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This paper presents the problem of nonlinear aero-thermo-elastic response of cracked plate. Bending equations of two-dimensional simply supported cracked plate subjected to supersonic flow and thermal effect is derived based on classical plate theory (CPT) and Von Kármán nonlinear relations. Linear piston theory is utilized to evaluate the aerodynamic pressure with uniform temperature variations. By applying Galerkin's method and Runge-Kutta scheme, the equations are solved. The effects of parameters such as flow condition, crack dimension, temperature changes, plate aspect ratio, mass ratio, static pressure on the plate stability, flutter point and limit cycle oscillation (LCO) of the plate are examined. [ABSTRACT FROM AUTHOR]

Shape memory effect is the key factor in the design of self-reconfigurable core using origami. Effects of heat treatment on transformation temperatures and stress-strain curve of shape memory alloys using differential scanning calorimetry and tensile testing is presented. Moreover, vibration of pre/post-buckled sandwich beam with self-deployable shape memory alloy (SMA) core and SMA wires reinforced hybrid composite faces is investigated. The Boyd and Lagoudas SMA constitutive model is utilized in ABAQUS UMAT subroutine. Extensive numerical studies presented for pre-strain, volume fraction, location, time and temperature of heat treatment depends on the properties of SMA fibers, along with core and hybrid composite temperature dependency. As can be seen from results, vibration behaviors, thermal stability and total thickness of self-foldable sandwich structure can be efficiently controlled by adjusting the values of SMA wires volume fraction, pre-strain and core type, respectively. Mechanical properties of SMA are decreased, as a result of increase in heat treatment time and temperature. Increasing heat treatment temperature leads to lower transformation temperatures of SMA. In contrast, higher transformation temperatures are the results of increasing heat treatment time. [ABSTRACT FROM AUTHOR]

This study deals with free vibration analysis of integrated and non-integrated corrugated core sandwich panels with rectangular core together with free vibration analysis of integrated corrugated core sandwich panels with hat-type and triangle core. Bonding of the core to skin in non-integrated sandwich panels was achieved by resin, while in the integrated sandwich panels that were reinforced with 3-D weft-knitted fabric bonding was achieved using yarns and resin. Results revealed that the integrated structures have higher natural frequency than the non-integrated structures. It was also found that the natural frequency of the triangular-core sandwich panels and the rectangular-core sandwich panels was the highest and the lowest, respectively. It was established that weft-knitting fabric technology is suitable for the production of both integrated and non-integrated corrugated core sandwich panels with a high degree of similarities in terms of geometry, weight, and characteristics. [ABSTRACT FROM AUTHOR]

This study presents a new method for strengthening the circular reinforced concrete (RC) column to foundation connections with shape memory alloy (SMA) bars and carbon fiber reinforced polymer (CFRP) sheets. In the experimental part of the study, three specimens of RC column-foundation connections were cast and tested. One specimen was used as the reference specimen without strengthening. Two other specimens were strengthened with longitudinal SMA bars and CFRP sheets. These specimens were under a constant axial compressive load and cyclic lateral displacements, simultaneously. Next, initial stiffness, energy dissipation capacity, lateral load capacity, ductility, and residual displacement of the specimens were investigated. Due to the superelastic behavior of SMA bars, the residual displacement of column-foundation connections was considerably less than that of the reference specimen. Compared to the reference specimen, the SMA-strengthened and SMA-CFRP-strengthened connections recovered 71.59% and 76.57% of the residual displacement. Therefore, SMA bars were able to recover residual displacements under cyclic loading. Also, the combination of the SMA bars with CFRP sheet was a promising solution for enhancing the amount of the energy dissipation, lateral load capacity, initial stiffness, and ductility parameters. Compared to the reference specimen, the energy dissipation, lateral load capacity, initial stiffness, and ductility ratio parameters of SMA-CFRP-strengthened connection increased about 43.45%, 76.20%, 81.69%, and 242.45%, respectively. In the numerical part of the study, a subroutine was applied for modeling the SMA materials. For the analysis, this subroutine was linked with ABAQUS software. The numerical results showed a close correlation with the experimental results. [ABSTRACT FROM AUTHOR]

The dynamic stability of composite sandwich plates with a smart elastomer layer subjected to an axial periodic load is investigated. A finite element model of the composite sandwich plate with Magnetorheological elastomer (MRE) core is developed. A MRE layer, which its mechanical properties change with the applied magnetic field, is used as a damping layer to improve the stability of the structure. Due to the intrinsic characteristics of the MREs, these materials commonly operate in their pre-yield region. In this region, complex shear modulus is used for these materials. The effect of different parameters such as stacking sequences, boundary conditions, geometry of the sandwich plate, thickness and partial activation of the MRE layer on the damping treatment and stability boundaries is investigated. The presented results show that the application of an MRE layer as a core in the composite sandwich plate changes the stability region of the structure. Therefore, the instability boundaries can be manipulated to achieve the desired dynamic response of the structure. [ABSTRACT FROM AUTHOR]

This paper, presents the static analysis of composite beams with transverse shear effects using polynomial based dimensional reduction method. In dimensional reduction method, a three dimensional elasticity problem is split into a two dimensional cross section analysis and a one dimensional beam analysis. FEM is commonly used to analyze beam cross section in the literature. In this study, polynomial functions and Rayleigh-Ritz method are used to present an analytical procedure for two dimensional cross section analysis. Variational Asymptotic Method (VAM) is employed considering shear stiffnesses of composite beam cross section. VAM, asymptotically generates fully coupled cross section stiffness matrix. VAM benefits small parameters, related to characteristic length of cross section, to find stationary values of beam energy functional. By minimizing the energy functional with respect to warping, in and out of plane warping functions are acquired. In this article, isotropic beams with different cross section geometries and symmetric as well as anti-symmetric composite box beams are investigated. Presented results show appropriate correlation of the present study with theoretical and experimental results, as well as 3D Finite Element analysis. Using dimensional reduction method reduces the computing time and empowers researchers to design and optimize composite beam-like structures. [ABSTRACT FROM AUTHOR]