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A nonlinear data-driven reduced order model for computational homogenization with physics/pattern-guided sampling

Submitted by karelmatous on
research
computational homogenization
nonlinear manifold
data driven
machine learning

Developing an accurate nonlinear reduced order model from simulation data has been an outstanding research topic for many years. For many physical systems, data collection is very expensive and the optimal data distribution is not known in advance. Thus, maximizing the information gain remains a grand challenge. In a recent paper, Bhattacharjee and Matous (2016) proposed a manifold-based nonlinear reduced order model for multiscale problems in mechanics of materials. Expanding this work here, we develop a novel sampling strategy based on the physics/pattern-guided data distribution.

Universal Displacements in Linear Elasticity

Submitted by arash_yavari on
research
Universal deformation
universal displacement
linear elasticity
anisotropy classes

In nonlinear elasticity, universal deformations are the deformations that exist for arbitrary strain-energy density functions and suitable tractions at the boundaries. Here, we discuss the equivalent problem for linear elasticity. We characterize the universal displacements of  linear elasticity: those displacement fields that can be maintained by applying boundary tractions in the absence of body forces for any linear elastic solid in a given anisotropy class.

On stickiness of multiscale randomly rough surfaces

Submitted by Antonio Papangelo on
research
Adhesion and fracture; adhesion; contact mechanics; friction;
A new stickiness criterion for solids having random fractal roughness is derived using Persson's theory with DMT-type adhesion. As expected, we find stickiness, i.e., the possibility to sustain macroscopic tensile pressures or else non-zero contact area without load, is not affected by the truncation of the PSD spectrum of roughness at short wavelengths and can persist up to roughness amplitudes orders of magnitude larger than the range of attractive forces.

Elastic behavior in porous materials

Submitted by Dr. Hanaor - D… on
research
porous materials
mechanical properties
fluid mechanics
multi-scale

In the work shown here:

Multiscale modeling of effective elastic properties of fluid-filled porous materials

The elastic deformation and its dependence on fluid displacement is studied at two distinct scales, to address the multi-scale nature of porous structures in nature.

 

 

 

 

 

Electrical resistance at rough surfaces in contact

Submitted by Dr. Hanaor - D… on
research
contact resistance
ECR
contact stiffness
Roughness
fractal surfaces

Electrical Contact Resistance of Fractal Rough Surfaces 

 

The presence of roughness at electrical contacts tends to involve contacting asperities across multiple scales. Depending on the nature of the contact between asperities on opposing surfaces, different conduction mechanisms take place. This is shown in the figure here.

Journal Club: Stretchy Electronics for Soft Robotics

Submitted by Martin Kaltenbrunner on
research

In essence, we are sensor-clad soft machines capable of myriad intricate tasks. Stripped from proprioceptive feedback, we can no longer walk despite intact locomotor system. Likewise, integration of sensors, complex control loops, or machine learning is crucial in “classical” robotics. This JClub entry discusses recent efforts and challenges of merging soft electronics with robotics.

Analytical Models for Fatigue Life Prediction of Metals in the Stress-Life Approach -- phd thesis by Pietro D’Antuono

Submitted by Mike Ciavarella on
research
Fatigue
sn curves
crack growth
variable amplitudes
notches

dear collegues

  I'd be very grateful if you could have a look, if not a deep reading, at the phd thesis of my last student, playing on classical results on uniaxial fatigue, but with a view of simple, unified perspective on constant and varying amplitude fatigue.  We made large use of e-fatigue.com web site and the data in there.
 
Thanks in advance for any remark.  The final thesis will be submitted in few weeks time.
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