arXiv subjects

Jasper van der Gucht

Publications and source records attributed to Jasper van der Gucht.

23 records · Page 2Linked to original sources

arXiv2019

Infrasonic wave propagation in ultrasoft solids at low Reynolds numbers

The propagation of elastic waves in soft materials plays a crucial role in the spatio-temporal transmission of mechanical signals, e.g. in biological mechanotransduction or in the failure of marginal solids. At high Reynolds numbers $Re \gg 1$, inertia dominates and wave propagation can be readily observed. However, mechanical cues in soft and biological materials often occur at low $Re$, where waves are overdamped. Not only have low $Re$ waves been difficult to observe in experiments, their theoretical description remains incomplete. In this paper, we present direct measurements of low $Re$ waves propagating in ordered and disordered soft solids, generated by an oscillating point force induced by an optical trap. We derive an analytical theory for low $Re$ wave propagation, which is in excellent agreement with the experiments. Our results present both a new method to characterize wave propagation in soft solids and a theoretical framework to understand how localized mechanical signals can provoke a remote and delayed response.

cond-mat.soft↗

arXiv2019

Stress management in composite biopolymer networks

Living tissues show an extraordinary adaptiveness to strain, which is crucial for their proper biological functioning. The physical origin of this mechanical behaviour has been widely investigated using reconstituted networks of collagen fibres, the principal load-bearing component of tissues. However, collagen fibres in tissues are embedded in a soft hydrated polysaccharide matrix which generates substantial internal stresses whose effect on tissue mechanics is unknown. Here, by combining mechanical measurements and computer simulations, we show that networks composed of collagen fibres and a hyaluronan matrix exhibit synergistic mechanics characterized by an enhanced stiffness and delayed strain-stiffening. We demonstrate that the polysaccharide matrix has a dual effect on the composite response involving both internal stress and elastic reinforcement. Our findings elucidate how tissues can tune their strain-sensitivity over a wide range and provide a novel design principle for synthetic materials with programmable mechanical properties.

cond-mat.soft↗

arXiv2017

Strand plasticity governs fatigue in colloidal gels

Repeated loading of a solid leads to microstructural damage that ultimately results in catastrophic material failure. While posing a major threat to the stability of virtually all materials, the microscopic origins of fatigue, especially for soft solids, remain elusive. Here we explore fatigue in colloidal gels as prototypical inhomogeneous soft solids by combining experiments and computer simulations. Our results reveal how mechanical loading leads to irreversible strand stretching, which builds slack into the network that softens the solid at small strains and causes strain hardening at larger deformations. We thus find that microscopic plasticity governs fatigue at much larger scales. This gives rise to a new picture of fatigue in soft thermal solids and calls for new theoretical descriptions of soft gel mechanics in which local plasticity is taken into account.

cond-mat.soft↗

arXiv2016

Connectivity dynamics in the vitrification of colloidal liquids

While various structural and dynamical precursors to vitrification have been identified, a predictive and quantitative description of how subtle changes at the microscopic scale give rise to the steep growth in macroscopic viscosity is missing. It was proposed that the presence of long-lived bonded structures within the liquid may provide this connection. Here we directly observe and quantify the connectivity dynamics in liquids of charged colloids en-route to vitrification. Based on these data, we extend Dyre's elastic model for the glass transition to account for particle-level dynamics; this results in a parameter-free expression for the slowing down of relaxations in the liquid that is in quantitative agreement with our experiments.

cond-mat.soft↗

arXiv2016

Criticality and mechanical enhancement in composite fibre networks

Many biological materials consist of sparse networks of disordered fibres, embedded in a soft elastic matrix. The interplay between rigid and soft elements in such composite networks leads to mechanical properties that can go far beyond the sum of those of the constituents. Here we present lattice-based simulations to unravel the microscopic origins of this mechanical synergy. We show that the competition between fibre stretching and bending and elastic deformations of the matrix gives rise to distinct mechanical regimes, with phase transitions between them that are characterized by critical behaviour and diverging strain fluctuations and with different mechanisms leading to mechanical enhancement.

cond-mat.soft↗