Two lineages: coarse graining of field–material coupling since 2016, soft-composite design and adhesion since 2025
Discrete-to-continuum limits of long-range electrostatic interactions, and joint material–structural design of hard-magnetic soft materials in MatTO, with 21 constitutive combinations compared before anything was optimized.
How composition, microstructure and field loading combine to produce mechanical response, and how those relationships can be exploited in design. Current work uses that connection to design materials and structures jointly, while extending the mechanics to failure, durability and controllable adhesion.
Field-responsive materials turn a remote stimulus into deformation, force, stiffness change or contact. The mechanisms are coupled: particle fraction alters stiffness and field coupling, finite deformation changes geometry, internal interfaces transfer load but may slip or debond, and external contacts concentrate or release energy.
This thrust has two lineages, and they meet at the same question. The older one is electrostatics and coarse graining: how a field couples to a material’s microstructure in the first place, and what survives when you pass from a discrete description to a continuum one. That runs from a thesis on coarse graining electric-field interactions with materials, through discrete-to-continuum limits of long-range electrical interactions, to a two-scale continuum limit for nonlocal electrostatics in random media. The newer one is design: taking a material whose response to a field is understood and deciding where to put material and magnetization so a structure does something useful.
The first lineage supplies the mechanism the second one designs against. The design calculations depend on which microscale interactions and fluctuations are retained in the effective material description. Omitting a consequential contribution can change the constitutive response the optimization is based on.
The scientific question. How do microstructure, interfaces, geometry and applied fields determine actuation, degradation and adhesion, and how can these mechanisms be composed into functional material–structure systems?
With Ian Galloway the group built 21 constitutive models, seven effective shear-modulus relations against three strain-energy functions, and compared them on actuation problems. Across those problems the strain-energy form changed the predicted deformation relatively little; the shear-modulus relation changed it a great deal wherever magnetic material overlapped a highly deforming region. Experimental stress–strain data then selected the relation to carry forward, and only after that came the joint optimization of structural density, particle fraction and remanent-magnetization direction. That ordering is the point: a design produced on top of an unexamined material description is an illustration, not a design.
The longer-range design target is a sequence: engage, carry load, tolerate defects, change shape or position, and release, rather than one peak response. Reaching it means varying material distribution, topology, interface geometry and field history together, and judging the result against geometry-only, material-only and sequential baselines.
A pull-off force is one number describing at least four different mechanisms. Separating them is what lets a measurement support a design rule that transfers, instead of one fitted curve.
Magnetic soft composites are designed as if the particle–matrix interface were perfect. This project asks what changes when it is not, and whether that is what sets how long the material keeps working.
Choosing where to put material and where to put magnetization, at the same time, so a soft structure moves the way a design problem asks it to.
Joint material and structural topology optimization for field-responsive soft materials, built on FEniCSx.