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The relationship between void size/location and mechanical behavior under biaxial loading of copper nanosheets containing voids are investigated by molecular dynamics method. The void location and the void radius on the model are discussed in the paper. The main reason of break is discovered by the congruent relationship between the shear stress and its dislocations. Dislocations are nucleated at the corner of system and approached to the center of void with increased deformation. Here, a higher stress is required to fail the voided sheets when smaller voids are utilized. The void radius influences the time of destruction. The larger the void radius is, the lower the shear stress and the earlier the model breaks. The void location impacts the dislocation distribution. [ABSTRACT FROM AUTHOR]

In this paper, we performed molecular dynamic simulations by Reax force field to study the mechanical properties of graphene–polythiophene nanocomposite. By computing elastic constant, breaking stress, breaking strain and Young's modulus from the stress–strain curve for the nanocomposites, we investigated effects of tension orientation, graphene loading to the polymer, temperature of nanocomposite and defect of graphene on these mechanical characters. It is found that mechanical characters of tension along the zigzag orientation are higher than other directions. Also, by increasing the weight concentration of graphene in composite, the Young's modulus and breaking strain increase. Our results showed that the Young's modulus decreased with increasing temperature. Finally by applying defect on graphene structure, we found that one atom missing defect has lower Young's modulus. Also, by increasing the defects concentration, elastic modulus decreases gradually. [ABSTRACT FROM AUTHOR]

• The 2H phase W 2 C and W 2 CO 2 are more stable MXenes than their 1T phase. • Oxygen functionalization increases the thermal conductivity of 2H phase W 2 C. • The 2H phase W 2 CO 2 has high Young's modulus up to 351 N m−1. • Spin-orbit coupling causes a metallic-semiconducting transition of 2H phase W 2 CO 2. MXenes, which are different from the 1T phase, have attracted increasing researches due to their unique physical and chemical properties. In this paper, we investigated the structure stabilities, lattice dynamics, mechanical properties and electronic structures of 2H phase W 2 C monolayer. Similar to the traditional 1T phase, functionalization also has a significant effect on these properties of 2H phase W 2 C. The O-functionalization improves the structural stability, thermal conductivity and mechanical properties. In particular, the Young's modulus of 2H phase W 2 C can be raised to 351 N m−1 after O-functionalized, which is higher than that of graphene. The electronic structures show that there is a metallic-semiconducting transition after O-functionalization when considering spin-orbit coupling effect. 2H phase W 2 CO 2 has semiconductor character with 0.199 eV band gap and a large spin splitting. We hope that our results can further contribute to the development of 2H phase MXenes in experimental synthesis and potential applications. [ABSTRACT FROM AUTHOR]

• A nonlinear molecular structural mechanics model is proposed for microtubules (MTs). • Lattice defect in MTs can reduce both their Young's modulus and fracture strain. • Predictive equations are developed for MTs with different lattice defect levels. A nonlinear molecular structural mechanics (MSM) model is proposed in this paper for studying the tensile properties of microtubules (MTs). In the nonlinear MSM models, the interactions between tubulin monomers in MTs are treated as nonlinear axial and torsional springs, whose stiffness coefficients are extracted from all-atom molecular dynamics simulations. The Young's modulus and fracture properties of MTs under tension extracted from the present nonlinear MSM models are found to agree well with the existing simulation and experiment results, which shows the efficiency and accuracy of the proposed nonlinear MSM models. In addition, the nonlinear MSM models are also extended to investigate the tensile properties including Young's modulus and fracture strain of MTs possessing lattice defects. The results obtained from nonlinear MSM models are utilized to develop a predictive equation for quickly predicting the tensile properties of MTs with different lattice defect levels. [ABSTRACT FROM AUTHOR]