dx.doi.org/10.1007/s00707-015-1407-2},  publisher={Springer Vienna},  author={Homel, Michael A. and Guilkey, James E. and Brannon, Rebecca M.},  pages={1-32},  language={English}  }

Linear algebra applied to sundials

CSM alumnus, Scot Swan, offers Sundials_and_Linear_Algebra,  which is a short (informal) writeup on the equations that are used for making standard horizontal dials.   Challenge: see if Scot’s write up is consistent with the calculator at http://www.anycalculator.com/horizontalsundial.htm.

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Undergraduate researcher applies binning to study aleatory uncertainty in nonlinear buckling foundation models


Sophomore undergraduate, Katharin Jensen, has developed an easily understood illustration of the effect of aleatory uncertainty, which means natural point-to-point variability in systems. She has put statistical variability on the lengths of buckling elements in the following system:


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