Structural materials creep simulations

Over the years there have been many attempts to simulate the behaviour of viscoelastic materials. This has been aimed at (i) facilitating analysis of the behaviour of plastic products, (ii) assisting with extrapolation and interpolation of experimental data and (iii) reducing the need for extensive, time-consuming creep tests. The most successful of the mathematical models have been based on spring and dashpot elements to represent, respectively, the elastic and viscous responses of plastic materials. Although there are no discrete molecular structures which behave like the individual elements of the models, nevertheless... 

The creep and recovery of plastics can be simulated by an appropriate combination of elementary mechanical models for ideal elastic and ideal viscous deformations. Although there are no discrete molecular structures which behave like individual elements of the models, they nevertheless aid in understanding the response of plastic materials. 

The creep of UPRs and the UPR composites filled with marble powder and powdery PVC was studied [235]. The authors proposed a jump-like character for the creep rate of materials. It was also assumed that the creep on the micron level reflected the structural inhomogeneity of UPRs and their composites. An optimized cure cycle with reduced process-induced residual stresses and the optimum temperature profile for the manufacturing of UPR composites were searched using the numerical simulation [236]. 

Hence, polymer nanocomposites represent a very attractive field of materials sciences, bringing new challenges for expeiimental, simulation, as well as theory scientists. Revealing those molecular mechanisms, which are responsible for the viscoelastic response of polymer nanocomposites, should be the first task to get a deeper understanding of the structure-property relationships in these materials. Afterward, one would be able to transfer the related knowledge in order to interpret other phenomena, such as creep, fatigue and impact behaviors accordingly. 

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