research

Our group has several openings for fully-funded graduate students in computational and experimental mechanics of biological and engineered materials. Our primary goal is to link traumatic brain injury (TBI) with multiscale, multiphysics damage evolution in the brain using experimentally verifiable computations and simulations. We are also interested in designing advanced material for TBI protection.

Experimental results on nonlinear vibration localization in a cyclic chain of weakly coupled oscillators with clearance nonlinearity are reported. Numerical modelling and analysis complements the experimental study. A reduced order model is derived and numerical analysis based on the harmonic balance method demonstrates the existence of multiple classes of stable spatially localized nonlinear vibration states. The experiments agree very well with the numerical results.

In this article, the effect of material aging of an elastomeric main spring (MS) inside a hydraulic engine mount (HEM) on its dynamic performance is investigated. A set of HEMs aged under realistic operational conditions are used to create an empirical material aging model of the elastomer at two different temperatures (35°C and 95°C) using dynamic mechanical thermal analysis (DMTA).

Strain rate and temperature dependent elastic limit of mild steel is investigated by developing a dislocation incipient motion-based proportionality limit stress model. Temperature effect on strain energy of an edge dislocation is modeled by using unified mechanics theory. Unified mechanics theory-based index, called thermodynamic state index, is used to model thermally assisted degradation of strain energy. Kinetic energy due to thermal vibrations is added to the kinetic energy of an accelerating dislocation.

Abstract

The current push toward lightweight structures in aerospace and aeronautical engineering is leading to slender design airfoils, which are more likely to undergo large deformation, hence experiencing geometrical nonlinearities. The problem of vibration localization in a rotor constituted by N coupled airfoils with plunge and pitch degrees of freedom subjected to flutter instability is considered.

Recently, Dalvi and co-authors have shown detailed experimental data of adhesion of soft spheres with rough substrates with roughness measured down to almost the atomic scale, finding that the Persson and Tosatti theory gave satisfactory predictions of the apparent work of adhesion during loading, once the increase of the surface area due to roughness is correctly computed at extremely small scales.

Dear Friends of EML,

Happy New Year! 

2020 was an extremely challenging year for all because of COVID 19. For most of us, the lockdowns and work from home negatively impacted our research activities; for some, it provided a time to reflect on the value of our work; and, for a few, it presented an unusual opportunity to explore new directions of research.

Nominations for the 2021 USACM Honors and Awards are now being accepted.  For information on guidelines and submitting nominations, go to this web page:

http://forms.usacm.org/2021_HA_Call

The deadline for submission is January 31, 2021.  As a past President of the USACM, I'd like to encourage members of the iMechanica community to consider suitable awardees and nominate individuals as appropriate.