No abstract

No abstract

The aerospace industry is widely employing strain-life methodologies for structural fatigue predictions. Under spectrum loading, overloads significantly affect the fatigue, therefore it is very important to accurately account for the cyclic transient deformation phenomena. Describing these phenomena requires advanced plasticity models that involve a set of material parameters. Even for the well-known Chaboche model, there is lack of understanding of each parameter's sensitivity

Nanocomposite application in automotive engineering materials is subject to continual stress fields together with recovery periods, under extremes of temperature variations. The aim is to prepare and characterize polyolefin-rubber nanocomposites developed for additive manufacturing in terms of their time-dependent deformation behaviour as revealed in creep-recovery experiments. The composites consisted of linear low density polyethylene and functionalized rubber particles. Maleic anhydride compatibilizer grafted to polyethylene was used to enhance adhesion between the polyethylene and rubber; and multi-walled carbon nanotubes were introduced to impart electrical conductivity. Various compositions of nanocomposites were tested under constant stress in creep and recovery. A four-element mechanistic Burger model was employed to model the creep phase of the composites, while a Weibull distribution function was employed to model the recovery phase of the composites. Finite element analysis using Abaqus enabled numerical modelling of the creep phase of the composites. Both analytical and numerical solutions were found to be consistent with the experimental results. Creep and recovery were dependent on: (i) composite composition; (ii) compatibilizers content; (iii) carbon nanotubes that formed a percolation network.

The paper presents a novel approach to comparative evaluation of engineering design concepts that exhibit non-linear structural behaviour under load. The developed method has extended the substructures technique in order to apply the Finite Element Analysis (FEA) method to complex non-linear structural problems in the conceptual design phase. As conventional FE models based on substructures allow only linear analysis, it was necessary in this research to introduce a new algorithm capable of linearizing non-linear structural problems with sufficient accuracy in order to enable comparative evaluation of design concepts relative to each other under the given constraints and loading conditions. A comparative study with respect to model size, efficiency, accuracy and confidence was performed to validate the developed method. Obtained results indicate significant improvement over more traditional approaches to applying FEA in the conceptual design phase. The improvements achieved using the developed method compared to the traditional FE based approach are superior by a factor of 2.7 in efficiency and by a factor of 4.5 in confidence while not sacrificing the optimality of the solutions.