Constitutive modelling of cork-polyurethane gel composites

The CPGC - Cork-Polyurethane Gel Composite is a rubber-like material produced by ACC-Amorim Cork Composites. The non-conventional combination of cork with polyurethane gel results in a composite material with particular mechanical characteristics that must be clearly understanded for potentiate new applications or optimize products already produced with CPGC. The application of CPGC in products such as comfort enhancement devices and vibration damping or other applications, must be supported by Computer Aided Enginnering (CAE) tools, that can predict the mechanical response of the CPGC and its adequability for particular loading case scenarios. The mechanical behaviour of the CPGC was evaluated from experimental tests conducted at di erent temperatures, that furnished crucial information for the constitutive modelling procedure. From the experimental tests was possible to conclude that CPGC is mechanically characterized by a nonlinear elastic behaviour at large deformations (hyperelastic behaviour) and a dissipative behaviour evidenced by the hysteretic e ect that occurs during loading-unloading cycles. The nonlinear elastic behaviour was modelled by hyperelastic constitutive models based on phenomenological strain energy functions what enabled a structured framework for CPGC's material modelling. A new methodology for modelling hysteretic cycles and consequent material heat build-up, is proposed in this work. This proposed methodology accounts separately the dissipative e ects arising from purely deviatoric and volumetric deformations. The calibration of material parameters and the development of speci c material subroutines for the modelling of the CPGC's mechanical behaviour, allowed a more versatile way of simulate the material mechanical behaviour through the use of the Finite Element Method (FEM/FEA). In order to simulate the mechanical response of the CPGC in real case applications, two case-studies were modelled during this work. The rst case-study corresponds to a anatomically detailed FEM model of the human foot. This model is a tool for evaluating the mechanical performance of CPGC shoe insoles, through the monitoring of the contact pressure (normal stress) values at the insole/foot interface. The second-case study corresponds to an initial approach in the modelling of hysteretic cycles and consequent material heat build-up during cyclic loading, applying nonlinear FEM techniques. Within this context the speci cally developed material user subroutines assumed a particular importance for the modelling of the CPGC's mechanical behaviour.

Name thesis:degree_name

Tese de doutoramento em Engenharia de Polímeros (ramo de conhecimento em Ciência de Materiais Poliméricos)

Year dc:date.issued

2009

Author dc:creator

• Antunes, Paulo Jorge da Rocha Soares

Advisors dc:contributor.advisor

• Dias, Gustavo R.
• Coelho, António T.

Statement dc:rights

• openAccess

Language dc:language.iso

eng

Handle dc:identifier.uri

https://hdl.handle.net/1822/9486

OAI record oai:identifier

http://repositorium.sdum.uminho.pt/oai/request?verb=GetRecord&metadataPrefix=dim&identifier=oai%3Arepositorium.uminho.pt%3A1822%2F9486