research

Multiscale mechanics and extreme materials lab (https://z.umn.edu/ravi-research-lab) at the University of Minnesota Twin Cities has two fully funded Ph.D. positions starting in fall 2023. Interested candidates may reach out to sravi [at] umn.edu (sravi[at]umn[dot]edu). The research will be on two main topics

Many biological structures exhibit intriguing morphological patterns adapted to environmental cues, which contribute to their important biological functions and also inspire material designs. Here, we report a chiral wrinkling topography in shrinking core–shell spheres, as observed in excessively dehydrated passion fruit and experimentally demonstrated in silicon core–shells under air extraction. Upon shrinkage deformation, the surface initially buckles into a buckyball pattern (periodic hexagons and pentagons) and then transforms into a chiral mode.

For orthotropic plane strain problems, the various existing calculation methods are very complex. The orthotropic plane strain problem with cracks have solved by using a new element model, and compared with the finite element method, it can be found that the displacements and the stresses of the two methods are in good agreement.
Supplemental Videos:
(1) https://www.bilibili.com/video/BV1QW4y1e7YQ/?spm_id_from=333.999.0.0

The plane stress problems have solved by using a new orthotropic element model, compared with the finite element method, it can be found that the results of the two methods are in good agreement.
Supplemental Videos:
(1) https://www.bilibili.com/video/BV1yd4y167i6/?spm_id_from=333.999.0.0
(2) https://www.bilibili.com/video/BV1CV4y1M7y6/?spm_id_from=333.999.0.0

This work presents a modified phase-field model for accurate coupling of phase transformation and cracking in shape memory ceramics. The existing phase-field models underestimate the elastic response at the beginning of the mechanical response. We modified the chemical free energy to control the rate of phase transformation and consequently obtain a physical elastic response before initiation of phase transformation. First, the forward and reverse martensitic phase transformation in a superelastic single crystal 3 mol% yttria-stabilized tetragonal zirconia is studied.

Dear Colleagues,

I invite you to read our recent paper on hierarchically architected foams published in Extreme Mechanics Letters: Read full article here.

Abstract

Meng, Z., Liu, M., Yan, H., Genin, G. M., & Chen, C. Q.* (2022). Deployable mechanical metamaterials with multistep programmable transformation. Science Advances, 8(23), eabn5460.

Mao, J. J.*, Wang, S., Tan, W.*, & Liu, M.* (2022). Modular multistable metamaterials with reprogrammable mechanical properties. Engineering Structures, 272, 114976.