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Abstract

A continuum-based sequential multiscale model is presented for application to nanofilms and nanowires with anisotropic surfaces. The surface effect is accounted for via the inclusion of surface energy due to surface stress and surface strain in the internal energy. For anisotropic surfaces such as a <110> surface, a linear surface elasticity model is used instead of the isotropic surface elasticity model proposed by Gurtin and Murdoch. A molecular dynamics simulation is performed in order to calculate initial surface stress and surface elastic tensor. Equilibrium strain and size-dependent elasticity are estimated by the proposed continuum model. 613 614 WONBAE KIM, SEUNG YUN RHEE AND MAENGHYO CHO MOLECULAR DYNAMICS MODELS FOR THE LINEAR ELASTICITY OF NANOFILMS AND NANOWIRES 617where matrices B m , B b , and B s represent the relationships between nodal displacement and membrane, bending, and transverse shear strains, as follows:The paper studies the dynamic behavior of autoclave aerated concrete (AAC) masonry walls externally strengthened with composite materials and subjected to in-plane dynamic loads. The study combines experimental, analytical and numerical methodologies, presents the results of two types of dynamic tests, and uses them for comparison with a finite element approach that is based on specially tailored high-order finite elements. The first dynamic test focuses on the natural frequencies and vibration modes of the patched wall. The second set of tests focuses on the dynamic response of the wall to in-plane base excitation. The analysis uses the specially tailored finite elements, combines them with conventional elements, and compares the results with the experiments. The discussion supports the validation of the model and throws light on a range of phenomena that characterize the dynamic behavior of the strengthened wall. These phenomena range from the global in-plane to out-of-plane coupling to the localized effects at the strengthened layer level.A compact form for the static Green's function for symmetric loading of an elastic sphere is derived. The expression captures the singularity in closed form using standard functions and quickly convergent series.The ballistic performance of equi-mass plates made from (i) stainless steel (SS); (ii) carbon fibre/epoxy (CF) laminate and (iii) a hybrid plate of both materials has been characterised for a spherical steel projectile. The hybrid plate was orientated with steel on the impact face (SSCF) and on the distal face (CFSS). The penetration velocity (V 50 ) was highest for the SS plate and lowest for the CF plate. A series of double impact tests were performed, with an initial velocity V I and a subsequent velocity V II at the same impact site. An interaction diagram in (V I , V II ) space was constructed to delineate penetration from survival under both impacts. The degree of interaction between the two impact events was greater for the CFSS plate than for the SSCF plate, implying that the distal face has the major effect upon the degree of interacti...