research
Critical thresholds for mode-coupling instability in viscoelastic sliding contacts
Mode-coupling instabilities are known to trigger self-excited vibrations in sliding contacts. Here, the conditions for mode-coupling (or "flutter") instability in the contact between a spherical oscillator and a moving viscoelastic substrate are studied. The work extends the classical 2-Degrees-Of-Freedom conveyor belt model and accounts for viscoelastic dissipation in the substrate, adhesive friction at the interface and non-linear normal contact stiffness as derived from numerical simulations based on a boundary element method capable of accounting for linear viscoelastic effects.
One Ring to Bind Them...Two Rings to Rule Them
In this paper, we discuss two problems concerning scattering and localisation of flexural waves in structured elastic plates. Firstly, we compare the scattering amplitudes of waves in a thin plate, generated by a point source, due to a single mass and to a large number of smaller masses, having the same equivalent mass and located around a circle. We show that in the second case, the scattering can be reduced, in particular in the medium- and high-frequency regimes.
Global Composites Experts Webinar by Dr. Nancy Sottos
dmHUB invites you to attend the Global Composites Experts Webinar Series.
Title: Control of Reaction Fronts for Rapid Energy-Efficient Manufacturing of Multifunctional Polymers and Composites
Speaker: Dr. Nancy R. Sottos
Time: 6/3, 11AM-12PM EST.
Please go to https://www.purdue.edu/cmsc/events/2020-webinars/ to register for this webinar.
Shear fracture in bulk metallic glass composites
In situ dendrite reinforced Bulk Metallic Glass matrix composites (BMGCs) are known to overcome poor ductility and fracture response exhibited by monolithic bulk metallic glasses (BMGs). In this paper (Shear fracture in bulk metallic glass composites) recently published by our group in Acta Materialia, we report mode I and mode II fracture experiments on the above in situ BMGCs containing transforming and non-transforming dendrites.
Inversion and perversion in twist incompatible isotropic tubes
How can we induce twist in tubular structures without applying a torque?
In nature, such behavior is enabled by material anisotropy. In our new work, we show that isotropic bi-layer tubes with twist incompatible layers can twist upon inflation and extension.
Interestingly, the direction of twist can spontaneously reverse as the load increases!
Check out our new paper at EML:
https://www.sciencedirect.com/science/article/pii/S2352431621000766
Flexoelectricity in soft elastomers and the molecular mechanisms underpinning the design and emergence of giant flexoelectricity
Dear colleagues,
We invite you to see the preprint of our new paper "Flexoelectricity in soft elastomers and the molecular mechanisms underpinning the design and emergence of giant flexoelectricity" that will appear in PNAS. Here we present a molecular-to-continuum scale theory for the flexoelectric effect in elastomers. The theory unveils a mechanism for achieving giant flexoelectricity--which finds support in prior experimental results; it is then leveraged for designing elastomers for 1) piezoelectricity, 2) tuning the direction of flexoelectricity, and 3) flexoelectricity which is invariant with respect to spurious deformations (https://doi.org/10.1073/pnas.2102477118).
Application of stress gradient plasticity model in different passivated problems
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In classical plasticity models, the physical length scale is not considered to control the size effects. Strain gradient plasticity models include one or more length scales that control size effects. Stress gradient plasticity model is introduced with a specific physical length scale and does not include any additional parameters.
On Eshelby's Inclusion Problem in Nonlinear Anisotropic Elasticity
The recent literature of finite eignestrains in nonlinear elastic solids is reviewed, and Eshelby's inclusion problem at finite strains is revisited. The subtleties of the analysis of combinations of finite eigenstrains for the example of combined finite radial, azimuthal, axial, and twist eigenstrains in a finite circular cylindrical bar are discussed. The stress field of a spherical inclusion with uniform pure dilatational eigenstrain in a radially-inhomogeneous spherical ball made of arbitrary incompressible isotropic solids is analyzed.