Examinando por Autor "Rico, A."

Mostrando 1 - 4 de 4

Assessment of the viscoelasticity effects on the fracture resistance of polyacrylamide-alginate hydrogels
(Elsevier, 2025-05-13) Salazar, A.; Martínez, M.; Reinhards , C.; Rico, A.; Rodríguez, J.
Hydrogels are conditioned by viscoelasticity and poroelasticity. This work aims to assess the viscoelastic dissipation on the fracture parameters of polyacrylamide-alginate hydrogels applying the Viscoelastic Fracture Mechanics approach. The viscoelastic and poroelastic contributions were separated and quantified and the analysis of the characteristic times revealed that the poroelastic contribution could be disregarded. The fracture behaviour was obtained using the viscoelastic response once the poroelastic contribution was discounted from the mechanical relaxation response. The viscoelastic dissipation on the fracture parameters was not pronounced, with better fracture resistance the higher the alginate content. A linear relation has been observed between the J-integral and Crack Tip Opening Displacement through a cohesive stress with values similar to the tensile strength.
Crosslinker concentration effect on the poroviscoelastic relaxation of polyacrylamide hydrogels using depth-sensing indentation
(Elsevier, 2021) Reinhards – Hervás, C.; Rico, A.; Rodríguez, J.
The effect of crosslinker concentration on the mechanical behaviour of polyacrylamide based hydrogels is established by using depth sensing indentation. In this work, hydrogels are considered as poroviscoelastic solids, being viscoelasticity and poroelasticity taken into account at intermediate length scales such as those here explored. A constrained fitting method is derived to implement a multiplicative rule that accommodates the contribution of each deformation mechanism on the global material response. The proposed method is robust enough to properly separate poroelastic and viscoelastic contributions from relaxation curves measured at different indentation depths and strain rates. At the length scales here tested viscoelasticity appears as dominant, but the poroelastic contribution becomes increasingly important as the crosslinker concentration is reduced.
Fracture resistance of polyacrylamide-alginate hydrogels
(Elsevier, 2024) Reinhards-Hervás, C.; Cano, A.J.; Rico, A.; Salazar, A.; Rodríguez, J.
Polyacrylamide-alginate hydrogels are biphasic materials with double-polymeric structure and considerable percentage of water inside. They exhibit complex mechanical behaviour in which finite deformations, non-linearity and time dependence are mixed. Fracture behaviour is less known, and this work analyses the fracture resistance obtained via methodologies of non-linear elastic materials such as that developed by Rivlin and Thomas and that attained with Non-Linear Fracture Mechanics procedures based on the use of J-integral. Special attention is paid to the fracture parameters on both crack growth initiation and crack propagation stages. The validity of the methodologies was evaluated, and conclusions were drawn about the effect of the alginate content on the fracture resistance of polyacrylamide.
Mechanical characterisation of hydrophobic and hydrophilic acrylates used in intraocular lenses through depth sensing indentation
(Elsevier, 2021) Cabeza-Gil, I.; Calvo, B.; Rico, A.; Reinhards-Hervás, C.; Rodríguez, J.
In this work, the mechanical behaviour of hydrophilic and hydrophobic acrylates has been characterised by depth sensing indentation. Time-dependent behaviour has been studied using load-relaxation tests. Experiments have been simulated with a finite element software using a visco-hyperelastic material model. The parameters of this model have been determined using deep learning techniques. The developed material models have been used to mechanically simulate a standard compression test of a prototype intraocular lens.